runtime: fix linux/arm nanotime?

TBR=r
CC=golang-dev
https://golang.org/cl/5354041

diff --git a/src/pkg/runtime/linux/arm/sys.s b/src/pkg/runtime/linux/arm/sys.s
index 45da858abda09db1a04ebe2e96fb953943d19fde..3d26ff0a41e674cbaf555ae1a66beb9d15ffd111 100644 (file)
--- a/src/pkg/runtime/linux/arm/sys.s
+++ b/src/pkg/runtime/linux/arm/sys.s
@@ -130,28 +130,25 @@ TEXT runtime·mincore(SB),7,$0
 // int64 nanotime(void) so really
 // void nanotime(int64 *nsec)
 TEXT runtime·nanotime(SB),7,$32
-       /* dummy version - return 0,0 */
-       MOVW    $0, R1
-       MOVW    0(FP), R0
-       MOVW    R1, 0(R0)
-       MOVW    R1, 4(R0)
-
-/*
-       attempt at real version - seg faults
-
-       MOVW    $8(SP), R0
-       MOVW    $0, R1
+       MOVW    $8(R13), R0  // timeval
+       MOVW    $0, R1  // zone
        MOVW    $SYS_gettimeofday, R7
        SWI     $0
-
-       MOVW    0(FP), R0       // sec
-       MOVW    8(SP), R1
-       MOVW    R1, 0(R0)
-
-       MOVW    4(FP), R0       // usec
-       MOVW    12(SP), R1
-       MOVW    R1, 0(R0)
-*/
+       
+       MOVW    8(R13), R0  // sec
+       MOVW    12(R13), R2  // usec
+       
+       MOVW    $1000000000, R3
+       MULLU   R0, R3, (R1, R0)
+       MOVW    $1000, R3
+       MOVW    $0, R4
+       MUL     R3, R2
+       ADD.S   R2, R0
+       ADC     R4, R1
+       
+       MOVW    0(FP), R3
+       MOVW    R0, 0(R3)
+       MOVW    R1, 4(R3)
        RET
 
 // int32 futex(int32 *uaddr, int32 op, int32 val,