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| author | Steve Capper <steve.capper@linaro.org> | 2013-05-17 12:32:55 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-02-05 22:35:38 -0800 |
| commit | 171b1455b3f59346412848703a41a9a8019c99c9 (patch) | |
| tree | acfed073a7c95d3d8c9ba4213a8a3b3da723c897 | |
| parent | 30e2adb098750046be48eb595a7c6732a4293d54 (diff) | |
| download | lwn-171b1455b3f59346412848703a41a9a8019c99c9.tar.gz lwn-171b1455b3f59346412848703a41a9a8019c99c9.zip | |
ARM: mm: correct pte_same behaviour for LPAE.
commit dde1b65110353517816bcbc58539463396202244 upstream.
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: Steve Capper <steve.capper@linaro.org>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Cc: Hou Pengyang <houpengyang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/arm/include/asm/pgtable-3level.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h index 86b8fe398b95..70f041cb50d1 100644 --- a/arch/arm/include/asm/pgtable-3level.h +++ b/arch/arm/include/asm/pgtable-3level.h @@ -166,6 +166,23 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr) 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))) #endif /* __ASSEMBLY__ */ |