From: H. Peter Anvin Date: Tue, 26 Aug 2008 05:39:15 +0000 (-0700) Subject: x86: msr: fix bogus return values from rdmsr_safe/wrmsr_safe X-Git-Tag: v2.6.27-rc5~5^2~1 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=08970fc4e0385790a7b093adfaa4165a189f9eb0;p=linux-2.6-omap-h63xx.git x86: msr: fix bogus return values from rdmsr_safe/wrmsr_safe Impact: bogus error codes (+other?) on x86-64 The rdmsr_safe/wrmsr_safe routines have macros for the handling of the edx:eax arguments. Those macros take a variable number of assembly arguments. This is rather inherently incompatible with using %digit-style escapes in the inline assembly; replace those with %[name]-style escapes. This fixes miscompilation on x86-64, which at the very least caused bogus return values. It is possible that this could also corrupt the return value; I am not sure. Signed-off-by: H. Peter Anvin --- diff --git a/include/asm-x86/msr.h b/include/asm-x86/msr.h index ad5f2decf7f..2362cfda1fb 100644 --- a/include/asm-x86/msr.h +++ b/include/asm-x86/msr.h @@ -52,14 +52,14 @@ static inline unsigned long long native_read_msr_safe(unsigned int msr, { DECLARE_ARGS(val, low, high); - asm volatile("2: rdmsr ; xor %0,%0\n" + asm volatile("2: rdmsr ; xor %[err],%[err]\n" "1:\n\t" ".section .fixup,\"ax\"\n\t" - "3: mov %3,%0 ; jmp 1b\n\t" + "3: mov %[fault],%[err] ; jmp 1b\n\t" ".previous\n\t" _ASM_EXTABLE(2b, 3b) - : "=r" (*err), EAX_EDX_RET(val, low, high) - : "c" (msr), "i" (-EFAULT)); + : [err] "=r" (*err), EAX_EDX_RET(val, low, high) + : "c" (msr), [fault] "i" (-EFAULT)); return EAX_EDX_VAL(val, low, high); } @@ -73,15 +73,15 @@ static inline int native_write_msr_safe(unsigned int msr, unsigned low, unsigned high) { int err; - asm volatile("2: wrmsr ; xor %0,%0\n" + asm volatile("2: wrmsr ; xor %[err],%[err]\n" "1:\n\t" ".section .fixup,\"ax\"\n\t" - "3: mov %4,%0 ; jmp 1b\n\t" + "3: mov %[fault],%[err] ; jmp 1b\n\t" ".previous\n\t" _ASM_EXTABLE(2b, 3b) - : "=a" (err) + : [err] "=a" (err) : "c" (msr), "0" (low), "d" (high), - "i" (-EFAULT) + [fault] "i" (-EFAULT) : "memory"); return err; }