[tip:x86/asm] x86: Require MOVBE feature in cpuid when we use it

[tip-bot for David Woodhouse]

Commit-ID:  2b9b6d8c715b23fa119261c32ad360681f4464a9
Gitweb:     http://git.kernel.org/tip/2b9b6d8c715b23fa119261c32ad360681f4464a9
Author:     David Woodhouse <dwmw2@xxxxxxxxxxxxx>
AuthorDate: Mon, 28 Jan 2013 17:49:50 +0000
Committer:  H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Mon, 28 Jan 2013 16:59:55 -0800

x86: Require MOVBE feature in cpuid when we use it

Add MOVBE to asm/required-features.h so we check for it during startup
and don't bother checking for it later.

CONFIG_MATOM is used because it corresponds to -march=atom in the
Makefiles.  If the rules get more complicated it may be necessary to
make this an explicit Kconfig option which uses -mmovbe/-mno-movbe to
control the use of this instruction explicitly.

Signed-off-by: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1359395390.3529.65.camel@xxxxxxxxxxxxxxxxxxxxxxx
[ hpa: added a patch description ]
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/required-features.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/required-features.h b/arch/x86/include/asm/required-features.h
index 6c7fc25..5c6e4fb 100644
--- a/arch/x86/include/asm/required-features.h
+++ b/arch/x86/include/asm/required-features.h
@@ -47,6 +47,12 @@
 # define NEED_NOPL	0
 #endif
 
+#ifdef CONFIG_MATOM
+# define NEED_MOVBE	(1<<(X86_FEATURE_MOVBE & 31))
+#else
+# define NEED_MOVBE	0
+#endif
+
 #ifdef CONFIG_X86_64
 #ifdef CONFIG_PARAVIRT
 /* Paravirtualized systems may not have PSE or PGE available */
@@ -80,7 +86,7 @@
 
 #define REQUIRED_MASK2	0
 #define REQUIRED_MASK3	(NEED_NOPL)
-#define REQUIRED_MASK4	0
+#define REQUIRED_MASK4	(NEED_MOVBE)
 #define REQUIRED_MASK5	0
 #define REQUIRED_MASK6	0
 #define REQUIRED_MASK7	0
--
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