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x86, cpufeature: Use new CC_HAVE_ASM_GOTO

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... for checking for "asm goto" compiler support. It is more explicit
this way and we cover the cases where distros have backported that
support even to gcc versions < 4.5.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1372437701-13351-1-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Borislav Petkov
2013-06-28 18:41:41 +02:00
committed by H. Peter Anvin
parent 9f84b6267c
commit 62122fd7da
1 changed files with 11 additions and 6 deletions
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17
arch/x86/include/asm/cpufeature.h
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@@ -366,9 +366,10 @@ extern bool __static_cpu_has_safe(u16 bit);
*/
static __always_inline __pure bool __static_cpu_has(u16 bit)
{
#if __GNUC__ > 4 || __GNUC_MINOR__ >= 5
#ifdef CC_HAVE_ASM_GOTO
#ifdef CONFIG_X86_DEBUG_STATIC_CPU_HAS
/*
* Catch too early usage of this before alternatives
* have run.
@@ -384,6 +385,7 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
".previous\n"
/* skipping size check since replacement size = 0 */
: : "i" (X86_FEATURE_ALWAYS) : : t_warn);
#endif
asm goto("1: jmp %l[t_no]\n"
@@ -406,7 +408,9 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
warn_pre_alternatives();
return false;
#endif
#else /* GCC_VERSION >= 40500 */
#else /* CC_HAVE_ASM_GOTO */
u8 flag;
/* Open-coded due to __stringify() in ALTERNATIVE() */
asm volatile("1: movb $0,%0\n"
@@ -427,7 +431,8 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
".previous\n"
: "=qm" (flag) : "i" (bit));
return flag;
#endif
#endif /* CC_HAVE_ASM_GOTO */
}
#define static_cpu_has(bit) \
@@ -441,7 +446,7 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
static __always_inline __pure bool _static_cpu_has_safe(u16 bit)
{
#if __GNUC__ > 4 || __GNUC_MINOR__ >= 5
#ifdef CC_HAVE_ASM_GOTO
/*
* We need to spell the jumps to the compiler because, depending on the offset,
* the replacement jump can be bigger than the original jump, and this we cannot
@@ -475,7 +480,7 @@ static __always_inline __pure bool _static_cpu_has_safe(u16 bit)
return false;
t_dynamic:
return __static_cpu_has_safe(bit);
#else /* GCC_VERSION >= 40500 */
#else
u8 flag;
/* Open-coded due to __stringify() in ALTERNATIVE() */
asm volatile("1: movb $2,%0\n"
@@ -511,7 +516,7 @@ static __always_inline __pure bool _static_cpu_has_safe(u16 bit)
: "=qm" (flag)
: "i" (bit), "i" (X86_FEATURE_ALWAYS));
return (flag == 2 ? __static_cpu_has_safe(bit) : flag);
#endif
#endif /* CC_HAVE_ASM_GOTO */
}
#define static_cpu_has_safe(bit) \