diff options
Diffstat (limited to 'arch/arm64/include/asm/alternative.h')
| -rw-r--r-- | arch/arm64/include/asm/alternative.h | 86 |
1 files changed, 60 insertions, 26 deletions
diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h index beccbdefa106..55101bd86b98 100644 --- a/arch/arm64/include/asm/alternative.h +++ b/arch/arm64/include/asm/alternative.h @@ -2,6 +2,7 @@ #define __ASM_ALTERNATIVE_H #include <asm/cpufeature.h> +#include <asm/insn.h> #ifndef __ASSEMBLY__ @@ -90,26 +91,15 @@ void apply_alternatives(void *start, size_t length); .endm /* - * Begin an alternative code sequence. + * Alternative sequences * - * 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 for the case where the capability is not present will be + * assembled and linked as normal. There are no restrictions on this + * code. * - * The code that follows this macro is assembled into a special - * section to be used for dynamic patching. Code that follows this - * macro must: + * The code for the case where the capability is present will be + * assembled into a special section to be used for dynamic patching. + * Code for that case must: * * 1. Be exactly the same length (in bytes) as the default code * sequence. @@ -118,27 +108,71 @@ void apply_alternatives(void *start, size_t length); * 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: + +/* + * Begin an alternative code sequence. + */ +.macro alternative_if_not cap + .set .Lasm_alt_mode, 0 + .pushsection .altinstructions, "a" + altinstruction_entry 661f, 663f, \cap, 662f-661f, 664f-663f + .popsection +661: +.endm + +.macro alternative_if cap + .set .Lasm_alt_mode, 1 + .pushsection .altinstructions, "a" + altinstruction_entry 663f, 661f, \cap, 664f-663f, 662f-661f + .popsection + .pushsection .altinstr_replacement, "ax" + .align 2 /* So GAS knows label 661 is suitably aligned */ +661: +.endm + +/* + * Provide the other half of the alternative code sequence. + */ +.macro alternative_else +662: + .if .Lasm_alt_mode==0 + .pushsection .altinstr_replacement, "ax" + .else + .popsection .endif +663: .endm /* * Complete an alternative code sequence. */ -.macro alternative_endif, enable = 1 - .if \enable -664: .popsection +.macro alternative_endif +664: + .if .Lasm_alt_mode==0 + .popsection + .endif .org . - (664b-663b) + (662b-661b) .org . - (662b-661b) + (664b-663b) - .endif +.endm + +/* + * Provides a trivial alternative or default sequence consisting solely + * of NOPs. The number of NOPs is chosen automatically to match the + * previous case. + */ +.macro alternative_else_nop_endif +alternative_else + nops (662b-661b) / AARCH64_INSN_SIZE +alternative_endif .endm #define _ALTERNATIVE_CFG(insn1, insn2, cap, cfg, ...) \ alternative_insn insn1, insn2, cap, IS_ENABLED(cfg) +.macro user_alt, label, oldinstr, newinstr, cond +9999: alternative_insn "\oldinstr", "\newinstr", \cond + _ASM_EXTABLE 9999b, \label +.endm /* * Generate the assembly for UAO alternatives with exception table entries. |