diff options
Diffstat (limited to 'arch/arm64/include/asm/alternative.h')
| -rw-r--r-- | arch/arm64/include/asm/alternative.h | 78 |
1 files changed, 74 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h index c385a0c40..d56ec0715 100644 --- a/arch/arm64/include/asm/alternative.h +++ b/arch/arm64/include/asm/alternative.h @@ -3,6 +3,8 @@ #ifndef __ASSEMBLY__ +#include <linux/init.h> +#include <linux/kconfig.h> #include <linux/types.h> #include <linux/stddef.h> #include <linux/stringify.h> @@ -15,7 +17,7 @@ struct alt_instr { u8 alt_len; /* size of new instruction(s), <= orig_len */ }; -void apply_alternatives_all(void); +void __init apply_alternatives_all(void); void apply_alternatives(void *start, size_t length); void free_alternatives_memory(void); @@ -40,7 +42,8 @@ void free_alternatives_memory(void); * be fixed in a binutils release posterior to 2.25.51.0.2 (anything * containing commit 4e4d08cf7399b606 or c1baaddf8861). */ -#define ALTERNATIVE(oldinstr, newinstr, feature) \ +#define __ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg_enabled) \ + ".if "__stringify(cfg_enabled)" == 1\n" \ "661:\n\t" \ oldinstr "\n" \ "662:\n" \ @@ -53,7 +56,11 @@ void free_alternatives_memory(void); "664:\n\t" \ ".popsection\n\t" \ ".org . - (664b-663b) + (662b-661b)\n\t" \ - ".org . - (662b-661b) + (664b-663b)\n" + ".org . - (662b-661b) + (664b-663b)\n" \ + ".endif\n" + +#define _ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg, ...) \ + __ALTERNATIVE_CFG(oldinstr, newinstr, feature, IS_ENABLED(cfg)) #else @@ -65,7 +72,8 @@ void free_alternatives_memory(void); .byte \alt_len .endm -.macro alternative_insn insn1 insn2 cap +.macro alternative_insn insn1, insn2, cap, enable = 1 + .if \enable 661: \insn1 662: .pushsection .altinstructions, "a" altinstruction_entry 661b, 663f, \cap, 662b-661b, 664f-663f @@ -75,8 +83,70 @@ void free_alternatives_memory(void); 664: .popsection .org . - (664b-663b) + (662b-661b) .org . - (662b-661b) + (664b-663b) + .endif +.endm + +/* + * Begin an alternative code sequence. + * + * The code that follows this macro will be assembled and linked as + * normal. There are no restrictions on this code. + */ +.macro alternative_if_not cap, enable = 1 + .if \enable + .pushsection .altinstructions, "a" + altinstruction_entry 661f, 663f, \cap, 662f-661f, 664f-663f + .popsection +661: + .endif +.endm + +/* + * Provide the alternative code sequence. + * + * The code that follows this macro is assembled into a special + * section to be used for dynamic patching. Code that follows this + * macro must: + * + * 1. Be exactly the same length (in bytes) as the default code + * sequence. + * + * 2. Not contain a branch target that is used outside of the + * alternative sequence it is defined in (branches into an + * alternative sequence are not fixed up). + */ +.macro alternative_else, enable = 1 + .if \enable +662: .pushsection .altinstr_replacement, "ax" +663: + .endif .endm +/* + * Complete an alternative code sequence. + */ +.macro alternative_endif, enable = 1 + .if \enable +664: .popsection + .org . - (664b-663b) + (662b-661b) + .org . - (662b-661b) + (664b-663b) + .endif +.endm + +#define _ALTERNATIVE_CFG(insn1, insn2, cap, cfg, ...) \ + alternative_insn insn1, insn2, cap, IS_ENABLED(cfg) + + #endif /* __ASSEMBLY__ */ +/* + * Usage: asm(ALTERNATIVE(oldinstr, newinstr, feature)); + * + * Usage: asm(ALTERNATIVE(oldinstr, newinstr, feature, CONFIG_FOO)); + * N.B. If CONFIG_FOO is specified, but not selected, the whole block + * will be omitted, including oldinstr. + */ +#define ALTERNATIVE(oldinstr, newinstr, ...) \ + _ALTERNATIVE_CFG(oldinstr, newinstr, __VA_ARGS__, 1) + #endif /* __ASM_ALTERNATIVE_H */ |