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arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect() 

With hardware dirty bit management, calling pte_wrprotect() on a writable,
dirty PTE will lose the dirty state and return a read-only, clean entry.

Move the logic from ptep_set_wrprotect() into pte_wrprotect() to ensure that
the dirty bit is preserved for writable entries, as this is required for
soft-dirty bit management if we enable it in the future.

Cc: <stable@vger.kernel.org>
Fixes: 2f4b829c62 ("arm64: Add support for hardware updates of the access and dirty pte bits")
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20201120143557.6715-3-will@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Will Deacon 2020-11-20 13:57:48 +00:00
parent 07509e10dc
commit ff1712f953
1 changed files with 14 additions and 13 deletions
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27
arch/arm64/include/asm/pgtable.h
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@ -165,13 +165,6 @@ static inline pmd_t set_pmd_bit(pmd_t pmd, pgprot_t prot)
return pmd;
}
static inline pte_t pte_wrprotect(pte_t pte)
{
pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
return pte;
}
static inline pte_t pte_mkwrite(pte_t pte)
{
pte = set_pte_bit(pte, __pgprot(PTE_WRITE));
@ -197,6 +190,20 @@ static inline pte_t pte_mkdirty(pte_t pte)
return pte;
}
static inline pte_t pte_wrprotect(pte_t pte)
{
/*
* If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
* clear), set the PTE_DIRTY bit.
*/
if (pte_hw_dirty(pte))
pte = pte_mkdirty(pte);
pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
return pte;
}
static inline pte_t pte_mkold(pte_t pte)
{
return clear_pte_bit(pte, __pgprot(PTE_AF));
@ -846,12 +853,6 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
pte = READ_ONCE(*ptep);
do {
old_pte = pte;
/*
* If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
* clear), set the PTE_DIRTY bit.
*/
if (pte_hw_dirty(pte))
pte = pte_mkdirty(pte);
pte = pte_wrprotect(pte);
pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
pte_val(old_pte), pte_val(pte));