[RFC PATCH v9 15/27] mm: Handle THP/HugeTLB Shadow Stack page fault
From: Yu-cheng Yu <hidden>
Date: 2020-02-05 18:21:52
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 | 11 +++++++++++ mm/huge_memory.c | 4 ++++ 3 files changed, 23 insertions(+)
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 2eb33794c08d..3340b1d4e9da 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c@@ -886,4 +886,12 @@ inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) else 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; +} #endif /* CONFIG_X86_INTEL_SHADOW_STACK_USER */
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 9cb2f9ba5895..a9df093fdf45 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h@@ -1201,9 +1201,20 @@ static inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) { return pte; } + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) +{ + return pmd; +} +#endif #else bool arch_copy_pte_mapping(vm_flags_t vm_flags); pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma); + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma); +#endif #endif #endif /* CONFIG_MMU */
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a88093213674..93ef368df2dd 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -636,6 +636,7 @@ 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);
@@ -1278,6 +1279,7 @@ 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);
@@ -1360,6 +1362,7 @@ 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;
@@ -1432,6 +1435,7 @@ 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);
--
2.21.0