Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6041b57c6c99dcb59524f1bb0db0628c2689a464 Commit: 6041b57c6c99dcb59524f1bb0db0628c2689a464 Parent: 129a84de2347002f09721cda3155ccfd19fade40 Author: Joerg Roedel <[EMAIL PROTECTED]> AuthorDate: Thu May 10 22:22:14 2007 -0700 Committer: Linus Torvalds <[EMAIL PROTECTED]> CommitDate: Fri May 11 08:29:32 2007 -0700
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 <[EMAIL PROTECTED]> Cc: Andi Kleen <[EMAIL PROTECTED]> Cc: Benny Halevy <[EMAIL PROTECTED]> Cc: Pete Zaitcev <[EMAIL PROTECTED]> Cc: "Joerg Roedel" <[EMAIL PROTECTED]> Signed-off-by: Andrew Morton <[EMAIL PROTECTED]> Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]> --- 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 --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; diff --git a/include/asm-x86_64/alternative.h b/include/asm-x86_64/alternative.h index a09fe85..a094276 100644 --- a/include/asm-x86_64/alternative.h +++ b/include/asm-x86_64/alternative.h @@ -103,6 +103,12 @@ 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 - To unsubscribe from this list: send the line "unsubscribe git-commits-head" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html