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, 1 deletions

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 8cb5dbb..a3ae8e6 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -116,12 +116,31 @@ static const unsigned char *const k7_nops[ASM_NOP_MAX+1] = {
 };
 #endif
 
+#ifdef P6_NOP1
+asm("\t.section .rodata, \"a\"\np6nops: "
+	P6_NOP1 P6_NOP2 P6_NOP3 P6_NOP4 P6_NOP5 P6_NOP6
+	P6_NOP7 P6_NOP8);
+extern const unsigned char p6nops[];
+static const unsigned char *const p6_nops[ASM_NOP_MAX+1] = {
+	NULL,
+	p6nops,
+	p6nops + 1,
+	p6nops + 1 + 2,
+	p6nops + 1 + 2 + 3,
+	p6nops + 1 + 2 + 3 + 4,
+	p6nops + 1 + 2 + 3 + 4 + 5,
+	p6nops + 1 + 2 + 3 + 4 + 5 + 6,
+	p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
+};
+#endif
+
 #ifdef CONFIG_X86_64
 
 extern char __vsyscall_0;
 static inline const unsigned char*const * find_nop_table(void)
 {
-	return k8_nops;
+	return boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
+	       boot_cpu_data.x86 < 6 ? k8_nops : p6_nops;
 }
 
 #else /* CONFIG_X86_64 */
@@ -132,6 +151,8 @@ static const struct nop {
 } noptypes[] = {
 	{ X86_FEATURE_K8, k8_nops },
 	{ X86_FEATURE_K7, k7_nops },
+	{ X86_FEATURE_P4, p6_nops },
+	{ X86_FEATURE_P3, p6_nops },
 	{ -1, NULL }
 };