From: Jia He <justin.he@arm.com> To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>, James Morse <james.morse@arm.com>, Marc Zyngier <maz@kernel.org>, Matthew Wilcox <willy@infradead.org>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose <Suzuki.Poulose@arm.com> Cc: "Punit Agrawal" <punitagrawal@gmail.com>, "Anshuman Khandual" <anshuman.khandual@arm.com>, "Alex Van Brunt" <avanbrunt@nvidia.com>, "Robin Murphy" <robin.murphy@arm.com>, "Thomas Gleixner" <tglx@linutronix.de>, "Andrew Morton" <akpm@linux-foundation.org>, "Jérôme Glisse" <jglisse@redhat.com>, "Ralph Campbell" <rcampbell@nvidia.com>, hejianet@gmail.com, "Kaly Xin" <Kaly.Xin@arm.com>, nd@arm.com, "Jia He" <justin.he@arm.com> Subject: [PATCH v8 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Date: Sat, 21 Sep 2019 21:50:53 +0800 [thread overview] Message-ID: <20190921135054.142360-3-justin.he@arm.com> (raw) In-Reply-To: <20190921135054.142360-1-justin.he@arm.com> On arm64 without hardware Access Flag, copying fromuser will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. we don't always have a hardware-managed access flag on arm64. Hence implement arch_faults_on_old_pte on arm64 to indicate that it might cause page fault when accessing old pte. Signed-off-by: Jia He <justin.he@arm.com> --- arch/arm64/include/asm/pgtable.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index e09760ece844..4a9939615e41 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -868,6 +868,18 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, #define phys_to_ttbr(addr) (addr) #endif +/* + * On arm64 without hardware Access Flag, copying fromuser will fail because + * the pte is old and cannot be marked young. So we always end up with zeroed + * page after fork() + CoW for pfn mappings. we don't always have a + * hardware-managed access flag on arm64. + */ +static inline bool arch_faults_on_old_pte(void) +{ + return !cpu_has_hw_af(); +} +#define arch_faults_on_old_pte arch_faults_on_old_pte + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_PGTABLE_H */ -- 2.17.1
WARNING: multiple messages have this Message-ID (diff)
From: Jia He <justin.he@arm.com> To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>, James Morse <james.morse@arm.com>, Marc Zyngier <maz@kernel.org>, Matthew Wilcox <willy@infradead.org>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose <Suzuki.Poulose@arm.com> Cc: "Ralph Campbell" <rcampbell@nvidia.com>, "Jia He" <justin.he@arm.com>, "Anshuman Khandual" <anshuman.khandual@arm.com>, "Alex Van Brunt" <avanbrunt@nvidia.com>, "Kaly Xin" <Kaly.Xin@arm.com>, "Jérôme Glisse" <jglisse@redhat.com>, "Punit Agrawal" <punitagrawal@gmail.com>, hejianet@gmail.com, "Andrew Morton" <akpm@linux-foundation.org>, nd@arm.com, "Robin Murphy" <robin.murphy@arm.com>, "Thomas Gleixner" <tglx@linutronix.de> Subject: [PATCH v8 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Date: Sat, 21 Sep 2019 21:50:53 +0800 [thread overview] Message-ID: <20190921135054.142360-3-justin.he@arm.com> (raw) In-Reply-To: <20190921135054.142360-1-justin.he@arm.com> On arm64 without hardware Access Flag, copying fromuser will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. we don't always have a hardware-managed access flag on arm64. Hence implement arch_faults_on_old_pte on arm64 to indicate that it might cause page fault when accessing old pte. Signed-off-by: Jia He <justin.he@arm.com> --- arch/arm64/include/asm/pgtable.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index e09760ece844..4a9939615e41 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -868,6 +868,18 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, #define phys_to_ttbr(addr) (addr) #endif +/* + * On arm64 without hardware Access Flag, copying fromuser will fail because + * the pte is old and cannot be marked young. So we always end up with zeroed + * page after fork() + CoW for pfn mappings. we don't always have a + * hardware-managed access flag on arm64. + */ +static inline bool arch_faults_on_old_pte(void) +{ + return !cpu_has_hw_af(); +} +#define arch_faults_on_old_pte arch_faults_on_old_pte + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_PGTABLE_H */ -- 2.17.1 _______________________________________________ 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:[~2019-09-21 13:51 UTC|newest] Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-09-21 13:50 [PATCH v8 0/3] fix double page fault on arm64 Jia He 2019-09-21 13:50 ` Jia He 2019-09-21 13:50 ` [PATCH v8 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af() Jia He 2019-09-21 13:50 ` Jia He 2019-09-23 16:07 ` Catalin Marinas 2019-09-23 16:07 ` Catalin Marinas 2019-09-24 1:50 ` Justin He (Arm Technology China) 2019-09-24 1:50 ` Justin He (Arm Technology China) 2019-09-21 13:50 ` Jia He [this message] 2019-09-21 13:50 ` [PATCH v8 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Jia He 2019-09-23 16:18 ` Catalin Marinas 2019-09-23 16:18 ` Catalin Marinas 2019-09-24 2:17 ` Justin He (Arm Technology China) 2019-09-24 2:17 ` Justin He (Arm Technology China) 2019-09-21 13:50 ` [PATCH v8 3/3] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He 2019-09-21 13:50 ` Jia He 2019-09-21 15:31 ` Matthew Wilcox 2019-09-21 15:31 ` Matthew Wilcox 2019-09-23 8:28 ` Kirill A. Shutemov 2019-09-23 8:28 ` Kirill A. Shutemov 2019-09-23 17:04 ` Catalin Marinas 2019-09-23 17:04 ` Catalin Marinas 2019-09-24 6:43 ` Justin He (Arm Technology China) 2019-09-24 6:43 ` Justin He (Arm Technology China) 2019-09-24 10:33 ` Catalin Marinas 2019-09-24 10:33 ` Catalin Marinas 2019-09-24 11:59 ` Kirill A. Shutemov 2019-09-24 11:59 ` Kirill A. Shutemov 2019-09-24 15:29 ` Jia He 2019-09-24 15:29 ` Jia He 2019-09-24 16:35 ` Catalin Marinas 2019-09-24 16:35 ` Catalin Marinas
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