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linux-next/arch/s390/include/asm/pgtable.h

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/*
* S390 version
* Copyright IBM Corp. 1999, 2000
* Author(s): Hartmut Penner (hp@de.ibm.com)
* Ulrich Weigand (weigand@de.ibm.com)
* Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* Derived from "include/asm-i386/pgtable.h"
*/
#ifndef _ASM_S390_PGTABLE_H
#define _ASM_S390_PGTABLE_H
/*
* The Linux memory management assumes a three-level page table setup. For
* s390 31 bit we "fold" the mid level into the top-level page table, so
* that we physically have the same two-level page table as the s390 mmu
* expects in 31 bit mode. For s390 64 bit we use three of the five levels
* the hardware provides (region first and region second tables are not
* used).
*
* The "pgd_xxx()" functions are trivial for a folded two-level
* setup: the pgd is never bad, and a pmd always exists (as it's folded
* into the pgd entry)
*
* This file contains the functions and defines necessary to modify and use
* the S390 page table tree.
*/
#ifndef __ASSEMBLY__
#include <linux/sched.h>
#include <linux/mm_types.h>
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
#include <linux/page-flags.h>
#include <asm/bug.h>
#include <asm/page.h>
extern pgd_t swapper_pg_dir[] __attribute__ ((aligned (4096)));
extern void paging_init(void);
extern void vmem_map_init(void);
/*
* The S390 doesn't have any external MMU info: the kernel page
* tables contain all the necessary information.
*/
#define update_mmu_cache(vma, address, ptep) do { } while (0)
#define update_mmu_cache_pmd(vma, address, ptep) do { } while (0)
/*
* ZERO_PAGE is a global shared page that is always zero; used
* for zero-mapped memory areas etc..
*/
extern unsigned long empty_zero_page;
extern unsigned long zero_page_mask;
#define ZERO_PAGE(vaddr) \
(virt_to_page((void *)(empty_zero_page + \
(((unsigned long)(vaddr)) &zero_page_mask))))
#define __HAVE_COLOR_ZERO_PAGE
/* TODO: s390 cannot support io_remap_pfn_range... */
#define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
remap_pfn_range(vma, vaddr, pfn, size, prot)
#endif /* !__ASSEMBLY__ */
/*
* PMD_SHIFT determines the size of the area a second-level page
* table can map
* PGDIR_SHIFT determines what a third-level page table entry can map
*/
#ifndef CONFIG_64BIT
# define PMD_SHIFT 20
# define PUD_SHIFT 20
# define PGDIR_SHIFT 20
#else /* CONFIG_64BIT */
# define PMD_SHIFT 20
# define PUD_SHIFT 31
# define PGDIR_SHIFT 42
#endif /* CONFIG_64BIT */
#define PMD_SIZE (1UL << PMD_SHIFT)
#define PMD_MASK (~(PMD_SIZE-1))
#define PUD_SIZE (1UL << PUD_SHIFT)
#define PUD_MASK (~(PUD_SIZE-1))
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
/*
* entries per page directory level: the S390 is two-level, so
* we don't really have any PMD directory physically.
* for S390 segment-table entries are combined to one PGD
* that leads to 1024 pte per pgd
*/
#define PTRS_PER_PTE 256
#ifndef CONFIG_64BIT
#define PTRS_PER_PMD 1
#define PTRS_PER_PUD 1
#else /* CONFIG_64BIT */
#define PTRS_PER_PMD 2048
#define PTRS_PER_PUD 2048
#endif /* CONFIG_64BIT */
#define PTRS_PER_PGD 2048
#define FIRST_USER_ADDRESS 0
#define pte_ERROR(e) \
printk("%s:%d: bad pte %p.\n", __FILE__, __LINE__, (void *) pte_val(e))
#define pmd_ERROR(e) \
printk("%s:%d: bad pmd %p.\n", __FILE__, __LINE__, (void *) pmd_val(e))
#define pud_ERROR(e) \
printk("%s:%d: bad pud %p.\n", __FILE__, __LINE__, (void *) pud_val(e))
#define pgd_ERROR(e) \
printk("%s:%d: bad pgd %p.\n", __FILE__, __LINE__, (void *) pgd_val(e))
#ifndef __ASSEMBLY__
/*
* The vmalloc and module area will always be on the topmost area of the kernel
* mapping. We reserve 96MB (31bit) / 128GB (64bit) for vmalloc and modules.
* On 64 bit kernels we have a 2GB area at the top of the vmalloc area where
* modules will reside. That makes sure that inter module branches always
* happen without trampolines and in addition the placement within a 2GB frame
* is branch prediction unit friendly.
*/
extern unsigned long VMALLOC_START;
extern unsigned long VMALLOC_END;
extern struct page *vmemmap;
#define VMEM_MAX_PHYS ((unsigned long) vmemmap)
#ifdef CONFIG_64BIT
extern unsigned long MODULES_VADDR;
extern unsigned long MODULES_END;
#define MODULES_VADDR MODULES_VADDR
#define MODULES_END MODULES_END
#define MODULES_LEN (1UL << 31)
#endif
/*
* A 31 bit pagetable entry of S390 has following format:
* | PFRA | | OS |
* 0 0IP0
* 00000000001111111111222222222233
* 01234567890123456789012345678901
*
* I Page-Invalid Bit: Page is not available for address-translation
* P Page-Protection Bit: Store access not possible for page
*
* A 31 bit segmenttable entry of S390 has following format:
* | P-table origin | |PTL
* 0 IC
* 00000000001111111111222222222233
* 01234567890123456789012345678901
*
* I Segment-Invalid Bit: Segment is not available for address-translation
* C Common-Segment Bit: Segment is not private (PoP 3-30)
* PTL Page-Table-Length: Page-table length (PTL+1*16 entries -> up to 256)
*
* The 31 bit segmenttable origin of S390 has following format:
*
* |S-table origin | | STL |
* X **GPS
* 00000000001111111111222222222233
* 01234567890123456789012345678901
*
* X Space-Switch event:
* G Segment-Invalid Bit: *
* P Private-Space Bit: Segment is not private (PoP 3-30)
* S Storage-Alteration:
* STL Segment-Table-Length: Segment-table length (STL+1*16 entries -> up to 2048)
*
* A 64 bit pagetable entry of S390 has following format:
* | PFRA |0IPC| OS |
* 0000000000111111111122222222223333333333444444444455555555556666
* 0123456789012345678901234567890123456789012345678901234567890123
*
* I Page-Invalid Bit: Page is not available for address-translation
* P Page-Protection Bit: Store access not possible for page
* C Change-bit override: HW is not required to set change bit
*
* A 64 bit segmenttable entry of S390 has following format:
* | P-table origin | TT
* 0000000000111111111122222222223333333333444444444455555555556666
* 0123456789012345678901234567890123456789012345678901234567890123
*
* I Segment-Invalid Bit: Segment is not available for address-translation
* C Common-Segment Bit: Segment is not private (PoP 3-30)
* P Page-Protection Bit: Store access not possible for page
* TT Type 00
*
* A 64 bit region table entry of S390 has following format:
* | S-table origin | TF TTTL
* 0000000000111111111122222222223333333333444444444455555555556666
* 0123456789012345678901234567890123456789012345678901234567890123
*
* I Segment-Invalid Bit: Segment is not available for address-translation
* TT Type 01
* TF
* TL Table length
*
* The 64 bit regiontable origin of S390 has following format:
* | region table origon | DTTL
* 0000000000111111111122222222223333333333444444444455555555556666
* 0123456789012345678901234567890123456789012345678901234567890123
*
* X Space-Switch event:
* G Segment-Invalid Bit:
* P Private-Space Bit:
* S Storage-Alteration:
* R Real space
* TL Table-Length:
*
* A storage key has the following format:
* | ACC |F|R|C|0|
* 0 3 4 5 6 7
* ACC: access key
* F : fetch protection bit
* R : referenced bit
* C : changed bit
*/
/* Hardware bits in the page table entry */
#define _PAGE_CO 0x100 /* HW Change-bit override */
#define _PAGE_RO 0x200 /* HW read-only bit */
#define _PAGE_INVALID 0x400 /* HW invalid bit */
/* Software bits in the page table entry */
#define _PAGE_SWT 0x001 /* SW pte type bit t */
#define _PAGE_SWX 0x002 /* SW pte type bit x */
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
#define _PAGE_SWC 0x004 /* SW pte changed bit */
#define _PAGE_SWR 0x008 /* SW pte referenced bit */
#define _PAGE_SWW 0x010 /* SW pte write bit */
#define _PAGE_SPECIAL 0x020 /* SW associated with special page */
#define __HAVE_ARCH_PTE_SPECIAL
/* Set of bits not changed in pte_modify */
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_SPECIAL | _PAGE_CO | \
_PAGE_SWC | _PAGE_SWR)
/* Six different types of pages. */
#define _PAGE_TYPE_EMPTY 0x400
#define _PAGE_TYPE_NONE 0x401
#define _PAGE_TYPE_SWAP 0x403
#define _PAGE_TYPE_FILE 0x601 /* bit 0x002 is used for offset !! */
#define _PAGE_TYPE_RO 0x200
#define _PAGE_TYPE_RW 0x000
/*
* Only four types for huge pages, using the invalid bit and protection bit
* of a segment table entry.
*/
#define _HPAGE_TYPE_EMPTY 0x020 /* _SEGMENT_ENTRY_INV */
#define _HPAGE_TYPE_NONE 0x220
#define _HPAGE_TYPE_RO 0x200 /* _SEGMENT_ENTRY_RO */
#define _HPAGE_TYPE_RW 0x000
/*
* PTE type bits are rather complicated. handle_pte_fault uses pte_present,
* pte_none and pte_file to find out the pte type WITHOUT holding the page
* table lock. ptep_clear_flush on the other hand uses ptep_clear_flush to
* invalidate a given pte. ipte sets the hw invalid bit and clears all tlbs
* for the page. The page table entry is set to _PAGE_TYPE_EMPTY afterwards.
* This change is done while holding the lock, but the intermediate step
* of a previously valid pte with the hw invalid bit set can be observed by
* handle_pte_fault. That makes it necessary that all valid pte types with
* the hw invalid bit set must be distinguishable from the four pte types
* empty, none, swap and file.
*
* irxt ipte irxt
* _PAGE_TYPE_EMPTY 1000 -> 1000
* _PAGE_TYPE_NONE 1001 -> 1001
* _PAGE_TYPE_SWAP 1011 -> 1011
* _PAGE_TYPE_FILE 11?1 -> 11?1
* _PAGE_TYPE_RO 0100 -> 1100
* _PAGE_TYPE_RW 0000 -> 1000
*
[S390] noexec protection This provides a noexec protection on s390 hardware. Our hardware does not have any bits left in the pte for a hw noexec bit, so this is a different approach using shadow page tables and a special addressing mode that allows separate address spaces for code and data. As a special feature of our "secondary-space" addressing mode, separate page tables can be specified for the translation of data addresses (storage operands) and instruction addresses. The shadow page table is used for the instruction addresses and the standard page table for the data addresses. The shadow page table is linked to the standard page table by a pointer in page->lru.next of the struct page corresponding to the page that contains the standard page table (since page->private is not really private with the pte_lock and the page table pages are not in the LRU list). Depending on the software bits of a pte, it is either inserted into both page tables or just into the standard (data) page table. Pages of a vma that does not have the VM_EXEC bit set get mapped only in the data address space. Any try to execute code on such a page will cause a page translation exception. The standard reaction to this is a SIGSEGV with two exceptions: the two system call opcodes 0x0a77 (sys_sigreturn) and 0x0aad (sys_rt_sigreturn) are allowed. They are stored by the kernel to the signal stack frame. Unfortunately, the signal return mechanism cannot be modified to use an SA_RESTORER because the exception unwinding code depends on the system call opcode stored behind the signal stack frame. This feature requires that user space is executed in secondary-space mode and the kernel in home-space mode, which means that the addressing modes need to be switched and that the noexec protection only works for user space. After switching the addressing modes, we cannot use the mvcp/mvcs instructions anymore to copy between kernel and user space. A new mvcos instruction has been added to the z9 EC/BC hardware which allows to copy between arbitrary address spaces, but on older hardware the page tables need to be walked manually. Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-02-06 04:18:17 +08:00
* pte_none is true for bits combinations 1000, 1010, 1100, 1110
* pte_present is true for bits combinations 0000, 0010, 0100, 0110, 1001
* pte_file is true for bits combinations 1101, 1111
[S390] noexec protection This provides a noexec protection on s390 hardware. Our hardware does not have any bits left in the pte for a hw noexec bit, so this is a different approach using shadow page tables and a special addressing mode that allows separate address spaces for code and data. As a special feature of our "secondary-space" addressing mode, separate page tables can be specified for the translation of data addresses (storage operands) and instruction addresses. The shadow page table is used for the instruction addresses and the standard page table for the data addresses. The shadow page table is linked to the standard page table by a pointer in page->lru.next of the struct page corresponding to the page that contains the standard page table (since page->private is not really private with the pte_lock and the page table pages are not in the LRU list). Depending on the software bits of a pte, it is either inserted into both page tables or just into the standard (data) page table. Pages of a vma that does not have the VM_EXEC bit set get mapped only in the data address space. Any try to execute code on such a page will cause a page translation exception. The standard reaction to this is a SIGSEGV with two exceptions: the two system call opcodes 0x0a77 (sys_sigreturn) and 0x0aad (sys_rt_sigreturn) are allowed. They are stored by the kernel to the signal stack frame. Unfortunately, the signal return mechanism cannot be modified to use an SA_RESTORER because the exception unwinding code depends on the system call opcode stored behind the signal stack frame. This feature requires that user space is executed in secondary-space mode and the kernel in home-space mode, which means that the addressing modes need to be switched and that the noexec protection only works for user space. After switching the addressing modes, we cannot use the mvcp/mvcs instructions anymore to copy between kernel and user space. A new mvcos instruction has been added to the z9 EC/BC hardware which allows to copy between arbitrary address spaces, but on older hardware the page tables need to be walked manually. Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-02-06 04:18:17 +08:00
* swap pte is 1011 and 0001, 0011, 0101, 0111 are invalid.
*/
#ifndef CONFIG_64BIT
/* Bits in the segment table address-space-control-element */
#define _ASCE_SPACE_SWITCH 0x80000000UL /* space switch event */
#define _ASCE_ORIGIN_MASK 0x7ffff000UL /* segment table origin */
#define _ASCE_PRIVATE_SPACE 0x100 /* private space control */
#define _ASCE_ALT_EVENT 0x80 /* storage alteration event control */
#define _ASCE_TABLE_LENGTH 0x7f /* 128 x 64 entries = 8k */
/* Bits in the segment table entry */
#define _SEGMENT_ENTRY_ORIGIN 0x7fffffc0UL /* page table origin */
#define _SEGMENT_ENTRY_RO 0x200 /* page protection bit */
#define _SEGMENT_ENTRY_INV 0x20 /* invalid segment table entry */
#define _SEGMENT_ENTRY_COMMON 0x10 /* common segment bit */
#define _SEGMENT_ENTRY_PTL 0x0f /* page table length */
#define _SEGMENT_ENTRY (_SEGMENT_ENTRY_PTL)
#define _SEGMENT_ENTRY_EMPTY (_SEGMENT_ENTRY_INV)
/* Page status table bits for virtualization */
#define RCP_ACC_BITS 0xf0000000UL
#define RCP_FP_BIT 0x08000000UL
#define RCP_PCL_BIT 0x00800000UL
#define RCP_HR_BIT 0x00400000UL
#define RCP_HC_BIT 0x00200000UL
#define RCP_GR_BIT 0x00040000UL
#define RCP_GC_BIT 0x00020000UL
#define RCP_IN_BIT 0x00002000UL /* IPTE notify bit */
/* User dirty / referenced bit for KVM's migration feature */
#define KVM_UR_BIT 0x00008000UL
#define KVM_UC_BIT 0x00004000UL
#else /* CONFIG_64BIT */
/* Bits in the segment/region table address-space-control-element */
#define _ASCE_ORIGIN ~0xfffUL/* segment table origin */
#define _ASCE_PRIVATE_SPACE 0x100 /* private space control */
#define _ASCE_ALT_EVENT 0x80 /* storage alteration event control */
#define _ASCE_SPACE_SWITCH 0x40 /* space switch event */
#define _ASCE_REAL_SPACE 0x20 /* real space control */
#define _ASCE_TYPE_MASK 0x0c /* asce table type mask */
#define _ASCE_TYPE_REGION1 0x0c /* region first table type */
#define _ASCE_TYPE_REGION2 0x08 /* region second table type */
#define _ASCE_TYPE_REGION3 0x04 /* region third table type */
#define _ASCE_TYPE_SEGMENT 0x00 /* segment table type */
#define _ASCE_TABLE_LENGTH 0x03 /* region table length */
/* Bits in the region table entry */
#define _REGION_ENTRY_ORIGIN ~0xfffUL/* region/segment table origin */
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
#define _REGION_ENTRY_RO 0x200 /* region protection bit */
#define _REGION_ENTRY_INV 0x20 /* invalid region table entry */
#define _REGION_ENTRY_TYPE_MASK 0x0c /* region/segment table type mask */
#define _REGION_ENTRY_TYPE_R1 0x0c /* region first table type */
#define _REGION_ENTRY_TYPE_R2 0x08 /* region second table type */
#define _REGION_ENTRY_TYPE_R3 0x04 /* region third table type */
#define _REGION_ENTRY_LENGTH 0x03 /* region third length */
#define _REGION1_ENTRY (_REGION_ENTRY_TYPE_R1 | _REGION_ENTRY_LENGTH)
#define _REGION1_ENTRY_EMPTY (_REGION_ENTRY_TYPE_R1 | _REGION_ENTRY_INV)
#define _REGION2_ENTRY (_REGION_ENTRY_TYPE_R2 | _REGION_ENTRY_LENGTH)
#define _REGION2_ENTRY_EMPTY (_REGION_ENTRY_TYPE_R2 | _REGION_ENTRY_INV)
#define _REGION3_ENTRY (_REGION_ENTRY_TYPE_R3 | _REGION_ENTRY_LENGTH)
#define _REGION3_ENTRY_EMPTY (_REGION_ENTRY_TYPE_R3 | _REGION_ENTRY_INV)
#define _REGION3_ENTRY_LARGE 0x400 /* RTTE-format control, large page */
#define _REGION3_ENTRY_RO 0x200 /* page protection bit */
#define _REGION3_ENTRY_CO 0x100 /* change-recording override */
/* Bits in the segment table entry */
#define _SEGMENT_ENTRY_ORIGIN_LARGE ~0xfffffUL /* large page address */
#define _SEGMENT_ENTRY_ORIGIN ~0x7ffUL/* segment table origin */
#define _SEGMENT_ENTRY_RO 0x200 /* page protection bit */
#define _SEGMENT_ENTRY_INV 0x20 /* invalid segment table entry */
#define _SEGMENT_ENTRY (0)
#define _SEGMENT_ENTRY_EMPTY (_SEGMENT_ENTRY_INV)
#define _SEGMENT_ENTRY_LARGE 0x400 /* STE-format control, large page */
#define _SEGMENT_ENTRY_CO 0x100 /* change-recording override */
#define _SEGMENT_ENTRY_SPLIT_BIT 0 /* THP splitting bit number */
#define _SEGMENT_ENTRY_SPLIT (1UL << _SEGMENT_ENTRY_SPLIT_BIT)
/* Set of bits not changed in pmd_modify */
#define _SEGMENT_CHG_MASK (_SEGMENT_ENTRY_ORIGIN | _SEGMENT_ENTRY_LARGE \
| _SEGMENT_ENTRY_SPLIT | _SEGMENT_ENTRY_CO)
/* Page status table bits for virtualization */
#define RCP_ACC_BITS 0xf000000000000000UL
#define RCP_FP_BIT 0x0800000000000000UL
#define RCP_PCL_BIT 0x0080000000000000UL
#define RCP_HR_BIT 0x0040000000000000UL
#define RCP_HC_BIT 0x0020000000000000UL
#define RCP_GR_BIT 0x0004000000000000UL
#define RCP_GC_BIT 0x0002000000000000UL
#define RCP_IN_BIT 0x0000200000000000UL /* IPTE notify bit */
/* User dirty / referenced bit for KVM's migration feature */
#define KVM_UR_BIT 0x0000800000000000UL
#define KVM_UC_BIT 0x0000400000000000UL
#endif /* CONFIG_64BIT */
/*
* A user page table pointer has the space-switch-event bit, the
* private-space-control bit and the storage-alteration-event-control
* bit set. A kernel page table pointer doesn't need them.
*/
#define _ASCE_USER_BITS (_ASCE_SPACE_SWITCH | _ASCE_PRIVATE_SPACE | \
_ASCE_ALT_EVENT)
/*
* Page protection definitions.
*/
#define PAGE_NONE __pgprot(_PAGE_TYPE_NONE)
#define PAGE_RO __pgprot(_PAGE_TYPE_RO)
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
#define PAGE_RW __pgprot(_PAGE_TYPE_RO | _PAGE_SWW)
#define PAGE_RWC __pgprot(_PAGE_TYPE_RW | _PAGE_SWW | _PAGE_SWC)
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
#define PAGE_KERNEL PAGE_RWC
#define PAGE_SHARED PAGE_KERNEL
#define PAGE_COPY PAGE_RO
/*
* On s390 the page table entry has an invalid bit and a read-only bit.
* Read permission implies execute permission and write permission
* implies read permission.
*/
/*xwr*/
#define __P000 PAGE_NONE
#define __P001 PAGE_RO
#define __P010 PAGE_RO
#define __P011 PAGE_RO
#define __P100 PAGE_RO
#define __P101 PAGE_RO
#define __P110 PAGE_RO
#define __P111 PAGE_RO
#define __S000 PAGE_NONE
#define __S001 PAGE_RO
#define __S010 PAGE_RW
#define __S011 PAGE_RW
#define __S100 PAGE_RO
#define __S101 PAGE_RO
#define __S110 PAGE_RW
#define __S111 PAGE_RW
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 06:07:23 +08:00
/*
* Segment entry (large page) protection definitions.
*/
#define SEGMENT_NONE __pgprot(_HPAGE_TYPE_NONE)
#define SEGMENT_RO __pgprot(_HPAGE_TYPE_RO)
#define SEGMENT_RW __pgprot(_HPAGE_TYPE_RW)
static inline int mm_exclusive(struct mm_struct *mm)
{
return likely(mm == current->active_mm &&
atomic_read(&mm->context.attach_count) <= 1);
}
static inline int mm_has_pgste(struct mm_struct *mm)
{
#ifdef CONFIG_PGSTE
if (unlikely(mm->context.has_pgste))
return 1;
#endif
return 0;
}
/*
* pgd/pmd/pte query functions
*/
#ifndef CONFIG_64BIT
static inline int pgd_present(pgd_t pgd) { return 1; }
static inline int pgd_none(pgd_t pgd) { return 0; }
static inline int pgd_bad(pgd_t pgd) { return 0; }
static inline int pud_present(pud_t pud) { return 1; }
static inline int pud_none(pud_t pud) { return 0; }
static inline int pud_large(pud_t pud) { return 0; }
static inline int pud_bad(pud_t pud) { return 0; }
#else /* CONFIG_64BIT */
static inline int pgd_present(pgd_t pgd)
{
if ((pgd_val(pgd) & _REGION_ENTRY_TYPE_MASK) < _REGION_ENTRY_TYPE_R2)
return 1;
return (pgd_val(pgd) & _REGION_ENTRY_ORIGIN) != 0UL;
}
static inline int pgd_none(pgd_t pgd)
{
if ((pgd_val(pgd) & _REGION_ENTRY_TYPE_MASK) < _REGION_ENTRY_TYPE_R2)
return 0;
return (pgd_val(pgd) & _REGION_ENTRY_INV) != 0UL;
}
static inline int pgd_bad(pgd_t pgd)
{
/*
* With dynamic page table levels the pgd can be a region table
* entry or a segment table entry. Check for the bit that are
* invalid for either table entry.
*/
unsigned long mask =
~_SEGMENT_ENTRY_ORIGIN & ~_REGION_ENTRY_INV &
~_REGION_ENTRY_TYPE_MASK & ~_REGION_ENTRY_LENGTH;
return (pgd_val(pgd) & mask) != 0;
}
static inline int pud_present(pud_t pud)
{
if ((pud_val(pud) & _REGION_ENTRY_TYPE_MASK) < _REGION_ENTRY_TYPE_R3)
return 1;
return (pud_val(pud) & _REGION_ENTRY_ORIGIN) != 0UL;
}
static inline int pud_none(pud_t pud)
{
if ((pud_val(pud) & _REGION_ENTRY_TYPE_MASK) < _REGION_ENTRY_TYPE_R3)
return 0;
return (pud_val(pud) & _REGION_ENTRY_INV) != 0UL;
}
static inline int pud_large(pud_t pud)
{
if ((pud_val(pud) & _REGION_ENTRY_TYPE_MASK) != _REGION_ENTRY_TYPE_R3)
return 0;
return !!(pud_val(pud) & _REGION3_ENTRY_LARGE);
}
static inline int pud_bad(pud_t pud)
{
/*
* With dynamic page table levels the pud can be a region table
* entry or a segment table entry. Check for the bit that are
* invalid for either table entry.
*/
unsigned long mask =
~_SEGMENT_ENTRY_ORIGIN & ~_REGION_ENTRY_INV &
~_REGION_ENTRY_TYPE_MASK & ~_REGION_ENTRY_LENGTH;
return (pud_val(pud) & mask) != 0;
}
#endif /* CONFIG_64BIT */
static inline int pmd_present(pmd_t pmd)
{
unsigned long mask = _SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO;
return (pmd_val(pmd) & mask) == _HPAGE_TYPE_NONE ||
!(pmd_val(pmd) & _SEGMENT_ENTRY_INV);
}
static inline int pmd_none(pmd_t pmd)
{
return (pmd_val(pmd) & _SEGMENT_ENTRY_INV) &&
!(pmd_val(pmd) & _SEGMENT_ENTRY_RO);
}
static inline int pmd_large(pmd_t pmd)
{
#ifdef CONFIG_64BIT
return !!(pmd_val(pmd) & _SEGMENT_ENTRY_LARGE);
#else
return 0;
#endif
}
static inline int pmd_bad(pmd_t pmd)
{
unsigned long mask = ~_SEGMENT_ENTRY_ORIGIN & ~_SEGMENT_ENTRY_INV;
return (pmd_val(pmd) & mask) != _SEGMENT_ENTRY;
}
#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
extern void pmdp_splitting_flush(struct vm_area_struct *vma,
unsigned long addr, pmd_t *pmdp);
#define __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
extern int pmdp_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp,
pmd_t entry, int dirty);
#define __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp);
#define __HAVE_ARCH_PMD_WRITE
static inline int pmd_write(pmd_t pmd)
{
return (pmd_val(pmd) & _SEGMENT_ENTRY_RO) == 0;
}
static inline int pmd_young(pmd_t pmd)
{
return 0;
}
static inline int pte_none(pte_t pte)
{
return (pte_val(pte) & _PAGE_INVALID) && !(pte_val(pte) & _PAGE_SWT);
}
static inline int pte_present(pte_t pte)
{
unsigned long mask = _PAGE_RO | _PAGE_INVALID | _PAGE_SWT | _PAGE_SWX;
return (pte_val(pte) & mask) == _PAGE_TYPE_NONE ||
(!(pte_val(pte) & _PAGE_INVALID) &&
!(pte_val(pte) & _PAGE_SWT));
}
static inline int pte_file(pte_t pte)
{
unsigned long mask = _PAGE_RO | _PAGE_INVALID | _PAGE_SWT;
return (pte_val(pte) & mask) == _PAGE_TYPE_FILE;
}
mm: introduce pte_special pte bit s390 for one, cannot implement VM_MIXEDMAP with pfn_valid, due to their memory model (which is more dynamic than most). Instead, they had proposed to implement it with an additional path through vm_normal_page(), using a bit in the pte to determine whether or not the page should be refcounted: vm_normal_page() { ... if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { if (vma->vm_flags & VM_MIXEDMAP) { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; #else if (!pfn_valid(pfn)) return NULL; #endif goto out; } ... } This is fine, however if we are allowed to use a bit in the pte to determine refcountedness, we can use that to _completely_ replace all the vma based schemes. So instead of adding more cases to the already complex vma-based scheme, we can have a clearly seperate and simple pte-based scheme (and get slightly better code generation in the process): vm_normal_page() { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; return pte_page(pte); #else ... #endif } And finally, we may rather make this concept usable by any architecture rather than making it s390 only, so implement a new type of pte state for this. Unfortunately the old vma based code must stay, because some architectures may not be able to spare pte bits. This makes vm_normal_page a little bit more ugly than we would like, but the 2 cases are clearly seperate. So introduce a pte_special pte state, and use it in mm/memory.c. It is currently a noop for all architectures, so this doesn't actually result in any compiled code changes to mm/memory.o. BTW: I haven't put vm_normal_page() into arch code as-per an earlier suggestion. The reason is that, regardless of where vm_normal_page is actually implemented, the *abstraction* is still exactly the same. Also, while it depends on whether the architecture has pte_special or not, that is the only two possible cases, and it really isn't an arch specific function -- the role of the arch code should be to provide primitive functions and accessors with which to build the core code; pte_special does that. We do not want architectures to know or care about vm_normal_page itself, and we definitely don't want them being able to invent something new there out of sight of mm/ code. If we made vm_normal_page an arch function, then we have to make vm_insert_mixed (next patch) an arch function too. So I don't think moving it to arch code fundamentally improves any abstractions, while it does practically make the code more difficult to follow, for both mm and arch developers, and easier to misuse. [akpm@linux-foundation.org: build fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Carsten Otte <cotte@de.ibm.com> Cc: Jared Hulbert <jaredeh@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 17:13:00 +08:00
static inline int pte_special(pte_t pte)
{
return (pte_val(pte) & _PAGE_SPECIAL);
mm: introduce pte_special pte bit s390 for one, cannot implement VM_MIXEDMAP with pfn_valid, due to their memory model (which is more dynamic than most). Instead, they had proposed to implement it with an additional path through vm_normal_page(), using a bit in the pte to determine whether or not the page should be refcounted: vm_normal_page() { ... if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { if (vma->vm_flags & VM_MIXEDMAP) { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; #else if (!pfn_valid(pfn)) return NULL; #endif goto out; } ... } This is fine, however if we are allowed to use a bit in the pte to determine refcountedness, we can use that to _completely_ replace all the vma based schemes. So instead of adding more cases to the already complex vma-based scheme, we can have a clearly seperate and simple pte-based scheme (and get slightly better code generation in the process): vm_normal_page() { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; return pte_page(pte); #else ... #endif } And finally, we may rather make this concept usable by any architecture rather than making it s390 only, so implement a new type of pte state for this. Unfortunately the old vma based code must stay, because some architectures may not be able to spare pte bits. This makes vm_normal_page a little bit more ugly than we would like, but the 2 cases are clearly seperate. So introduce a pte_special pte state, and use it in mm/memory.c. It is currently a noop for all architectures, so this doesn't actually result in any compiled code changes to mm/memory.o. BTW: I haven't put vm_normal_page() into arch code as-per an earlier suggestion. The reason is that, regardless of where vm_normal_page is actually implemented, the *abstraction* is still exactly the same. Also, while it depends on whether the architecture has pte_special or not, that is the only two possible cases, and it really isn't an arch specific function -- the role of the arch code should be to provide primitive functions and accessors with which to build the core code; pte_special does that. We do not want architectures to know or care about vm_normal_page itself, and we definitely don't want them being able to invent something new there out of sight of mm/ code. If we made vm_normal_page an arch function, then we have to make vm_insert_mixed (next patch) an arch function too. So I don't think moving it to arch code fundamentally improves any abstractions, while it does practically make the code more difficult to follow, for both mm and arch developers, and easier to misuse. [akpm@linux-foundation.org: build fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Carsten Otte <cotte@de.ibm.com> Cc: Jared Hulbert <jaredeh@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 17:13:00 +08:00
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
#define __HAVE_ARCH_PTE_SAME
static inline int pte_same(pte_t a, pte_t b)
{
return pte_val(a) == pte_val(b);
}
static inline pgste_t pgste_get_lock(pte_t *ptep)
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
{
unsigned long new = 0;
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
#ifdef CONFIG_PGSTE
unsigned long old;
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
preempt_disable();
asm(
" lg %0,%2\n"
"0: lgr %1,%0\n"
" nihh %0,0xff7f\n" /* clear RCP_PCL_BIT in old */
" oihh %1,0x0080\n" /* set RCP_PCL_BIT in new */
" csg %0,%1,%2\n"
" jl 0b\n"
: "=&d" (old), "=&d" (new), "=Q" (ptep[PTRS_PER_PTE])
: "Q" (ptep[PTRS_PER_PTE]) : "cc");
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
#endif
return __pgste(new);
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
}
static inline void pgste_set_unlock(pte_t *ptep, pgste_t pgste)
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
{
#ifdef CONFIG_PGSTE
asm(
" nihh %1,0xff7f\n" /* clear RCP_PCL_BIT */
" stg %1,%0\n"
: "=Q" (ptep[PTRS_PER_PTE])
: "d" (pgste_val(pgste)), "Q" (ptep[PTRS_PER_PTE]) : "cc");
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
preempt_enable();
#endif
}
static inline pgste_t pgste_update_all(pte_t *ptep, pgste_t pgste)
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
{
#ifdef CONFIG_PGSTE
[S390] mm: fix storage key handling page_get_storage_key() and page_set_storage_key() expect a page address and not its page frame number. This got inconsistent with 2d42552d "[S390] merge page_test_dirty and page_clear_dirty". Result is that we read/write storage keys from random pages and do not have a working dirty bit tracking at all. E.g. SetPageUpdate() doesn't clear the dirty bit of requested pages, which for example ext4 doesn't like very much and panics after a while. Unable to handle kernel paging request at virtual user address (null) Oops: 0004 [#1] PREEMPT SMP DEBUG_PAGEALLOC Modules linked in: CPU: 1 Not tainted 2.6.39-07551-g139f37f-dirty #152 Process flush-94:0 (pid: 1576, task: 000000003eb34538, ksp: 000000003c287b70) Krnl PSW : 0704c00180000000 0000000000316b12 (jbd2_journal_file_inode+0x10e/0x138) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 EA:3 Krnl GPRS: 0000000000000000 0000000000000000 0000000000000000 0700000000000000 0000000000316a62 000000003eb34cd0 0000000000000025 000000003c287b88 0000000000000001 000000003c287a70 000000003f1ec678 000000003f1ec000 0000000000000000 000000003e66ec00 0000000000316a62 000000003c287988 Krnl Code: 0000000000316b04: f0a0000407f4 srp 4(11,%r0),2036,0 0000000000316b0a: b9020022 ltgr %r2,%r2 0000000000316b0e: a7740015 brc 7,316b38 >0000000000316b12: e3d0c0000024 stg %r13,0(%r12) 0000000000316b18: 4120c010 la %r2,16(%r12) 0000000000316b1c: 4130d060 la %r3,96(%r13) 0000000000316b20: e340d0600004 lg %r4,96(%r13) 0000000000316b26: c0e50002b567 brasl %r14,36d5f4 Call Trace: ([<0000000000316a62>] jbd2_journal_file_inode+0x5e/0x138) [<00000000002da13c>] mpage_da_map_and_submit+0x2e8/0x42c [<00000000002daac2>] ext4_da_writepages+0x2da/0x504 [<00000000002597e8>] writeback_single_inode+0xf8/0x268 [<0000000000259f06>] writeback_sb_inodes+0xd2/0x18c [<000000000025a700>] writeback_inodes_wb+0x80/0x168 [<000000000025aa92>] wb_writeback+0x2aa/0x324 [<000000000025abde>] wb_do_writeback+0xd2/0x274 [<000000000025ae3a>] bdi_writeback_thread+0xba/0x1c4 [<00000000001737be>] kthread+0xa6/0xb0 [<000000000056c1da>] kernel_thread_starter+0x6/0xc [<000000000056c1d4>] kernel_thread_starter+0x0/0xc INFO: lockdep is turned off. Last Breaking-Event-Address: [<0000000000316a8a>] jbd2_journal_file_inode+0x86/0x138 Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2011-05-29 18:40:50 +08:00
unsigned long address, bits;
unsigned char skey;
if (!pte_present(*ptep))
return pgste;
[S390] mm: fix storage key handling page_get_storage_key() and page_set_storage_key() expect a page address and not its page frame number. This got inconsistent with 2d42552d "[S390] merge page_test_dirty and page_clear_dirty". Result is that we read/write storage keys from random pages and do not have a working dirty bit tracking at all. E.g. SetPageUpdate() doesn't clear the dirty bit of requested pages, which for example ext4 doesn't like very much and panics after a while. Unable to handle kernel paging request at virtual user address (null) Oops: 0004 [#1] PREEMPT SMP DEBUG_PAGEALLOC Modules linked in: CPU: 1 Not tainted 2.6.39-07551-g139f37f-dirty #152 Process flush-94:0 (pid: 1576, task: 000000003eb34538, ksp: 000000003c287b70) Krnl PSW : 0704c00180000000 0000000000316b12 (jbd2_journal_file_inode+0x10e/0x138) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 EA:3 Krnl GPRS: 0000000000000000 0000000000000000 0000000000000000 0700000000000000 0000000000316a62 000000003eb34cd0 0000000000000025 000000003c287b88 0000000000000001 000000003c287a70 000000003f1ec678 000000003f1ec000 0000000000000000 000000003e66ec00 0000000000316a62 000000003c287988 Krnl Code: 0000000000316b04: f0a0000407f4 srp 4(11,%r0),2036,0 0000000000316b0a: b9020022 ltgr %r2,%r2 0000000000316b0e: a7740015 brc 7,316b38 >0000000000316b12: e3d0c0000024 stg %r13,0(%r12) 0000000000316b18: 4120c010 la %r2,16(%r12) 0000000000316b1c: 4130d060 la %r3,96(%r13) 0000000000316b20: e340d0600004 lg %r4,96(%r13) 0000000000316b26: c0e50002b567 brasl %r14,36d5f4 Call Trace: ([<0000000000316a62>] jbd2_journal_file_inode+0x5e/0x138) [<00000000002da13c>] mpage_da_map_and_submit+0x2e8/0x42c [<00000000002daac2>] ext4_da_writepages+0x2da/0x504 [<00000000002597e8>] writeback_single_inode+0xf8/0x268 [<0000000000259f06>] writeback_sb_inodes+0xd2/0x18c [<000000000025a700>] writeback_inodes_wb+0x80/0x168 [<000000000025aa92>] wb_writeback+0x2aa/0x324 [<000000000025abde>] wb_do_writeback+0xd2/0x274 [<000000000025ae3a>] bdi_writeback_thread+0xba/0x1c4 [<00000000001737be>] kthread+0xa6/0xb0 [<000000000056c1da>] kernel_thread_starter+0x6/0xc [<000000000056c1d4>] kernel_thread_starter+0x0/0xc INFO: lockdep is turned off. Last Breaking-Event-Address: [<0000000000316a8a>] jbd2_journal_file_inode+0x86/0x138 Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2011-05-29 18:40:50 +08:00
address = pte_val(*ptep) & PAGE_MASK;
skey = page_get_storage_key(address);
bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
/* Clear page changed & referenced bit in the storage key */
if (bits & _PAGE_CHANGED)
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
page_set_storage_key(address, skey ^ bits, 0);
else if (bits)
page_reset_referenced(address);
/* Transfer page changed & referenced bit to guest bits in pgste */
pgste_val(pgste) |= bits << 48; /* RCP_GR_BIT & RCP_GC_BIT */
/* Get host changed & referenced bits from pgste */
bits |= (pgste_val(pgste) & (RCP_HR_BIT | RCP_HC_BIT)) >> 52;
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
/* Transfer page changed & referenced bit to kvm user bits */
pgste_val(pgste) |= bits << 45; /* KVM_UR_BIT & KVM_UC_BIT */
/* Clear relevant host bits in pgste. */
pgste_val(pgste) &= ~(RCP_HR_BIT | RCP_HC_BIT);
pgste_val(pgste) &= ~(RCP_ACC_BITS | RCP_FP_BIT);
/* Copy page access key and fetch protection bit to pgste */
pgste_val(pgste) |=
(unsigned long) (skey & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
/* Transfer referenced bit to pte */
pte_val(*ptep) |= (bits & _PAGE_REFERENCED) << 1;
#endif
return pgste;
}
static inline pgste_t pgste_update_young(pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
int young;
if (!pte_present(*ptep))
return pgste;
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
/* Get referenced bit from storage key */
young = page_reset_referenced(pte_val(*ptep) & PAGE_MASK);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
if (young)
pgste_val(pgste) |= RCP_GR_BIT;
/* Get host referenced bit from pgste */
if (pgste_val(pgste) & RCP_HR_BIT) {
pgste_val(pgste) &= ~RCP_HR_BIT;
young = 1;
}
/* Transfer referenced bit to kvm user bits and pte */
if (young) {
pgste_val(pgste) |= KVM_UR_BIT;
pte_val(*ptep) |= _PAGE_SWR;
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
}
#endif
return pgste;
}
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
static inline void pgste_set_key(pte_t *ptep, pgste_t pgste, pte_t entry)
{
#ifdef CONFIG_PGSTE
[S390] mm: fix storage key handling page_get_storage_key() and page_set_storage_key() expect a page address and not its page frame number. This got inconsistent with 2d42552d "[S390] merge page_test_dirty and page_clear_dirty". Result is that we read/write storage keys from random pages and do not have a working dirty bit tracking at all. E.g. SetPageUpdate() doesn't clear the dirty bit of requested pages, which for example ext4 doesn't like very much and panics after a while. Unable to handle kernel paging request at virtual user address (null) Oops: 0004 [#1] PREEMPT SMP DEBUG_PAGEALLOC Modules linked in: CPU: 1 Not tainted 2.6.39-07551-g139f37f-dirty #152 Process flush-94:0 (pid: 1576, task: 000000003eb34538, ksp: 000000003c287b70) Krnl PSW : 0704c00180000000 0000000000316b12 (jbd2_journal_file_inode+0x10e/0x138) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 EA:3 Krnl GPRS: 0000000000000000 0000000000000000 0000000000000000 0700000000000000 0000000000316a62 000000003eb34cd0 0000000000000025 000000003c287b88 0000000000000001 000000003c287a70 000000003f1ec678 000000003f1ec000 0000000000000000 000000003e66ec00 0000000000316a62 000000003c287988 Krnl Code: 0000000000316b04: f0a0000407f4 srp 4(11,%r0),2036,0 0000000000316b0a: b9020022 ltgr %r2,%r2 0000000000316b0e: a7740015 brc 7,316b38 >0000000000316b12: e3d0c0000024 stg %r13,0(%r12) 0000000000316b18: 4120c010 la %r2,16(%r12) 0000000000316b1c: 4130d060 la %r3,96(%r13) 0000000000316b20: e340d0600004 lg %r4,96(%r13) 0000000000316b26: c0e50002b567 brasl %r14,36d5f4 Call Trace: ([<0000000000316a62>] jbd2_journal_file_inode+0x5e/0x138) [<00000000002da13c>] mpage_da_map_and_submit+0x2e8/0x42c [<00000000002daac2>] ext4_da_writepages+0x2da/0x504 [<00000000002597e8>] writeback_single_inode+0xf8/0x268 [<0000000000259f06>] writeback_sb_inodes+0xd2/0x18c [<000000000025a700>] writeback_inodes_wb+0x80/0x168 [<000000000025aa92>] wb_writeback+0x2aa/0x324 [<000000000025abde>] wb_do_writeback+0xd2/0x274 [<000000000025ae3a>] bdi_writeback_thread+0xba/0x1c4 [<00000000001737be>] kthread+0xa6/0xb0 [<000000000056c1da>] kernel_thread_starter+0x6/0xc [<000000000056c1d4>] kernel_thread_starter+0x0/0xc INFO: lockdep is turned off. Last Breaking-Event-Address: [<0000000000316a8a>] jbd2_journal_file_inode+0x86/0x138 Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2011-05-29 18:40:50 +08:00
unsigned long address;
unsigned long okey, nkey;
if (!pte_present(entry))
return;
address = pte_val(entry) & PAGE_MASK;
[S390] mm: fix storage key handling page_get_storage_key() and page_set_storage_key() expect a page address and not its page frame number. This got inconsistent with 2d42552d "[S390] merge page_test_dirty and page_clear_dirty". Result is that we read/write storage keys from random pages and do not have a working dirty bit tracking at all. E.g. SetPageUpdate() doesn't clear the dirty bit of requested pages, which for example ext4 doesn't like very much and panics after a while. Unable to handle kernel paging request at virtual user address (null) Oops: 0004 [#1] PREEMPT SMP DEBUG_PAGEALLOC Modules linked in: CPU: 1 Not tainted 2.6.39-07551-g139f37f-dirty #152 Process flush-94:0 (pid: 1576, task: 000000003eb34538, ksp: 000000003c287b70) Krnl PSW : 0704c00180000000 0000000000316b12 (jbd2_journal_file_inode+0x10e/0x138) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 EA:3 Krnl GPRS: 0000000000000000 0000000000000000 0000000000000000 0700000000000000 0000000000316a62 000000003eb34cd0 0000000000000025 000000003c287b88 0000000000000001 000000003c287a70 000000003f1ec678 000000003f1ec000 0000000000000000 000000003e66ec00 0000000000316a62 000000003c287988 Krnl Code: 0000000000316b04: f0a0000407f4 srp 4(11,%r0),2036,0 0000000000316b0a: b9020022 ltgr %r2,%r2 0000000000316b0e: a7740015 brc 7,316b38 >0000000000316b12: e3d0c0000024 stg %r13,0(%r12) 0000000000316b18: 4120c010 la %r2,16(%r12) 0000000000316b1c: 4130d060 la %r3,96(%r13) 0000000000316b20: e340d0600004 lg %r4,96(%r13) 0000000000316b26: c0e50002b567 brasl %r14,36d5f4 Call Trace: ([<0000000000316a62>] jbd2_journal_file_inode+0x5e/0x138) [<00000000002da13c>] mpage_da_map_and_submit+0x2e8/0x42c [<00000000002daac2>] ext4_da_writepages+0x2da/0x504 [<00000000002597e8>] writeback_single_inode+0xf8/0x268 [<0000000000259f06>] writeback_sb_inodes+0xd2/0x18c [<000000000025a700>] writeback_inodes_wb+0x80/0x168 [<000000000025aa92>] wb_writeback+0x2aa/0x324 [<000000000025abde>] wb_do_writeback+0xd2/0x274 [<000000000025ae3a>] bdi_writeback_thread+0xba/0x1c4 [<00000000001737be>] kthread+0xa6/0xb0 [<000000000056c1da>] kernel_thread_starter+0x6/0xc [<000000000056c1d4>] kernel_thread_starter+0x0/0xc INFO: lockdep is turned off. Last Breaking-Event-Address: [<0000000000316a8a>] jbd2_journal_file_inode+0x86/0x138 Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2011-05-29 18:40:50 +08:00
okey = nkey = page_get_storage_key(address);
nkey &= ~(_PAGE_ACC_BITS | _PAGE_FP_BIT);
/* Set page access key and fetch protection bit from pgste */
nkey |= (pgste_val(pgste) & (RCP_ACC_BITS | RCP_FP_BIT)) >> 56;
if (okey != nkey)
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
page_set_storage_key(address, nkey, 0);
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
#endif
}
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
static inline void pgste_set_pte(pte_t *ptep, pte_t entry)
{
if (!MACHINE_HAS_ESOP && (pte_val(entry) & _PAGE_SWW)) {
/*
* Without enhanced suppression-on-protection force
* the dirty bit on for all writable ptes.
*/
pte_val(entry) |= _PAGE_SWC;
pte_val(entry) &= ~_PAGE_RO;
}
*ptep = entry;
}
/**
* struct gmap_struct - guest address space
* @mm: pointer to the parent mm_struct
* @table: pointer to the page directory
* @asce: address space control element for gmap page table
* @crst_list: list of all crst tables used in the guest address space
*/
struct gmap {
struct list_head list;
struct mm_struct *mm;
unsigned long *table;
unsigned long asce;
struct list_head crst_list;
};
/**
* struct gmap_rmap - reverse mapping for segment table entries
* @gmap: pointer to the gmap_struct
* @entry: pointer to a segment table entry
* @vmaddr: virtual address in the guest address space
*/
struct gmap_rmap {
struct list_head list;
struct gmap *gmap;
unsigned long *entry;
unsigned long vmaddr;
};
/**
* struct gmap_pgtable - gmap information attached to a page table
* @vmaddr: address of the 1MB segment in the process virtual memory
* @mapper: list of segment table entries mapping a page table
*/
struct gmap_pgtable {
unsigned long vmaddr;
struct list_head mapper;
};
/**
* struct gmap_notifier - notify function block for page invalidation
* @notifier_call: address of callback function
*/
struct gmap_notifier {
struct list_head list;
void (*notifier_call)(struct gmap *gmap, unsigned long address);
};
struct gmap *gmap_alloc(struct mm_struct *mm);
void gmap_free(struct gmap *gmap);
void gmap_enable(struct gmap *gmap);
void gmap_disable(struct gmap *gmap);
int gmap_map_segment(struct gmap *gmap, unsigned long from,
unsigned long to, unsigned long len);
int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len);
unsigned long __gmap_translate(unsigned long address, struct gmap *);
unsigned long gmap_translate(unsigned long address, struct gmap *);
unsigned long __gmap_fault(unsigned long address, struct gmap *);
unsigned long gmap_fault(unsigned long address, struct gmap *);
void gmap_discard(unsigned long from, unsigned long to, struct gmap *);
void gmap_register_ipte_notifier(struct gmap_notifier *);
void gmap_unregister_ipte_notifier(struct gmap_notifier *);
int gmap_ipte_notify(struct gmap *, unsigned long start, unsigned long len);
void gmap_do_ipte_notify(struct mm_struct *, unsigned long addr, pte_t *);
static inline pgste_t pgste_ipte_notify(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
if (pgste_val(pgste) & RCP_IN_BIT) {
pgste_val(pgste) &= ~RCP_IN_BIT;
gmap_do_ipte_notify(mm, addr, ptep);
}
#endif
return pgste;
}
/*
* Certain architectures need to do special things when PTEs
* within a page table are directly modified. Thus, the following
* hook is made available.
*/
static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t entry)
{
pgste_t pgste;
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
pgste_set_key(ptep, pgste, entry);
pgste_set_pte(ptep, entry);
pgste_set_unlock(ptep, pgste);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
} else {
if (!(pte_val(entry) & _PAGE_INVALID) && MACHINE_HAS_EDAT1)
pte_val(entry) |= _PAGE_CO;
*ptep = entry;
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
}
}
/*
* query functions pte_write/pte_dirty/pte_young only work if
* pte_present() is true. Undefined behaviour if not..
*/
static inline int pte_write(pte_t pte)
{
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
return (pte_val(pte) & _PAGE_SWW) != 0;
}
static inline int pte_dirty(pte_t pte)
{
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
return (pte_val(pte) & _PAGE_SWC) != 0;
}
static inline int pte_young(pte_t pte)
{
#ifdef CONFIG_PGSTE
if (pte_val(pte) & _PAGE_SWR)
return 1;
#endif
return 0;
}
/*
* pgd/pmd/pte modification functions
*/
static inline void pgd_clear(pgd_t *pgd)
{
#ifdef CONFIG_64BIT
if ((pgd_val(*pgd) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R2)
pgd_val(*pgd) = _REGION2_ENTRY_EMPTY;
#endif
}
static inline void pud_clear(pud_t *pud)
{
#ifdef CONFIG_64BIT
if ((pud_val(*pud) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3)
pud_val(*pud) = _REGION3_ENTRY_EMPTY;
#endif
}
static inline void pmd_clear(pmd_t *pmdp)
{
pmd_val(*pmdp) = _SEGMENT_ENTRY_EMPTY;
}
static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
pte_val(*ptep) = _PAGE_TYPE_EMPTY;
}
/*
* The following pte modification functions only work if
* pte_present() is true. Undefined behaviour if not..
*/
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
pte_val(pte) &= _PAGE_CHG_MASK;
pte_val(pte) |= pgprot_val(newprot);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
if ((pte_val(pte) & _PAGE_SWC) && (pte_val(pte) & _PAGE_SWW))
pte_val(pte) &= ~_PAGE_RO;
return pte;
}
static inline pte_t pte_wrprotect(pte_t pte)
{
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
pte_val(pte) &= ~_PAGE_SWW;
/* Do not clobber _PAGE_TYPE_NONE pages! */
if (!(pte_val(pte) & _PAGE_INVALID))
pte_val(pte) |= _PAGE_RO;
return pte;
}
static inline pte_t pte_mkwrite(pte_t pte)
{
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
pte_val(pte) |= _PAGE_SWW;
if (pte_val(pte) & _PAGE_SWC)
pte_val(pte) &= ~_PAGE_RO;
return pte;
}
static inline pte_t pte_mkclean(pte_t pte)
{
pte_val(pte) &= ~_PAGE_SWC;
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
/* Do not clobber _PAGE_TYPE_NONE pages! */
if (!(pte_val(pte) & _PAGE_INVALID))
pte_val(pte) |= _PAGE_RO;
return pte;
}
static inline pte_t pte_mkdirty(pte_t pte)
{
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
pte_val(pte) |= _PAGE_SWC;
if (pte_val(pte) & _PAGE_SWW)
pte_val(pte) &= ~_PAGE_RO;
return pte;
}
static inline pte_t pte_mkold(pte_t pte)
{
#ifdef CONFIG_PGSTE
pte_val(pte) &= ~_PAGE_SWR;
#endif
return pte;
}
static inline pte_t pte_mkyoung(pte_t pte)
{
return pte;
}
mm: introduce pte_special pte bit s390 for one, cannot implement VM_MIXEDMAP with pfn_valid, due to their memory model (which is more dynamic than most). Instead, they had proposed to implement it with an additional path through vm_normal_page(), using a bit in the pte to determine whether or not the page should be refcounted: vm_normal_page() { ... if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { if (vma->vm_flags & VM_MIXEDMAP) { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; #else if (!pfn_valid(pfn)) return NULL; #endif goto out; } ... } This is fine, however if we are allowed to use a bit in the pte to determine refcountedness, we can use that to _completely_ replace all the vma based schemes. So instead of adding more cases to the already complex vma-based scheme, we can have a clearly seperate and simple pte-based scheme (and get slightly better code generation in the process): vm_normal_page() { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; return pte_page(pte); #else ... #endif } And finally, we may rather make this concept usable by any architecture rather than making it s390 only, so implement a new type of pte state for this. Unfortunately the old vma based code must stay, because some architectures may not be able to spare pte bits. This makes vm_normal_page a little bit more ugly than we would like, but the 2 cases are clearly seperate. So introduce a pte_special pte state, and use it in mm/memory.c. It is currently a noop for all architectures, so this doesn't actually result in any compiled code changes to mm/memory.o. BTW: I haven't put vm_normal_page() into arch code as-per an earlier suggestion. The reason is that, regardless of where vm_normal_page is actually implemented, the *abstraction* is still exactly the same. Also, while it depends on whether the architecture has pte_special or not, that is the only two possible cases, and it really isn't an arch specific function -- the role of the arch code should be to provide primitive functions and accessors with which to build the core code; pte_special does that. We do not want architectures to know or care about vm_normal_page itself, and we definitely don't want them being able to invent something new there out of sight of mm/ code. If we made vm_normal_page an arch function, then we have to make vm_insert_mixed (next patch) an arch function too. So I don't think moving it to arch code fundamentally improves any abstractions, while it does practically make the code more difficult to follow, for both mm and arch developers, and easier to misuse. [akpm@linux-foundation.org: build fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Carsten Otte <cotte@de.ibm.com> Cc: Jared Hulbert <jaredeh@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 17:13:00 +08:00
static inline pte_t pte_mkspecial(pte_t pte)
{
pte_val(pte) |= _PAGE_SPECIAL;
mm: introduce pte_special pte bit s390 for one, cannot implement VM_MIXEDMAP with pfn_valid, due to their memory model (which is more dynamic than most). Instead, they had proposed to implement it with an additional path through vm_normal_page(), using a bit in the pte to determine whether or not the page should be refcounted: vm_normal_page() { ... if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { if (vma->vm_flags & VM_MIXEDMAP) { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; #else if (!pfn_valid(pfn)) return NULL; #endif goto out; } ... } This is fine, however if we are allowed to use a bit in the pte to determine refcountedness, we can use that to _completely_ replace all the vma based schemes. So instead of adding more cases to the already complex vma-based scheme, we can have a clearly seperate and simple pte-based scheme (and get slightly better code generation in the process): vm_normal_page() { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; return pte_page(pte); #else ... #endif } And finally, we may rather make this concept usable by any architecture rather than making it s390 only, so implement a new type of pte state for this. Unfortunately the old vma based code must stay, because some architectures may not be able to spare pte bits. This makes vm_normal_page a little bit more ugly than we would like, but the 2 cases are clearly seperate. So introduce a pte_special pte state, and use it in mm/memory.c. It is currently a noop for all architectures, so this doesn't actually result in any compiled code changes to mm/memory.o. BTW: I haven't put vm_normal_page() into arch code as-per an earlier suggestion. The reason is that, regardless of where vm_normal_page is actually implemented, the *abstraction* is still exactly the same. Also, while it depends on whether the architecture has pte_special or not, that is the only two possible cases, and it really isn't an arch specific function -- the role of the arch code should be to provide primitive functions and accessors with which to build the core code; pte_special does that. We do not want architectures to know or care about vm_normal_page itself, and we definitely don't want them being able to invent something new there out of sight of mm/ code. If we made vm_normal_page an arch function, then we have to make vm_insert_mixed (next patch) an arch function too. So I don't think moving it to arch code fundamentally improves any abstractions, while it does practically make the code more difficult to follow, for both mm and arch developers, and easier to misuse. [akpm@linux-foundation.org: build fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Carsten Otte <cotte@de.ibm.com> Cc: Jared Hulbert <jaredeh@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 17:13:00 +08:00
return pte;
}
#ifdef CONFIG_HUGETLB_PAGE
static inline pte_t pte_mkhuge(pte_t pte)
{
pte_val(pte) |= (_SEGMENT_ENTRY_LARGE | _SEGMENT_ENTRY_CO);
return pte;
}
#endif
/*
* Get (and clear) the user dirty bit for a pte.
*/
static inline int ptep_test_and_clear_user_dirty(struct mm_struct *mm,
pte_t *ptep)
{
pgste_t pgste;
int dirty = 0;
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
pgste = pgste_update_all(ptep, pgste);
dirty = !!(pgste_val(pgste) & KVM_UC_BIT);
pgste_val(pgste) &= ~KVM_UC_BIT;
pgste_set_unlock(ptep, pgste);
return dirty;
}
return dirty;
}
/*
* Get (and clear) the user referenced bit for a pte.
*/
static inline int ptep_test_and_clear_user_young(struct mm_struct *mm,
pte_t *ptep)
{
pgste_t pgste;
int young = 0;
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
pgste = pgste_update_young(ptep, pgste);
young = !!(pgste_val(pgste) & KVM_UR_BIT);
pgste_val(pgste) &= ~KVM_UR_BIT;
pgste_set_unlock(ptep, pgste);
}
return young;
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep)
{
pgste_t pgste;
pte_t pte;
if (mm_has_pgste(vma->vm_mm)) {
pgste = pgste_get_lock(ptep);
pgste = pgste_update_young(ptep, pgste);
pte = *ptep;
*ptep = pte_mkold(pte);
pgste_set_unlock(ptep, pgste);
return pte_young(pte);
}
return 0;
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
#define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep)
{
s390: KVM preparation: host memory management changes for s390 kvm This patch changes the s390 memory management defintions to use the pgste field for dirty and reference bit tracking of host and guest code. Usually on s390, dirty and referenced are tracked in storage keys, which belong to the physical page. This changes with virtualization: The guest and host dirty/reference bits are defined to be the logical OR of the values for the mapping and the physical page. This patch implements the necessary changes in pgtable.h for s390. There is a common code change in mm/rmap.c, the call to page_test_and_clear_young must be moved. This is a no-op for all architecture but s390. page_referenced checks the referenced bits for the physiscal page and for all mappings: o The physical page is checked with page_test_and_clear_young. o The mappings are checked with ptep_test_and_clear_young and friends. Without pgstes (the current implementation on Linux s390) the physical page check is implemented but the mapping callbacks are no-ops because dirty and referenced are not tracked in the s390 page tables. The pgstes introduces guest and host dirty and reference bits for s390 in the host mapping. These mapping must be checked before page_test_and_clear_young resets the reference bit. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-26 01:47:12 +08:00
/* No need to flush TLB
* On s390 reference bits are in storage key and never in TLB
* With virtualization we handle the reference bit, without we
* we can simply return */
return ptep_test_and_clear_young(vma, address, ptep);
}
static inline void __ptep_ipte(unsigned long address, pte_t *ptep)
{
if (!(pte_val(*ptep) & _PAGE_INVALID)) {
#ifndef CONFIG_64BIT
/* pto must point to the start of the segment table */
pte_t *pto = (pte_t *) (((unsigned long) ptep) & 0x7ffffc00);
#else
/* ipte in zarch mode can do the math */
pte_t *pto = ptep;
#endif
asm volatile(
" ipte %2,%3"
: "=m" (*ptep) : "m" (*ptep),
"a" (pto), "a" (address));
}
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
/*
* This is hard to understand. ptep_get_and_clear and ptep_clear_flush
* both clear the TLB for the unmapped pte. The reason is that
* ptep_get_and_clear is used in common code (e.g. change_pte_range)
* to modify an active pte. The sequence is
* 1) ptep_get_and_clear
* 2) set_pte_at
* 3) flush_tlb_range
* On s390 the tlb needs to get flushed with the modification of the pte
* if the pte is active. The only way how this can be implemented is to
* have ptep_get_and_clear do the tlb flush. In exchange flush_tlb_range
* is a nop.
*/
#define __HAVE_ARCH_PTEP_GET_AND_CLEAR
static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
unsigned long address, pte_t *ptep)
{
pgste_t pgste;
pte_t pte;
mm->context.flush_mm = 1;
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
pgste = pgste_ipte_notify(mm, address, ptep, pgste);
}
pte = *ptep;
if (!mm_exclusive(mm))
__ptep_ipte(address, ptep);
pte_val(*ptep) = _PAGE_TYPE_EMPTY;
if (mm_has_pgste(mm)) {
pgste = pgste_update_all(&pte, pgste);
pgste_set_unlock(ptep, pgste);
}
return pte;
}
#define __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
static inline pte_t ptep_modify_prot_start(struct mm_struct *mm,
unsigned long address,
pte_t *ptep)
{
pgste_t pgste;
pte_t pte;
mm->context.flush_mm = 1;
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
pgste_ipte_notify(mm, address, ptep, pgste);
}
pte = *ptep;
if (!mm_exclusive(mm))
__ptep_ipte(address, ptep);
return pte;
}
static inline void ptep_modify_prot_commit(struct mm_struct *mm,
unsigned long address,
pte_t *ptep, pte_t pte)
{
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
if (mm_has_pgste(mm)) {
pgste_set_pte(ptep, pte);
pgste_set_unlock(ptep, *(pgste_t *)(ptep + PTRS_PER_PTE));
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
} else
*ptep = pte;
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
#define __HAVE_ARCH_PTEP_CLEAR_FLUSH
static inline pte_t ptep_clear_flush(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep)
{
pgste_t pgste;
pte_t pte;
if (mm_has_pgste(vma->vm_mm)) {
pgste = pgste_get_lock(ptep);
pgste = pgste_ipte_notify(vma->vm_mm, address, ptep, pgste);
}
pte = *ptep;
__ptep_ipte(address, ptep);
pte_val(*ptep) = _PAGE_TYPE_EMPTY;
if (mm_has_pgste(vma->vm_mm)) {
pgste = pgste_update_all(&pte, pgste);
pgste_set_unlock(ptep, pgste);
}
return pte;
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
/*
* The batched pte unmap code uses ptep_get_and_clear_full to clear the
* ptes. Here an optimization is possible. tlb_gather_mmu flushes all
* tlbs of an mm if it can guarantee that the ptes of the mm_struct
* cannot be accessed while the batched unmap is running. In this case
* full==1 and a simple pte_clear is enough. See tlb.h.
*/
#define __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
unsigned long address,
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
pte_t *ptep, int full)
{
pgste_t pgste;
pte_t pte;
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
if (!full)
pgste = pgste_ipte_notify(mm, address, ptep, pgste);
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
pte = *ptep;
if (!full)
__ptep_ipte(address, ptep);
pte_val(*ptep) = _PAGE_TYPE_EMPTY;
if (mm_has_pgste(mm)) {
pgste = pgste_update_all(&pte, pgste);
pgste_set_unlock(ptep, pgste);
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
return pte;
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
#define __HAVE_ARCH_PTEP_SET_WRPROTECT
static inline pte_t ptep_set_wrprotect(struct mm_struct *mm,
unsigned long address, pte_t *ptep)
{
pgste_t pgste;
pte_t pte = *ptep;
if (pte_write(pte)) {
mm->context.flush_mm = 1;
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
pgste = pgste_ipte_notify(mm, address, ptep, pgste);
}
if (!mm_exclusive(mm))
__ptep_ipte(address, ptep);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
pte = pte_wrprotect(pte);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
if (mm_has_pgste(mm)) {
pgste_set_pte(ptep, pte);
pgste_set_unlock(ptep, pgste);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
} else
*ptep = pte;
}
return pte;
}
[S390] tlb flush fix. The current tlb flushing code for page table entries violates the s390 architecture in a small detail. The relevant section from the principles of operation (SA22-7832-02 page 3-47): "A valid table entry must not be changed while it is attached to any CPU and may be used for translation by that CPU except to (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table entry, or (3) make a change by means of a COMPARE AND SWAP AND PURGE instruction that purges the TLB." That means if one thread of a multithreaded applciation uses a vma while another thread does an unmap on it, the page table entries of that vma needs to get removed with IPTE, IDTE or CSP. In some strange and rare situations a cpu could check-stop (die) because a entry has been pushed out of the TLB that is still needed to complete a (milli-coded) instruction. I've never seen it happen with the current code on any of the supported machines, so right now this is a theoretical problem. But I want to fix it nevertheless, to avoid headaches in the futures. To get this implemented correctly without changing common code the primitives ptep_get_and_clear, ptep_get_and_clear_full and ptep_set_wrprotect need to use the IPTE instruction to invalidate the pte before the new pte value gets stored. If IPTE is always used for the three primitives three important operations will have a performace hit: fork, mprotect and exit_mmap. Time for some workarounds: * 1: ptep_get_and_clear_full is used in unmap_vmas to remove page tables entries in a batched tlb gather operation. If the mmu_gather context passed to unmap_vmas has been started with full_mm_flush==1 or if only one cpu is online or if the only user of a mm_struct is the current process then the fullmm indication in the mmu_gather context is set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu call. No new TLBs can be created while the unmap is in progress. In this case ptep_get_and_clear_full clears the ptes with a simple store. * 2: ptep_get_and_clear is used in change_protection to clear the ptes from the page tables before they are reentered with the new access flags. At the end of the update flush_tlb_range clears the remaining TLBs. In general the ptep_get_and_clear has to issue IPTE for each pte and flush_tlb_range is a nop. But if there is only one user of the mm_struct then ptep_get_and_clear uses simple stores to do the update and flush_tlb_range will flush the TLBs. * 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range for a fork to make all ptes of a cow mapping read-only. At the end of of copy_page_range dup_mmap will flush the TLBs with a call to flush_tlb_mm. Check for mm->mm_users and if there is only one user avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the TLBs. Overall for single threaded programs the tlb flush code now performs better, for multi threaded programs it is slightly worse. In particular exit_mmap() now does a single IDTE for the mm and then just frees every page cache reference and every page table page directly without a delay over the mmu_gather structure. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-10-22 18:52:44 +08:00
#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
static inline int ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep,
pte_t entry, int dirty)
{
pgste_t pgste;
if (pte_same(*ptep, entry))
return 0;
if (mm_has_pgste(vma->vm_mm)) {
pgste = pgste_get_lock(ptep);
pgste = pgste_ipte_notify(vma->vm_mm, address, ptep, pgste);
}
__ptep_ipte(address, ptep);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
if (mm_has_pgste(vma->vm_mm)) {
pgste_set_pte(ptep, entry);
pgste_set_unlock(ptep, pgste);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
} else
*ptep = entry;
return 1;
}
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
static inline pte_t mk_pte_phys(unsigned long physpage, pgprot_t pgprot)
{
pte_t __pte;
pte_val(__pte) = physpage + pgprot_val(pgprot);
return __pte;
}
static inline pte_t mk_pte(struct page *page, pgprot_t pgprot)
{
unsigned long physpage = page_to_phys(page);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
pte_t __pte = mk_pte_phys(physpage, pgprot);
s390/mm: implement software dirty bits The s390 architecture is unique in respect to dirty page detection, it uses the change bit in the per-page storage key to track page modifications. All other architectures track dirty bits by means of page table entries. This property of s390 has caused numerous problems in the past, e.g. see git commit ef5d437f71afdf4a "mm: fix XFS oops due to dirty pages without buffers on s390". To avoid future issues in regard to per-page dirty bits convert s390 to a fault based software dirty bit detection mechanism. All user page table entries which are marked as clean will be hardware read-only, even if the pte is supposed to be writable. A write by the user process will trigger a protection fault which will cause the user pte to be marked as dirty and the hardware read-only bit is removed. With this change the dirty bit in the storage key is irrelevant for Linux as a host, but the storage key is still required for KVM guests. The effect is that page_test_and_clear_dirty and the related code can be removed. The referenced bit in the storage key is still used by the page_test_and_clear_young primitive to provide page age information. For page cache pages of mappings with mapping_cap_account_dirty there will not be any change in behavior as the dirty bit tracking already uses read-only ptes to control the amount of dirty pages. Only for swap cache pages and pages of mappings without mapping_cap_account_dirty there can be additional protection faults. To avoid an excessive number of additional faults the mk_pte primitive checks for PageDirty if the pgprot value allows for writes and pre-dirties the pte. That avoids all additional faults for tmpfs and shmem pages until these pages are added to the swap cache. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-07 20:17:37 +08:00
if ((pte_val(__pte) & _PAGE_SWW) && PageDirty(page)) {
pte_val(__pte) |= _PAGE_SWC;
pte_val(__pte) &= ~_PAGE_RO;
}
return __pte;
}
#define pgd_index(address) (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
#define pud_index(address) (((address) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
#define pmd_index(address) (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
#define pte_index(address) (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE-1))
#define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address))
#define pgd_offset_k(address) pgd_offset(&init_mm, address)
#ifndef CONFIG_64BIT
#define pmd_deref(pmd) (pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN)
#define pud_deref(pmd) ({ BUG(); 0UL; })
#define pgd_deref(pmd) ({ BUG(); 0UL; })
#define pud_offset(pgd, address) ((pud_t *) pgd)
#define pmd_offset(pud, address) ((pmd_t *) pud + pmd_index(address))
#else /* CONFIG_64BIT */
#define pmd_deref(pmd) (pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN)
#define pud_deref(pud) (pud_val(pud) & _REGION_ENTRY_ORIGIN)
#define pgd_deref(pgd) (pgd_val(pgd) & _REGION_ENTRY_ORIGIN)
static inline pud_t *pud_offset(pgd_t *pgd, unsigned long address)
{
pud_t *pud = (pud_t *) pgd;
if ((pgd_val(*pgd) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R2)
pud = (pud_t *) pgd_deref(*pgd);
return pud + pud_index(address);
}
static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
{
pmd_t *pmd = (pmd_t *) pud;
if ((pud_val(*pud) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3)
pmd = (pmd_t *) pud_deref(*pud);
return pmd + pmd_index(address);
}
#endif /* CONFIG_64BIT */
#define pfn_pte(pfn,pgprot) mk_pte_phys(__pa((pfn) << PAGE_SHIFT),(pgprot))
#define pte_pfn(x) (pte_val(x) >> PAGE_SHIFT)
#define pte_page(x) pfn_to_page(pte_pfn(x))
#define pmd_page(pmd) pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
/* Find an entry in the lowest level page table.. */
#define pte_offset(pmd, addr) ((pte_t *) pmd_deref(*(pmd)) + pte_index(addr))
#define pte_offset_kernel(pmd, address) pte_offset(pmd,address)
#define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
#define pte_unmap(pte) do { } while (0)
static inline void __pmd_idte(unsigned long address, pmd_t *pmdp)
{
unsigned long sto = (unsigned long) pmdp -
pmd_index(address) * sizeof(pmd_t);
if (!(pmd_val(*pmdp) & _SEGMENT_ENTRY_INV)) {
asm volatile(
" .insn rrf,0xb98e0000,%2,%3,0,0"
: "=m" (*pmdp)
: "m" (*pmdp), "a" (sto),
"a" ((address & HPAGE_MASK))
: "cc"
);
}
}
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 06:07:23 +08:00
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLB_PAGE)
static inline unsigned long massage_pgprot_pmd(pgprot_t pgprot)
{
/*
* pgprot is PAGE_NONE, PAGE_RO, or PAGE_RW (see __Pxxx / __Sxxx)
* Convert to segment table entry format.
*/
if (pgprot_val(pgprot) == pgprot_val(PAGE_NONE))
return pgprot_val(SEGMENT_NONE);
if (pgprot_val(pgprot) == pgprot_val(PAGE_RO))
return pgprot_val(SEGMENT_RO);
return pgprot_val(SEGMENT_RW);
}
static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
{
pmd_val(pmd) &= _SEGMENT_CHG_MASK;
pmd_val(pmd) |= massage_pgprot_pmd(newprot);
return pmd;
}
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 06:07:23 +08:00
static inline pmd_t mk_pmd_phys(unsigned long physpage, pgprot_t pgprot)
{
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 06:07:23 +08:00
pmd_t __pmd;
pmd_val(__pmd) = physpage + massage_pgprot_pmd(pgprot);
return __pmd;
}
static inline pmd_t pmd_mkwrite(pmd_t pmd)
{
/* Do not clobber _HPAGE_TYPE_NONE pages! */
if (!(pmd_val(pmd) & _SEGMENT_ENTRY_INV))
pmd_val(pmd) &= ~_SEGMENT_ENTRY_RO;
return pmd;
}
mm/hugetlb: add more arch-defined huge_pte functions Commit abf09bed3cce ("s390/mm: implement software dirty bits") introduced another difference in the pte layout vs. the pmd layout on s390, thoroughly breaking the s390 support for hugetlbfs. This requires replacing some more pte_xxx functions in mm/hugetlbfs.c with a huge_pte_xxx version. This patch introduces those huge_pte_xxx functions and their generic implementation in asm-generic/hugetlb.h, which will now be included on all architectures supporting hugetlbfs apart from s390. This change will be a no-op for those architectures. [akpm@linux-foundation.org: fix warning] Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> [for !s390 parts] Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 06:07:23 +08:00
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLB_PAGE */
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define __HAVE_ARCH_PGTABLE_DEPOSIT
extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pgtable_t pgtable);
#define __HAVE_ARCH_PGTABLE_WITHDRAW
extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm);
static inline int pmd_trans_splitting(pmd_t pmd)
{
return pmd_val(pmd) & _SEGMENT_ENTRY_SPLIT;
}
static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t entry)
{
if (!(pmd_val(entry) & _SEGMENT_ENTRY_INV) && MACHINE_HAS_EDAT1)
pmd_val(entry) |= _SEGMENT_ENTRY_CO;
*pmdp = entry;
}
static inline pmd_t pmd_mkhuge(pmd_t pmd)
{
pmd_val(pmd) |= _SEGMENT_ENTRY_LARGE;
return pmd;
}
static inline pmd_t pmd_wrprotect(pmd_t pmd)
{
pmd_val(pmd) |= _SEGMENT_ENTRY_RO;
return pmd;
}
static inline pmd_t pmd_mkdirty(pmd_t pmd)
{
/* No dirty bit in the segment table entry. */
return pmd;
}
static inline pmd_t pmd_mkold(pmd_t pmd)
{
/* No referenced bit in the segment table entry. */
return pmd;
}
static inline pmd_t pmd_mkyoung(pmd_t pmd)
{
/* No referenced bit in the segment table entry. */
return pmd;
}
#define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp)
{
unsigned long pmd_addr = pmd_val(*pmdp) & HPAGE_MASK;
long tmp, rc;
int counter;
rc = 0;
if (MACHINE_HAS_RRBM) {
counter = PTRS_PER_PTE >> 6;
asm volatile(
"0: .insn rre,0xb9ae0000,%0,%3\n" /* rrbm */
" ogr %1,%0\n"
" la %3,0(%4,%3)\n"
" brct %2,0b\n"
: "=&d" (tmp), "+&d" (rc), "+d" (counter),
"+a" (pmd_addr)
: "a" (64 * 4096UL) : "cc");
rc = !!rc;
} else {
counter = PTRS_PER_PTE;
asm volatile(
"0: rrbe 0,%2\n"
" la %2,0(%3,%2)\n"
" brc 12,1f\n"
" lhi %0,1\n"
"1: brct %1,0b\n"
: "+d" (rc), "+d" (counter), "+a" (pmd_addr)
: "a" (4096UL) : "cc");
}
return rc;
}
#define __HAVE_ARCH_PMDP_GET_AND_CLEAR
static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm,
unsigned long address, pmd_t *pmdp)
{
pmd_t pmd = *pmdp;
__pmd_idte(address, pmdp);
pmd_clear(pmdp);
return pmd;
}
#define __HAVE_ARCH_PMDP_CLEAR_FLUSH
static inline pmd_t pmdp_clear_flush(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp)
{
return pmdp_get_and_clear(vma->vm_mm, address, pmdp);
}
#define __HAVE_ARCH_PMDP_INVALIDATE
static inline void pmdp_invalidate(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp)
{
__pmd_idte(address, pmdp);
}
#define __HAVE_ARCH_PMDP_SET_WRPROTECT
static inline void pmdp_set_wrprotect(struct mm_struct *mm,
unsigned long address, pmd_t *pmdp)
{
pmd_t pmd = *pmdp;
if (pmd_write(pmd)) {
__pmd_idte(address, pmdp);
set_pmd_at(mm, address, pmdp, pmd_wrprotect(pmd));
}
}
#define pfn_pmd(pfn, pgprot) mk_pmd_phys(__pa((pfn) << PAGE_SHIFT), (pgprot))
#define mk_pmd(page, pgprot) pfn_pmd(page_to_pfn(page), (pgprot))
static inline int pmd_trans_huge(pmd_t pmd)
{
return pmd_val(pmd) & _SEGMENT_ENTRY_LARGE;
}
static inline int has_transparent_hugepage(void)
{
return MACHINE_HAS_HPAGE ? 1 : 0;
}
static inline unsigned long pmd_pfn(pmd_t pmd)
{
return pmd_val(pmd) >> PAGE_SHIFT;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
/*
* 31 bit swap entry format:
* A page-table entry has some bits we have to treat in a special way.
* Bits 0, 20 and bit 23 have to be zero, otherwise an specification
* exception will occur instead of a page translation exception. The
* specifiation exception has the bad habit not to store necessary
* information in the lowcore.
* Bit 21 and bit 22 are the page invalid bit and the page protection
* bit. We set both to indicate a swapped page.
* Bit 30 and 31 are used to distinguish the different page types. For
* a swapped page these bits need to be zero.
* This leaves the bits 1-19 and bits 24-29 to store type and offset.
* We use the 5 bits from 25-29 for the type and the 20 bits from 1-19
* plus 24 for the offset.
* 0| offset |0110|o|type |00|
* 0 0000000001111111111 2222 2 22222 33
* 0 1234567890123456789 0123 4 56789 01
*
* 64 bit swap entry format:
* A page-table entry has some bits we have to treat in a special way.
* Bits 52 and bit 55 have to be zero, otherwise an specification
* exception will occur instead of a page translation exception. The
* specifiation exception has the bad habit not to store necessary
* information in the lowcore.
* Bit 53 and bit 54 are the page invalid bit and the page protection
* bit. We set both to indicate a swapped page.
* Bit 62 and 63 are used to distinguish the different page types. For
* a swapped page these bits need to be zero.
* This leaves the bits 0-51 and bits 56-61 to store type and offset.
* We use the 5 bits from 57-61 for the type and the 53 bits from 0-51
* plus 56 for the offset.
* | offset |0110|o|type |00|
* 0000000000111111111122222222223333333333444444444455 5555 5 55566 66
* 0123456789012345678901234567890123456789012345678901 2345 6 78901 23
*/
#ifndef CONFIG_64BIT
#define __SWP_OFFSET_MASK (~0UL >> 12)
#else
#define __SWP_OFFSET_MASK (~0UL >> 11)
#endif
static inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
{
pte_t pte;
offset &= __SWP_OFFSET_MASK;
pte_val(pte) = _PAGE_TYPE_SWAP | ((type & 0x1f) << 2) |
((offset & 1UL) << 7) | ((offset & ~1UL) << 11);
return pte;
}
#define __swp_type(entry) (((entry).val >> 2) & 0x1f)
#define __swp_offset(entry) (((entry).val >> 11) | (((entry).val >> 7) & 1))
#define __swp_entry(type,offset) ((swp_entry_t) { pte_val(mk_swap_pte((type),(offset))) })
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
#ifndef CONFIG_64BIT
# define PTE_FILE_MAX_BITS 26
#else /* CONFIG_64BIT */
# define PTE_FILE_MAX_BITS 59
#endif /* CONFIG_64BIT */
#define pte_to_pgoff(__pte) \
((((__pte).pte >> 12) << 7) + (((__pte).pte >> 1) & 0x7f))
#define pgoff_to_pte(__off) \
((pte_t) { ((((__off) & 0x7f) << 1) + (((__off) >> 7) << 12)) \
| _PAGE_TYPE_FILE })
#endif /* !__ASSEMBLY__ */
#define kern_addr_valid(addr) (1)
extern int vmem_add_mapping(unsigned long start, unsigned long size);
extern int vmem_remove_mapping(unsigned long start, unsigned long size);
extern int s390_enable_sie(void);
/*
* No page table caches to initialise
*/
static inline void pgtable_cache_init(void) { }
static inline void check_pgt_cache(void) { }
#include <asm-generic/pgtable.h>
#endif /* _S390_PAGE_H */