diff options
Diffstat (limited to 'src/runtime/proc1.go')
| -rw-r--r-- | src/runtime/proc1.go | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/src/runtime/proc1.go b/src/runtime/proc1.go index 54cb3eb77f..72ab524bd2 100644 --- a/src/runtime/proc1.go +++ b/src/runtime/proc1.go @@ -945,6 +945,15 @@ func needm(x byte) { mp.needextram = mp.schedlink == 0 unlockextra(mp.schedlink.ptr()) + // Save and block signals before installing g. + // Once g is installed, any incoming signals will try to execute, + // but we won't have the sigaltstack settings and other data + // set up appropriately until the end of minit, which will + // unblock the signals. This is the same dance as when + // starting a new m to run Go code via newosproc. + msigsave(mp) + sigblock() + // Install g (= m->g0) and set the stack bounds // to match the current stack. We don't actually know // how big the stack is, like we don't know how big any @@ -956,7 +965,6 @@ func needm(x byte) { _g_.stack.lo = uintptr(noescape(unsafe.Pointer(&x))) - 32*1024 _g_.stackguard0 = _g_.stack.lo + _StackGuard - msigsave(mp) // Initialize this thread to use the m. asminit() minit() @@ -1027,9 +1035,6 @@ func newextram() { // We may have to keep the current version on systems with cgo // but without pthreads, like Windows. func dropm() { - // Undo whatever initialization minit did during needm. - unminit() - // Clear m and g, and return m to the extra list. // After the call to setg we can only call nosplit functions // with no pointer manipulation. @@ -1037,7 +1042,16 @@ func dropm() { mnext := lockextra(true) mp.schedlink.set(mnext) + // Block signals before unminit. + // Unminit unregisters the signal handling stack (but needs g on some systems). + // Setg(nil) clears g, which is the signal handler's cue not to run Go handlers. + // It's important not to try to handle a signal between those two steps. + sigblock() + unminit() setg(nil) + msigrestore(mp) + + // Commit the release of mp. unlockextra(mp) } |