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arm64: mm: only wrprotect clean ptes if they are present 

Marking non-present ptes as read-only can corrupt file ptes, breaking
things like swap and file mappings.

This patch ensures that we only manipulate user pte bits when the pte
is marked present.

Cc: <stable@vger.kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon 2013-01-09 11:08:10 +00:00 committed by Catalin Marinas
parent bdba0051eb
commit 02522463c8
1 changed files with 9 additions and 7 deletions
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16
arch/arm64/include/asm/pgtable.h
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@ -132,9 +132,8 @@ extern struct page *empty_zero_page;
#define pte_write(pte) (!(pte_val(pte) & PTE_RDONLY))
#define pte_exec(pte) (!(pte_val(pte) & PTE_UXN))
#define pte_present_exec_user(pte) \
((pte_val(pte) & (PTE_VALID | PTE_USER | PTE_UXN)) == \
(PTE_VALID | PTE_USER))
#define pte_present_user(pte) \
((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER))
#define PTE_BIT_FUNC(fn,op) \
static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
@ -157,10 +156,13 @@ extern void __sync_icache_dcache(pte_t pteval, unsigned long addr);
static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
if (pte_present_exec_user(pte))
__sync_icache_dcache(pte, addr);
if (!pte_dirty(pte))
pte = pte_wrprotect(pte);
if (pte_present_user(pte)) {
if (pte_exec(pte))
__sync_icache_dcache(pte, addr);
if (!pte_dirty(pte))
pte = pte_wrprotect(pte);
}
set_pte(ptep, pte);
}