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runtime: add deletion barriers on gobuf.ctxt

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gobuf.ctxt is set to nil from many places in assembly code and these
assignments require write barriers with the hybrid barrier.

Conveniently, in most of these places ctxt should already be nil, in
which case we don't need the barrier. This commit changes these places
to assert that ctxt is already nil.

gogo is more complicated, since ctxt may not already be nil. For gogo,
we manually perform the write barrier if ctxt is not nil.

Updates #17503.

Change-Id: I9d75e27c75a1b7f8b715ad112fc5d45ffa856d30
Reviewed-on: https://go-review.googlesource.com/31764
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Austin Clements 2016-10-19 15:49:31 -04:00
parent 8f81dfe8b4
commit 70c107c68d
9 changed files with 186 additions and 25 deletions
Download patch file Download diff file Expand all files Collapse all files

26
src/runtime/asm_386.s
View file

@ -209,7 +209,11 @@ TEXT runtime·gosave(SB), NOSPLIT, $0-4
MOVL 0(SP), BX // caller's PC
MOVL BX, gobuf_pc(AX)
MOVL $0, gobuf_ret(AX)
MOVL $0, gobuf_ctxt(AX)
// Assert ctxt is zero. See func save.
MOVL gobuf_ctxt(AX), BX
TESTL BX, BX
JZ 2(PC)
CALL runtime·badctxt(SB)
get_tls(CX)
MOVL g(CX), BX
MOVL BX, gobuf_g(AX)
@ -217,8 +221,20 @@ TEXT runtime·gosave(SB), NOSPLIT, $0-4
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB), NOSPLIT, $0-4
TEXT runtime·gogo(SB), NOSPLIT, $8-4
MOVL buf+0(FP), BX // gobuf
// If ctxt is not nil, invoke deletion barrier before overwriting.
MOVL gobuf_ctxt(BX), DX
TESTL DX, DX
JZ nilctxt
LEAL gobuf_ctxt(BX), AX
MOVL AX, 0(SP)
MOVL $0, 4(SP)
CALL runtime·writebarrierptr_prewrite(SB)
MOVL buf+0(FP), BX
nilctxt:
MOVL gobuf_g(BX), DX
MOVL 0(DX), CX // make sure g != nil
get_tls(CX)
@ -572,7 +588,11 @@ TEXT gosave<>(SB),NOSPLIT,$0
MOVL -4(AX), AX
MOVL AX, (g_sched+gobuf_pc)(BX)
MOVL $0, (g_sched+gobuf_ret)(BX)
MOVL $0, (g_sched+gobuf_ctxt)(BX)
// Assert ctxt is zero. See func save.
MOVL (g_sched+gobuf_ctxt)(BX), AX
TESTL AX, AX
JZ 2(PC)
CALL runtime·badctxt(SB)
POPL BX
POPL AX
RET

26
src/runtime/asm_amd64.s
View file

@ -182,8 +182,12 @@ TEXT runtime·gosave(SB), NOSPLIT, $0-8
MOVQ 0(SP), BX // caller's PC
MOVQ BX, gobuf_pc(AX)
MOVQ $0, gobuf_ret(AX)
MOVQ $0, gobuf_ctxt(AX)
MOVQ BP, gobuf_bp(AX)
// Assert ctxt is zero. See func save.
MOVQ gobuf_ctxt(AX), BX
TESTQ BX, BX
JZ 2(PC)
CALL runtime·badctxt(SB)
get_tls(CX)
MOVQ g(CX), BX
MOVQ BX, gobuf_g(AX)
@ -191,8 +195,20 @@ TEXT runtime·gosave(SB), NOSPLIT, $0-8
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB), NOSPLIT, $0-8
TEXT runtime·gogo(SB), NOSPLIT, $16-8
MOVQ buf+0(FP), BX // gobuf
// If ctxt is not nil, invoke deletion barrier before overwriting.
MOVQ gobuf_ctxt(BX), AX
TESTQ AX, AX
JZ nilctxt
LEAQ gobuf_ctxt(BX), AX
MOVQ AX, 0(SP)
MOVQ $0, 8(SP)
CALL runtime·writebarrierptr_prewrite(SB)
MOVQ buf+0(FP), BX
nilctxt:
MOVQ gobuf_g(BX), DX
MOVQ 0(DX), CX // make sure g != nil
get_tls(CX)
@ -546,8 +562,12 @@ TEXT gosave<>(SB),NOSPLIT,$0
LEAQ 8(SP), R9
MOVQ R9, (g_sched+gobuf_sp)(R8)
MOVQ $0, (g_sched+gobuf_ret)(R8)
MOVQ $0, (g_sched+gobuf_ctxt)(R8)
MOVQ BP, (g_sched+gobuf_bp)(R8)
// Assert ctxt is zero. See func save.
MOVQ (g_sched+gobuf_ctxt)(R8), R9
TESTQ R9, R9
JZ 2(PC)
CALL runtime·badctxt(SB)
RET
// func asmcgocall(fn, arg unsafe.Pointer) int32

20
src/runtime/asm_amd64p32.s
View file

@ -107,8 +107,12 @@ TEXT runtime·gosave(SB), NOSPLIT, $0-4
MOVL BX, gobuf_sp(AX)
MOVL 0(SP), BX // caller's PC
MOVL BX, gobuf_pc(AX)
MOVL $0, gobuf_ctxt(AX)
MOVQ $0, gobuf_ret(AX)
// Assert ctxt is zero. See func save.
MOVL gobuf_ctxt(AX), BX
TESTL BX, BX
JZ 2(PC)
CALL runtime·badctxt(SB)
get_tls(CX)
MOVL g(CX), BX
MOVL BX, gobuf_g(AX)
@ -116,8 +120,20 @@ TEXT runtime·gosave(SB), NOSPLIT, $0-4
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB), NOSPLIT, $0-4
TEXT runtime·gogo(SB), NOSPLIT, $8-4
MOVL buf+0(FP), BX // gobuf
// If ctxt is not nil, invoke deletion barrier before overwriting.
MOVL gobuf_ctxt(BX), DX
TESTL DX, DX
JZ nilctxt
LEAL gobuf_ctxt(BX), AX
MOVL AX, 0(SP)
MOVL $0, 4(SP)
CALL runtime·writebarrierptr_prewrite(SB)
MOVL buf+0(FP), BX
nilctxt:
MOVL gobuf_g(BX), DX
MOVL 0(DX), CX // make sure g != nil
get_tls(CX)

28
src/runtime/asm_arm.s
View file

@ -118,13 +118,30 @@ TEXT runtime·gosave(SB),NOSPLIT,$-4-4
MOVW $0, R11
MOVW R11, gobuf_lr(R0)
MOVW R11, gobuf_ret(R0)
MOVW R11, gobuf_ctxt(R0)
// Assert ctxt is zero. See func save.
MOVW gobuf_ctxt(R0), R0
CMP R0, R11
B.EQ 2(PC)
CALL runtime·badctxt(SB)
RET
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB),NOSPLIT,$-4-4
TEXT runtime·gogo(SB),NOSPLIT,$8-4
MOVW buf+0(FP), R1
// If ctxt is not nil, invoke deletion barrier before overwriting.
MOVW gobuf_ctxt(R1), R0
CMP $0, R0
B.EQ nilctxt
MOVW $gobuf_ctxt(R1), R0
MOVW R0, 4(R13)
MOVW $0, R0
MOVW R0, 8(R13)
BL runtime·writebarrierptr_prewrite(SB)
MOVW buf+0(FP), R1
nilctxt:
MOVW gobuf_g(R1), R0
BL setg<>(SB)
@ -476,13 +493,18 @@ TEXT runtime·jmpdefer(SB),NOSPLIT,$0-8
B (R1)
// Save state of caller into g->sched. Smashes R11.
TEXT gosave<>(SB),NOSPLIT,$0
TEXT gosave<>(SB),NOSPLIT,$-4
MOVW LR, (g_sched+gobuf_pc)(g)
MOVW R13, (g_sched+gobuf_sp)(g)
MOVW $0, R11
MOVW R11, (g_sched+gobuf_lr)(g)
MOVW R11, (g_sched+gobuf_ret)(g)
MOVW R11, (g_sched+gobuf_ctxt)(g)
// Assert ctxt is zero. See func save.
MOVW (g_sched+gobuf_ctxt)(g), R11
CMP $0, R11
B.EQ 2(PC)
CALL runtime·badctxt(SB)
RET
// func asmcgocall(fn, arg unsafe.Pointer) int32

26
src/runtime/asm_arm64.s
View file

@ -111,13 +111,29 @@ TEXT runtime·gosave(SB), NOSPLIT, $-8-8
MOVD g, gobuf_g(R3)
MOVD ZR, gobuf_lr(R3)
MOVD ZR, gobuf_ret(R3)
MOVD ZR, gobuf_ctxt(R3)
// Assert ctxt is zero. See func save.
MOVD gobuf_ctxt(R3), R0
CMP $0, R0
BEQ 2(PC)
CALL runtime·badctxt(SB)
RET
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB), NOSPLIT, $-8-8
TEXT runtime·gogo(SB), NOSPLIT, $24-8
MOVD buf+0(FP), R5
// If ctxt is not nil, invoke deletion barrier before overwriting.
MOVD gobuf_ctxt(R5), R0
CMP $0, R0
BEQ nilctxt
MOVD $gobuf_ctxt(R5), R0
MOVD R0, 8(RSP)
MOVD ZR, 16(RSP)
BL runtime·writebarrierptr_prewrite(SB)
MOVD buf+0(FP), R5
nilctxt:
MOVD gobuf_g(R5), g
BL runtime·save_g(SB)
@ -483,7 +499,11 @@ TEXT gosave<>(SB),NOSPLIT,$-8
MOVD R0, (g_sched+gobuf_sp)(g)
MOVD $0, (g_sched+gobuf_lr)(g)
MOVD $0, (g_sched+gobuf_ret)(g)
MOVD $0, (g_sched+gobuf_ctxt)(g)
// Assert ctxt is zero. See func save.
MOVD (g_sched+gobuf_ctxt)(g), R0
CMP $0, R0
BEQ 2(PC)
CALL runtime·badctxt(SB)
RET
// func asmcgocall(fn, arg unsafe.Pointer) int32

25
src/runtime/asm_mips64x.s
View file

@ -98,13 +98,27 @@ TEXT runtime·gosave(SB), NOSPLIT, $-8-8
MOVV g, gobuf_g(R1)
MOVV R0, gobuf_lr(R1)
MOVV R0, gobuf_ret(R1)
MOVV R0, gobuf_ctxt(R1)
// Assert ctxt is zero. See func save.
MOVV gobuf_ctxt(R1), R1
BEQ R1, 2(PC)
JAL runtime·badctxt(SB)
RET
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB), NOSPLIT, $-8-8
TEXT runtime·gogo(SB), NOSPLIT, $16-8
MOVV buf+0(FP), R3
// If ctxt is not nil, invoke deletion barrier before overwriting.
MOVV gobuf_ctxt(R3), R1
BEQ R1, nilctxt
MOVV $gobuf_ctxt(R3), R1
MOVV R1, 8(R29)
MOVV R0, 16(R29)
JAL runtime·writebarrierptr_prewrite(SB)
MOVV buf+0(FP), R3
nilctxt:
MOVV gobuf_g(R3), g // make sure g is not nil
JAL runtime·save_g(SB)
@ -429,13 +443,16 @@ TEXT runtime·jmpdefer(SB), NOSPLIT, $-8-16
MOVV 0(REGCTXT), R4
JMP (R4)
// Save state of caller into g->sched. Smashes R31.
// Save state of caller into g->sched. Smashes R1.
TEXT gosave<>(SB),NOSPLIT,$-8
MOVV R31, (g_sched+gobuf_pc)(g)
MOVV R29, (g_sched+gobuf_sp)(g)
MOVV R0, (g_sched+gobuf_lr)(g)
MOVV R0, (g_sched+gobuf_ret)(g)
MOVV R0, (g_sched+gobuf_ctxt)(g)
// Assert ctxt is zero. See func save.
MOVV (g_sched+gobuf_ctxt)(g), R1
BEQ R1, 2(PC)
JAL runtime·badctxt(SB)
RET
// func asmcgocall(fn, arg unsafe.Pointer) int32

26
src/runtime/asm_ppc64x.s
View file

@ -122,13 +122,29 @@ TEXT runtime·gosave(SB), NOSPLIT|NOFRAME, $0-8
MOVD g, gobuf_g(R3)
MOVD R0, gobuf_lr(R3)
MOVD R0, gobuf_ret(R3)
MOVD R0, gobuf_ctxt(R3)
// Assert ctxt is zero. See func save.
MOVD gobuf_ctxt(R3), R3
CMP R0, R3
BEQ 2(PC)
BL runtime·badctxt(SB)
RET
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB), NOSPLIT|NOFRAME, $0-8
TEXT runtime·gogo(SB), NOSPLIT, $16-8
MOVD buf+0(FP), R5
// If ctxt is not nil, invoke deletion barrier before overwriting.
MOVD gobuf_ctxt(R5), R3
CMP R0, R3
BEQ nilctxt
MOVD $gobuf_ctxt(R5), R3
MOVD R3, FIXED_FRAME+0(R1)
MOVD R0, FIXED_FRAME+8(R1)
BL runtime·writebarrierptr_prewrite(SB)
MOVD buf+0(FP), R5
nilctxt:
MOVD gobuf_g(R5), g // make sure g is not nil
BL runtime·save_g(SB)
@ -497,7 +513,11 @@ TEXT gosave<>(SB),NOSPLIT|NOFRAME,$0
MOVD R1, (g_sched+gobuf_sp)(g)
MOVD R0, (g_sched+gobuf_lr)(g)
MOVD R0, (g_sched+gobuf_ret)(g)
MOVD R0, (g_sched+gobuf_ctxt)(g)
// Assert ctxt is zero. See func save.
MOVD (g_sched+gobuf_ctxt)(g), R31
CMP R0, R31
BEQ 2(PC)
BL runtime·badctxt(SB)
RET
// func asmcgocall(fn, arg unsafe.Pointer) int32

25
src/runtime/asm_s390x.s
View file

@ -106,13 +106,27 @@ TEXT runtime·gosave(SB), NOSPLIT, $-8-8
MOVD g, gobuf_g(R3)
MOVD $0, gobuf_lr(R3)
MOVD $0, gobuf_ret(R3)
MOVD $0, gobuf_ctxt(R3)
// Assert ctxt is zero. See func save.
MOVD gobuf_ctxt(R3), R3
CMPBEQ R3, $0, 2(PC)
BL runtime·badctxt(SB)
RET
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB), NOSPLIT, $-8-8
TEXT runtime·gogo(SB), NOSPLIT, $16-8
MOVD buf+0(FP), R5
// If ctxt is not nil, invoke deletion barrier before overwriting.
MOVD gobuf_ctxt(R5), R1
CMPBEQ R1, $0, nilctxt
MOVD $gobuf_ctxt(R5), R1
MOVD R1, 8(R15)
MOVD R0, 16(R15)
BL runtime·writebarrierptr_prewrite(SB)
MOVD buf+0(FP), R5
nilctxt:
MOVD gobuf_g(R5), g // make sure g is not nil
BL runtime·save_g(SB)
@ -447,13 +461,16 @@ TEXT runtime·jmpdefer(SB),NOSPLIT|NOFRAME,$0-16
MOVD 0(R12), R3
BR (R3)
// Save state of caller into g->sched. Smashes R31.
// Save state of caller into g->sched. Smashes R1.
TEXT gosave<>(SB),NOSPLIT|NOFRAME,$0
MOVD LR, (g_sched+gobuf_pc)(g)
MOVD R15, (g_sched+gobuf_sp)(g)
MOVD $0, (g_sched+gobuf_lr)(g)
MOVD $0, (g_sched+gobuf_ret)(g)
MOVD $0, (g_sched+gobuf_ctxt)(g)
// Assert ctxt is zero. See func save.
MOVD (g_sched+gobuf_ctxt)(g), R1
CMPBEQ R1, $0, 2(PC)
BL runtime·badctxt(SB)
RET
// func asmcgocall(fn, arg unsafe.Pointer) int32

9
src/runtime/runtime2.go
View file

@ -239,6 +239,15 @@ func setMNoWB(mp **m, new *m) {
type gobuf struct {
// The offsets of sp, pc, and g are known to (hard-coded in) libmach.
//
// ctxt is unusual with respect to GC: it may be a
// heap-allocated funcval so write require a write barrier,
// but gobuf needs to be cleared from assembly. We take
// advantage of the fact that the only path that uses a
// non-nil ctxt is morestack. As a result, gogo is the only
// place where it may not already be nil, so gogo uses an
// explicit write barrier. Everywhere else that resets the
// gobuf asserts that ctxt is already nil.
sp uintptr
pc uintptr
g guintptr