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go/misc/cgo/test/issue9400/asm_amd64x.s

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misc/cgo/test/issue9400: fix to build with gccgo This doesn't test much with gccgo, but at least it builds now, and the test does, unsurprisingly, pass. A proper test would require adding assembly files in GCC syntax for all platforms that gccgo supports, which would be infeasible. Also added copyright headers to the asm files. Change-Id: Icea5af29d7d521a0681506ddb617a79705b76d33 Reviewed-on: https://go-review.googlesource.com/9417 Reviewed-by: Minux Ma <minux@golang.org>
2015-04-28 18:58:17 -06:00
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
runtime: run libc SIGSETXID and SIGCANCEL handlers on signal stack These signals are used by glibc to broadcast setuid/setgid to all threads and to send pthread cancellations. Unlike other signals, the Go runtime does not intercept these because they must invoke the libc handlers (see issues #3871 and #6997). However, because 1) these signals may be issued asynchronously by a thread running C code to another thread running Go code and 2) glibc does not set SA_ONSTACK for its handlers, glibc's signal handler may be run on a Go stack. Signal frames range from 1.5K on amd64 to many kilobytes on ppc64, so this may overflow the Go stack and corrupt heap (or other stack) data. Fix this by ensuring that these signal handlers have the SA_ONSTACK flag (but not otherwise taking over the handler). This has been a problem since Go 1.1, but it's likely that people haven't encountered it because it only affects setuid/setgid and pthread_cancel. Fixes #9600. Change-Id: I6cf5f5c2d3aa48998d632f61f1ddc2778dcfd300 Reviewed-on: https://go-review.googlesource.com/1887 Reviewed-by: Ian Lance Taylor <iant@golang.org>
2014-12-19 14:16:17 -07:00
// +build amd64 amd64p32
misc/cgo/test/issue9400: fix to build with gccgo This doesn't test much with gccgo, but at least it builds now, and the test does, unsurprisingly, pass. A proper test would require adding assembly files in GCC syntax for all platforms that gccgo supports, which would be infeasible. Also added copyright headers to the asm files. Change-Id: Icea5af29d7d521a0681506ddb617a79705b76d33 Reviewed-on: https://go-review.googlesource.com/9417 Reviewed-by: Minux Ma <minux@golang.org>
2015-04-28 18:58:17 -06:00
// +build !gccgo
runtime: run libc SIGSETXID and SIGCANCEL handlers on signal stack These signals are used by glibc to broadcast setuid/setgid to all threads and to send pthread cancellations. Unlike other signals, the Go runtime does not intercept these because they must invoke the libc handlers (see issues #3871 and #6997). However, because 1) these signals may be issued asynchronously by a thread running C code to another thread running Go code and 2) glibc does not set SA_ONSTACK for its handlers, glibc's signal handler may be run on a Go stack. Signal frames range from 1.5K on amd64 to many kilobytes on ppc64, so this may overflow the Go stack and corrupt heap (or other stack) data. Fix this by ensuring that these signal handlers have the SA_ONSTACK flag (but not otherwise taking over the handler). This has been a problem since Go 1.1, but it's likely that people haven't encountered it because it only affects setuid/setgid and pthread_cancel. Fixes #9600. Change-Id: I6cf5f5c2d3aa48998d632f61f1ddc2778dcfd300 Reviewed-on: https://go-review.googlesource.com/1887 Reviewed-by: Ian Lance Taylor <iant@golang.org>
2014-12-19 14:16:17 -07:00
#include "textflag.h"
TEXT ·RewindAndSetgid(SB),NOSPLIT,$0-0
// Rewind stack pointer so anything that happens on the stack
// will clobber the test pattern created by the caller
ADDQ $(1024 * 8), SP
// Ask signaller to setgid
MOVL $1, ·Baton(SB)
// Wait for setgid completion
loop:
PAUSE
MOVL ·Baton(SB), AX
CMPL AX, $0
JNE loop
// Restore stack
SUBQ $(1024 * 8), SP
RET
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