From: Ryan Roberts <ryan.roberts@arm.com> To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Joey Gouly <joey.gouly@arm.com>, Ard Biesheuvel <ardb@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Anshuman Khandual <anshuman.khandual@arm.com>, David Hildenbrand <david@redhat.com>, Peter Xu <peterx@redhat.com>, Mike Rapoport <rppt@linux.ibm.com>, Shivansh Vij <shivanshvij@outlook.com> Cc: Ryan Roberts <ryan.roberts@arm.com>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v1 2/2] arm64/mm: Add uffd write-protect support Date: Wed, 24 Apr 2024 12:10:17 +0100 [thread overview] Message-ID: <20240424111017.3160195-3-ryan.roberts@arm.com> (raw) In-Reply-To: <20240424111017.3160195-1-ryan.roberts@arm.com> 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 entry pte bit (3). Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/pgtable-prot.h | 8 ++++ arch/arm64/include/asm/pgtable.h | 55 +++++++++++++++++++++++++++ 3 files changed, 64 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 7b11c98b3e84..763e221f2169 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 ef952d69fd04..f1e1f6306e03 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -20,6 +20,14 @@ #define PTE_DEVMAP (_AT(pteval_t, 1) << 57) #define PTE_PROT_NONE (PTE_UXN) /* Reuse PTE_UXN; 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 */ + /* * This bit indicates that the entry is present i.e. pmd_page() * still points to a valid huge page in memory even if the pmd diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 23aabff4fa6f..3f4748741fdb 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -271,6 +271,34 @@ 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) +{ + bool wp = !!(pte_val(pte) & PTE_UFFD_WP); + +#ifdef CONFIG_DEBUG_VM + /* + * Having write bit for wr-protect-marked present ptes is fatal, because + * it means the uffd-wp bit will be ignored and write will just go + * through. See comment in x86 implementation. + */ + WARN_ON_ONCE(wp && pte_write(pte)); +#endif + + return 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(pte_t *ptep, pte_t pte) { WRITE_ONCE(*ptep, pte); @@ -463,6 +491,23 @@ 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 @@ -508,6 +553,15 @@ static inline int pmd_trans_huge(pmd_t pmd) #define pmd_mkclean(pmd) pte_pmd(pte_mkclean(pmd_pte(pmd))) #define pmd_mkdirty(pmd) pte_pmd(pte_mkdirty(pmd_pte(pmd))) #define pmd_mkyoung(pmd) pte_pmd(pte_mkyoung(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 */ static inline pmd_t pmd_mkinvalid(pmd_t pmd) { @@ -1248,6 +1302,7 @@ 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 4-53: swap offset * bit 54: PTE_PROT_NONE (overlays PTE_UXN) (must be zero) * bits 55-59: swap type -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Ryan Roberts <ryan.roberts@arm.com> To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Joey Gouly <joey.gouly@arm.com>, Ard Biesheuvel <ardb@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Anshuman Khandual <anshuman.khandual@arm.com>, David Hildenbrand <david@redhat.com>, Peter Xu <peterx@redhat.com>, Mike Rapoport <rppt@linux.ibm.com>, Shivansh Vij <shivanshvij@outlook.com> Cc: Ryan Roberts <ryan.roberts@arm.com>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v1 2/2] arm64/mm: Add uffd write-protect support Date: Wed, 24 Apr 2024 12:10:17 +0100 [thread overview] Message-ID: <20240424111017.3160195-3-ryan.roberts@arm.com> (raw) In-Reply-To: <20240424111017.3160195-1-ryan.roberts@arm.com> 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 entry pte bit (3). Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/pgtable-prot.h | 8 ++++ arch/arm64/include/asm/pgtable.h | 55 +++++++++++++++++++++++++++ 3 files changed, 64 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 7b11c98b3e84..763e221f2169 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 ef952d69fd04..f1e1f6306e03 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -20,6 +20,14 @@ #define PTE_DEVMAP (_AT(pteval_t, 1) << 57) #define PTE_PROT_NONE (PTE_UXN) /* Reuse PTE_UXN; 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 */ + /* * This bit indicates that the entry is present i.e. pmd_page() * still points to a valid huge page in memory even if the pmd diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 23aabff4fa6f..3f4748741fdb 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -271,6 +271,34 @@ 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) +{ + bool wp = !!(pte_val(pte) & PTE_UFFD_WP); + +#ifdef CONFIG_DEBUG_VM + /* + * Having write bit for wr-protect-marked present ptes is fatal, because + * it means the uffd-wp bit will be ignored and write will just go + * through. See comment in x86 implementation. + */ + WARN_ON_ONCE(wp && pte_write(pte)); +#endif + + return 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(pte_t *ptep, pte_t pte) { WRITE_ONCE(*ptep, pte); @@ -463,6 +491,23 @@ 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 @@ -508,6 +553,15 @@ static inline int pmd_trans_huge(pmd_t pmd) #define pmd_mkclean(pmd) pte_pmd(pte_mkclean(pmd_pte(pmd))) #define pmd_mkdirty(pmd) pte_pmd(pte_mkdirty(pmd_pte(pmd))) #define pmd_mkyoung(pmd) pte_pmd(pte_mkyoung(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 */ static inline pmd_t pmd_mkinvalid(pmd_t pmd) { @@ -1248,6 +1302,7 @@ 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 4-53: swap offset * bit 54: PTE_PROT_NONE (overlays PTE_UXN) (must be zero) * bits 55-59: swap type -- 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2024-04-24 11:10 UTC|newest] Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-04-24 11:10 [PATCH v1 0/2] arm64/mm: Enable userfaultfd write-protect Ryan Roberts 2024-04-24 11:10 ` Ryan Roberts 2024-04-24 11:10 ` [PATCH v1 1/2] arm64/mm: Move PTE_PROT_NONE and PMD_PRESENT_INVALID Ryan Roberts 2024-04-24 11:10 ` Ryan Roberts 2024-04-24 16:43 ` Catalin Marinas 2024-04-24 16:43 ` Catalin Marinas 2024-04-25 8:40 ` Ryan Roberts 2024-04-25 8:40 ` Ryan Roberts 2024-04-25 9:16 ` David Hildenbrand 2024-04-25 9:16 ` David Hildenbrand 2024-04-25 10:29 ` Ryan Roberts 2024-04-25 10:29 ` Ryan Roberts 2024-04-25 10:37 ` Ryan Roberts 2024-04-25 10:37 ` Ryan Roberts 2024-04-26 14:48 ` Catalin Marinas 2024-04-26 14:48 ` Catalin Marinas 2024-04-29 10:04 ` Ryan Roberts 2024-04-29 10:04 ` Ryan Roberts 2024-04-29 12:38 ` Catalin Marinas 2024-04-29 12:38 ` Catalin Marinas 2024-04-29 13:01 ` Ryan Roberts 2024-04-29 13:01 ` Ryan Roberts 2024-04-29 13:23 ` Ryan Roberts 2024-04-29 13:23 ` Ryan Roberts 2024-04-29 14:18 ` Catalin Marinas 2024-04-29 14:18 ` Catalin Marinas 2024-04-29 15:04 ` Ryan Roberts 2024-04-29 15:04 ` Ryan Roberts 2024-04-24 11:10 ` Ryan Roberts [this message] 2024-04-24 11:10 ` [PATCH v1 2/2] arm64/mm: Add uffd write-protect support Ryan Roberts 2024-04-24 11:57 ` Peter Xu 2024-04-24 11:57 ` Peter Xu 2024-04-24 12:51 ` Ryan Roberts 2024-04-24 12:51 ` Ryan Roberts 2024-04-26 13:17 ` Ryan Roberts 2024-04-26 13:17 ` Ryan Roberts 2024-04-26 13:54 ` Peter Xu 2024-04-26 13:54 ` Peter Xu 2024-04-29 9:39 ` Ryan Roberts 2024-04-29 9:39 ` Ryan Roberts 2024-04-24 16:46 ` Catalin Marinas 2024-04-24 16:46 ` Catalin Marinas
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