diff options
Diffstat (limited to 'arch/x86/lib/memset_64.S')
| -rw-r--r-- | arch/x86/lib/memset_64.S | 61 |
1 files changed, 24 insertions, 37 deletions
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S index 6f44935c6a60..93118fb23976 100644 --- a/arch/x86/lib/memset_64.S +++ b/arch/x86/lib/memset_64.S @@ -5,19 +5,30 @@ #include <asm/cpufeature.h> #include <asm/alternative-asm.h> +.weak memset + /* * ISO C memset - set a memory block to a byte value. This function uses fast * string to get better performance than the original function. The code is * simpler and shorter than the orignal function as well. - * + * * rdi destination - * rsi value (char) - * rdx count (bytes) - * + * rsi value (char) + * rdx count (bytes) + * * rax original destination - */ - .section .altinstr_replacement, "ax", @progbits -.Lmemset_c: + */ +ENTRY(memset) +ENTRY(__memset) + /* + * Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended + * to use it when possible. If not available, use fast string instructions. + * + * Otherwise, use original memset function. + */ + ALTERNATIVE_2 "jmp memset_orig", "", X86_FEATURE_REP_GOOD, \ + "jmp memset_erms", X86_FEATURE_ERMS + movq %rdi,%r9 movq %rdx,%rcx andl $7,%edx @@ -31,8 +42,8 @@ rep stosb movq %r9,%rax ret -.Lmemset_e: - .previous +ENDPROC(memset) +ENDPROC(__memset) /* * ISO C memset - set a memory block to a byte value. This function uses @@ -45,21 +56,16 @@ * * rax original destination */ - .section .altinstr_replacement, "ax", @progbits -.Lmemset_c_e: +ENTRY(memset_erms) movq %rdi,%r9 movb %sil,%al movq %rdx,%rcx rep stosb movq %r9,%rax ret -.Lmemset_e_e: - .previous - -.weak memset +ENDPROC(memset_erms) -ENTRY(memset) -ENTRY(__memset) +ENTRY(memset_orig) CFI_STARTPROC movq %rdi,%r10 @@ -134,23 +140,4 @@ ENTRY(__memset) jmp .Lafter_bad_alignment .Lfinal: CFI_ENDPROC -ENDPROC(memset) -ENDPROC(__memset) - - /* Some CPUs support enhanced REP MOVSB/STOSB feature. - * It is recommended to use this when possible. - * - * If enhanced REP MOVSB/STOSB feature is not available, use fast string - * instructions. - * - * Otherwise, use original memset function. - * - * In .altinstructions section, ERMS feature is placed after REG_GOOD - * feature to implement the right patch order. - */ - .section .altinstructions,"a" - altinstruction_entry __memset,.Lmemset_c,X86_FEATURE_REP_GOOD,\ - .Lfinal-__memset,.Lmemset_e-.Lmemset_c - altinstruction_entry __memset,.Lmemset_c_e,X86_FEATURE_ERMS, \ - .Lfinal-__memset,.Lmemset_e_e-.Lmemset_c_e - .previous +ENDPROC(memset_orig) |