From 004fc58f917cfea5d7190139e3ed1b7a13e39c25 Mon Sep 17 00:00:00 2001 From: Anshuman Khandual Date: Mon, 30 Jan 2023 17:44:57 +0530 Subject: arm64/mm: Intercept pfn changes in set_pte_at() Changing pfn on a user page table mapped entry, without first going through break-before-make (BBM) procedure is unsafe. This just updates set_pte_at() to intercept such changes, via an updated pgattr_change_is_safe(). This new check happens via __check_racy_pte_update(), which has now been renamed as __check_safe_pte_update(). Cc: Will Deacon Cc: Mark Rutland Cc: Andrew Morton Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Acked-by: Mark Rutland Signed-off-by: Anshuman Khandual Link: https://lore.kernel.org/r/20230130121457.1607675-1-anshuman.khandual@arm.com Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/pgtable.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'arch/arm64/include/asm/pgtable.h') diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index b4bbeed80fb6..832c9c8fb58f 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -275,6 +275,7 @@ static inline void set_pte(pte_t *ptep, pte_t pte) } extern void __sync_icache_dcache(pte_t pteval); +bool pgattr_change_is_safe(u64 old, u64 new); /* * PTE bits configuration in the presence of hardware Dirty Bit Management @@ -292,7 +293,7 @@ extern void __sync_icache_dcache(pte_t pteval); * PTE_DIRTY || (PTE_WRITE && !PTE_RDONLY) */ -static inline void __check_racy_pte_update(struct mm_struct *mm, pte_t *ptep, +static inline void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, pte_t pte) { pte_t old_pte; @@ -318,6 +319,9 @@ static inline void __check_racy_pte_update(struct mm_struct *mm, pte_t *ptep, VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte), "%s: racy dirty state clearing: 0x%016llx -> 0x%016llx", __func__, pte_val(old_pte), pte_val(pte)); + VM_WARN_ONCE(!pgattr_change_is_safe(pte_val(old_pte), pte_val(pte)), + "%s: unsafe attribute change: 0x%016llx -> 0x%016llx", + __func__, pte_val(old_pte), pte_val(pte)); } static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, @@ -346,7 +350,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, mte_sync_tags(old_pte, pte); } - __check_racy_pte_update(mm, ptep, pte); + __check_safe_pte_update(mm, ptep, pte); set_pte(ptep, pte); } -- cgit