diff options
| author | Joerg Roedel <joerg.roedel@amd.com> | 2007-05-10 22:22:14 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-11 08:29:32 -0700 |
| commit | 6041b57c6c99dcb59524f1bb0db0628c2689a464 (patch) | |
| tree | 0509eb54f13e94b08afab9fb6bd2947fca73492c /include/asm-i386 | |
| parent | 129a84de2347002f09721cda3155ccfd19fade40 (diff) | |
| download | op-kernel-dev-6041b57c6c99dcb59524f1bb0db0628c2689a464.zip op-kernel-dev-6041b57c6c99dcb59524f1bb0db0628c2689a464.tar.gz | |
i386: work around miscompilation of alternatives code
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@amd.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Benny Halevy <bhalevy@panasas.com>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: "Joerg Roedel" <joerg.roedel@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/asm-i386')
| -rw-r--r-- | include/asm-i386/alternative.h | 6 | ||||
| -rw-r--r-- | include/asm-i386/tsc.h | 6 |
2 files changed, 10 insertions, 2 deletions
diff --git a/include/asm-i386/alternative.h b/include/asm-i386/alternative.h index 0f70b37..eb7da54 100644 --- a/include/asm-i386/alternative.h +++ b/include/asm-i386/alternative.h @@ -98,6 +98,12 @@ static inline void alternatives_smp_switch(int smp) {} ".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 --git a/include/asm-i386/tsc.h b/include/asm-i386/tsc.h index 3f3c1fa..62c091f 100644 --- a/include/asm-i386/tsc.h +++ b/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; |
