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Commit 02522463 authored by Will Deacon's avatar Will Deacon Committed by Catalin Marinas
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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: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent bdba0051

arch/arm64/include/asm/pgtable.h

+9 −7
Original line number Diff line number Diff line
@@ -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))

	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);

}