diff options
Diffstat (limited to 'arch/x86/kernel/alternative.c')
| -rw-r--r-- | arch/x86/kernel/alternative.c | 88 |
1 files changed, 65 insertions, 23 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index e2d30b8e08a2..0c92ad4d257a 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -11,6 +11,8 @@ #include <asm/mce.h> #include <asm/nmi.h> #include <asm/vsyscall.h> +#include <asm/cacheflush.h> +#include <asm/io.h> #define MAX_PATCH_LEN (255-1) @@ -177,7 +179,7 @@ static const unsigned char*const * find_nop_table(void) #endif /* CONFIG_X86_64 */ /* Use this to add nops to a buffer, then text_poke the whole buffer. */ -static void add_nops(void *insns, unsigned int len) +void add_nops(void *insns, unsigned int len) { const unsigned char *const *noptable = find_nop_table(); @@ -190,6 +192,7 @@ static void add_nops(void *insns, unsigned int len) len -= noplen; } } +EXPORT_SYMBOL_GPL(add_nops); extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; extern u8 *__smp_locks[], *__smp_locks_end[]; @@ -223,7 +226,7 @@ void apply_alternatives(struct alt_instr *start, struct alt_instr *end) memcpy(insnbuf, a->replacement, a->replacementlen); add_nops(insnbuf + a->replacementlen, a->instrlen - a->replacementlen); - text_poke(instr, insnbuf, a->instrlen); + text_poke_early(instr, insnbuf, a->instrlen); } } @@ -284,7 +287,6 @@ void alternatives_smp_module_add(struct module *mod, char *name, void *text, void *text_end) { struct smp_alt_module *smp; - unsigned long flags; if (noreplace_smp) return; @@ -310,39 +312,37 @@ void alternatives_smp_module_add(struct module *mod, char *name, __func__, smp->locks, smp->locks_end, smp->text, smp->text_end, smp->name); - spin_lock_irqsave(&smp_alt, flags); + spin_lock(&smp_alt); list_add_tail(&smp->next, &smp_alt_modules); if (boot_cpu_has(X86_FEATURE_UP)) alternatives_smp_unlock(smp->locks, smp->locks_end, smp->text, smp->text_end); - spin_unlock_irqrestore(&smp_alt, flags); + spin_unlock(&smp_alt); } void alternatives_smp_module_del(struct module *mod) { struct smp_alt_module *item; - unsigned long flags; if (smp_alt_once || noreplace_smp) return; - spin_lock_irqsave(&smp_alt, flags); + spin_lock(&smp_alt); list_for_each_entry(item, &smp_alt_modules, next) { if (mod != item->mod) continue; list_del(&item->next); - spin_unlock_irqrestore(&smp_alt, flags); + spin_unlock(&smp_alt); DPRINTK("%s: %s\n", __func__, item->name); kfree(item); return; } - spin_unlock_irqrestore(&smp_alt, flags); + spin_unlock(&smp_alt); } void alternatives_smp_switch(int smp) { struct smp_alt_module *mod; - unsigned long flags; #ifdef CONFIG_LOCKDEP /* @@ -359,7 +359,7 @@ void alternatives_smp_switch(int smp) return; BUG_ON(!smp && (num_online_cpus() > 1)); - spin_lock_irqsave(&smp_alt, flags); + spin_lock(&smp_alt); /* * Avoid unnecessary switches because it forces JIT based VMs to @@ -383,7 +383,7 @@ void alternatives_smp_switch(int smp) mod->text, mod->text_end); } smp_mode = smp; - spin_unlock_irqrestore(&smp_alt, flags); + spin_unlock(&smp_alt); } #endif @@ -411,7 +411,7 @@ void apply_paravirt(struct paravirt_patch_site *start, /* Pad the rest with nops */ add_nops(insnbuf + used, p->len - used); - text_poke(p->instr, insnbuf, p->len); + text_poke_early(p->instr, insnbuf, p->len); } } extern struct paravirt_patch_site __start_parainstructions[], @@ -420,8 +420,6 @@ extern struct paravirt_patch_site __start_parainstructions[], void __init alternative_instructions(void) { - unsigned long flags; - /* The patching is not fully atomic, so try to avoid local interruptions that might execute the to be patched code. Other CPUs are not running. */ @@ -430,7 +428,6 @@ void __init alternative_instructions(void) stop_mce(); #endif - local_irq_save(flags); apply_alternatives(__alt_instructions, __alt_instructions_end); /* switch to patch-once-at-boottime-only mode and free the @@ -462,7 +459,6 @@ void __init alternative_instructions(void) } #endif apply_paravirt(__parainstructions, __parainstructions_end); - local_irq_restore(flags); if (smp_alt_once) free_init_pages("SMP alternatives", @@ -475,18 +471,64 @@ void __init alternative_instructions(void) #endif } -/* - * Warning: +/** + * text_poke_early - Update instructions on a live kernel at boot time + * @addr: address to modify + * @opcode: source of the copy + * @len: length to copy + * * When you use this code to patch more than one byte of an instruction * you need to make sure that other CPUs cannot execute this code in parallel. - * Also no thread must be currently preempted in the middle of these instructions. - * And on the local CPU you need to be protected again NMI or MCE handlers - * seeing an inconsistent instruction while you patch. + * Also no thread must be currently preempted in the middle of these + * instructions. And on the local CPU you need to be protected again NMI or MCE + * handlers seeing an inconsistent instruction while you patch. */ -void __kprobes text_poke(void *addr, unsigned char *opcode, int len) +void *text_poke_early(void *addr, const void *opcode, size_t len) { + unsigned long flags; + local_irq_save(flags); memcpy(addr, opcode, len); + local_irq_restore(flags); + sync_core(); + /* Could also do a CLFLUSH here to speed up CPU recovery; but + that causes hangs on some VIA CPUs. */ + return addr; +} + +/** + * text_poke - Update instructions on a live kernel + * @addr: address to modify + * @opcode: source of the copy + * @len: length to copy + * + * Only atomic text poke/set should be allowed when not doing early patching. + * It means the size must be writable atomically and the address must be aligned + * in a way that permits an atomic write. It also makes sure we fit on a single + * page. + */ +void *__kprobes text_poke(void *addr, const void *opcode, size_t len) +{ + unsigned long flags; + char *vaddr; + int nr_pages = 2; + + BUG_ON(len > sizeof(long)); + BUG_ON((((long)addr + len - 1) & ~(sizeof(long) - 1)) + - ((long)addr & ~(sizeof(long) - 1))); + { + struct page *pages[2] = { virt_to_page(addr), + virt_to_page(addr + PAGE_SIZE) }; + if (!pages[1]) + nr_pages = 1; + vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL); + BUG_ON(!vaddr); + local_irq_save(flags); + memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len); + local_irq_restore(flags); + vunmap(vaddr); + } sync_core(); /* Could also do a CLFLUSH here to speed up CPU recovery; but that causes hangs on some VIA CPUs. */ + return addr; } |