alpha: don't bother passing switch_stack separately from regs

It's needed only in setup_sigcontext() and it's always reg - <constant>;
no point passing it all way down through the call chain.  This is just
the signal.c side of that stuff; next will come the asm glue one...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/alpha/kernel/signal.c

@@ -298,8 +298,9 @@ get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 
 static long
 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 
-		 struct switch_stack *sw, unsigned long mask, unsigned long sp)
+		 unsigned long mask, unsigned long sp)
 {
+	struct switch_stack *sw = (struct switch_stack *)regs - 1;
 	long i, err = 0;
 
 	err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
@@ -354,7 +355,7 @@ setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 
 static int
 setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
-	    struct pt_regs *regs, struct switch_stack * sw)
+	    struct pt_regs *regs)
 {
 	unsigned long oldsp, r26, err = 0;
 	struct sigframe __user *frame;
@@ -364,7 +365,7 @@ setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 		return -EFAULT;
 
-	err |= setup_sigcontext(&frame->sc, regs, sw, set->sig[0], oldsp);
+	err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
 	if (err)
 		return -EFAULT;
 
@@ -401,7 +402,7 @@ setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 
 static int
 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
-	       sigset_t *set, struct pt_regs *regs, struct switch_stack * sw)
+	       sigset_t *set, struct pt_regs *regs)
 {
 	unsigned long oldsp, r26, err = 0;
 	struct rt_sigframe __user *frame;
@@ -420,7 +421,7 @@ setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 	err |= __put_user(sas_ss_flags(oldsp), &frame->uc.uc_stack.ss_flags);
 	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
-	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, sw,
+	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, 
 				set->sig[0], oldsp);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 	if (err)
@@ -464,15 +465,15 @@ setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
  */
 static inline void
 handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
-	      struct pt_regs * regs, struct switch_stack *sw)
+	      struct pt_regs * regs)
 {
 	sigset_t *oldset = sigmask_to_save();
 	int ret;
 
 	if (ka->sa.sa_flags & SA_SIGINFO)
-		ret = setup_rt_frame(sig, ka, info, oldset, regs, sw);
+		ret = setup_rt_frame(sig, ka, info, oldset, regs);
 	else
-		ret = setup_frame(sig, ka, oldset, regs, sw);
+		ret = setup_frame(sig, ka, oldset, regs);
 
 	if (ret) {
 		force_sigsegv(sig, current);
@@ -519,8 +520,7 @@ syscall_restart(unsigned long r0, unsigned long r19,
  * all (if we get here from anything but a syscall return, it will be 0)
  */
 static void
-do_signal(struct pt_regs * regs, struct switch_stack * sw,
-	  unsigned long r0, unsigned long r19)
+do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
 {
 	siginfo_t info;
 	int signr;
@@ -537,7 +537,7 @@ do_signal(struct pt_regs * regs, struct switch_stack * sw,
 		/* Whee!  Actually deliver the signal.  */
 		if (r0)
 			syscall_restart(r0, r19, regs, &ka);
-		handle_signal(signr, &ka, &info, regs, sw);
+		handle_signal(signr, &ka, &info, regs);
 		if (single_stepping) 
 			ptrace_set_bpt(current); /* re-set bpt */
 		return;
@@ -568,7 +568,7 @@ do_signal(struct pt_regs * regs, struct switch_stack * sw,
 }
 
 void
-do_work_pending(struct pt_regs *regs, struct switch_stack *sw,
+do_work_pending(struct pt_regs *regs, struct switch_stack *unused,
 		 unsigned long thread_flags,
 		 unsigned long r0, unsigned long r19)
 {
@@ -578,7 +578,7 @@ do_work_pending(struct pt_regs *regs, struct switch_stack *sw,
 		} else {
 			local_irq_enable();
 			if (thread_flags & _TIF_SIGPENDING) {
-				do_signal(regs, sw, r0, r19);
+				do_signal(regs, r0, r19);
 				r0 = 0;
 			} else {
 				clear_thread_flag(TIF_NOTIFY_RESUME);