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@xxxxxxxxx Cc: "Edgecombe, Rick P" <rick.p.edgecombe@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: x86@xxxxxxxxxx Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> --- 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 25fc6d809572..cdf044c2ad6e 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -169,6 +169,13 @@ 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) { /* @@ -1662,6 +1669,9 @@ 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 93e54ba91fbf..564b8945951e 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 9fec5bd1c8b0..c10247bef08a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2291,12 +2291,14 @@ 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
