From: Jan Beulich Date: Wed, 17 Oct 2007 16:04:41 +0000 (+0200) Subject: x86: multi-byte single instruction NOPs X-Git-Tag: v2.6.24-rc1~476^2~29 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=32c464f5d9701db45bc1673288594e664065388e;p=linux-2.6 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 Signed-off-by: Andi Kleen Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner 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(-) --- diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 8cb5dbbd9c..a3ae8e6c8b 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 } }; diff --git a/include/asm-x86/processor_32.h b/include/asm-x86/processor_32.h index 38cc106148..83800e7496 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 diff --git a/include/asm-x86/processor_64.h b/include/asm-x86/processor_64.h index 2f12eb6e46..f422becbdd 100644 --- a/include/asm-x86/processor_64.h +++ b/include/asm-x86/processor_64.h @@ -334,6 +334,16 @@ struct extended_sigtable { }; +#if defined(CONFIG_MPSC) || defined(CONFIG_MCORE2) +#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 K8_NOP1 #define ASM_NOP2 K8_NOP2 #define ASM_NOP3 K8_NOP3 @@ -342,6 +352,7 @@ struct extended_sigtable { #define ASM_NOP6 K8_NOP6 #define ASM_NOP7 K8_NOP7 #define ASM_NOP8 K8_NOP8 +#endif /* Opteron nops */ #define K8_NOP1 ".byte 0x90\n" @@ -353,6 +364,17 @@ struct extended_sigtable { #define K8_NOP7 K8_NOP4 K8_NOP3 #define K8_NOP8 K8_NOP4 K8_NOP4 +/* P6 nops */ +/* uses eax dependencies (Intel-recommended choice) */ +#define P6_NOP1 ".byte 0x90\n" +#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" + #define ASM_NOP_MAX 8 /* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */