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Date: Fri, 28 Jun 2013 18:41:41 +0200
From: Borislav Petkov <bp@...en8.de>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: X86 ML <x86@...nel.org>, Wedson Almeida Filho <wedsonaf@...il.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
LKML <linux-kernel@...r.kernel.org>, Borislav Petkov <bp@...e.de>
Subject: [PATCH] x86, cpufeature: Use new CC_HAVE_ASM_GOTO
From: Borislav Petkov <bp@...e.de>
... 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@...e.de>
---
arch/x86/include/asm/cpufeature.h | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 47538a61c91b..d3f5c63078d8 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -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) \
--
1.8.3
--
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