[PATCH v14 10/26] x86/mm: Update pte_modify for _PAGE_COW
From: Yu-cheng Yu <hidden>
Date: 2020-10-09 18:34:01
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Pte_modify() changes a PTE to 'newprot'. It doesn't use the pte_*() helpers that a previous patch fixed up, so we need a new site. Introduce fixup_dirty_pte() to set the dirty bits based on _PAGE_RW, and apply the same changes to pmd_modify(). Signed-off-by: Yu-cheng Yu <redacted> v14: - Update fixup_dirty_pte() and fixup_dirty_pmd() with cpu_feature_enabled(X86_FEATURE_SHSTK). v10: - Replace _PAGE_CHG_MASK approach with fixup functions. --- arch/x86/include/asm/pgtable.h | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index ac4ed814be96..8d4c09831e67 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h@@ -727,6 +727,21 @@ static inline pmd_t pmd_mkinvalid(pmd_t pmd) static inline u64 flip_protnone_guard(u64 oldval, u64 val, u64 mask); +static inline pteval_t fixup_dirty_pte(pteval_t pteval) +{ + pte_t pte = __pte(pteval); + + if (cpu_feature_enabled(X86_FEATURE_SHSTK) && pte_dirty(pte)) { + pte = pte_mkclean(pte); + + if (pte_flags(pte) & _PAGE_RW) + pte = pte_set_flags(pte, _PAGE_DIRTY_HW); + else + pte = pte_set_flags(pte, _PAGE_COW); + } + return pte_val(pte); +} + static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { pteval_t val = pte_val(pte), oldval = val;
@@ -737,16 +752,34 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) */ val &= _PAGE_CHG_MASK; val |= check_pgprot(newprot) & ~_PAGE_CHG_MASK; + val = fixup_dirty_pte(val); val = flip_protnone_guard(oldval, val, PTE_PFN_MASK); return __pte(val); } +static inline int pmd_write(pmd_t pmd); +static inline pmdval_t fixup_dirty_pmd(pmdval_t pmdval) +{ + pmd_t pmd = __pmd(pmdval); + + if (cpu_feature_enabled(X86_FEATURE_SHSTK) && pmd_dirty(pmd)) { + pmd = pmd_mkclean(pmd); + + if (pmd_flags(pmd) & _PAGE_RW) + pmd = pmd_set_flags(pmd, _PAGE_DIRTY_HW); + else + pmd = pmd_set_flags(pmd, _PAGE_COW); + } + return pmd_val(pmd); +} + static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) { pmdval_t val = pmd_val(pmd), oldval = val; val &= _HPAGE_CHG_MASK; val |= check_pgprot(newprot) & ~_HPAGE_CHG_MASK; + val = fixup_dirty_pmd(val); val = flip_protnone_guard(oldval, val, PHYSICAL_PMD_PAGE_MASK); return __pmd(val); }
--
2.21.0