[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>

1 files changed, 11 insertions, 1 deletions

diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index 3afde92ad2c0..ff203625a4bd 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -246,7 +246,17 @@ void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int))
                 set_sigstack(sig_stack, pages * page_size());
                 flags = SA_ONSTACK;
         }
-        if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1);
+        if(usr1_handler){
+                struct sigaction sa;
+
+                sa.sa_handler = usr1_handler;
+                sigemptyset(&sa.sa_mask);
+                sa.sa_flags = flags;
+                sa.sa_restorer = NULL;
+                if(sigaction(SIGUSR1, &sa, NULL) < 0)
+                        panic("init_new_thread_stack - sigaction failed - "
+                              "errno = %d\n", errno);
+        }
 }
 
 void init_new_thread_signals(void)