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runtime: duplicate code for runtime.nanotime to avoid stack overflow in vDSO clock_gettime

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Fixes #4402.

R=remyoudompheng, shivakumar.gn, random0x00, rsc
CC=golang-dev
https://golang.org/cl/6842063
This commit is contained in:
Shenghou Ma 2012-11-27 01:42:01 +08:00
parent 76fa4f430a
commit 2637777527
1 changed files with 35 additions and 12 deletions
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47
src/pkg/runtime/sys_linux_amd64.s
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@ -101,36 +101,59 @@ TEXT runtime·mincore(SB),7,$0-24
RET
// func now() (sec int64, nsec int32)
TEXT time·now(SB), 7, $32
TEXT time·now(SB),7,$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.
// That leaves 104 for the gettime code to use. Hope that's enough!
MOVQ runtime·__vdso_clock_gettime_sym(SB), AX
CMPQ AX, $0
JEQ fallback_gtod
MOVL $0, DI // CLOCK_REALTIME
LEAQ 8(SP), SI
LEAQ 0(SP), SI
CALL AX
MOVQ 8(SP), AX // sec
MOVQ 16(SP), DX // nsec
MOVQ 0(SP), AX // sec
MOVQ 8(SP), DX // nsec
MOVQ AX, sec+0(FP)
MOVL DX, nsec+8(FP)
RET
fallback_gtod:
LEAQ 8(SP), DI
LEAQ 0(SP), DI
MOVQ $0, SI
MOVQ runtime·__vdso_gettimeofday_sym(SB), AX
CALL AX
MOVQ 8(SP), AX // sec
MOVL 16(SP), DX // usec
MOVQ 0(SP), AX // sec
MOVL 8(SP), DX // usec
IMULQ $1000, DX
MOVQ AX, sec+0(FP)
MOVL DX, nsec+8(FP)
RET
TEXT runtime·nanotime(SB), 7, $32
CALL time·now(SB)
TEXT runtime·nanotime(SB),7,$16
// Duplicate time.now here to avoid using up precious stack space.
// See comment above in time.now.
MOVQ runtime·__vdso_clock_gettime_sym(SB), AX
CMPQ AX, $0
JEQ fallback_gtod_nt
MOVL $0, DI // CLOCK_REALTIME
LEAQ 0(SP), SI
CALL AX
MOVQ 0(SP), AX // sec
MOVL 8(SP), DX // nsec
// sec is in AX, usec in DX
MOVQ 8(SP), DX // nsec
// sec is in AX, nsec in DX
// return nsec in AX
IMULQ $1000000000, AX
ADDQ DX, AX
RET
fallback_gtod_nt:
LEAQ 0(SP), DI
MOVQ $0, SI
MOVQ runtime·__vdso_gettimeofday_sym(SB), AX
CALL AX
MOVQ 0(SP), AX // sec
MOVL 8(SP), DX // usec
IMULQ $1000, DX
// sec is in AX, nsec in DX
// return nsec in AX
IMULQ $1000000000, AX
ADDQ DX, AX