diff options
Diffstat (limited to 'include/asm-x86/alternative.h')
| -rw-r--r-- | include/asm-x86/alternative.h | 32 |
1 files changed, 26 insertions, 6 deletions
diff --git a/include/asm-x86/alternative.h b/include/asm-x86/alternative.h index d8bacf3c4b08..1f6a9ca10126 100644 --- a/include/asm-x86/alternative.h +++ b/include/asm-x86/alternative.h @@ -66,8 +66,8 @@ extern void alternatives_smp_module_del(struct module *mod); extern void alternatives_smp_switch(int smp); #else static inline void alternatives_smp_module_add(struct module *mod, char *name, - void *locks, void *locks_end, - void *text, void *text_end) {} + void *locks, void *locks_end, + void *text, void *text_end) {} static inline void alternatives_smp_module_del(struct module *mod) {} static inline void alternatives_smp_switch(int smp) {} #endif /* CONFIG_SMP */ @@ -148,14 +148,34 @@ struct paravirt_patch_site; void apply_paravirt(struct paravirt_patch_site *start, struct paravirt_patch_site *end); #else -static inline void -apply_paravirt(struct paravirt_patch_site *start, - struct paravirt_patch_site *end) +static inline void apply_paravirt(struct paravirt_patch_site *start, + struct paravirt_patch_site *end) {} #define __parainstructions NULL #define __parainstructions_end NULL #endif -extern void text_poke(void *addr, unsigned char *opcode, int len); +extern void add_nops(void *insns, unsigned int len); + +/* + * Clear and restore the kernel write-protection flag on the local CPU. + * Allows the kernel to edit read-only pages. + * Side-effect: any interrupt handler running between save and restore will have + * the ability to write to read-only pages. + * + * Warning: + * Code patching in the UP case is safe if NMIs and MCE handlers are stopped and + * no thread can be preempted in the instructions being modified (no iret to an + * invalid instruction possible) or if the instructions are changed from a + * consistent state to another consistent state atomically. + * More care must be taken when modifying code in the SMP case because of + * Intel's errata. + * On the local CPU you need to be protected again NMI or MCE handlers seeing an + * inconsistent instruction while you patch. + * The _early version expects the memory to already be RW. + */ + +extern void *text_poke(void *addr, const void *opcode, size_t len); +extern void *text_poke_early(void *addr, const void *opcode, size_t len); #endif /* _ASM_X86_ALTERNATIVE_H */ |