From 6ab7e5465a4d6188e29398fb43a30dbab1015b75 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Wed, 20 Feb 2013 15:21:09 +0000 Subject: Replace all setjmp()/longjmp() with sigsetjmp()/siglongjmp() The setjmp() function doesn't specify whether signal masks are saved and restored; on Linux they are not, but on BSD (including MacOSX) they are. We want to have consistent behaviour across platforms, so we should always use "don't save/restore signal mask" (this is also generally going to be faster). This also works around a bug in MacOSX where the signal-restoration on longjmp() affects the signal mask for a completely different thread, not just the mask for the thread which did the longjmp. The most visible effect of this was that ctrl-C was ignored on MacOSX because the CPU thread did a longjmp which resulted in its signal mask being applied to every thread, so that all threads had SIGINT and SIGTERM blocked. The POSIX-sanctioned portable way to do a jump without affecting signal masks is to siglongjmp() to a sigjmp_buf which was created by calling sigsetjmp() with a zero savemask parameter, so change all uses of setjmp()/longjmp() accordingly. [Technically POSIX allows sigsetjmp(buf, 0) to save the signal mask; however the following siglongjmp() must not restore the signal mask, so the pair can be effectively considered as "sigjmp/longjmp which don't touch the mask".] For Windows we provide a trivial sigsetjmp/siglongjmp in terms of setjmp/longjmp -- this is OK because no user will ever pass a non-zero savemask. The setjmp() uses in tests/tcg/test-i386.c and tests/tcg/linux-test.c are left untouched because these are self-contained singlethreaded test programs intended to be run under QEMU's Linux emulation, so they have neither the portability nor the multithreading issues to deal with. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Tested-by: Stefan Weil Reviewed-by: Laszlo Ersek Signed-off-by: Blue Swirl --- cpu-exec.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'cpu-exec.c') diff --git a/cpu-exec.c b/cpu-exec.c index 9fcfe9e0db..afbe4977ab 100644 --- a/cpu-exec.c +++ b/cpu-exec.c @@ -35,7 +35,7 @@ void cpu_loop_exit(CPUArchState *env) CPUState *cpu = ENV_GET_CPU(env); cpu->current_tb = NULL; - longjmp(env->jmp_env, 1); + siglongjmp(env->jmp_env, 1); } /* exit the current TB from a signal handler. The host registers are @@ -47,7 +47,7 @@ void cpu_resume_from_signal(CPUArchState *env, void *puc) /* XXX: restore cpu registers saved in host registers */ env->exception_index = -1; - longjmp(env->jmp_env, 1); + siglongjmp(env->jmp_env, 1); } #endif @@ -234,7 +234,7 @@ int cpu_exec(CPUArchState *env) /* prepare setjmp context for exception handling */ for(;;) { - if (setjmp(env->jmp_env) == 0) { + if (sigsetjmp(env->jmp_env, 0) == 0) { /* if an exception is pending, we execute it here */ if (env->exception_index >= 0) { if (env->exception_index >= EXCP_INTERRUPT) { -- cgit v1.2.1