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| author | Peter Maydell <peter.maydell@linaro.org> | 2013-02-20 15:21:09 +0000 |
|---|---|---|
| committer | Blue Swirl <blauwirbel@gmail.com> | 2013-02-23 16:11:19 +0000 |
| commit | 6ab7e5465a4d6188e29398fb43a30dbab1015b75 (patch) | |
| tree | 1e8bc48fc86c89b32a07f9379a40ed907d2a91dd /include/exec | |
| parent | d1c36ba707637173b818652e51181370d51b6c58 (diff) | |
| download | qemu-6ab7e5465a4d6188e29398fb43a30dbab1015b75.zip | |
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 'include/exec')
| -rw-r--r-- | include/exec/cpu-defs.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/exec/cpu-defs.h b/include/exec/cpu-defs.h index ae64590cdf..3dc96568ac 100644 --- a/include/exec/cpu-defs.h +++ b/include/exec/cpu-defs.h @@ -184,7 +184,7 @@ typedef struct CPUWatchpoint { struct GDBRegisterState *gdb_regs; \ \ /* Core interrupt code */ \ - jmp_buf jmp_env; \ + sigjmp_buf jmp_env; \ int exception_index; \ \ CPUArchState *next_cpu; /* next CPU sharing TB cache */ \ |