[PATCH v4 5/7] mm/x86: arch_check_zapped_pud()
From: Peter Xu <peterx@redhat.com>
Date: 2024-08-07 19:48:29
Also in:
lkml
Subsystem:
memory management, memory management - core, memory management - thp (transparent huge page), the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers:
Andrew Morton, David Hildenbrand, Lorenzo Stoakes, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra
Introduce arch_check_zapped_pud() to sanity check shadow stack on PUD zaps. It has the same logic of the PMD helper. One thing to mention is, it might be a good idea to use page_table_check in the future for trapping wrong setups of shadow stack pgtable entries [1]. That is left for the future as a separate effort. [1] https://lore.kernel.org/all/59d518698f664e07c036a5098833d7b56b953305.camel@intel.com (local) Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com> Cc: Thomas Gleixner <redacted> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: x86@kernel.org Acked-by: David Hildenbrand <redacted> Signed-off-by: Peter Xu <peterx@redhat.com> --- arch/x86/include/asm/pgtable.h | 10 ++++++++++ arch/x86/mm/pgtable.c | 7 +++++++ include/linux/pgtable.h | 7 +++++++ mm/huge_memory.c | 4 +++- 4 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index a2a3bd4c1bda..fdb8ac9e7030 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h@@ -174,6 +174,13 @@ static inline int pud_young(pud_t pud) return pud_flags(pud) & _PAGE_ACCESSED; } +static inline bool pud_shstk(pud_t pud) +{ + return cpu_feature_enabled(X86_FEATURE_SHSTK) && + (pud_flags(pud) & (_PAGE_RW | _PAGE_DIRTY | _PAGE_PSE)) == + (_PAGE_DIRTY | _PAGE_PSE); +} + static inline int pte_write(pte_t pte) { /*
@@ -1667,6 +1674,9 @@ void arch_check_zapped_pte(struct vm_area_struct *vma, pte_t pte); #define arch_check_zapped_pmd arch_check_zapped_pmd void arch_check_zapped_pmd(struct vm_area_struct *vma, pmd_t pmd); +#define arch_check_zapped_pud arch_check_zapped_pud +void arch_check_zapped_pud(struct vm_area_struct *vma, pud_t pud); + #ifdef CONFIG_XEN_PV #define arch_has_hw_nonleaf_pmd_young arch_has_hw_nonleaf_pmd_young static inline bool arch_has_hw_nonleaf_pmd_young(void)
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index f5931499c2d6..d4b3ccf90236 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c@@ -926,3 +926,10 @@ void arch_check_zapped_pmd(struct vm_area_struct *vma, pmd_t pmd) VM_WARN_ON_ONCE(!(vma->vm_flags & VM_SHADOW_STACK) && pmd_shstk(pmd)); } + +void arch_check_zapped_pud(struct vm_area_struct *vma, pud_t pud) +{ + /* See note in arch_check_zapped_pte() */ + VM_WARN_ON_ONCE(!(vma->vm_flags & VM_SHADOW_STACK) && + pud_shstk(pud)); +}
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 2a6a3cccfc36..2289e9f7aa1b 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h@@ -447,6 +447,13 @@ static inline void arch_check_zapped_pmd(struct vm_area_struct *vma, } #endif +#ifndef arch_check_zapped_pud +static inline void arch_check_zapped_pud(struct vm_area_struct *vma, + pud_t pud) +{ +} +#endif + #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long address,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 0024266dea0a..81c5da0708ed 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -2293,12 +2293,14 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, pud_t *pud, unsigned long addr) { spinlock_t *ptl; + pud_t orig_pud; ptl = __pud_trans_huge_lock(pud, vma); if (!ptl) return 0; - pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); + orig_pud = pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); + arch_check_zapped_pud(vma, orig_pud); tlb_remove_pud_tlb_entry(tlb, pud, addr); if (vma_is_special_huge(vma)) { spin_unlock(ptl);
--
2.45.0