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| author | Rich Felker <dalias@aerifal.cx> | 2022-08-20 12:24:49 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2022-08-20 12:24:49 -0400 |
| commit | 2e5fff43dd7fc808197744c67cca7908ac19bb4f (patch) | |
| tree | e62bcaa00019889aa5fa574a71336b364934c7f7 /src | |
| parent | 379b18218d18a049b5423bbb9bb22e066ffc3f78 (diff) | |
| download | musl-2e5fff43dd7fc808197744c67cca7908ac19bb4f.tar.gz musl-2e5fff43dd7fc808197744c67cca7908ac19bb4f.tar.xz musl-2e5fff43dd7fc808197744c67cca7908ac19bb4f.zip | |
use alt signal stack when present for implementation-internal signals
a request for this behavior has been open for a long time. the motivation is that application code, particularly under some language runtimes designed around very-low-footprint coroutine type constructs, may be operating with extremely small stack sizes unsuitable for receiving signals, using a separate signal stack for any signals it might handle. progress on this was blocked at one point trying to determine whether the implementation is actually entitled to clobber the alt stack, but the phrasing "available to the implementation" in the POSIX spec for sigaltstack seems to make it clear that the application cannot rely on the contents of this memory to be preserved in the absence of signal delivery (on the abstract machine, excluding implementation-internal signals) and that we can therefore use it for delivery of signals that "don't exist" on the abstract machine. no change is made for SIGTIMER since it is always blocked when used, and accepted via sigwaitinfo rather than execution of the signal handler.
Diffstat (limited to 'src')
| -rw-r--r-- | src/linux/membarrier.c | 2 | ||||
| -rw-r--r-- | src/thread/pthread_cancel.c | 2 | ||||
| -rw-r--r-- | src/thread/synccall.c | 2 |
3 files changed, 3 insertions, 3 deletions
diff --git a/src/linux/membarrier.c b/src/linux/membarrier.c index 343f7360..f64fe7e1 100644 --- a/src/linux/membarrier.c +++ b/src/linux/membarrier.c @@ -35,7 +35,7 @@ int __membarrier(int cmd, int flags) __tl_lock(); sem_init(&barrier_sem, 0, 0); struct sigaction sa = { - .sa_flags = SA_RESTART, + .sa_flags = SA_RESTART | SA_ONSTACK, .sa_handler = bcast_barrier }; memset(&sa.sa_mask, -1, sizeof sa.sa_mask); diff --git a/src/thread/pthread_cancel.c b/src/thread/pthread_cancel.c index 2f9d5e97..2d3a98ea 100644 --- a/src/thread/pthread_cancel.c +++ b/src/thread/pthread_cancel.c @@ -77,7 +77,7 @@ void __testcancel() static void init_cancellation() { struct sigaction sa = { - .sa_flags = SA_SIGINFO | SA_RESTART, + .sa_flags = SA_SIGINFO | SA_RESTART | SA_ONSTACK, .sa_sigaction = cancel_handler }; memset(&sa.sa_mask, -1, _NSIG/8); diff --git a/src/thread/synccall.c b/src/thread/synccall.c index d58c851f..a6b177c0 100644 --- a/src/thread/synccall.c +++ b/src/thread/synccall.c @@ -45,7 +45,7 @@ void __synccall(void (*func)(void *), void *ctx) { sigset_t oldmask; int cs, i, r; - struct sigaction sa = { .sa_flags = SA_RESTART, .sa_handler = handler }; + struct sigaction sa = { .sa_flags = SA_RESTART | SA_ONSTACK, .sa_handler = handler }; pthread_t self = __pthread_self(), td; int count = 0; |