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x86: Fix crash in text_poke_early() on 486-class processors (Closes: #515982) 

svn path=/dists/trunk/linux-2.6/; revision=14223
This commit is contained in:
Ben Hutchings 2009-09-13 18:18:22 +00:00
parent f8a907c5d8
commit 6888a95d4b
3 changed files with 83 additions and 0 deletions
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2
debian/changelog vendored
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@ -81,6 +81,8 @@ linux-2.6 (2.6.31-1~experimental.1) UNRELEASED; urgency=low
* rt{2860,2870,3070}sta: Use existing CCITT CRC implementation on
firmware rather than adding an equivalent variant of ITU-T CRC
* rd: Build as a module since we do not require initrd support
* x86: Fix crash in text_poke_early() on 486-class processors
(Closes: #515982)
[ Martin Michlmayr ]
* [armel/orion5x, armel/kirkwood] Set GPIO_SYSFS=y since these

80
debian/patches/bugfix/x86/fix-alternatives-on-486.patch vendored Normal file
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@ -0,0 +1,80 @@
Subject: [PATCH v2] x86: Fix code patching for paravirt-alternatives on 486
From: Ben Hutchings <ben@decadent.org.uk>
To: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org
Date: Thu, 10 Sep 2009 02:53:51 +0100
As reported in <http://bugs.debian.org/511703> and
<http://bugs.debian.org/515982>, kernels with paravirt-alternatives
enabled crash in text_poke_early() on at least some 486-class
processors.
The problem is that text_poke_early() itself uses inline functions
affected by paravirt-alternatives and so will modify instructions that
have already been prefetched. Pentium and later processors will
invalidate the prefetched instructions in this case, but 486-class
processors do not.
Change sync_core() to limit prefetching on 486-class (and 386-class)
processors, and move the call to sync_core() above the call to the
modifiable local_irq_restore().
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
Second try, incorporating the jmp into sync_core().
Also not signed as I know git has trouble with MIME.
Ben.
arch/x86/include/asm/processor.h | 16 +++++++++++++---
arch/x86/kernel/alternative.c | 2 +-
2 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c776826..2db56c5 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -703,13 +703,23 @@ static inline void cpu_relax(void)
rep_nop();
}
-/* Stop speculative execution: */
+/* Stop speculative execution and prefetching of modified code. */
static inline void sync_core(void)
{
int tmp;
- asm volatile("cpuid" : "=a" (tmp) : "0" (1)
- : "ebx", "ecx", "edx", "memory");
+#if defined(CONFIG_M386) || defined(CONFIG_M486)
+ if (boot_cpu_data.x86 < 5)
+ /* There is no speculative execution.
+ * jmp is a barrier to prefetching. */
+ asm volatile("jmp 1f\n1:\n" ::: "memory");
+ else
+#endif
+ /* cpuid is a barrier to speculative execution.
+ * Prefetched instructions are automatically
+ * invalidated when modified. */
+ asm volatile("cpuid" : "=a" (tmp) : "0" (1)
+ : "ebx", "ecx", "edx", "memory");
}
static inline void __monitor(const void *eax, unsigned long ecx,
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 4869351..de7353c 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -498,8 +498,8 @@ static void *__init_or_module text_poke_early(void *addr, const void *opcode,
unsigned long flags;
local_irq_save(flags);
memcpy(addr, opcode, len);
- local_irq_restore(flags);
sync_core();
+ local_irq_restore(flags);
/* Could also do a CLFLUSH here to speed up CPU recovery; but
that causes hangs on some VIA CPUs. */
return addr;
--
1.6.3.3

1
debian/patches/series/base vendored
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@ -32,3 +32,4 @@
+ features/arm/openrd-sata.patch
+ bugfix/all/drivers-scsi-qla1280-request-firmware-unlocked.patch
+ bugfix/all/drivers-gpu-drm-r128-ioctl-add-init-test.patch
+ bugfix/x86/fix-alternatives-on-486.patch