diff options
Diffstat (limited to 'arch/arm64/include/asm/alternative.h')
| -rw-r--r-- | arch/arm64/include/asm/alternative.h | 41 |
1 files changed, 37 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h index 669028172fd6..a91933b1e2e6 100644 --- a/arch/arm64/include/asm/alternative.h +++ b/arch/arm64/include/asm/alternative.h @@ -5,6 +5,8 @@ #include <asm/cpucaps.h> #include <asm/insn.h> +#define ARM64_CB_PATCH ARM64_NCAPS + #ifndef __ASSEMBLY__ #include <linux/init.h> @@ -22,12 +24,19 @@ struct alt_instr { u8 alt_len; /* size of new instruction(s), <= orig_len */ }; +typedef void (*alternative_cb_t)(struct alt_instr *alt, + __le32 *origptr, __le32 *updptr, int nr_inst); + void __init apply_alternatives_all(void); void apply_alternatives(void *start, size_t length); -#define ALTINSTR_ENTRY(feature) \ +#define ALTINSTR_ENTRY(feature,cb) \ " .word 661b - .\n" /* label */ \ + " .if " __stringify(cb) " == 0\n" \ " .word 663f - .\n" /* new instruction */ \ + " .else\n" \ + " .word " __stringify(cb) "- .\n" /* callback */ \ + " .endif\n" \ " .hword " __stringify(feature) "\n" /* feature bit */ \ " .byte 662b-661b\n" /* source len */ \ " .byte 664f-663f\n" /* replacement len */ @@ -45,15 +54,18 @@ void apply_alternatives(void *start, size_t length); * but most assemblers die if insn1 or insn2 have a .inst. This should * be fixed in a binutils release posterior to 2.25.51.0.2 (anything * containing commit 4e4d08cf7399b606 or c1baaddf8861). + * + * Alternatives with callbacks do not generate replacement instructions. */ -#define __ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg_enabled) \ +#define __ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg_enabled, cb) \ ".if "__stringify(cfg_enabled)" == 1\n" \ "661:\n\t" \ oldinstr "\n" \ "662:\n" \ ".pushsection .altinstructions,\"a\"\n" \ - ALTINSTR_ENTRY(feature) \ + ALTINSTR_ENTRY(feature,cb) \ ".popsection\n" \ + " .if " __stringify(cb) " == 0\n" \ ".pushsection .altinstr_replacement, \"a\"\n" \ "663:\n\t" \ newinstr "\n" \ @@ -61,11 +73,17 @@ void apply_alternatives(void *start, size_t length); ".popsection\n\t" \ ".org . - (664b-663b) + (662b-661b)\n\t" \ ".org . - (662b-661b) + (664b-663b)\n" \ + ".else\n\t" \ + "663:\n\t" \ + "664:\n\t" \ + ".endif\n" \ ".endif\n" #define _ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg, ...) \ - __ALTERNATIVE_CFG(oldinstr, newinstr, feature, IS_ENABLED(cfg)) + __ALTERNATIVE_CFG(oldinstr, newinstr, feature, IS_ENABLED(cfg), 0) +#define ALTERNATIVE_CB(oldinstr, cb) \ + __ALTERNATIVE_CFG(oldinstr, "NOT_AN_INSTRUCTION", ARM64_CB_PATCH, 1, cb) #else #include <asm/assembler.h> @@ -132,6 +150,14 @@ void apply_alternatives(void *start, size_t length); 661: .endm +.macro alternative_cb cb + .set .Lasm_alt_mode, 0 + .pushsection .altinstructions, "a" + altinstruction_entry 661f, \cb, ARM64_CB_PATCH, 662f-661f, 0 + .popsection +661: +.endm + /* * Provide the other half of the alternative code sequence. */ @@ -158,6 +184,13 @@ void apply_alternatives(void *start, size_t length); .endm /* + * Callback-based alternative epilogue + */ +.macro alternative_cb_end +662: +.endm + +/* * Provides a trivial alternative or default sequence consisting solely * of NOPs. The number of NOPs is chosen automatically to match the * previous case. |