From: Ryan Roberts Date: Fri, 3 May 2024 14:46:02 +0000 (+0100) Subject: arm64/mm: Add uffd write-protect support X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=5b32510af77bdb275b022dc0d6d5b9c61751065b;p=linux.git arm64/mm: Add uffd write-protect support Let's use the newly-free PTE SW bit (58) to add support for uffd-wp. The standard handlers are implemented for set/test/clear for both pte and pmd. Additionally we must also track the uffd-wp state as a pte swp bit, so use a free swap pte bit (3). Acked-by: Peter Xu Reviewed-by: Catalin Marinas Reviewed-by: David Hildenbrand Signed-off-by: Ryan Roberts Link: https://lore.kernel.org/r/20240503144604.151095-5-ryan.roberts@arm.com Signed-off-by: Will Deacon --- diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 7b11c98b3e84b..763e221f21698 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -255,6 +255,7 @@ config ARM64 select SYSCTL_EXCEPTION_TRACE select THREAD_INFO_IN_TASK select HAVE_ARCH_USERFAULTFD_MINOR if USERFAULTFD + select HAVE_ARCH_USERFAULTFD_WP if USERFAULTFD select TRACE_IRQFLAGS_SUPPORT select TRACE_IRQFLAGS_NMI_SUPPORT select HAVE_SOFTIRQ_ON_OWN_STACK diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h index 35c9de13f7ed4..b11cfb9fdd379 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -26,6 +26,14 @@ */ #define PTE_PRESENT_INVALID (PTE_NG) /* only when !PTE_VALID */ +#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP +#define PTE_UFFD_WP (_AT(pteval_t, 1) << 58) /* uffd-wp tracking */ +#define PTE_SWP_UFFD_WP (_AT(pteval_t, 1) << 3) /* only for swp ptes */ +#else +#define PTE_UFFD_WP (_AT(pteval_t, 0)) +#define PTE_SWP_UFFD_WP (_AT(pteval_t, 0)) +#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */ + #define _PROT_DEFAULT (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED) #define _PROT_SECT_DEFAULT (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 6c0e322211cb1..78fd3e2ef8c63 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -280,6 +280,23 @@ static inline pte_t pte_mkdevmap(pte_t pte) return set_pte_bit(pte, __pgprot(PTE_DEVMAP | PTE_SPECIAL)); } +#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP +static inline int pte_uffd_wp(pte_t pte) +{ + return !!(pte_val(pte) & PTE_UFFD_WP); +} + +static inline pte_t pte_mkuffd_wp(pte_t pte) +{ + return pte_wrprotect(set_pte_bit(pte, __pgprot(PTE_UFFD_WP))); +} + +static inline pte_t pte_clear_uffd_wp(pte_t pte) +{ + return clear_pte_bit(pte, __pgprot(PTE_UFFD_WP)); +} +#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */ + static inline void __set_pte_nosync(pte_t *ptep, pte_t pte) { WRITE_ONCE(*ptep, pte); @@ -477,6 +494,23 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte) return clear_pte_bit(pte, __pgprot(PTE_SWP_EXCLUSIVE)); } +#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP +static inline pte_t pte_swp_mkuffd_wp(pte_t pte) +{ + return set_pte_bit(pte, __pgprot(PTE_SWP_UFFD_WP)); +} + +static inline int pte_swp_uffd_wp(pte_t pte) +{ + return !!(pte_val(pte) & PTE_SWP_UFFD_WP); +} + +static inline pte_t pte_swp_clear_uffd_wp(pte_t pte) +{ + return clear_pte_bit(pte, __pgprot(PTE_SWP_UFFD_WP)); +} +#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */ + #ifdef CONFIG_NUMA_BALANCING /* * See the comment in include/linux/pgtable.h @@ -527,6 +561,15 @@ static inline int pmd_trans_huge(pmd_t pmd) #define pmd_mkdirty(pmd) pte_pmd(pte_mkdirty(pmd_pte(pmd))) #define pmd_mkyoung(pmd) pte_pmd(pte_mkyoung(pmd_pte(pmd))) #define pmd_mkinvalid(pmd) pte_pmd(pte_mkinvalid(pmd_pte(pmd))) +#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP +#define pmd_uffd_wp(pmd) pte_uffd_wp(pmd_pte(pmd)) +#define pmd_mkuffd_wp(pmd) pte_pmd(pte_mkuffd_wp(pmd_pte(pmd))) +#define pmd_clear_uffd_wp(pmd) pte_pmd(pte_clear_uffd_wp(pmd_pte(pmd))) +#define pmd_swp_uffd_wp(pmd) pte_swp_uffd_wp(pmd_pte(pmd)) +#define pmd_swp_mkuffd_wp(pmd) pte_pmd(pte_swp_mkuffd_wp(pmd_pte(pmd))) +#define pmd_swp_clear_uffd_wp(pmd) \ + pte_pmd(pte_swp_clear_uffd_wp(pmd_pte(pmd))) +#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */ #define pmd_thp_or_huge(pmd) (pmd_huge(pmd) || pmd_trans_huge(pmd)) @@ -1261,6 +1304,7 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma, * Encode and decode a swap entry: * bits 0-1: present (must be zero) * bits 2: remember PG_anon_exclusive + * bit 3: remember uffd-wp state * bits 6-10: swap type * bit 11: PTE_PRESENT_INVALID (must be zero) * bits 12-61: swap offset