x86: multi-byte single instruction NOPs

Add support for and use the multi-byte NOPs recently documented to be
available on all PentiumPro and later processors.

This patch only applies cleanly on top of the "x86: misc.
constifications" patch sent earlier.

[ tglx: arch/x86 adaptation ]

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

 arch/x86/kernel/alternative.c  |   23 ++++++++++++++++++++++-
 include/asm-x86/processor_32.h |   22 ++++++++++++++++++++++
 include/asm-x86/processor_64.h |   22 ++++++++++++++++++++++
 3 files changed, 66 insertions(+), 1 deletion(-)

1 files changed, 22 insertions, 0 deletions

diff --git a/include/asm-x86/processor_32.h b/include/asm-x86/processor_32.h
index 38cc1061487e..83800e7496ee 100644
--- a/include/asm-x86/processor_32.h
+++ b/include/asm-x86/processor_32.h
@@ -677,6 +677,17 @@ static inline unsigned int cpuid_edx(unsigned int op)
 #define K7_NOP7        ".byte 0x8D,0x04,0x05,0,0,0,0\n"
 #define K7_NOP8        K7_NOP7 ASM_NOP1
 
+/* P6 nops */
+/* uses eax dependencies (Intel-recommended choice) */
+#define P6_NOP1 GENERIC_NOP1
+#define P6_NOP2 ".byte 0x66,0x90\n"
+#define P6_NOP3 ".byte 0x0f,0x1f,0x00\n"
+#define P6_NOP4 ".byte 0x0f,0x1f,0x40,0\n"
+#define P6_NOP5 ".byte 0x0f,0x1f,0x44,0x00,0\n"
+#define P6_NOP6 ".byte 0x66,0x0f,0x1f,0x44,0x00,0\n"
+#define P6_NOP7 ".byte 0x0f,0x1f,0x80,0,0,0,0\n"
+#define P6_NOP8 ".byte 0x0f,0x1f,0x84,0x00,0,0,0,0\n"
+
 #ifdef CONFIG_MK8
 #define ASM_NOP1 K8_NOP1
 #define ASM_NOP2 K8_NOP2
@@ -695,6 +706,17 @@ static inline unsigned int cpuid_edx(unsigned int op)
 #define ASM_NOP6 K7_NOP6
 #define ASM_NOP7 K7_NOP7
 #define ASM_NOP8 K7_NOP8
+#elif defined(CONFIG_M686) || defined(CONFIG_MPENTIUMII) || \
+      defined(CONFIG_MPENTIUMIII) || defined(CONFIG_MPENTIUMM) || \
+      defined(CONFIG_MCORE2) || defined(CONFIG_PENTIUM4)
+#define ASM_NOP1 P6_NOP1
+#define ASM_NOP2 P6_NOP2
+#define ASM_NOP3 P6_NOP3
+#define ASM_NOP4 P6_NOP4
+#define ASM_NOP5 P6_NOP5
+#define ASM_NOP6 P6_NOP6
+#define ASM_NOP7 P6_NOP7
+#define ASM_NOP8 P6_NOP8
 #else
 #define ASM_NOP1 GENERIC_NOP1
 #define ASM_NOP2 GENERIC_NOP2