From: Tony Luck <tony.luck@intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Tony Luck <tony.luck@intel.com>,
x86@kernel.org, Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Darren Hart <dvhart@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org,
linux-mm@kvack.org
Subject: [PATCH 2/2] futex, x86/mce: Avoid double machine checks
Date: Fri, 8 Jan 2021 14:22:51 -0800 [thread overview]
Message-ID: <20210108222251.14391-3-tony.luck@intel.com> (raw)
In-Reply-To: <20210108222251.14391-1-tony.luck@intel.com>
futex_wait_setup() first tries to read the user value with page faults
disabled (because it holds a lock, and so cannot sleep). If that read
fails it drops the lock and tries again.
But there are now two reasons why the user space read can fail. Either:
1) legacy case of a page fault, in which case it is reasonable to retry
2) machine check on the user address, bad idea to re-read
Add some infrastructure to differentiate these cases.
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/include/asm/mmu.h | 7 +++++++
arch/x86/kernel/cpu/mce/core.c | 10 ++++++++++
include/linux/mm.h | 4 ++++
kernel/futex.c | 3 +++
4 files changed, 24 insertions(+)
diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index 5d7494631ea9..a46c78381388 100644
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -66,4 +66,11 @@ typedef struct {
void leave_mm(int cpu);
#define leave_mm leave_mm
+#if defined(CONFIG_X86_MCE) && defined(CONFIG_MEMORY_FAILURE)
+#undef arch_memory_failure
+#define arch_memory_failure x86_memory_failure
+#endif
+
+bool x86_memory_failure(u32 __user *addr);
+
#endif /* _ASM_X86_MMU_H */
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 1bf11213e093..b27aa30290bb 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1236,6 +1236,16 @@ static void __mc_scan_banks(struct mce *m, struct pt_regs *regs, struct mce *fin
*m = *final;
}
+bool x86_memory_failure(u32 __user *addr)
+{
+ if (current->mce_busy == 0)
+ return false;
+
+ WARN_ON(current->mce_vaddr != addr);
+
+ return true;
+}
+
static void kill_me_now(struct callback_head *ch)
{
force_sig(SIGBUS);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ecdf8a8cd6ae..470708a71dd3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3177,5 +3177,9 @@ unsigned long wp_shared_mapping_range(struct address_space *mapping,
extern int sysctl_nr_trim_pages;
+#ifndef arch_memory_failure
+#define arch_memory_failure(vaddr) (0)
+#endif
+
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */
diff --git a/kernel/futex.c b/kernel/futex.c
index c47d1015d759..8fa2fc854026 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2658,6 +2658,9 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags,
if (ret) {
queue_unlock(*hb);
+ if (arch_memory_failure(uaddr))
+ return ret;
+
ret = get_user(uval, uaddr);
if (ret)
return ret;
--
2.21.1
next prev parent reply other threads:[~2021-01-08 22:24 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-08 22:22 [PATCH 0/2] Fix infinite machine check loop in futex_wait_setup() Tony Luck
2021-01-08 22:22 ` [PATCH 1/2] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-01-08 22:22 ` Tony Luck [this message]
2021-01-08 22:47 ` [PATCH 2/2] futex, x86/mce: Avoid double machine checks Peter Zijlstra
2021-01-08 23:08 ` Luck, Tony
2021-01-08 23:14 ` Peter Zijlstra
2021-01-08 23:20 ` Luck, Tony
2021-01-11 21:44 ` [PATCH v2 0/3] Fix infinite machine check loop in futex_wait_setup() Tony Luck
2021-01-11 21:44 ` [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-01-11 22:11 ` Andy Lutomirski
2021-01-11 22:20 ` Luck, Tony
2021-01-12 17:00 ` Andy Lutomirski
2021-01-12 17:16 ` Luck, Tony
2021-01-12 17:21 ` Andy Lutomirski
2021-01-12 18:23 ` Luck, Tony
2021-01-12 18:57 ` Andy Lutomirski
2021-01-12 20:52 ` Luck, Tony
2021-01-12 22:04 ` Andy Lutomirski
2021-01-13 1:50 ` Luck, Tony
2021-01-13 4:15 ` Andy Lutomirski
2021-01-13 10:00 ` Borislav Petkov
2021-01-13 16:06 ` Luck, Tony
2021-01-13 16:19 ` Borislav Petkov
2021-01-13 16:32 ` Luck, Tony
2021-01-13 17:35 ` Borislav Petkov
2021-01-14 20:22 ` Borislav Petkov
2021-01-14 21:05 ` Luck, Tony
2021-01-11 21:44 ` [PATCH v2 2/3] x86/mce: Add new return value to get_user() for machine check Tony Luck
2021-01-11 21:44 ` [PATCH v2 3/3] futex, x86/mce: Avoid double machine checks Tony Luck
2021-01-14 17:22 ` [PATCH v2 0/3] Fix infinite machine check loop in futex_wait_setup() Andy Lutomirski
2021-01-15 0:38 ` [PATCH v3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-01-15 15:27 ` Borislav Petkov
2021-01-15 19:34 ` Luck, Tony
2021-01-15 20:51 ` [PATCH v4] " Luck, Tony
2021-01-15 23:23 ` Luck, Tony
2021-01-19 10:56 ` Borislav Petkov
2021-01-19 23:57 ` Luck, Tony
2021-01-20 12:18 ` Borislav Petkov
2021-01-20 17:17 ` Luck, Tony
2021-01-21 21:09 ` Luck, Tony
2021-01-25 22:55 ` [PATCH v5] " Luck, Tony
2021-01-26 11:03 ` Borislav Petkov
2021-01-26 22:36 ` Luck, Tony
2021-01-28 17:57 ` Borislav Petkov
2021-02-01 18:58 ` Luck, Tony
2021-02-02 11:01 ` Borislav Petkov
2021-02-02 16:04 ` Luck, Tony
2021-02-02 21:06 ` Borislav Petkov
2021-02-02 22:12 ` Luck, Tony
2021-01-18 15:39 ` [PATCH v3] " Borislav Petkov
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