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Diffstat (limited to 'arch/arm64/include/asm/alternative.h')
| -rw-r--r-- | arch/arm64/include/asm/alternative.h | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h new file mode 100644 index 000000000000..d261f01e2bae --- /dev/null +++ b/arch/arm64/include/asm/alternative.h @@ -0,0 +1,44 @@ +#ifndef __ASM_ALTERNATIVE_H +#define __ASM_ALTERNATIVE_H + +#include <linux/types.h> +#include <linux/stddef.h> +#include <linux/stringify.h> + +struct alt_instr { + s32 orig_offset; /* offset to original instruction */ + s32 alt_offset; /* offset to replacement instruction */ + u16 cpufeature; /* cpufeature bit set for replacement */ + u8 orig_len; /* size of original instruction(s) */ + u8 alt_len; /* size of new instruction(s), <= orig_len */ +}; + +void apply_alternatives_all(void); +void apply_alternatives(void *start, size_t length); +void free_alternatives_memory(void); + +#define ALTINSTR_ENTRY(feature) \ + " .word 661b - .\n" /* label */ \ + " .word 663f - .\n" /* new instruction */ \ + " .hword " __stringify(feature) "\n" /* feature bit */ \ + " .byte 662b-661b\n" /* source len */ \ + " .byte 664f-663f\n" /* replacement len */ + +/* alternative assembly primitive: */ +#define ALTERNATIVE(oldinstr, newinstr, feature) \ + "661:\n\t" \ + oldinstr "\n" \ + "662:\n" \ + ".pushsection .altinstructions,\"a\"\n" \ + ALTINSTR_ENTRY(feature) \ + ".popsection\n" \ + ".pushsection .altinstr_replacement, \"a\"\n" \ + "663:\n\t" \ + newinstr "\n" \ + "664:\n\t" \ + ".popsection\n\t" \ + ".if ((664b-663b) != (662b-661b))\n\t" \ + " .error \"Alternatives instruction length mismatch\"\n\t"\ + ".endif\n" + +#endif /* __ASM_ALTERNATIVE_H */ |