time: record monotonic clock reading in time.Now, for more accurate comparisons

See https://golang.org/design/12914-monotonic for details.

Fixes #12914.

Change-Id: I80edc2e6c012b4ace7161c84cf067d444381a009
Reviewed-on: https://go-review.googlesource.com/36255
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Caleb Spare <cespare@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

33 files changed, 68 insertions, 61 deletions

diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index 107f2604b1..616b7167ef 100644
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -241,8 +241,7 @@ func stackBarrier()
 // in asm_*.s
 func return0()
 
-//go:linkname time_now time.now
-func time_now() (sec int64, nsec int32)
+func walltime() (sec int64, nsec int32)
 
 // in asm_*.s
 // not called directly; definitions here supply type information for traceback.
@@ -281,7 +280,7 @@ func prefetcht2(addr uintptr)
 func prefetchnta(addr uintptr)
 
 func unixnanotime() int64 {
-	sec, nsec := time_now()
+	sec, nsec := walltime()
 	return sec*1e9 + int64(nsec)
 }
 
diff --git a/src/runtime/sys_darwin_386.s b/src/runtime/sys_darwin_386.s
index 200961f225..e911339c84 100644
--- a/src/runtime/sys_darwin_386.s
+++ b/src/runtime/sys_darwin_386.s
@@ -217,8 +217,8 @@ inreg:
 	ADCL	$0, DX
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$0
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$0
 	CALL	runtime·now(SB)
 	MOVL	$1000000000, CX
 	DIVL	CX
diff --git a/src/runtime/sys_darwin_amd64.s b/src/runtime/sys_darwin_amd64.s
index f94482856c..de8e9e37c9 100644
--- a/src/runtime/sys_darwin_amd64.s
+++ b/src/runtime/sys_darwin_amd64.s
@@ -198,8 +198,8 @@ TEXT runtime·nanotime(SB),NOSPLIT,$0-8
 	MOVQ	AX, ret+0(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$0-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$0-12
 	CALL	nanotime<>(SB)
 
 	// generated code for
diff --git a/src/runtime/sys_darwin_arm.s b/src/runtime/sys_darwin_arm.s
index 2c03c91683..490a410fa4 100644
--- a/src/runtime/sys_darwin_arm.s
+++ b/src/runtime/sys_darwin_arm.s
@@ -159,7 +159,7 @@ TEXT runtime·mincore(SB),NOSPLIT,$0
 	MOVW	R0, ret+12(FP)
 	RET
 
-TEXT time·now(SB), 7, $32
+TEXT runtime·walltime(SB), 7, $32
 	MOVW	$8(R13), R0  // timeval
 	MOVW	$0, R1  // zone
 	MOVW	$0, R2	// see issue 16570
diff --git a/src/runtime/sys_darwin_arm64.s b/src/runtime/sys_darwin_arm64.s
index c02d000774..0e91d5bd10 100644
--- a/src/runtime/sys_darwin_arm64.s
+++ b/src/runtime/sys_darwin_arm64.s
@@ -151,7 +151,7 @@ TEXT runtime·setitimer(SB),NOSPLIT,$0
 	SVC	$0x80
 	RET
 
-TEXT time·now(SB),NOSPLIT,$40-12
+TEXT runtime·walltime(SB),NOSPLIT,$40-12
 	MOVD	RSP, R0	// timeval
 	MOVD	R0, R9	// this is how dyld calls gettimeofday
 	MOVW	$0, R1	// zone
diff --git a/src/runtime/sys_dragonfly_amd64.s b/src/runtime/sys_dragonfly_amd64.s
index b950b69fe0..f355268b99 100644
--- a/src/runtime/sys_dragonfly_amd64.s
+++ b/src/runtime/sys_dragonfly_amd64.s
@@ -148,8 +148,8 @@ TEXT runtime·setitimer(SB), NOSPLIT, $-8
 	SYSCALL
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVL	$232, AX // clock_gettime
 	MOVQ	$0, DI  	// CLOCK_REALTIME
 	LEAQ	8(SP), SI
diff --git a/src/runtime/sys_freebsd_386.s b/src/runtime/sys_freebsd_386.s
index 8b6ee1f2a6..2c056feb46 100644
--- a/src/runtime/sys_freebsd_386.s
+++ b/src/runtime/sys_freebsd_386.s
@@ -159,8 +159,8 @@ TEXT runtime·setitimer(SB), NOSPLIT, $-4
 	INT	$0x80
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVL	$232, AX // clock_gettime
 	LEAL	12(SP), BX
 	MOVL	$0, 4(SP)	// CLOCK_REALTIME
diff --git a/src/runtime/sys_freebsd_amd64.s b/src/runtime/sys_freebsd_amd64.s
index 158a60dec2..43aafe56b8 100644
--- a/src/runtime/sys_freebsd_amd64.s
+++ b/src/runtime/sys_freebsd_amd64.s
@@ -142,8 +142,8 @@ TEXT runtime·setitimer(SB), NOSPLIT, $-8
 	SYSCALL
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVL	$232, AX // clock_gettime
 	MOVQ	$0, DI		// CLOCK_REALTIME
 	LEAQ	8(SP), SI
diff --git a/src/runtime/sys_freebsd_arm.s b/src/runtime/sys_freebsd_arm.s
index 3c5a5cbbb0..97aea65074 100644
--- a/src/runtime/sys_freebsd_arm.s
+++ b/src/runtime/sys_freebsd_arm.s
@@ -166,8 +166,8 @@ TEXT runtime·setitimer(SB), NOSPLIT, $-8
 	SWI $0
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVW $0, R0 // CLOCK_REALTIME
 	MOVW $8(R13), R1
 	MOVW $SYS_clock_gettime, R7
diff --git a/src/runtime/sys_linux_386.s b/src/runtime/sys_linux_386.s
index 45320c068a..5c5afac990 100644
--- a/src/runtime/sys_linux_386.s
+++ b/src/runtime/sys_linux_386.s
@@ -151,8 +151,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$0-16
 	MOVL	AX, ret+12(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVL	$265, AX			// syscall - clock_gettime
 	MOVL	$0, BX		// CLOCK_REALTIME
 	LEAL	8(SP), CX
diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
index 6ddcb30ae2..be6f396cfa 100644
--- a/src/runtime/sys_linux_amd64.s
+++ b/src/runtime/sys_linux_amd64.s
@@ -135,8 +135,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$0-28
 	MOVL	AX, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$16
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	// Be careful. We're calling a function with gcc calling convention here.
 	// We're guaranteed 128 bytes on entry, and we've taken 16, and the
 	// call uses another 8.
diff --git a/src/runtime/sys_linux_arm.s b/src/runtime/sys_linux_arm.s
index 666b879f02..1712e9d76c 100644
--- a/src/runtime/sys_linux_arm.s
+++ b/src/runtime/sys_linux_arm.s
@@ -197,7 +197,7 @@ TEXT runtime·mincore(SB),NOSPLIT,$0
 	MOVW	R0, ret+12(FP)
 	RET
 
-TEXT time·now(SB), NOSPLIT, $32
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVW	$0, R0  // CLOCK_REALTIME
 	MOVW	$8(R13), R1  // timespec
 	MOVW	$SYS_clock_gettime, R7
diff --git a/src/runtime/sys_linux_arm64.s b/src/runtime/sys_linux_arm64.s
index 1b91b4499d..204aee7c51 100644
--- a/src/runtime/sys_linux_arm64.s
+++ b/src/runtime/sys_linux_arm64.s
@@ -182,8 +182,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$-8-28
 	MOVW	R0, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$24-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$24-12
 	MOVW	$0, R0 // CLOCK_REALTIME
 	MOVD	RSP, R1
 	MOVD	$SYS_clock_gettime, R8
diff --git a/src/runtime/sys_linux_mips64x.s b/src/runtime/sys_linux_mips64x.s
index 5a75bb81ae..a4bcc72dd8 100644
--- a/src/runtime/sys_linux_mips64x.s
+++ b/src/runtime/sys_linux_mips64x.s
@@ -172,8 +172,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$-8-28
 	MOVW	R2, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$16
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVW	$0, R4 // CLOCK_REALTIME
 	MOVV	$0(R29), R5
 	MOVV	$SYS_clock_gettime, R2
diff --git a/src/runtime/sys_linux_mipsx.s b/src/runtime/sys_linux_mipsx.s
index 73ce06114c..3b446b15ef 100644
--- a/src/runtime/sys_linux_mipsx.s
+++ b/src/runtime/sys_linux_mipsx.s
@@ -175,8 +175,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$0-16
 	MOVW	R2, ret+12(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	MOVW	$0, R4	// CLOCK_REALTIME
 	MOVW	$4(R29), R5
 	MOVW	$SYS_clock_gettime, R2
diff --git a/src/runtime/sys_linux_ppc64x.s b/src/runtime/sys_linux_ppc64x.s
index a40fe3bc00..b43bda1ef2 100644
--- a/src/runtime/sys_linux_ppc64x.s
+++ b/src/runtime/sys_linux_ppc64x.s
@@ -157,8 +157,8 @@ TEXT runtime·mincore(SB),NOSPLIT|NOFRAME,$0-28
 	MOVW	R3, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$16
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVD	$0, R3 // CLOCK_REALTIME
 	MOVD	$0(R1), R4
 	SYSCALL	$SYS_clock_gettime
diff --git a/src/runtime/sys_linux_s390x.s b/src/runtime/sys_linux_s390x.s
index 47f34d9ea4..2291718074 100644
--- a/src/runtime/sys_linux_s390x.s
+++ b/src/runtime/sys_linux_s390x.s
@@ -169,8 +169,8 @@ TEXT runtime·mincore(SB),NOSPLIT|NOFRAME,$0-28
 	MOVW	R2, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$16
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVW	$0, R2 // CLOCK_REALTIME
 	MOVD	$tp-16(SP), R3
 	MOVW	$SYS_clock_gettime, R1
diff --git a/src/runtime/sys_nacl_386.s b/src/runtime/sys_nacl_386.s
index 05de20c546..31e9b97a09 100644
--- a/src/runtime/sys_nacl_386.s
+++ b/src/runtime/sys_nacl_386.s
@@ -233,7 +233,7 @@ TEXT runtime·mmap(SB),NOSPLIT,$32
 	MOVL	AX, ret+24(FP)
 	RET
 
-TEXT time·now(SB),NOSPLIT,$20
+TEXT runtime·walltime(SB),NOSPLIT,$20
 	MOVL $0, 0(SP) // real time clock
 	LEAL 8(SP), AX
 	MOVL AX, 4(SP) // timespec
@@ -249,7 +249,7 @@ TEXT time·now(SB),NOSPLIT,$20
 	RET
 
 TEXT syscall·now(SB),NOSPLIT,$0
-	JMP time·now(SB)
+	JMP runtime·walltime(SB)
 
 TEXT runtime·nacl_clock_gettime(SB),NOSPLIT,$8
 	MOVL arg1+0(FP), AX
diff --git a/src/runtime/sys_nacl_amd64p32.s b/src/runtime/sys_nacl_amd64p32.s
index c2a24e8a62..db07ae51fd 100644
--- a/src/runtime/sys_nacl_amd64p32.s
+++ b/src/runtime/sys_nacl_amd64p32.s
@@ -242,7 +242,7 @@ TEXT runtime·mmap(SB),NOSPLIT,$8
 	MOVL	AX, ret+24(FP)
 	RET
 
-TEXT time·now(SB),NOSPLIT,$16
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVQ runtime·faketime(SB), AX
 	CMPQ AX, $0
 	JEQ realtime
@@ -268,7 +268,7 @@ realtime:
 	RET
 
 TEXT syscall·now(SB),NOSPLIT,$0
-	JMP time·now(SB)
+	JMP runtime·walltime(SB)
 
 TEXT runtime·nacl_clock_gettime(SB),NOSPLIT,$0
 	MOVL arg1+0(FP), DI
diff --git a/src/runtime/sys_nacl_arm.s b/src/runtime/sys_nacl_arm.s
index 6cbc23fd7d..aa3a09876a 100644
--- a/src/runtime/sys_nacl_arm.s
+++ b/src/runtime/sys_nacl_arm.s
@@ -196,7 +196,7 @@ TEXT runtime·mmap(SB),NOSPLIT,$8
 	MOVW	R0, ret+24(FP)
 	RET
 
-TEXT time·now(SB),NOSPLIT,$16
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVW	$0, R0 // real time clock
 	MOVW	$4(R13), R1
 	NACL_SYSCALL(SYS_clock_gettime)
@@ -209,7 +209,7 @@ TEXT time·now(SB),NOSPLIT,$16
 	RET
 
 TEXT syscall·now(SB),NOSPLIT,$0
-	B time·now(SB)
+	B runtime·walltime(SB)
 
 TEXT runtime·nacl_clock_gettime(SB),NOSPLIT,$0
 	MOVW	arg1+0(FP), R0
diff --git a/src/runtime/sys_netbsd_386.s b/src/runtime/sys_netbsd_386.s
index 8c4f004a4b..5c15794d5f 100644
--- a/src/runtime/sys_netbsd_386.s
+++ b/src/runtime/sys_netbsd_386.s
@@ -134,8 +134,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-4
 	INT	$0x80
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	LEAL	12(SP), BX
 	MOVL	$0, 4(SP)		// arg 1 - clock_id
 	MOVL	BX, 8(SP)		// arg 2 - tp
diff --git a/src/runtime/sys_netbsd_amd64.s b/src/runtime/sys_netbsd_amd64.s
index 7c7771bcba..c632a0b969 100644
--- a/src/runtime/sys_netbsd_amd64.s
+++ b/src/runtime/sys_netbsd_amd64.s
@@ -169,8 +169,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-8
 	SYSCALL
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVQ	$0, DI			// arg 1 - clock_id
 	LEAQ	8(SP), SI		// arg 2 - tp
 	MOVL	$427, AX		// sys_clock_gettime
diff --git a/src/runtime/sys_netbsd_arm.s b/src/runtime/sys_netbsd_arm.s
index a8914c11cb..789b12ef5b 100644
--- a/src/runtime/sys_netbsd_arm.s
+++ b/src/runtime/sys_netbsd_arm.s
@@ -137,8 +137,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-4
 	SWI $0xa001a9	// sys_setitimer
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVW $0, R0	// CLOCK_REALTIME
 	MOVW $8(R13), R1
 	SWI $0xa001ab	// clock_gettime
diff --git a/src/runtime/sys_openbsd_386.s b/src/runtime/sys_openbsd_386.s
index 76d22b0131..b86875fd7d 100644
--- a/src/runtime/sys_openbsd_386.s
+++ b/src/runtime/sys_openbsd_386.s
@@ -140,8 +140,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-4
 	INT	$0x80
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	LEAL	12(SP), BX
 	MOVL	$0, 4(SP)		// arg 1 - clock_id
 	MOVL	BX, 8(SP)		// arg 2 - tp
diff --git a/src/runtime/sys_openbsd_amd64.s b/src/runtime/sys_openbsd_amd64.s
index cf7a3fb7a9..9a52e5d9ef 100644
--- a/src/runtime/sys_openbsd_amd64.s
+++ b/src/runtime/sys_openbsd_amd64.s
@@ -180,8 +180,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-8
 	SYSCALL
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVQ	$0, DI			// arg 1 - clock_id
 	LEAQ	8(SP), SI		// arg 2 - tp
 	MOVL	$87, AX			// sys_clock_gettime
diff --git a/src/runtime/sys_openbsd_arm.s b/src/runtime/sys_openbsd_arm.s
index f573a028a0..93a5d5b7f6 100644
--- a/src/runtime/sys_openbsd_arm.s
+++ b/src/runtime/sys_openbsd_arm.s
@@ -150,8 +150,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$0
 	SWI	$0
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVW	CLOCK_REALTIME, R0	// arg 1 - clock_id
 	MOVW	$8(R13), R1		// arg 2 - tp
 	MOVW	$87, R12		// sys_clock_gettime
diff --git a/src/runtime/sys_plan9_386.s b/src/runtime/sys_plan9_386.s
index 41aa2fd982..6baa8138d6 100644
--- a/src/runtime/sys_plan9_386.s
+++ b/src/runtime/sys_plan9_386.s
@@ -102,8 +102,8 @@ TEXT runtime·nsec(SB),NOSPLIT,$8
 	MOVL	$-1, ret_hi+8(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	CALL	runtime·nanotime(SB)
 	MOVL	0(SP), AX
 	MOVL	4(SP), DX
diff --git a/src/runtime/sys_plan9_amd64.s b/src/runtime/sys_plan9_amd64.s
index 149505fa7e..d7bd92c1b4 100644
--- a/src/runtime/sys_plan9_amd64.s
+++ b/src/runtime/sys_plan9_amd64.s
@@ -92,8 +92,8 @@ TEXT runtime·nsec(SB),NOSPLIT,$0
 	MOVQ	AX, ret+8(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	CALL	runtime·nanotime(SB)
 	MOVQ	0(SP), AX
 
diff --git a/src/runtime/sys_plan9_arm.s b/src/runtime/sys_plan9_arm.s
index d54f56f132..f5c5e18de0 100644
--- a/src/runtime/sys_plan9_arm.s
+++ b/src/runtime/sys_plan9_arm.s
@@ -139,7 +139,7 @@ TEXT runtime·nsec(SB),NOSPLIT,$-4-12
 	RET
 
 // time.now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$12-12
+TEXT runtime·walltime(SB),NOSPLIT,$12-12
 	// use nsec system call to get current time in nanoseconds
 	MOVW	$sysnsec_lo-8(SP), R0	// destination addr
 	MOVW	R0,res-12(SP)
diff --git a/src/runtime/sys_solaris_amd64.s b/src/runtime/sys_solaris_amd64.s
index c542db3986..aeb2e2c897 100644
--- a/src/runtime/sys_solaris_amd64.s
+++ b/src/runtime/sys_solaris_amd64.s
@@ -354,8 +354,8 @@ TEXT runtime·osyield1(SB),NOSPLIT,$0
 	CALL	AX
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	CALL	runtime·nanotime(SB)
 	MOVQ	0(SP), AX
 
diff --git a/src/runtime/sys_windows_386.s b/src/runtime/sys_windows_386.s
index bd5de33946..42583dd106 100644
--- a/src/runtime/sys_windows_386.s
+++ b/src/runtime/sys_windows_386.s
@@ -432,8 +432,8 @@ TEXT runtime·switchtothread(SB),NOSPLIT,$0
 	MOVL	BP, SP
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	CALL	runtime·unixnano(SB)
 	MOVL	0(SP), AX
 	MOVL	4(SP), DX
diff --git a/src/runtime/sys_windows_amd64.s b/src/runtime/sys_windows_amd64.s
index c61b79d24f..56079f6aa3 100644
--- a/src/runtime/sys_windows_amd64.s
+++ b/src/runtime/sys_windows_amd64.s
@@ -465,8 +465,8 @@ TEXT runtime·switchtothread(SB),NOSPLIT|NOFRAME,$0
 	MOVQ	32(SP), SP
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	CALL	runtime·unixnano(SB)
 	MOVQ	0(SP), AX
 
diff --git a/src/runtime/time.go b/src/runtime/time.go
index 604ccded89..98057534c0 100644
--- a/src/runtime/time.go
+++ b/src/runtime/time.go
@@ -301,3 +301,11 @@ func net_runtimeNano() int64 {
 func time_runtimeNano() int64 {
 	return nanotime()
 }
+
+var startNano = nanotime()
+
+//go:linkname time_now time.now
+func time_now() (sec int64, nsec int32, mono uint64) {
+	sec, nsec = walltime()
+	return sec, nsec, uint64(nanotime() - startNano + 1)
+}