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path: root/util/coroutine-sigaltstack.c
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2023-10-04osdep: set _FORTIFY_SOURCE=2 when optimization is enabledDaniel P. Berrangé
Currently we set _FORTIFY_SOURCE=2 as a compiler argument when the meson 'optimization' setting is non-zero, the compiler is GCC and the target is Linux. While the default QEMU optimization level is 2, user could override this by setting CFLAGS="-O0" or --extra-cflags="-O0" when running configure and this won't be reflected in the meson 'optimization' setting. As a result we try to enable _FORTIFY_SOURCE=2 and then the user gets compile errors as it only works with optimization. Rather than trying to improve detection in meson, it is simpler to just check the __OPTIMIZE__ define from osdep.h. The comment about being incompatible with clang appears to be outdated, as compilation works fine without excluding clang. In the coroutine code we must set _FORTIFY_SOURCE=0 to stop the logic in osdep.h then enabling it. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Message-id: 20231003091549.223020-1-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-04-06Remove qemu-common.h include from most unitsMarc-André Lureau
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20220323155743.1585078-33-marcandre.lureau@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-01-26coroutine-sigaltstack: Add SIGUSR2 mutexMax Reitz
Disposition (action) for any given signal is global for the process. When two threads run coroutine-sigaltstack's qemu_coroutine_new() concurrently, they may interfere with each other: One of them may revert the SIGUSR2 handler to SIG_DFL, between the other thread (a) setting up coroutine_trampoline() as the handler and (b) raising SIGUSR2. That SIGUSR2 will then terminate the QEMU process abnormally. We have to ensure that only one thread at a time can modify the process-global SIGUSR2 handler. To do so, wrap the whole section where that is done in a mutex. Alternatively, we could for example have the SIGUSR2 handler always be coroutine_trampoline(), so there would be no need to invoke sigaction() in qemu_coroutine_new(). Laszlo has posted a patch to do so here: https://lists.nongnu.org/archive/html/qemu-devel/2021-01/msg05962.html However, given that coroutine-sigaltstack is more of a fallback implementation for platforms that do not support ucontext, that change may be a bit too invasive to be comfortable with it. The mutex proposed here may negatively impact performance, but the change is much simpler. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20210125120305.19520-1-mreitz@redhat.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2020-06-23coroutine: add check for SafeStack in sigaltstackDaniele Buono
Current implementation of LLVM's SafeStack is not compatible with code that uses an alternate stack created with sigaltstack(). Since coroutine-sigaltstack relies on sigaltstack(), it is not compatible with SafeStack. The resulting binary is incorrect, with different coroutines sharing the same unsafe stack and producing undefined behavior at runtime. In the future LLVM may provide a SafeStack implementation compatible with sigaltstack(). In the meantime, if SafeStack is desired, the coroutine implementation from coroutine-ucontext should be used. As a safety check, add a control in coroutine-sigaltstack to throw a preprocessor #error if SafeStack is enabled and we are trying to use coroutine-sigaltstack to implement coroutines. Signed-off-by: Daniele Buono <dbuono@linux.vnet.ibm.com> Message-id: 20200529205122.714-3-dbuono@linux.vnet.ibm.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-09-29coroutine-sigaltstack: use helper for allocating stack memoryPeter Lieven
Signed-off-by: Peter Lieven <pl@kamp.de> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-09-29coroutine: add a macro for the coroutine stack sizePeter Lieven
Signed-off-by: Peter Lieven <pl@kamp.de> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-09-29coroutine-sigaltstack: rename coroutine struct appropriatelyPeter Lieven
The name of the sigaltstack coroutine struct was misleading. Signed-off-by: Peter Lieven <pl@kamp.de> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-03-22Remove unneeded include statements for setjmp.hStefan Weil
As soon as setjmp.h is included from qemu/osdep.h, those old include statements are no longer needed. Add also setjmp.h to the list in scripts/clean-includes. Signed-off-by: Stefan Weil <sw@weilnetz.de>
2016-02-04util: Clean up includesPeter Maydell
Clean up includes so that osdep.h is included first and headers which it implies are not included manually. This commit was created with scripts/clean-includes. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Message-id: 1454089805-5470-6-git-send-email-peter.maydell@linaro.org
2015-10-20coroutine: move into libqemuutil.a libraryDaniel P. Berrange
The coroutine files are currently referenced by the block-obj-y variable. The coroutine functionality though is already used by more than just the block code. eg migration code uses coroutine yield. In the future the I/O channel code will also use the coroutine yield functionality. Since the coroutine code is nicely self-contained it can be easily built as part of the libqemuutil.a library, making it widely available. The headers are also moved into include/qemu, instead of the include/block directory, since they are now part of the util codebase, and the impl was never in the block/ directory either. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>