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Diffstat (limited to 'src/runtime/time_linux_amd64.s')
| -rw-r--r-- | src/runtime/time_linux_amd64.s | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/src/runtime/time_linux_amd64.s b/src/runtime/time_linux_amd64.s new file mode 100644 index 0000000000..0dd7919896 --- /dev/null +++ b/src/runtime/time_linux_amd64.s @@ -0,0 +1,97 @@ +// Copyright 2021 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +//go:build !faketime +// +build !faketime + +#include "go_asm.h" +#include "go_tls.h" +#include "textflag.h" + +#define SYS_clock_gettime 228 + +// func time.now() (sec int64, nsec int32, mono int64) +TEXT time·now(SB),NOSPLIT,$16-24 + MOVQ SP, R12 // Save old SP; R12 unchanged by C code. + +#ifdef GOEXPERIMENT_regabig + MOVQ g_m(R14), BX // BX unchanged by C code. +#else + get_tls(CX) + MOVQ g(CX), AX + MOVQ g_m(AX), BX // BX unchanged by C code. +#endif + + // Store CLOCK_REALTIME results directly to return space. + LEAQ sec+0(FP), SI + + // Set vdsoPC and vdsoSP for SIGPROF traceback. + // Save the old values on stack and restore them on exit, + // so this function is reentrant. + MOVQ m_vdsoPC(BX), CX + MOVQ m_vdsoSP(BX), DX + MOVQ CX, 0(SP) + MOVQ DX, 8(SP) + + MOVQ -8(SI), CX // Sets CX to function return address. + MOVQ CX, m_vdsoPC(BX) + MOVQ SI, m_vdsoSP(BX) + +#ifdef GOEXPERIMENT_regabig + CMPQ R14, m_curg(BX) // Only switch if on curg. +#else + CMPQ AX, m_curg(BX) // Only switch if on curg. +#endif + JNE noswitch + + MOVQ m_g0(BX), DX + MOVQ (g_sched+gobuf_sp)(DX), SP // Set SP to g0 stack + +noswitch: + SUBQ $16, SP // Space for monotonic time results + ANDQ $~15, SP // Align for C code + + MOVL $0, DI // CLOCK_REALTIME + MOVQ runtime·vdsoClockgettimeSym(SB), AX + CMPQ AX, $0 + JEQ fallback + CALL AX + + MOVL $1, DI // CLOCK_MONOTONIC + LEAQ 0(SP), SI + MOVQ runtime·vdsoClockgettimeSym(SB), AX + CALL AX + +ret: + MOVQ 0(SP), AX // sec + MOVQ 8(SP), DX // nsec + + MOVQ R12, SP // Restore real SP + // Restore vdsoPC, vdsoSP + // We don't worry about being signaled between the two stores. + // If we are not in a signal handler, we'll restore vdsoSP to 0, + // and no one will care about vdsoPC. If we are in a signal handler, + // we cannot receive another signal. + MOVQ 8(SP), CX + MOVQ CX, m_vdsoSP(BX) + MOVQ 0(SP), CX + MOVQ CX, m_vdsoPC(BX) + + // sec is in AX, nsec in DX + // return nsec in AX + IMULQ $1000000000, AX + ADDQ DX, AX + MOVQ AX, mono+16(FP) + RET + +fallback: + MOVQ $SYS_clock_gettime, AX + SYSCALL + + MOVL $1, DI // CLOCK_MONOTONIC + LEAQ 0(SP), SI + MOVQ $SYS_clock_gettime, AX + SYSCALL + + JMP ret |