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runtime: unify handling of alternate signal stack

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Change all Unix systems to use stackt for the alternate signal
stack (some were using sigaltstackt). Add OS-specific setSignalstackSP
function to handle different types for ss_sp field, and unify all
OS-specific signalstack functions into one. Unify handling of alternate
signal stack in OS-specific minit and sigtrampgo functions via new
functions minitSignalstack and setGsignalStack.

Change-Id: Idc316dc69b1dd725717acdf61a1cd8b9f33ed174
Reviewed-on: https://go-review.googlesource.com/29757
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Ian Lance Taylor 2016-09-25 13:38:54 -07:00
parent e6143e17d3
commit d15295c679
40 changed files with 110 additions and 286 deletions
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52
src/runtime/signal_unix.go
View file

@ -525,6 +525,58 @@ func unblocksig(sig int32) {
sigprocmask(_SIG_UNBLOCK, &set, nil)
}
// minitSignalStack is called when initializing a new m to set the
// alternate signal stack. If the alternate signal stack is not set
// for the thread (the normal case) then set the alternate signal
// stack to the gsignal stack. If the alternate signal stack is set
// for the thread (the case when a non-Go thread sets the alternate
// signal stack and then calls a Go function) then set the gsignal
// stack to the alternate signal stack. Record which choice was made
// in newSigstack, so that it can be undone in unminit.
func minitSignalStack() {
_g_ := getg()
var st stackt
sigaltstack(nil, &st)
if st.ss_flags&_SS_DISABLE != 0 {
signalstack(&_g_.m.gsignal.stack)
_g_.m.newSigstack = true
} else {
setGsignalStack(&st)
_g_.m.newSigstack = false
}
}
// setGsignalStack sets the gsignal stack of the current m to an
// alternate signal stack returned from the sigaltstack system call.
// This is used when handling a signal if non-Go code has set the
// alternate signal stack.
//go:nosplit
//go:nowritebarrierrec
func setGsignalStack(st *stackt) {
g := getg()
stsp := uintptr(unsafe.Pointer(st.ss_sp))
g.m.gsignal.stack.lo = stsp
g.m.gsignal.stack.hi = stsp + st.ss_size
g.m.gsignal.stackguard0 = stsp + _StackGuard
g.m.gsignal.stackguard1 = stsp + _StackGuard
g.m.gsignal.stackAlloc = st.ss_size
}
// signalstack sets the current thread's alternate signal stack to s.
// If s is nil, the current thread's alternate signal stack is disabled.
//go:nosplit
func signalstack(s *stack) {
var st stackt
if s == nil {
st.ss_flags = _SS_DISABLE
} else {
setSignalstackSP(&st, s.lo)
st.ss_size = s.hi - s.lo
st.ss_flags = 0
}
sigaltstack(&st, nil)
}
// setsigsegv is used on darwin/arm{,64} to fake a segmentation fault.
//go:nosplit
func setsigsegv(pc uintptr) {