diff options
Diffstat (limited to 'src/runtime/asm_386.s')
| -rw-r--r-- | src/runtime/asm_386.s | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/src/runtime/asm_386.s b/src/runtime/asm_386.s index 58a0d502bd..1574b3060d 100644 --- a/src/runtime/asm_386.s +++ b/src/runtime/asm_386.s @@ -30,6 +30,19 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0 CPUID CMPL AX, $0 JE nocpuinfo + + // Figure out how to serialize RDTSC. + // On Intel processors LFENCE is enough. AMD requires MFENCE. + // Don't know about the rest, so let's do MFENCE. + CMPL BX, $0x756E6547 // "Genu" + JNE notintel + CMPL DX, $0x49656E69 // "ineI" + JNE notintel + CMPL CX, $0x6C65746E // "ntel" + JNE notintel + MOVB $1, runtime·lfenceBeforeRdtsc(SB) +notintel: + MOVL $1, AX CPUID MOVL CX, runtime·cpuid_ecx(SB) @@ -868,9 +881,17 @@ TEXT runtime·gogetcallersp(SB),NOSPLIT,$0-8 MOVL AX, ret+4(FP) RET -// int64 runtime·cputicks(void), so really -// void runtime·cputicks(int64 *ticks) +// func cputicks() int64 TEXT runtime·cputicks(SB),NOSPLIT,$0-8 + TESTL $0x4000000, runtime·cpuid_edx(SB) // no sse2, no mfence + JEQ done + CMPB runtime·lfenceBeforeRdtsc(SB), $1 + JNE mfence + BYTE $0x0f; BYTE $0xae; BYTE $0xe8 // LFENCE + JMP done +mfence: + BYTE $0x0f; BYTE $0xae; BYTE $0xf0 // MFENCE +done: RDTSC MOVL AX, ret_lo+0(FP) MOVL DX, ret_hi+4(FP) |