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
Cc: Punit Agrawal <punitagrawal@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
hejianet@gmail.com, Kaly Xin <Kaly.Xin@arm.com>,
Jia He <justin.he@arm.com>
Subject: [PATCH v10 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64
Date: Mon, 30 Sep 2019 09:57:39 +0800 [thread overview]
Message-ID: <20190930015740.84362-3-justin.he@arm.com> (raw)
In-Reply-To: <20190930015740.84362-1-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>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/include/asm/pgtable.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7576df00eb50..e96fb82f62de 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -885,6 +885,20 @@ 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 from user 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)
+{
+ WARN_ON(preemptible());
+
+ 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
next prev parent reply other threads:[~2019-09-30 1:58 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-30 1:57 [PATCH v10 0/3] fix double page fault on arm64 Jia He
2019-09-30 1:57 ` [PATCH v10 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af() Jia He
2019-10-01 12:54 ` Will Deacon
2019-10-01 13:18 ` Marc Zyngier
2019-10-08 1:12 ` Justin He (Arm Technology China)
2019-10-08 15:32 ` Suzuki K Poulose
2019-10-09 6:29 ` Jia He
2019-09-30 1:57 ` Jia He [this message]
2019-10-01 12:50 ` [PATCH v10 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Will Deacon
2019-10-01 13:32 ` Marc Zyngier
2019-10-08 1:55 ` Justin He (Arm Technology China)
2019-10-08 2:30 ` Justin He (Arm Technology China)
2019-10-08 7:46 ` Marc Zyngier
2019-09-30 1:57 ` [PATCH v10 3/3] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
2019-10-01 12:54 ` Will Deacon
2019-10-08 2:19 ` Justin He (Arm Technology China)
2019-10-08 12:39 ` Will Deacon
2019-10-08 12:58 ` Justin He (Arm Technology China)
2019-10-08 14:32 ` Kirill A. Shutemov
2019-10-16 23:21 ` Palmer Dabbelt
2019-10-16 23:46 ` Will Deacon
2019-10-18 20:38 ` Palmer Dabbelt
2019-10-19 2:59 ` Jia He
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190930015740.84362-3-justin.he@arm.com \
--to=justin.he@arm.com \
--cc=Kaly.Xin@arm.com \
--cc=akpm@linux-foundation.org \
--cc=catalin.marinas@arm.com \
--cc=hejianet@gmail.com \
--cc=james.morse@arm.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.org \
--cc=punitagrawal@gmail.com \
--cc=tglx@linutronix.de \
--cc=will@kernel.org \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).