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Diffstat (limited to 'include/asm-x86/alternative_32.h')
| -rw-r--r-- | include/asm-x86/alternative_32.h | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/include/asm-x86/alternative_32.h b/include/asm-x86/alternative_32.h new file mode 100644 index 00000000000..bda6c810c0f --- /dev/null +++ b/include/asm-x86/alternative_32.h @@ -0,0 +1,154 @@ +#ifndef _I386_ALTERNATIVE_H +#define _I386_ALTERNATIVE_H + +#include <asm/types.h> +#include <linux/stddef.h> +#include <linux/types.h> + +struct alt_instr { + u8 *instr; /* original instruction */ + u8 *replacement; + u8 cpuid; /* cpuid bit set for replacement */ + u8 instrlen; /* length of original instruction */ + u8 replacementlen; /* length of new instruction, <= instrlen */ + u8 pad; +}; + +extern void alternative_instructions(void); +extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end); + +struct module; +#ifdef CONFIG_SMP +extern void alternatives_smp_module_add(struct module *mod, char *name, + void *locks, void *locks_end, + void *text, void *text_end); +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) {} +static inline void alternatives_smp_module_del(struct module *mod) {} +static inline void alternatives_smp_switch(int smp) {} +#endif /* CONFIG_SMP */ + +/* + * Alternative instructions for different CPU types or capabilities. + * + * This allows to use optimized instructions even on generic binary + * kernels. + * + * length of oldinstr must be longer or equal the length of newinstr + * It can be padded with nops as needed. + * + * For non barrier like inlines please define new variants + * without volatile and memory clobber. + */ +#define alternative(oldinstr, newinstr, feature) \ + asm volatile ("661:\n\t" oldinstr "\n662:\n" \ + ".section .altinstructions,\"a\"\n" \ + " .align 4\n" \ + " .long 661b\n" /* label */ \ + " .long 663f\n" /* new instruction */ \ + " .byte %c0\n" /* feature bit */ \ + " .byte 662b-661b\n" /* sourcelen */ \ + " .byte 664f-663f\n" /* replacementlen */ \ + ".previous\n" \ + ".section .altinstr_replacement,\"ax\"\n" \ + "663:\n\t" newinstr "\n664:\n" /* replacement */\ + ".previous" :: "i" (feature) : "memory") + +/* + * Alternative inline assembly with input. + * + * Pecularities: + * No memory clobber here. + * Argument numbers start with 1. + * Best is to use constraints that are fixed size (like (%1) ... "r") + * If you use variable sized constraints like "m" or "g" in the + * replacement maake sure to pad to the worst case length. + */ +#define alternative_input(oldinstr, newinstr, feature, input...) \ + asm volatile ("661:\n\t" oldinstr "\n662:\n" \ + ".section .altinstructions,\"a\"\n" \ + " .align 4\n" \ + " .long 661b\n" /* label */ \ + " .long 663f\n" /* new instruction */ \ + " .byte %c0\n" /* feature bit */ \ + " .byte 662b-661b\n" /* sourcelen */ \ + " .byte 664f-663f\n" /* replacementlen */ \ + ".previous\n" \ + ".section .altinstr_replacement,\"ax\"\n" \ + "663:\n\t" newinstr "\n664:\n" /* replacement */\ + ".previous" :: "i" (feature), ##input) + +/* Like alternative_input, but with a single output argument */ +#define alternative_io(oldinstr, newinstr, feature, output, input...) \ + asm volatile ("661:\n\t" oldinstr "\n662:\n" \ + ".section .altinstructions,\"a\"\n" \ + " .align 4\n" \ + " .long 661b\n" /* label */ \ + " .long 663f\n" /* new instruction */ \ + " .byte %c[feat]\n" /* feature bit */ \ + " .byte 662b-661b\n" /* sourcelen */ \ + " .byte 664f-663f\n" /* replacementlen */ \ + ".previous\n" \ + ".section .altinstr_replacement,\"ax\"\n" \ + "663:\n\t" newinstr "\n664:\n" /* replacement */ \ + ".previous" : output : [feat] "i" (feature), ##input) + +/* + * use this macro(s) if you need more than one output parameter + * in alternative_io + */ +#define ASM_OUTPUT2(a, b) a, b + +/* + * Alternative inline assembly for SMP. + * + * The LOCK_PREFIX macro defined here replaces the LOCK and + * LOCK_PREFIX macros used everywhere in the source tree. + * + * SMP alternatives use the same data structures as the other + * alternatives and the X86_FEATURE_UP flag to indicate the case of a + * UP system running a SMP kernel. The existing apply_alternatives() + * works fine for patching a SMP kernel for UP. + * + * The SMP alternative tables can be kept after boot and contain both + * UP and SMP versions of the instructions to allow switching back to + * SMP at runtime, when hotplugging in a new CPU, which is especially + * useful in virtualized environments. + * + * The very common lock prefix is handled as special case in a + * separate table which is a pure address list without replacement ptr + * and size information. That keeps the table sizes small. + */ + +#ifdef CONFIG_SMP +#define LOCK_PREFIX \ + ".section .smp_locks,\"a\"\n" \ + " .align 4\n" \ + " .long 661f\n" /* address */ \ + ".previous\n" \ + "661:\n\tlock; " + +#else /* ! CONFIG_SMP */ +#define LOCK_PREFIX "" +#endif + +struct paravirt_patch_site; +#ifdef CONFIG_PARAVIRT +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) +{} +#define __parainstructions NULL +#define __parainstructions_end NULL +#endif + +extern void text_poke(void *addr, unsigned char *opcode, int len); + +#endif /* _I386_ALTERNATIVE_H */ |