powerpc/signal: Move access_ok() out of get_sigframe()

This access_ok() will soon be performed by user_access_begin().
So move it out of get_sigframe().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/900b93744732ed0887f28f5b6a40730fb04a43fa.1597770847.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/signal.c

@@ -154,10 +154,6 @@ void __user *get_sigframe(struct ksignal *ksig, unsigned long sp,
 	oldsp = sigsp(oldsp, ksig);
 	newsp = (oldsp - frame_size) & ~0xFUL;
 
-	/* Check access */
-	if (!access_ok((void __user *)newsp, oldsp - newsp))
-		return NULL;
-
         return (void __user *)newsp;
 }
 

arch/powerpc/kernel/signal_32.c

@@ -768,7 +768,7 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,
 	/* Put a Real Time Context onto stack */
 	rt_sf = get_sigframe(ksig, get_tm_stackpointer(tsk), sizeof(*rt_sf), 1);
 	addr = rt_sf;
-	if (unlikely(rt_sf == NULL))
+	if (!access_ok(rt_sf, sizeof(*rt_sf)))
 		goto badframe;
 
 	/* Put the siginfo & fill in most of the ucontext */
@@ -1227,7 +1227,7 @@ int handle_signal32(struct ksignal *ksig, sigset_t *oldset,
 
 	/* Set up Signal Frame */
 	frame = get_sigframe(ksig, get_tm_stackpointer(tsk), sizeof(*frame), 1);
-	if (unlikely(frame == NULL))
+	if (!access_ok(frame, sizeof(*frame)))
 		goto badframe;
 	sc = (struct sigcontext __user *) &frame->sctx;
 

arch/powerpc/kernel/signal_64.c

@@ -823,7 +823,7 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
 #endif
 
 	frame = get_sigframe(ksig, get_tm_stackpointer(tsk), sizeof(*frame), 0);
-	if (unlikely(frame == NULL))
+	if (!access_ok(frame, sizeof(*frame)))
 		goto badframe;
 
 	err |= __put_user(&frame->info, &frame->pinfo);