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@intel.com>
Link: http://lkml.kernel.org/r/1359395390.3529.65.camel@shinybook.infradead.org
[ hpa: added a patch description ]
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/include/asm/required-features.h b/arch/x86/include/asm/required-features.h
index 6c7fc25..5c6e4fb 100644 (file)
--- 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