diff options
Diffstat (limited to 'arch/x86/kernel/alternative.c')
-rw-r--r-- | arch/x86/kernel/alternative.c | 123 |
1 files changed, 58 insertions, 65 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index a36bb90aef53..123608531c8f 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -353,6 +353,7 @@ void __init_or_module alternatives_smp_module_del(struct module *mod) mutex_unlock(&smp_alt); } +bool skip_smp_alternatives; void alternatives_smp_switch(int smp) { struct smp_alt_module *mod; @@ -368,7 +369,7 @@ void alternatives_smp_switch(int smp) printk("lockdep: fixing up alternatives.\n"); #endif - if (noreplace_smp || smp_alt_once) + if (noreplace_smp || smp_alt_once || skip_smp_alternatives) return; BUG_ON(!smp && (num_online_cpus() > 1)); @@ -591,17 +592,21 @@ static atomic_t stop_machine_first; static int wrote_text; struct text_poke_params { - void *addr; - const void *opcode; - size_t len; + struct text_poke_param *params; + int nparams; }; static int __kprobes stop_machine_text_poke(void *data) { struct text_poke_params *tpp = data; + struct text_poke_param *p; + int i; if (atomic_dec_and_test(&stop_machine_first)) { - text_poke(tpp->addr, tpp->opcode, tpp->len); + for (i = 0; i < tpp->nparams; i++) { + p = &tpp->params[i]; + text_poke(p->addr, p->opcode, p->len); + } smp_wmb(); /* Make sure other cpus see that this has run */ wrote_text = 1; } else { @@ -610,8 +615,12 @@ static int __kprobes stop_machine_text_poke(void *data) smp_mb(); /* Load wrote_text before following execution */ } - flush_icache_range((unsigned long)tpp->addr, - (unsigned long)tpp->addr + tpp->len); + for (i = 0; i < tpp->nparams; i++) { + p = &tpp->params[i]; + flush_icache_range((unsigned long)p->addr, + (unsigned long)p->addr + p->len); + } + return 0; } @@ -631,78 +640,62 @@ static int __kprobes stop_machine_text_poke(void *data) void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len) { struct text_poke_params tpp; + struct text_poke_param p; - tpp.addr = addr; - tpp.opcode = opcode; - tpp.len = len; + p.addr = addr; + p.opcode = opcode; + p.len = len; + tpp.params = &p; + tpp.nparams = 1; atomic_set(&stop_machine_first, 1); wrote_text = 0; /* Use __stop_machine() because the caller already got online_cpus. */ - __stop_machine(stop_machine_text_poke, (void *)&tpp, NULL); + __stop_machine(stop_machine_text_poke, (void *)&tpp, cpu_online_mask); return addr; } +/** + * text_poke_smp_batch - Update instructions on a live kernel on SMP + * @params: an array of text_poke parameters + * @n: the number of elements in params. + * + * Modify multi-byte instruction by using stop_machine() on SMP. Since the + * stop_machine() is heavy task, it is better to aggregate text_poke requests + * and do it once if possible. + * + * Note: Must be called under get_online_cpus() and text_mutex. + */ +void __kprobes text_poke_smp_batch(struct text_poke_param *params, int n) +{ + struct text_poke_params tpp = {.params = params, .nparams = n}; + + atomic_set(&stop_machine_first, 1); + wrote_text = 0; + stop_machine(stop_machine_text_poke, (void *)&tpp, NULL); +} + #if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL) -unsigned char ideal_nop5[IDEAL_NOP_SIZE_5]; +#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) { - extern const unsigned char ftrace_test_p6nop[]; - extern const unsigned char ftrace_test_nop5[]; - extern const unsigned char ftrace_test_jmp[]; - int faulted = 0; - /* - * There is no good nop for all x86 archs. - * We will default to using the P6_NOP5, but first we - * will test to make sure that the nop will actually - * work on this CPU. If it faults, we will then - * go to a lesser efficient 5 byte nop. If that fails - * we then just use a jmp as our nop. This isn't the most - * efficient nop, but we can not use a multi part nop - * since we would then risk being preempted in the middle - * of that nop, and if we enabled tracing then, it might - * cause a system crash. + * 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. * - * TODO: check the cpuid to determine the best nop. + * For cases other than the ones below, use the safe (as in + * always functional) defaults above. */ - asm volatile ( - "ftrace_test_jmp:" - "jmp ftrace_test_p6nop\n" - "nop\n" - "nop\n" - "nop\n" /* 2 byte jmp + 3 bytes */ - "ftrace_test_p6nop:" - P6_NOP5 - "jmp 1f\n" - "ftrace_test_nop5:" - ".byte 0x66,0x66,0x66,0x66,0x90\n" - "1:" - ".section .fixup, \"ax\"\n" - "2: movl $1, %0\n" - " jmp ftrace_test_nop5\n" - "3: movl $2, %0\n" - " jmp 1b\n" - ".previous\n" - _ASM_EXTABLE(ftrace_test_p6nop, 2b) - _ASM_EXTABLE(ftrace_test_nop5, 3b) - : "=r"(faulted) : "0" (faulted)); - - switch (faulted) { - case 0: - pr_info("converting mcount calls to 0f 1f 44 00 00\n"); - memcpy(ideal_nop5, ftrace_test_p6nop, IDEAL_NOP_SIZE_5); - break; - case 1: - pr_info("converting mcount calls to 66 66 66 66 90\n"); - memcpy(ideal_nop5, ftrace_test_nop5, IDEAL_NOP_SIZE_5); - break; - case 2: - pr_info("converting mcount calls to jmp . + 5\n"); - memcpy(ideal_nop5, ftrace_test_jmp, IDEAL_NOP_SIZE_5); - break; - } - +#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 |