From: Steve Capper Date: Fri, 17 May 2013 11:32:55 +0000 (+0100) Subject: ARM: mm: correct pte_same behaviour for LPAE. X-Git-Tag: Ubuntu-snapdragon-4.4.0-1050.54~12215^2^2~4^2~3 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=dde1b65110353517816bcbc58539463396202244;p=mirror_ubuntu-artful-kernel.git 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: Steve Capper Reviewed-by: Will Deacon --- 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__ */