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authorWill Deacon <will.deacon@arm.com>2014-05-27 19:11:58 +0100
committerWill Deacon <will.deacon@arm.com>2014-05-29 11:31:14 +0100
commitceb218359de22e70980801d4fa04fffbfc44adb8 (patch)
tree2dcc2e79259de68babe78e3a1c4d20641dd7ff7c
parentc7208164e66f63e3ec1759b98087849286410741 (diff)
downloadlinux-ceb218359de22e70980801d4fa04fffbfc44adb8.tar.gz
arm64: mm: fix pmd_write CoW brokenness
Commit 9c7e535fcc17 ("arm64: mm: Route pmd thp functions through pte equivalents") changed the pmd manipulator and accessor functions to convert the target pmd to a pte, process it with the pte functions, then convert it back. Along the way, we gained support for PTE_WRITE, however this is completely ignored by set_pmd_at, and so we fail to set the PMD_SECT_RDONLY for PMDs, resulting in all sorts of lovely failures (like CoW not working). Partially reverting the offending commit (by making use of PMD_SECT_RDONLY explicitly for pmd_{write,wrprotect,mkwrite} functions) leads to further issues because pmd_write can then return potentially incorrect values for page table entries marked as RDONLY, leading to BUG_ON(pmd_write(entry)) tripping under some THP workloads. This patch fixes the issue by routing set_pmd_at through set_pte_at, which correctly takes the PTE_WRITE flag into account. Given that THP mappings are always anonymous, the additional cache-flushing code in __sync_icache_dcache won't impose any significant overhead as the flush will be skipped. Cc: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Tested-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
-rw-r--r--arch/arm64/include/asm/pgtable.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 90c811f05a2..7b1c67a0b48 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -266,7 +266,7 @@ static inline pmd_t pte_pmd(pte_t pte)
#define pmd_page(pmd) pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
-#define set_pmd_at(mm, addr, pmdp, pmd) set_pmd(pmdp, pmd)
+#define set_pmd_at(mm, addr, pmdp, pmd) set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd))
static inline int has_transparent_hugepage(void)
{