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authorSteve Capper <steve.capper@linaro.org>2013-05-17 12:32:55 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-02-05 22:35:38 -0800
commit171b1455b3f59346412848703a41a9a8019c99c9 (patch)
treeacfed073a7c95d3d8c9ba4213a8a3b3da723c897
parent30e2adb098750046be48eb595a7c6732a4293d54 (diff)
downloadlinux-linaro-stable-171b1455b3f59346412848703a41a9a8019c99c9.tar.gz
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.h17
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__ */