Commit dde1b651 authored by Steve Capper's avatar Steve Capper

ARM: mm: correct pte_same behaviour for LPAE.

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.

This can cause some comparison tests made by pte_same to fail
spuriously and lead to other problems.

To correct this behaviour, we mask off PTE_EXT_NG for any pte that
is present before running the comparison.
Signed-off-by: default avatarSteve Capper <steve.capper@linaro.org>
Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
parent e4aa937e
...@@ -166,6 +166,23 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr) ...@@ -166,6 +166,23 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
clean_pmd_entry(pmdp); \ clean_pmd_entry(pmdp); \
} while (0) } 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 set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,__pte(pte_val(pte)|(ext)))
#endif /* __ASSEMBLY__ */ #endif /* __ASSEMBLY__ */
......
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