path: root/cpu-exec.c
diff options
authorPeter Maydell <peter.maydell@linaro.org>2013-02-20 15:21:09 +0000
committerBlue Swirl <blauwirbel@gmail.com>2013-02-23 16:11:19 +0000
commit6ab7e5465a4d6188e29398fb43a30dbab1015b75 (patch)
tree1e8bc48fc86c89b32a07f9379a40ed907d2a91dd /cpu-exec.c
parentd1c36ba707637173b818652e51181370d51b6c58 (diff)
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 <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Tested-by: Stefan Weil <sw@weilnetz.de> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Diffstat (limited to 'cpu-exec.c')
1 files changed, 3 insertions, 3 deletions
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);
@@ -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) {