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linux/include/asm-mn10300/pgtable.h
Nick Piggin 7e675137a8 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 08:58:23 -07:00

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/* MN10300 Page table manipulators and constants
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*
*
* The Linux memory management assumes a three-level page table setup. On
* the i386, we use that, but "fold" the mid level into the top-level page
* table, so that we physically have the same two-level page table as the
* i386 mmu expects.
*
* This file contains the functions and defines necessary to modify and use
* the i386 page table tree for the purposes of the MN10300 TLB handler
* functions.
*/
#ifndef _ASM_PGTABLE_H
#define _ASM_PGTABLE_H
#include <asm/cpu-regs.h>
#ifndef __ASSEMBLY__
#include <asm/processor.h>
#include <asm/cache.h>
#include <linux/threads.h>
#include <asm/bitops.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/spinlock.h>
/*
* ZERO_PAGE is a global shared page that is always zero: used
* for zero-mapped memory areas etc..
*/
#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
extern unsigned long empty_zero_page[1024];
extern spinlock_t pgd_lock;
extern struct page *pgd_list;
extern void pmd_ctor(void *, struct kmem_cache *, unsigned long);
extern void pgtable_cache_init(void);
extern void paging_init(void);
#endif /* !__ASSEMBLY__ */
/*
* The Linux mn10300 paging architecture only implements both the traditional
* 2-level page tables
*/
#define PGDIR_SHIFT 22
#define PTRS_PER_PGD 1024
#define PTRS_PER_PUD 1 /* we don't really have any PUD physically */
#define PTRS_PER_PMD 1 /* we don't really have any PMD physically */
#define PTRS_PER_PTE 1024
#define PGD_SIZE PAGE_SIZE
#define PMD_SIZE (1UL << PMD_SHIFT)
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE - 1))
#define USER_PTRS_PER_PGD (TASK_SIZE / PGDIR_SIZE)
#define FIRST_USER_ADDRESS 0
#define USER_PGD_PTRS (PAGE_OFFSET >> PGDIR_SHIFT)
#define KERNEL_PGD_PTRS (PTRS_PER_PGD - USER_PGD_PTRS)
#define TWOLEVEL_PGDIR_SHIFT 22
#define BOOT_USER_PGD_PTRS (__PAGE_OFFSET >> TWOLEVEL_PGDIR_SHIFT)
#define BOOT_KERNEL_PGD_PTRS (1024 - BOOT_USER_PGD_PTRS)
#ifndef __ASSEMBLY__
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
#endif
/*
* Unfortunately, due to the way the MMU works on the MN10300, the vmalloc VM
* area has to be in the lower half of the virtual address range (the upper
* half is not translated through the TLB).
*
* So in this case, the vmalloc area goes at the bottom of the address map
* (leaving a hole at the very bottom to catch addressing errors), and
* userspace starts immediately above.
*
* The vmalloc() routines also leaves a hole of 4kB between each vmalloced
* area to catch addressing errors.
*/
#define VMALLOC_OFFSET (8 * 1024 * 1024)
#define VMALLOC_START (0x70000000)
#define VMALLOC_END (0x7C000000)
#ifndef __ASSEMBLY__
extern pte_t kernel_vmalloc_ptes[(VMALLOC_END - VMALLOC_START) / PAGE_SIZE];
#endif
/* IPTEL/DPTEL bit assignments */
#define _PAGE_BIT_VALID xPTEL_V_BIT
#define _PAGE_BIT_ACCESSED xPTEL_UNUSED1_BIT /* mustn't be loaded into IPTEL/DPTEL */
#define _PAGE_BIT_NX xPTEL_UNUSED2_BIT /* mustn't be loaded into IPTEL/DPTEL */
#define _PAGE_BIT_CACHE xPTEL_C_BIT
#define _PAGE_BIT_PRESENT xPTEL_PV_BIT
#define _PAGE_BIT_DIRTY xPTEL_D_BIT
#define _PAGE_BIT_GLOBAL xPTEL_G_BIT
#define _PAGE_VALID xPTEL_V
#define _PAGE_ACCESSED xPTEL_UNUSED1
#define _PAGE_NX xPTEL_UNUSED2 /* no-execute bit */
#define _PAGE_CACHE xPTEL_C
#define _PAGE_PRESENT xPTEL_PV
#define _PAGE_DIRTY xPTEL_D
#define _PAGE_PROT xPTEL_PR
#define _PAGE_PROT_RKNU xPTEL_PR_ROK
#define _PAGE_PROT_WKNU xPTEL_PR_RWK
#define _PAGE_PROT_RKRU xPTEL_PR_ROK_ROU
#define _PAGE_PROT_WKRU xPTEL_PR_RWK_ROU
#define _PAGE_PROT_WKWU xPTEL_PR_RWK_RWU
#define _PAGE_GLOBAL xPTEL_G
#define _PAGE_PSE xPTEL_PS_4Mb /* 4MB page */
#define _PAGE_FILE xPTEL_UNUSED1_BIT /* set:pagecache unset:swap */
#define __PAGE_PROT_UWAUX 0x040
#define __PAGE_PROT_USER 0x080
#define __PAGE_PROT_WRITE 0x100
#define _PAGE_PRESENTV (_PAGE_PRESENT|_PAGE_VALID)
#define _PAGE_PROTNONE 0x000 /* If not present */
#ifndef __ASSEMBLY__
#define VMALLOC_VMADDR(x) ((unsigned long)(x))
#define _PAGE_TABLE (_PAGE_PRESENTV | _PAGE_PROT_WKNU | _PAGE_ACCESSED | _PAGE_DIRTY)
#define _PAGE_CHG_MASK (PTE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
#define __PAGE_NONE (_PAGE_PRESENTV | _PAGE_PROT_RKNU | _PAGE_ACCESSED | _PAGE_CACHE)
#define __PAGE_SHARED (_PAGE_PRESENTV | _PAGE_PROT_WKWU | _PAGE_ACCESSED | _PAGE_CACHE)
#define __PAGE_COPY (_PAGE_PRESENTV | _PAGE_PROT_RKRU | _PAGE_ACCESSED | _PAGE_CACHE)
#define __PAGE_READONLY (_PAGE_PRESENTV | _PAGE_PROT_RKRU | _PAGE_ACCESSED | _PAGE_CACHE)
#define PAGE_NONE __pgprot(__PAGE_NONE | _PAGE_NX)
#define PAGE_SHARED_NOEXEC __pgprot(__PAGE_SHARED | _PAGE_NX)
#define PAGE_COPY_NOEXEC __pgprot(__PAGE_COPY | _PAGE_NX)
#define PAGE_READONLY_NOEXEC __pgprot(__PAGE_READONLY | _PAGE_NX)
#define PAGE_SHARED_EXEC __pgprot(__PAGE_SHARED)
#define PAGE_COPY_EXEC __pgprot(__PAGE_COPY)
#define PAGE_READONLY_EXEC __pgprot(__PAGE_READONLY)
#define PAGE_COPY PAGE_COPY_NOEXEC
#define PAGE_READONLY PAGE_READONLY_NOEXEC
#define PAGE_SHARED PAGE_SHARED_EXEC
#define __PAGE_KERNEL_BASE (_PAGE_PRESENTV | _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_GLOBAL)
#define __PAGE_KERNEL (__PAGE_KERNEL_BASE | _PAGE_PROT_WKNU | _PAGE_CACHE | _PAGE_NX)
#define __PAGE_KERNEL_NOCACHE (__PAGE_KERNEL_BASE | _PAGE_PROT_WKNU | _PAGE_NX)
#define __PAGE_KERNEL_EXEC (__PAGE_KERNEL & ~_PAGE_NX)
#define __PAGE_KERNEL_RO (__PAGE_KERNEL_BASE | _PAGE_PROT_RKNU | _PAGE_CACHE | _PAGE_NX)
#define __PAGE_KERNEL_LARGE (__PAGE_KERNEL | _PAGE_PSE)
#define __PAGE_KERNEL_LARGE_EXEC (__PAGE_KERNEL_EXEC | _PAGE_PSE)
#define PAGE_KERNEL __pgprot(__PAGE_KERNEL)
#define PAGE_KERNEL_RO __pgprot(__PAGE_KERNEL_RO)
#define PAGE_KERNEL_EXEC __pgprot(__PAGE_KERNEL_EXEC)
#define PAGE_KERNEL_NOCACHE __pgprot(__PAGE_KERNEL_NOCACHE)
#define PAGE_KERNEL_LARGE __pgprot(__PAGE_KERNEL_LARGE)
#define PAGE_KERNEL_LARGE_EXEC __pgprot(__PAGE_KERNEL_LARGE_EXEC)
/*
* Whilst the MN10300 can do page protection for execute (given separate data
* and insn TLBs), we are not supporting it at the moment. Write permission,
* however, always implies read permission (but not execute permission).
*/
#define __P000 PAGE_NONE
#define __P001 PAGE_READONLY_NOEXEC
#define __P010 PAGE_COPY_NOEXEC
#define __P011 PAGE_COPY_NOEXEC
#define __P100 PAGE_READONLY_EXEC
#define __P101 PAGE_READONLY_EXEC
#define __P110 PAGE_COPY_EXEC
#define __P111 PAGE_COPY_EXEC
#define __S000 PAGE_NONE
#define __S001 PAGE_READONLY_NOEXEC
#define __S010 PAGE_SHARED_NOEXEC
#define __S011 PAGE_SHARED_NOEXEC
#define __S100 PAGE_READONLY_EXEC
#define __S101 PAGE_READONLY_EXEC
#define __S110 PAGE_SHARED_EXEC
#define __S111 PAGE_SHARED_EXEC
/*
* Define this to warn about kernel memory accesses that are
* done without a 'verify_area(VERIFY_WRITE,..)'
*/
#undef TEST_VERIFY_AREA
#define pte_present(x) (pte_val(x) & _PAGE_VALID)
#define pte_clear(mm, addr, xp) \
do { \
set_pte_at((mm), (addr), (xp), __pte(0)); \
} while (0)
#define pmd_none(x) (!pmd_val(x))
#define pmd_present(x) (!pmd_none(x))
#define pmd_clear(xp) do { set_pmd(xp, __pmd(0)); } while (0)
#define pmd_bad(x) 0
#define pages_to_mb(x) ((x) >> (20 - PAGE_SHIFT))
#ifndef __ASSEMBLY__
/*
* The following only work if pte_present() is true.
* Undefined behaviour if not..
*/
static inline int pte_user(pte_t pte) { return pte_val(pte) & __PAGE_PROT_USER; }
static inline int pte_read(pte_t pte) { return pte_val(pte) & __PAGE_PROT_USER; }
static inline int pte_dirty(pte_t pte) { return pte_val(pte) & _PAGE_DIRTY; }
static inline int pte_young(pte_t pte) { return pte_val(pte) & _PAGE_ACCESSED; }
static inline int pte_write(pte_t pte) { return pte_val(pte) & __PAGE_PROT_WRITE; }
static inline int pte_special(pte_t pte){ return 0; }
/*
* The following only works if pte_present() is not true.
*/
static inline int pte_file(pte_t pte) { return pte_val(pte) & _PAGE_FILE; }
static inline pte_t pte_rdprotect(pte_t pte)
{
pte_val(pte) &= ~(__PAGE_PROT_USER|__PAGE_PROT_UWAUX); return pte;
}
static inline pte_t pte_exprotect(pte_t pte)
{
pte_val(pte) |= _PAGE_NX; return pte;
}
static inline pte_t pte_wrprotect(pte_t pte)
{
pte_val(pte) &= ~(__PAGE_PROT_WRITE|__PAGE_PROT_UWAUX); return pte;
}
static inline pte_t pte_mkclean(pte_t pte) { pte_val(pte) &= ~_PAGE_DIRTY; return pte; }
static inline pte_t pte_mkold(pte_t pte) { pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkdirty(pte_t pte) { pte_val(pte) |= _PAGE_DIRTY; return pte; }
static inline pte_t pte_mkyoung(pte_t pte) { pte_val(pte) |= _PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkexec(pte_t pte) { pte_val(pte) &= ~_PAGE_NX; return pte; }
static inline pte_t pte_mkread(pte_t pte)
{
pte_val(pte) |= __PAGE_PROT_USER;
if (pte_write(pte))
pte_val(pte) |= __PAGE_PROT_UWAUX;
return pte;
}
static inline pte_t pte_mkwrite(pte_t pte)
{
pte_val(pte) |= __PAGE_PROT_WRITE;
if (pte_val(pte) & __PAGE_PROT_USER)
pte_val(pte) |= __PAGE_PROT_UWAUX;
return pte;
}
static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
#define pte_ERROR(e) \
printk(KERN_ERR "%s:%d: bad pte %08lx.\n", \
__FILE__, __LINE__, pte_val(e))
#define pgd_ERROR(e) \
printk(KERN_ERR "%s:%d: bad pgd %08lx.\n", \
__FILE__, __LINE__, pgd_val(e))
/*
* The "pgd_xxx()" functions here 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)
*/
#define pgd_clear(xp) do { } while (0)
/*
* Certain architectures need to do special things when PTEs
* within a page table are directly modified. Thus, the following
* hook is made available.
*/
#define set_pte(pteptr, pteval) (*(pteptr) = pteval)
#define set_pte_at(mm, addr, ptep, pteval) set_pte((ptep), (pteval))
#define set_pte_atomic(pteptr, pteval) set_pte((pteptr), (pteval))
/*
* (pmds are folded into pgds so this doesn't get actually called,
* but the define is needed for a generic inline function.)
*/
#define set_pmd(pmdptr, pmdval) (*(pmdptr) = pmdval)
#define ptep_get_and_clear(mm, addr, ptep) \
__pte(xchg(&(ptep)->pte, 0))
#define pte_same(a, b) (pte_val(a) == pte_val(b))
#define pte_page(x) pfn_to_page(pte_pfn(x))
#define pte_none(x) (!pte_val(x))
#define pte_pfn(x) ((unsigned long) (pte_val(x) >> PAGE_SHIFT))
#define __pfn_addr(pfn) ((pfn) << PAGE_SHIFT)
#define pfn_pte(pfn, prot) __pte(__pfn_addr(pfn) | pgprot_val(prot))
#define pfn_pmd(pfn, prot) __pmd(__pfn_addr(pfn) | pgprot_val(prot))
/*
* All present user pages are user-executable:
*/
static inline int pte_exec(pte_t pte)
{
return pte_user(pte);
}
/*
* All present pages are kernel-executable:
*/
static inline int pte_exec_kernel(pte_t pte)
{
return 1;
}
/*
* Bits 0 and 1 are taken, split up the 29 bits of offset
* into this range:
*/
#define PTE_FILE_MAX_BITS 29
#define pte_to_pgoff(pte) (pte_val(pte) >> 2)
#define pgoff_to_pte(off) __pte((off) << 2 | _PAGE_FILE)
/* Encode and de-code a swap entry */
#define __swp_type(x) (((x).val >> 2) & 0x3f)
#define __swp_offset(x) ((x).val >> 8)
#define __swp_entry(type, offset) \
((swp_entry_t) { ((type) << 2) | ((offset) << 8) })
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
#define __swp_entry_to_pte(x) __pte((x).val)
static inline
int ptep_test_and_clear_dirty(struct vm_area_struct *vma, unsigned long addr,
pte_t *ptep)
{
if (!pte_dirty(*ptep))
return 0;
return test_and_clear_bit(_PAGE_BIT_DIRTY, &ptep->pte);
}
static inline
int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long addr,
pte_t *ptep)
{
if (!pte_young(*ptep))
return 0;
return test_and_clear_bit(_PAGE_BIT_ACCESSED, &ptep->pte);
}
static inline
void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
pte_val(*ptep) &= ~(__PAGE_PROT_WRITE|__PAGE_PROT_UWAUX);
}
static inline void ptep_mkdirty(pte_t *ptep)
{
set_bit(_PAGE_BIT_DIRTY, &ptep->pte);
}
/*
* Macro to mark a page protection value as "uncacheable". On processors which
* do not support it, this is a no-op.
*/
#define pgprot_noncached(prot) __pgprot(pgprot_val(prot) | _PAGE_CACHE)
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
#define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot))
#define mk_pte_huge(entry) \
((entry).pte |= _PAGE_PRESENT | _PAGE_PSE | _PAGE_VALID)
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
pte_val(pte) &= _PAGE_CHG_MASK;
pte_val(pte) |= pgprot_val(newprot);
return pte;
}
#define page_pte(page) page_pte_prot((page), __pgprot(0))
#define pmd_page_kernel(pmd) \
((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
#define pmd_page(pmd) pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
#define pmd_large(pmd) \
((pmd_val(pmd) & (_PAGE_PSE | _PAGE_PRESENT)) == \
(_PAGE_PSE | _PAGE_PRESENT))
/*
* the pgd page can be thought of an array like this: pgd_t[PTRS_PER_PGD]
*
* this macro returns the index of the entry in the pgd page which would
* control the given virtual address
*/
#define pgd_index(address) (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
/*
* pgd_offset() returns a (pgd_t *)
* pgd_index() is used get the offset into the pgd page's array of pgd_t's;
*/
#define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address))
/*
* a shortcut which implies the use of the kernel's pgd, instead
* of a process's
*/
#define pgd_offset_k(address) pgd_offset(&init_mm, address)
/*
* the pmd page can be thought of an array like this: pmd_t[PTRS_PER_PMD]
*
* this macro returns the index of the entry in the pmd page which would
* control the given virtual address
*/
#define pmd_index(address) \
(((address) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
/*
* the pte page can be thought of an array like this: pte_t[PTRS_PER_PTE]
*
* this macro returns the index of the entry in the pte page which would
* control the given virtual address
*/
#define pte_index(address) \
(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
#define pte_offset_kernel(dir, address) \
((pte_t *) pmd_page_kernel(*(dir)) + pte_index(address))
/*
* Make a given kernel text page executable/non-executable.
* Returns the previous executability setting of that page (which
* is used to restore the previous state). Used by the SMP bootup code.
* NOTE: this is an __init function for security reasons.
*/
static inline int set_kernel_exec(unsigned long vaddr, int enable)
{
return 0;
}
#define pte_offset_map(dir, address) \
((pte_t *) page_address(pmd_page(*(dir))) + pte_index(address))
#define pte_offset_map_nested(dir, address) pte_offset_map(dir, address)
#define pte_unmap(pte) do {} while (0)
#define pte_unmap_nested(pte) do {} while (0)
/*
* The MN10300 has external MMU info in the form of a TLB: this is adapted from
* the kernel page tables containing the necessary information by tlb-mn10300.S
*/
extern void update_mmu_cache(struct vm_area_struct *vma,
unsigned long address, pte_t pte);
#endif /* !__ASSEMBLY__ */
#define kern_addr_valid(addr) (1)
#define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
remap_pfn_range((vma), (vaddr), (pfn), (size), (prot))
#define MK_IOSPACE_PFN(space, pfn) (pfn)
#define GET_IOSPACE(pfn) 0
#define GET_PFN(pfn) (pfn)
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY
#define __HAVE_ARCH_PTEP_GET_AND_CLEAR
#define __HAVE_ARCH_PTEP_SET_WRPROTECT
#define __HAVE_ARCH_PTEP_MKDIRTY
#define __HAVE_ARCH_PTE_SAME
#include <asm-generic/pgtable.h>
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_PGTABLE_H */
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