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linux/arch/arm/include/asm/pgtable-3level.h
Steve Capper 56530f5d2d ARM: 8579/1: mm: Fix definition of pmd_mknotpresent 
Currently pmd_mknotpresent will use a zero entry to respresent an
invalidated pmd.

Unfortunately this definition clashes with pmd_none, thus it is
possible for a race condition to occur if zap_pmd_range sees pmd_none
whilst __split_huge_pmd_locked is running too with pmdp_invalidate
just called.

This patch fixes the race condition by modifying pmd_mknotpresent to
create non-zero faulting entries (as is done in other architectures),
removing the ambiguity with pmd_none.

[catalin.marinas@arm.com: using L_PMD_SECT_VALID instead of PMD_TYPE_SECT]

Fixes: 8d96250700 ("ARM: mm: Transparent huge page support for LPAE systems.")
Cc: <stable@vger.kernel.org> # 3.11+
Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2016-06-09 17:51:47 +01:00

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/*
* arch/arm/include/asm/pgtable-3level.h
*
* Copyright (C) 2011 ARM Ltd.
* Author: Catalin Marinas <catalin.marinas@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _ASM_PGTABLE_3LEVEL_H
#define _ASM_PGTABLE_3LEVEL_H
/*
* With LPAE, there are 3 levels of page tables. Each level has 512 entries of
* 8 bytes each, occupying a 4K page. The first level table covers a range of
* 512GB, each entry representing 1GB. Since we are limited to 4GB input
* address range, only 4 entries in the PGD are used.
*
* There are enough spare bits in a page table entry for the kernel specific
* state.
*/
#define PTRS_PER_PTE 512
#define PTRS_PER_PMD 512
#define PTRS_PER_PGD 4
#define PTE_HWTABLE_PTRS (0)
#define PTE_HWTABLE_OFF (0)
#define PTE_HWTABLE_SIZE (PTRS_PER_PTE * sizeof(u64))
/*
* PGDIR_SHIFT determines the size a top-level page table entry can map.
*/
#define PGDIR_SHIFT 30
/*
* PMD_SHIFT determines the size a middle-level page table entry can map.
*/
#define PMD_SHIFT 21
#define PMD_SIZE (1UL << PMD_SHIFT)
#define PMD_MASK (~((1 << PMD_SHIFT) - 1))
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~((1 << PGDIR_SHIFT) - 1))
/*
* section address mask and size definitions.
*/
#define SECTION_SHIFT 21
#define SECTION_SIZE (1UL << SECTION_SHIFT)
#define SECTION_MASK (~((1 << SECTION_SHIFT) - 1))
#define USER_PTRS_PER_PGD (PAGE_OFFSET / PGDIR_SIZE)
/*
* Hugetlb definitions.
*/
#define HPAGE_SHIFT PMD_SHIFT
#define HPAGE_SIZE (_AC(1, UL) << HPAGE_SHIFT)
#define HPAGE_MASK (~(HPAGE_SIZE - 1))
#define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
/*
* "Linux" PTE definitions for LPAE.
*
* These bits overlap with the hardware bits but the naming is preserved for
* consistency with the classic page table format.
*/
#define L_PTE_VALID (_AT(pteval_t, 1) << 0) /* Valid */
#define L_PTE_PRESENT (_AT(pteval_t, 3) << 0) /* Present */
#define L_PTE_USER (_AT(pteval_t, 1) << 6) /* AP[1] */
#define L_PTE_SHARED (_AT(pteval_t, 3) << 8) /* SH[1:0], inner shareable */
#define L_PTE_YOUNG (_AT(pteval_t, 1) << 10) /* AF */
#define L_PTE_XN (_AT(pteval_t, 1) << 54) /* XN */
#define L_PTE_DIRTY (_AT(pteval_t, 1) << 55)
#define L_PTE_SPECIAL (_AT(pteval_t, 1) << 56)
#define L_PTE_NONE (_AT(pteval_t, 1) << 57) /* PROT_NONE */
#define L_PTE_RDONLY (_AT(pteval_t, 1) << 58) /* READ ONLY */
#define L_PMD_SECT_VALID (_AT(pmdval_t, 1) << 0)
#define L_PMD_SECT_DIRTY (_AT(pmdval_t, 1) << 55)
#define L_PMD_SECT_NONE (_AT(pmdval_t, 1) << 57)
#define L_PMD_SECT_RDONLY (_AT(pteval_t, 1) << 58)
/*
* To be used in assembly code with the upper page attributes.
*/
#define L_PTE_XN_HIGH (1 << (54 - 32))
#define L_PTE_DIRTY_HIGH (1 << (55 - 32))
/*
* AttrIndx[2:0] encoding (mapping attributes defined in the MAIR* registers).
*/
#define L_PTE_MT_UNCACHED (_AT(pteval_t, 0) << 2) /* strongly ordered */
#define L_PTE_MT_BUFFERABLE (_AT(pteval_t, 1) << 2) /* normal non-cacheable */
#define L_PTE_MT_WRITETHROUGH (_AT(pteval_t, 2) << 2) /* normal inner write-through */
#define L_PTE_MT_WRITEBACK (_AT(pteval_t, 3) << 2) /* normal inner write-back */
#define L_PTE_MT_WRITEALLOC (_AT(pteval_t, 7) << 2) /* normal inner write-alloc */
#define L_PTE_MT_DEV_SHARED (_AT(pteval_t, 4) << 2) /* device */
#define L_PTE_MT_DEV_NONSHARED (_AT(pteval_t, 4) << 2) /* device */
#define L_PTE_MT_DEV_WC (_AT(pteval_t, 1) << 2) /* normal non-cacheable */
#define L_PTE_MT_DEV_CACHED (_AT(pteval_t, 3) << 2) /* normal inner write-back */
#define L_PTE_MT_MASK (_AT(pteval_t, 7) << 2)
/*
* Software PGD flags.
*/
#define L_PGD_SWAPPER (_AT(pgdval_t, 1) << 55) /* swapper_pg_dir entry */
/*
* 2nd stage PTE definitions for LPAE.
*/
#define L_PTE_S2_MT_UNCACHED (_AT(pteval_t, 0x0) << 2) /* strongly ordered */
#define L_PTE_S2_MT_WRITETHROUGH (_AT(pteval_t, 0xa) << 2) /* normal inner write-through */
#define L_PTE_S2_MT_WRITEBACK (_AT(pteval_t, 0xf) << 2) /* normal inner write-back */
#define L_PTE_S2_MT_DEV_SHARED (_AT(pteval_t, 0x1) << 2) /* device */
#define L_PTE_S2_MT_MASK (_AT(pteval_t, 0xf) << 2)
#define L_PTE_S2_RDONLY (_AT(pteval_t, 1) << 6) /* HAP[1] */
#define L_PTE_S2_RDWR (_AT(pteval_t, 3) << 6) /* HAP[2:1] */
#define L_PMD_S2_RDONLY (_AT(pmdval_t, 1) << 6) /* HAP[1] */
#define L_PMD_S2_RDWR (_AT(pmdval_t, 3) << 6) /* HAP[2:1] */
/*
* Hyp-mode PL2 PTE definitions for LPAE.
*/
#define L_PTE_HYP L_PTE_USER
#ifndef __ASSEMBLY__
#define pud_none(pud) (!pud_val(pud))
#define pud_bad(pud) (!(pud_val(pud) & 2))
#define pud_present(pud) (pud_val(pud))
#define pmd_table(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \
PMD_TYPE_TABLE)
#define pmd_sect(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \
PMD_TYPE_SECT)
#define pmd_large(pmd) pmd_sect(pmd)
#define pud_clear(pudp) \
do { \
*pudp = __pud(0); \
clean_pmd_entry(pudp); \
} while (0)
#define set_pud(pudp, pud) \
do { \
*pudp = pud; \
flush_pmd_entry(pudp); \
} while (0)
static inline pmd_t *pud_page_vaddr(pud_t pud)
{
return __va(pud_val(pud) & PHYS_MASK & (s32)PAGE_MASK);
}
/* Find an entry in the second-level page table.. */
#define pmd_index(addr) (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
{
return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(addr);
}
#define pmd_bad(pmd) (!(pmd_val(pmd) & 2))
#define copy_pmd(pmdpd,pmdps) \
do { \
*pmdpd = *pmdps; \
flush_pmd_entry(pmdpd); \
} while (0)
#define pmd_clear(pmdp) \
do { \
*pmdp = __pmd(0); \
clean_pmd_entry(pmdp); \
} while (0)
/*
* For 3 levels of paging the PTE_EXT_NG bit will be set for user address ptes
* that are written to a page table but not for ptes created with mk_pte.
*
* In hugetlb_no_page, a new huge pte (new_pte) is generated and passed to
* hugetlb_cow, where it is compared with an entry in a page table.
* This comparison test fails erroneously leading ultimately to a memory leak.
*
* To correct this behaviour, we mask off PTE_EXT_NG for any pte that is
* present before running the comparison.
*/
#define __HAVE_ARCH_PTE_SAME
#define pte_same(pte_a,pte_b) ((pte_present(pte_a) ? pte_val(pte_a) & ~PTE_EXT_NG \
: pte_val(pte_a)) \
== (pte_present(pte_b) ? pte_val(pte_b) & ~PTE_EXT_NG \
: pte_val(pte_b)))
#define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,__pte(pte_val(pte)|(ext)))
#define pte_huge(pte) (pte_val(pte) && !(pte_val(pte) & PTE_TABLE_BIT))
#define pte_mkhuge(pte) (__pte(pte_val(pte) & ~PTE_TABLE_BIT))
#define pmd_isset(pmd, val) ((u32)(val) == (val) ? pmd_val(pmd) & (val) \
: !!(pmd_val(pmd) & (val)))
#define pmd_isclear(pmd, val) (!(pmd_val(pmd) & (val)))
#define pmd_present(pmd) (pmd_isset((pmd), L_PMD_SECT_VALID))
#define pmd_young(pmd) (pmd_isset((pmd), PMD_SECT_AF))
#define pte_special(pte) (pte_isset((pte), L_PTE_SPECIAL))
static inline pte_t pte_mkspecial(pte_t pte)
{
pte_val(pte) |= L_PTE_SPECIAL;
return pte;
}
#define __HAVE_ARCH_PTE_SPECIAL
#define __HAVE_ARCH_PMD_WRITE
#define pmd_write(pmd) (pmd_isclear((pmd), L_PMD_SECT_RDONLY))
#define pmd_dirty(pmd) (pmd_isset((pmd), L_PMD_SECT_DIRTY))
#define pud_page(pud) pmd_page(__pmd(pud_val(pud)))
#define pud_write(pud) pmd_write(__pmd(pud_val(pud)))
#define pmd_hugewillfault(pmd) (!pmd_young(pmd) || !pmd_write(pmd))
#define pmd_thp_or_huge(pmd) (pmd_huge(pmd) || pmd_trans_huge(pmd))
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define pmd_trans_huge(pmd) (pmd_val(pmd) && !pmd_table(pmd))
#endif
#define PMD_BIT_FUNC(fn,op) \
static inline pmd_t pmd_##fn(pmd_t pmd) { pmd_val(pmd) op; return pmd; }
PMD_BIT_FUNC(wrprotect, |= L_PMD_SECT_RDONLY);
PMD_BIT_FUNC(mkold, &= ~PMD_SECT_AF);
PMD_BIT_FUNC(mkwrite, &= ~L_PMD_SECT_RDONLY);
PMD_BIT_FUNC(mkdirty, |= L_PMD_SECT_DIRTY);
PMD_BIT_FUNC(mkclean, &= ~L_PMD_SECT_DIRTY);
PMD_BIT_FUNC(mkyoung, |= PMD_SECT_AF);
#define pmd_mkhuge(pmd) (__pmd(pmd_val(pmd) & ~PMD_TABLE_BIT))
#define pmd_pfn(pmd) (((pmd_val(pmd) & PMD_MASK) & PHYS_MASK) >> PAGE_SHIFT)
#define pfn_pmd(pfn,prot) (__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
#define mk_pmd(page,prot) pfn_pmd(page_to_pfn(page),prot)
/* represent a notpresent pmd by faulting entry, this is used by pmdp_invalidate */
static inline pmd_t pmd_mknotpresent(pmd_t pmd)
{
return __pmd(pmd_val(pmd) & ~L_PMD_SECT_VALID);
}
static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
{
const pmdval_t mask = PMD_SECT_USER | PMD_SECT_XN | L_PMD_SECT_RDONLY |
L_PMD_SECT_VALID | L_PMD_SECT_NONE;
pmd_val(pmd) = (pmd_val(pmd) & ~mask) | (pgprot_val(newprot) & mask);
return pmd;
}
static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t pmd)
{
BUG_ON(addr >= TASK_SIZE);
/* create a faulting entry if PROT_NONE protected */
if (pmd_val(pmd) & L_PMD_SECT_NONE)
pmd_val(pmd) &= ~L_PMD_SECT_VALID;
if (pmd_write(pmd) && pmd_dirty(pmd))
pmd_val(pmd) &= ~PMD_SECT_AP2;
else
pmd_val(pmd) |= PMD_SECT_AP2;
*pmdp = __pmd(pmd_val(pmd) | PMD_SECT_nG);
flush_pmd_entry(pmdp);
}
#endif /* __ASSEMBLY__ */
#endif /* _ASM_PGTABLE_3LEVEL_H */
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