The patch titled
i386: work around miscompilation of alternatives code
has been added to the -mm tree. Its filename is
i386-work-around-miscompilation-of-alternatives-code.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: i386: work around miscompilation of alternatives code
From: "Joerg Roedel" <joerg.roedel@xxxxxxx>
A recent change makes my Dell 1501 hang on boot. It's an AMD MK-36. I use
an x86_64 kernel. It is 100% reproducible.
I debugged this problem a bit and my compiler[1]interprets the =A constraint
as %rax instead of %edx:%eax on x86_64 which causes the problem. The appended
patch provides a workaround for this and fixed the hang on my machine.
[1] gcc version 4.1.3 20070429 (prerelease) (Debian 4.1.2-5)
Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Cc: Benny Halevy <bhalevy@xxxxxxxxxxx>
Cc: Pete Zaitcev <zaitcev@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/asm-i386/alternative.h | 6 ++++++
include/asm-i386/tsc.h | 6 ++++--
include/asm-x86_64/alternative.h | 6 ++++++
3 files changed, 16 insertions(+), 2 deletions(-)
diff -puN include/asm-i386/alternative.h~i386-work-around-miscompilation-of-alternatives-code include/asm-i386/alternative.h
--- a/include/asm-i386/alternative.h~i386-work-around-miscompilation-of-alternatives-code
+++ a/include/asm-i386/alternative.h
@@ -98,6 +98,12 @@ static inline void alternatives_smp_swit
".previous" : output : [feat] "i" (feature), ##input)
/*
+ * use this macro(s) if you need more than one output parameter
+ * in alternative_io
+ */
+#define ASM_OUTPUT2(a, b) a, b
+
+/*
* Alternative inline assembly for SMP.
*
* The LOCK_PREFIX macro defined here replaces the LOCK and
diff -puN include/asm-i386/tsc.h~i386-work-around-miscompilation-of-alternatives-code include/asm-i386/tsc.h
--- a/include/asm-i386/tsc.h~i386-work-around-miscompilation-of-alternatives-code
+++ a/include/asm-i386/tsc.h
@@ -35,14 +35,16 @@ static inline cycles_t get_cycles(void)
static __always_inline cycles_t get_cycles_sync(void)
{
unsigned long long ret;
- unsigned eax;
+ unsigned eax, edx;
/*
* Use RDTSCP if possible; it is guaranteed to be synchronous
* and doesn't cause a VMEXIT on Hypervisors
*/
alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP,
- "=A" (ret), "0" (0ULL) : "ecx", "memory");
+ ASM_OUTPUT2("=a" (eax), "=d" (edx)),
+ "a" (0U), "d" (0U) : "ecx", "memory");
+ ret = (((unsigned long long)edx) << 32) | ((unsigned long long)eax);
if (ret)
return ret;
diff -puN include/asm-x86_64/alternative.h~i386-work-around-miscompilation-of-alternatives-code include/asm-x86_64/alternative.h
--- a/include/asm-x86_64/alternative.h~i386-work-around-miscompilation-of-alternatives-code
+++ a/include/asm-x86_64/alternative.h
@@ -103,6 +103,12 @@ static inline void alternatives_smp_swit
".previous" : output : [feat] "i" (feature), ##input)
/*
+ * use this macro(s) if you need more than one output parameter
+ * in alternative_io
+ */
+#define ASM_OUTPUT2(a, b) a, b
+
+/*
* Alternative inline assembly for SMP.
*
* The LOCK_PREFIX macro defined here replaces the LOCK and
_
Patches currently in -mm which might be from joerg.roedel@xxxxxxx are
origin.patch
i386-work-around-miscompilation-of-alternatives-code.patch
andi-you-broke-my-laptop.patch
-
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