[PATCH] uml: Move signal handlers to arch code
Have most signals go through an arch-provided handler which recovers the
sigcontext and then calls a generic handler. This replaces the
ARCH_GET_SIGCONTEXT macro, which was somewhat fragile. On x86_64, recovering
%rdx (which holds the sigcontext pointer) must be the first thing that
happens. sig_handler duly invokes that first, but there is no guarantee that
I can see that instructions won't be reordered such that %rdx is used before
that. Having the arch provide the handler seems much more robust.
Some signals in some parts of UML require their own handlers - these places
don't call set_handler any more. They call sigaction or signal themselves.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 50418a5..88ff0de 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -189,14 +189,25 @@
}
}
if(!ptrace_faultinfo && (stack != NULL)){
+ struct sigaction sa;
+
unsigned long v = UML_CONFIG_STUB_CODE +
(unsigned long) stub_segv_handler -
(unsigned long) &__syscall_stub_start;
set_sigstack((void *) UML_CONFIG_STUB_DATA, page_size());
- set_handler(SIGSEGV, (void *) v, SA_ONSTACK,
- SIGIO, SIGWINCH, SIGALRM, SIGVTALRM,
- SIGUSR1, -1);
+ sigemptyset(&sa.sa_mask);
+ sigaddset(&sa.sa_mask, SIGIO);
+ sigaddset(&sa.sa_mask, SIGWINCH);
+ sigaddset(&sa.sa_mask, SIGALRM);
+ sigaddset(&sa.sa_mask, SIGVTALRM);
+ sigaddset(&sa.sa_mask, SIGUSR1);
+ sa.sa_flags = SA_ONSTACK;
+ sa.sa_handler = (void *) v;
+ sa.sa_restorer = NULL;
+ if(sigaction(SIGSEGV, &sa, NULL) < 0)
+ panic("userspace_tramp - setting SIGSEGV handler "
+ "failed - errno = %d\n", errno);
}
os_stop_process(os_getpid());