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https://github.com/golang/go
synced 2024-11-20 00:14:44 -07:00
532dee3842
Signal handlers are global resources but many language environments (Go, C++ at Google, etc) assume they have sole ownership of a particular handler. Signal handlers in mixed-language applications must therefore be robust against unexpected delivery of certain signals, such as SIGPROF. The default Go signal handler runtime·sigtramp assumes that it will never be called on a non-Go thread, but this assumption is violated by when linking in C++ code that spawns threads. Specifically, the handler asserts the thread has an associated "m" (Go scheduler). This CL is a very simple workaround: discard SIGPROF delivered to non-Go threads. runtime.badsignal(int32) now receives the signal number; if it returns without panicking (e.g. sig==SIGPROF) the signal is discarded. I don't think there is any really satisfactory solution to the problem of signal-based profiling in a mixed-language application. It's not only the issue of handler clobbering, but also that a C++ SIGPROF handler called in a Go thread can't unwind the Go stack (and vice versa). The best we can hope for is not crashing. Note: - I've ported this to all POSIX platforms, except ARM-linux which already ignores unexpected signals on m-less threads. - I've avoided tail-calling runtime.badsignal because AFAICT the 6a/6l don't support it. - I've avoided hoisting 'push sig' (common to both function calls) because it makes the code harder to read. - Fixed an (apparently incorrect?) docstring. R=iant, rsc, minux.ma CC=golang-dev https://golang.org/cl/6498057
253 lines
4.6 KiB
ArmAsm
253 lines
4.6 KiB
ArmAsm
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//
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// System calls and other sys.stuff for AMD64, FreeBSD
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// /usr/src/sys/kern/syscalls.master for syscall numbers.
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//
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#include "zasm_GOOS_GOARCH.h"
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TEXT runtime·sys_umtx_op(SB),7,$0
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MOVQ 8(SP), DI
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MOVL 16(SP), SI
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MOVL 20(SP), DX
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MOVQ 24(SP), R10
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MOVQ 32(SP), R8
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MOVL $454, AX
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SYSCALL
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RET
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TEXT runtime·thr_new(SB),7,$0
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MOVQ 8(SP), DI
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MOVQ 16(SP), SI
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MOVL $455, AX
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SYSCALL
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RET
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TEXT runtime·thr_start(SB),7,$0
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MOVQ DI, R13 // m
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// set up FS to point at m->tls
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LEAQ m_tls(R13), DI
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CALL runtime·settls(SB) // smashes DI
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// set up m, g
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get_tls(CX)
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MOVQ R13, m(CX)
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MOVQ m_g0(R13), DI
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MOVQ DI, g(CX)
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CALL runtime·stackcheck(SB)
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CALL runtime·mstart(SB)
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MOVQ 0, AX // crash (not reached)
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// Exit the entire program (like C exit)
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TEXT runtime·exit(SB),7,$-8
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MOVL 8(SP), DI // arg 1 exit status
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MOVL $1, AX
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SYSCALL
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MOVL $0xf1, 0xf1 // crash
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RET
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TEXT runtime·exit1(SB),7,$-8
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MOVQ 8(SP), DI // arg 1 exit status
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MOVL $431, AX
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SYSCALL
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MOVL $0xf1, 0xf1 // crash
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RET
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TEXT runtime·write(SB),7,$-8
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MOVL 8(SP), DI // arg 1 fd
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MOVQ 16(SP), SI // arg 2 buf
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MOVL 24(SP), DX // arg 3 count
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MOVL $4, AX
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SYSCALL
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RET
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TEXT runtime·getrlimit(SB),7,$-8
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MOVL 8(SP), DI
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MOVQ 16(SP), SI
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MOVL $194, AX
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SYSCALL
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RET
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TEXT runtime·raisesigpipe(SB),7,$16
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// thr_self(&8(SP))
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LEAQ 8(SP), DI // arg 1 &8(SP)
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MOVL $432, AX
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SYSCALL
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// thr_kill(self, SIGPIPE)
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MOVQ 8(SP), DI // arg 1 id
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MOVQ $13, SI // arg 2 SIGPIPE
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MOVL $433, AX
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SYSCALL
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RET
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TEXT runtime·setitimer(SB), 7, $-8
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MOVL 8(SP), DI
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MOVQ 16(SP), SI
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MOVQ 24(SP), DX
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MOVL $83, AX
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SYSCALL
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RET
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// func now() (sec int64, nsec int32)
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TEXT time·now(SB), 7, $32
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MOVL $116, AX
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LEAQ 8(SP), DI
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MOVQ $0, SI
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SYSCALL
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MOVQ 8(SP), AX // sec
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MOVL 16(SP), DX // usec
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// sec is in AX, usec in DX
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MOVQ AX, sec+0(FP)
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IMULQ $1000, DX
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MOVL DX, nsec+8(FP)
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RET
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TEXT runtime·nanotime(SB), 7, $32
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MOVL $116, AX
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LEAQ 8(SP), DI
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MOVQ $0, SI
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SYSCALL
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MOVQ 8(SP), AX // sec
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MOVL 16(SP), DX // usec
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// sec is in AX, usec in DX
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// return nsec in AX
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IMULQ $1000000000, AX
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IMULQ $1000, DX
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ADDQ DX, AX
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RET
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TEXT runtime·sigaction(SB),7,$-8
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MOVL 8(SP), DI // arg 1 sig
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MOVQ 16(SP), SI // arg 2 act
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MOVQ 24(SP), DX // arg 3 oact
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MOVL $416, AX
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SYSCALL
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JCC 2(PC)
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MOVL $0xf1, 0xf1 // crash
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RET
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TEXT runtime·sigtramp(SB),7,$64
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get_tls(BX)
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// check that m exists
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MOVQ m(BX), BP
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CMPQ BP, $0
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JNE 4(PC)
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MOVQ DI, 0(SP)
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CALL runtime·badsignal(SB)
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RET
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// save g
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MOVQ g(BX), R10
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MOVQ R10, 40(SP)
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// g = m->signal
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MOVQ m_gsignal(BP), BP
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MOVQ BP, g(BX)
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MOVQ DI, 0(SP)
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MOVQ SI, 8(SP)
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MOVQ DX, 16(SP)
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MOVQ R10, 24(SP)
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CALL runtime·sighandler(SB)
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// restore g
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get_tls(BX)
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MOVQ 40(SP), R10
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MOVQ R10, g(BX)
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RET
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TEXT runtime·mmap(SB),7,$0
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MOVQ 8(SP), DI // arg 1 addr
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MOVQ 16(SP), SI // arg 2 len
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MOVL 24(SP), DX // arg 3 prot
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MOVL 28(SP), R10 // arg 4 flags
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MOVL 32(SP), R8 // arg 5 fid
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MOVL 36(SP), R9 // arg 6 offset
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MOVL $477, AX
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SYSCALL
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RET
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TEXT runtime·munmap(SB),7,$0
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MOVQ 8(SP), DI // arg 1 addr
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MOVQ 16(SP), SI // arg 2 len
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MOVL $73, AX
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SYSCALL
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JCC 2(PC)
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MOVL $0xf1, 0xf1 // crash
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RET
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TEXT runtime·sigaltstack(SB),7,$-8
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MOVQ new+8(SP), DI
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MOVQ old+16(SP), SI
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MOVQ $53, AX
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SYSCALL
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JCC 2(PC)
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MOVL $0xf1, 0xf1 // crash
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RET
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TEXT runtime·usleep(SB),7,$16
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MOVL $0, DX
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MOVL usec+0(FP), AX
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MOVL $1000000, CX
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DIVL CX
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MOVQ AX, 0(SP) // tv_sec
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MOVL $1000, AX
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MULL DX
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MOVQ AX, 8(SP) // tv_nsec
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MOVQ SP, DI // arg 1 - rqtp
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MOVQ $0, SI // arg 2 - rmtp
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MOVL $240, AX // sys_nanosleep
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SYSCALL
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RET
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// set tls base to DI
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TEXT runtime·settls(SB),7,$8
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ADDQ $16, DI // adjust for ELF: wants to use -16(FS) and -8(FS) for g and m
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MOVQ DI, 0(SP)
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MOVQ SP, SI
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MOVQ $129, DI // AMD64_SET_FSBASE
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MOVQ $165, AX // sysarch
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SYSCALL
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JCC 2(PC)
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MOVL $0xf1, 0xf1 // crash
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RET
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TEXT runtime·sysctl(SB),7,$0
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MOVQ 8(SP), DI // arg 1 - name
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MOVL 16(SP), SI // arg 2 - namelen
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MOVQ 24(SP), DX // arg 3 - oldp
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MOVQ 32(SP), R10 // arg 4 - oldlenp
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MOVQ 40(SP), R8 // arg 5 - newp
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MOVQ 48(SP), R9 // arg 6 - newlen
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MOVQ $202, AX // sys___sysctl
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SYSCALL
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JCC 3(PC)
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NEGL AX
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RET
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MOVL $0, AX
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RET
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TEXT runtime·osyield(SB),7,$-4
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MOVL $331, AX // sys_sched_yield
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SYSCALL
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RET
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TEXT runtime·sigprocmask(SB),7,$0
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MOVL $3, DI // arg 1 - how (SIG_SETMASK)
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MOVQ 8(SP), SI // arg 2 - set
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MOVQ 16(SP), DX // arg 3 - oset
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MOVL $340, AX // sys_sigprocmask
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SYSCALL
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JAE 2(PC)
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MOVL $0xf1, 0xf1 // crash
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RET
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