[PATCH v8 16/27] mm: Handle THP/HugeTLB shadow stack page fault
From: Yu-cheng Yu <hidden>
Date: 2019-08-13 21:05:16
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
generic include/asm header files, memory management, memory management - thp (transparent huge page), the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers:
Arnd Bergmann, Andrew Morton, David Hildenbrand, Lorenzo Stoakes, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra
This patch implements THP shadow stack (SHSTK) copying in the same way as in the previous patch for regular PTE. In copy_huge_pmd(), clear the dirty bit from the PMD to cause a page fault upon the next SHSTK access to the PMD. At that time, fix the PMD and copy/re-use the page. Signed-off-by: Yu-cheng Yu <redacted> --- arch/x86/mm/pgtable.c | 8 ++++++++ include/asm-generic/pgtable.h | 6 ++++++ mm/huge_memory.c | 4 ++++ 3 files changed, 18 insertions(+)
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 0c10d0c5e329..6f3959ca2a08 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c@@ -886,6 +886,14 @@ inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) return pte; } +inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_SHSTK) + return pmd_mkdirty_shstk(pmd); + else + return pmd; +} + inline bool arch_copy_pte_mapping(vm_flags_t vm_flags) { return (vm_flags & VM_SHSTK);
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 89b0fa132f1f..438ce73b57ea 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h@@ -1194,12 +1194,18 @@ static inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) return pte; } +static inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) +{ + return pmd; +} + static inline bool arch_copy_pte_mapping(vm_flags_t vm_flags) { return false; } #else pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma); +pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma); bool arch_copy_pte_mapping(vm_flags_t vm_flags); #endif
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1334ede667a8..39d66c628121 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -611,6 +611,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, entry = mk_huge_pmd(page, vma->vm_page_prot); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + entry = pmd_set_vma_features(entry, vma); page_add_new_anon_rmap(page, vma, haddr, true); mem_cgroup_commit_charge(page, memcg, false, true); lru_cache_add_active_or_unevictable(page, vma);
@@ -1253,6 +1254,7 @@ static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pte_t entry; entry = mk_pte(pages[i], vma->vm_page_prot); entry = maybe_mkwrite(pte_mkdirty(entry), vma); + entry = pte_set_vma_features(entry, vma); memcg = (void *)page_private(pages[i]); set_page_private(pages[i], 0); page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
@@ -1335,6 +1337,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) pmd_t entry; entry = pmd_mkyoung(orig_pmd); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + entry = pmd_set_vma_features(entry, vma); if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); ret |= VM_FAULT_WRITE;
@@ -1407,6 +1410,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) pmd_t entry; entry = mk_huge_pmd(new_page, vma->vm_page_prot); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + entry = pmd_set_vma_features(entry, vma); pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); page_add_new_anon_rmap(new_page, vma, haddr, true); mem_cgroup_commit_charge(new_page, memcg, false, true);
--
2.17.1