Split 4.x and 5.x signal handling so that we can keep 4.x signal

handling clean and functional as 5.x evolves.  This allows some of the
nasty bandaids in the 5.x codepaths to be unwound.

Encapsulate 4.x signal handling under COMPAT_FREEBSD4 (there is an
anti-foot-shooting measure in place, 5.x folks need this for a while) and
finish encapsulating the older stuff under COMPAT_43.  Since the ancient
stuff is required on alpha (longjmp(3) passes a 'struct osigcontext *'
to the current sigreturn(2), instead of the 'ucontext_t *' that sigreturn
is supposed to take), add a compile time check to prevent foot shooting
there too.  Add uniform COMPAT_43 stubs for ia64/sparc64/powerpc.

Tested on: i386, alpha, ia64.  Compiled on sparc64 (a few days ago).
Approved by: re

2 files changed, 10 insertions, 22 deletions

diff --git a/sys/sparc64/include/signal.h b/sys/sparc64/include/signal.h
index c27ad57..2b834ad 100644
--- a/sys/sparc64/include/signal.h
+++ b/sys/sparc64/include/signal.h
@@ -46,14 +46,6 @@ typedef	long sig_atomic_t;
 #define	MINSIGSTKSZ	(1024 * 4)
 #endif
 
-#ifdef _KERNEL
-typedef	int osigset_t;
-
-struct osigcontext {
-	int	dummy;
-};
-#endif
-
 #if __BSD_VISIBLE
 struct sigcontext {
 	int	_dummy;
diff --git a/sys/sparc64/sparc64/machdep.c b/sys/sparc64/sparc64/machdep.c
index 55ef2a9..8203056 100644
--- a/sys/sparc64/sparc64/machdep.c
+++ b/sys/sparc64/sparc64/machdep.c
@@ -40,6 +40,7 @@
  * $FreeBSD$
  */
 
+#include "opt_compat.h"
 #include "opt_ddb.h"
 #include "opt_msgbuf.h"
 
@@ -449,20 +450,6 @@ sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
 	PROC_LOCK(p);
 }
 
-/*
- * Stub to satisfy the reference to osigreturn in the syscall table.  This
- * is needed even for newer arches that don't support old signals because
- * the syscall table is machine-independent.
- *
- * MPSAFE
- */
-int
-osigreturn(struct thread *td, struct osigreturn_args *uap)
-{
-
-	return (nosys(td, (struct nosys_args *)uap));
-}
-
 #ifndef	_SYS_SYSPROTO_H_
 struct sigreturn_args {
 	ucontext_t *ucp;
@@ -506,6 +493,15 @@ sigreturn(struct thread *td, struct sigreturn_args *uap)
 	return (EJUSTRETURN);
 }
 
+#ifdef COMPAT_FREEBSD4
+int
+freebsd4_sigreturn(struct thread *td, struct freebsd4_sigreturn_args *uap)
+{
+
+	return sigreturn(td, (struct sigreturn_args *)uap);
+}
+#endif
+
 /*
  * Exit the kernel and execute a firmware call that will not return, as
  * specified by the arguments.