diff options
Diffstat (limited to 'arch/x86/kernel/alternative.c')
| -rw-r--r-- | arch/x86/kernel/alternative.c | 203 |
1 files changed, 121 insertions, 82 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 4a234677e213..a81f2d52f869 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -67,17 +67,30 @@ __setup("noreplace-paravirt", setup_noreplace_paravirt); #define DPRINTK(fmt, args...) if (debug_alternative) \ printk(KERN_DEBUG fmt, args) +/* + * Each GENERIC_NOPX is of X bytes, and defined as an array of bytes + * that correspond to that nop. Getting from one nop to the next, we + * add to the array the offset that is equal to the sum of all sizes of + * nops preceding the one we are after. + * + * Note: The GENERIC_NOP5_ATOMIC is at the end, as it breaks the + * nice symmetry of sizes of the previous nops. + */ #if defined(GENERIC_NOP1) && !defined(CONFIG_X86_64) -/* Use inline assembly to define this because the nops are defined - as inline assembly strings in the include files and we cannot - get them easily into strings. */ -asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nintelnops: " - GENERIC_NOP1 GENERIC_NOP2 GENERIC_NOP3 GENERIC_NOP4 GENERIC_NOP5 GENERIC_NOP6 - GENERIC_NOP7 GENERIC_NOP8 - "\t.previous"); -extern const unsigned char intelnops[]; -static const unsigned char *const __initconst_or_module -intel_nops[ASM_NOP_MAX+1] = { +static const unsigned char intelnops[] = +{ + GENERIC_NOP1, + GENERIC_NOP2, + GENERIC_NOP3, + GENERIC_NOP4, + GENERIC_NOP5, + GENERIC_NOP6, + GENERIC_NOP7, + GENERIC_NOP8, + GENERIC_NOP5_ATOMIC +}; +static const unsigned char * const intel_nops[ASM_NOP_MAX+2] = +{ NULL, intelnops, intelnops + 1, @@ -87,17 +100,25 @@ intel_nops[ASM_NOP_MAX+1] = { intelnops + 1 + 2 + 3 + 4 + 5, intelnops + 1 + 2 + 3 + 4 + 5 + 6, intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7, + intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8, }; #endif #ifdef K8_NOP1 -asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nk8nops: " - K8_NOP1 K8_NOP2 K8_NOP3 K8_NOP4 K8_NOP5 K8_NOP6 - K8_NOP7 K8_NOP8 - "\t.previous"); -extern const unsigned char k8nops[]; -static const unsigned char *const __initconst_or_module -k8_nops[ASM_NOP_MAX+1] = { +static const unsigned char k8nops[] = +{ + K8_NOP1, + K8_NOP2, + K8_NOP3, + K8_NOP4, + K8_NOP5, + K8_NOP6, + K8_NOP7, + K8_NOP8, + K8_NOP5_ATOMIC +}; +static const unsigned char * const k8_nops[ASM_NOP_MAX+2] = +{ NULL, k8nops, k8nops + 1, @@ -107,17 +128,25 @@ k8_nops[ASM_NOP_MAX+1] = { k8nops + 1 + 2 + 3 + 4 + 5, k8nops + 1 + 2 + 3 + 4 + 5 + 6, k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, + k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8, }; #endif #if defined(K7_NOP1) && !defined(CONFIG_X86_64) -asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nk7nops: " - K7_NOP1 K7_NOP2 K7_NOP3 K7_NOP4 K7_NOP5 K7_NOP6 - K7_NOP7 K7_NOP8 - "\t.previous"); -extern const unsigned char k7nops[]; -static const unsigned char *const __initconst_or_module -k7_nops[ASM_NOP_MAX+1] = { +static const unsigned char k7nops[] = +{ + K7_NOP1, + K7_NOP2, + K7_NOP3, + K7_NOP4, + K7_NOP5, + K7_NOP6, + K7_NOP7, + K7_NOP8, + K7_NOP5_ATOMIC +}; +static const unsigned char * const k7_nops[ASM_NOP_MAX+2] = +{ NULL, k7nops, k7nops + 1, @@ -127,17 +156,25 @@ k7_nops[ASM_NOP_MAX+1] = { k7nops + 1 + 2 + 3 + 4 + 5, k7nops + 1 + 2 + 3 + 4 + 5 + 6, k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, + k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8, }; #endif #ifdef P6_NOP1 -asm("\t" __stringify(__INITRODATA_OR_MODULE) "\np6nops: " - P6_NOP1 P6_NOP2 P6_NOP3 P6_NOP4 P6_NOP5 P6_NOP6 - P6_NOP7 P6_NOP8 - "\t.previous"); -extern const unsigned char p6nops[]; -static const unsigned char *const __initconst_or_module -p6_nops[ASM_NOP_MAX+1] = { +static const unsigned char __initconst_or_module p6nops[] = +{ + P6_NOP1, + P6_NOP2, + P6_NOP3, + P6_NOP4, + P6_NOP5, + P6_NOP6, + P6_NOP7, + P6_NOP8, + P6_NOP5_ATOMIC +}; +static const unsigned char * const p6_nops[ASM_NOP_MAX+2] = +{ NULL, p6nops, p6nops + 1, @@ -147,47 +184,65 @@ p6_nops[ASM_NOP_MAX+1] = { p6nops + 1 + 2 + 3 + 4 + 5, p6nops + 1 + 2 + 3 + 4 + 5 + 6, p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, + p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8, }; #endif +/* Initialize these to a safe default */ #ifdef CONFIG_X86_64 +const unsigned char * const *ideal_nops = p6_nops; +#else +const unsigned char * const *ideal_nops = intel_nops; +#endif -extern char __vsyscall_0; -static const unsigned char *const *__init_or_module find_nop_table(void) +void __init arch_init_ideal_nops(void) { - if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && - boot_cpu_has(X86_FEATURE_NOPL)) - return p6_nops; - else - return k8_nops; -} - -#else /* CONFIG_X86_64 */ + switch (boot_cpu_data.x86_vendor) { + case X86_VENDOR_INTEL: + /* + * Due to a decoder implementation quirk, some + * specific Intel CPUs actually perform better with + * the "k8_nops" than with the SDM-recommended NOPs. + */ + if (boot_cpu_data.x86 == 6 && + boot_cpu_data.x86_model >= 0x0f && + boot_cpu_data.x86_model != 0x1c && + boot_cpu_data.x86_model != 0x26 && + boot_cpu_data.x86_model != 0x27 && + boot_cpu_data.x86_model < 0x30) { + ideal_nops = k8_nops; + } else if (boot_cpu_has(X86_FEATURE_NOPL)) { + ideal_nops = p6_nops; + } else { +#ifdef CONFIG_X86_64 + ideal_nops = k8_nops; +#else + ideal_nops = intel_nops; +#endif + } -static const unsigned char *const *__init_or_module find_nop_table(void) -{ - if (boot_cpu_has(X86_FEATURE_K8)) - return k8_nops; - else if (boot_cpu_has(X86_FEATURE_K7)) - return k7_nops; - else if (boot_cpu_has(X86_FEATURE_NOPL)) - return p6_nops; - else - return intel_nops; + default: +#ifdef CONFIG_X86_64 + ideal_nops = k8_nops; +#else + if (boot_cpu_has(X86_FEATURE_K8)) + ideal_nops = k8_nops; + else if (boot_cpu_has(X86_FEATURE_K7)) + ideal_nops = k7_nops; + else + ideal_nops = intel_nops; +#endif + } } -#endif /* CONFIG_X86_64 */ - /* Use this to add nops to a buffer, then text_poke the whole buffer. */ static void __init_or_module add_nops(void *insns, unsigned int len) { - const unsigned char *const *noptable = find_nop_table(); - while (len > 0) { unsigned int noplen = len; if (noplen > ASM_NOP_MAX) noplen = ASM_NOP_MAX; - memcpy(insns, noptable[noplen], noplen); + memcpy(insns, ideal_nops[noplen], noplen); insns += noplen; len -= noplen; } @@ -195,6 +250,7 @@ static void __init_or_module add_nops(void *insns, unsigned int len) extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; extern s32 __smp_locks[], __smp_locks_end[]; +extern char __vsyscall_0; void *text_poke_early(void *addr, const void *opcode, size_t len); /* Replace instructions with better alternatives for this CPU type. @@ -210,6 +266,15 @@ void __init_or_module apply_alternatives(struct alt_instr *start, u8 insnbuf[MAX_PATCH_LEN]; DPRINTK("%s: alt table %p -> %p\n", __func__, start, end); + /* + * The scan order should be from start to end. A later scanned + * alternative code can overwrite a previous scanned alternative code. + * Some kernel functions (e.g. memcpy, memset, etc) use this order to + * patch code. + * + * So be careful if you want to change the scan order to any other + * order. + */ for (a = start; a < end; a++) { u8 *instr = a->instr; BUG_ON(a->replacementlen > a->instrlen); @@ -678,29 +743,3 @@ void __kprobes text_poke_smp_batch(struct text_poke_param *params, int n) wrote_text = 0; __stop_machine(stop_machine_text_poke, (void *)&tpp, NULL); } - -#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL) - -#ifdef CONFIG_X86_64 -unsigned char ideal_nop5[5] = { 0x66, 0x66, 0x66, 0x66, 0x90 }; -#else -unsigned char ideal_nop5[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 }; -#endif - -void __init arch_init_ideal_nop5(void) -{ - /* - * There is no good nop for all x86 archs. This selection - * algorithm should be unified with the one in find_nop_table(), - * but this should be good enough for now. - * - * For cases other than the ones below, use the safe (as in - * always functional) defaults above. - */ -#ifdef CONFIG_X86_64 - /* Don't use these on 32 bits due to broken virtualizers */ - if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) - memcpy(ideal_nop5, p6_nops[5], 5); -#endif -} -#endif |
