From 21a43af0f18335af4abb1959aa28ee9d159a2d43 Mon Sep 17 00:00:00 2001 From: Roman Bolshakov Date: Mon, 17 Dec 2018 23:26:02 +0300 Subject: qemu-thread: Don't block SEGV, ILL and FPE MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If any of these signals happen on macOS, they are not delivered to other threads and signalfd_compat receives nothing. Indeed, POSIX reference and sigprocmask(2) note that an attempt to block the signals results in undefined behaviour. SEGV and FPE can't also be received by signalfd(2) on Linux. An ability to retrieve SIGBUS via signalfd(2) is used by QEMU for memory preallocation therefore we can't unblock it without consequences. But it's important to leave a remark that the signal is lost on macOS. Signed-off-by: Roman Bolshakov Reviewed-by: Daniel P. Berrangé Signed-off-by: Peter Maydell --- util/qemu-thread-posix.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c index c6934bd..1bf5e65 100644 --- a/util/qemu-thread-posix.c +++ b/util/qemu-thread-posix.c @@ -524,6 +524,11 @@ void qemu_thread_create(QemuThread *thread, const char *name, /* Leave signal handling to the iothread. */ sigfillset(&set); + /* Blocking the signals can result in undefined behaviour. */ + sigdelset(&set, SIGSEGV); + sigdelset(&set, SIGFPE); + sigdelset(&set, SIGILL); + /* TODO avoid SIGBUS loss on macOS */ pthread_sigmask(SIG_SETMASK, &set, &oldset); qemu_thread_args = g_new0(QemuThreadArgs, 1); -- cgit v1.1