um: switch stub_segv_handler to SA_SIGINFO variant, get rid of magic crap in there

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 2a72bfc..f481d74 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -255,8 +255,8 @@
 
 		set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
 		sigemptyset(&sa.sa_mask);
-		sa.sa_flags = SA_ONSTACK | SA_NODEFER;
-		sa.sa_handler = (void *) v;
+		sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
+		sa.sa_sigaction = (void *) v;
 		sa.sa_restorer = NULL;
 		if (sigaction(SIGSEGV, &sa, NULL) < 0) {
 			printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "