powerpc: Add TIF_NOTIFY_RESUME support for tracehook

This adds TIF_NOTIFY_RESUME support for powerpc.  When set,
we call tracehook_notify_resume() on the way to user mode.
This overloads do_signal() to do the work, but changes its
arguments to it has the TIF_* bits handy in a register and
drops the useless first argument that was always zero.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index e6fca6a..1cbbf70 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1060,8 +1060,8 @@
 	SAVE_NVGPRS(r1)
 	rlwinm	r3,r3,0,0,30
 	stw	r3,_TRAP(r1)
-2:	li	r3,0
-	addi	r4,r1,STACK_FRAME_OVERHEAD
+2:	addi	r3,r1,STACK_FRAME_OVERHEAD
+	mr	r4,r9
 	bl	do_signal
 	REST_NVGPRS(r1)
 	b	recheck
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 79c089e..2d802e9 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -643,8 +643,7 @@
 	b	.ret_from_except_lite
 
 1:	bl	.save_nvgprs
-	li	r3,0
-	addi	r4,r1,STACK_FRAME_OVERHEAD
+	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	.do_signal
 	b	.ret_from_except
 
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index e74aa0e..a54405e 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -112,7 +112,7 @@
 	}
 }
 
-int do_signal(sigset_t *oldset, struct pt_regs *regs)
+static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs)
 {
 	siginfo_t info;
 	int signr;
@@ -188,6 +188,17 @@
 	return ret;
 }
 
+void do_signal(struct pt_regs *regs, unsigned long thread_info_flags)
+{
+	if (thread_info_flags & _TIF_SIGPENDING)
+		do_signal_pending(NULL, regs);
+
+	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
+		clear_thread_flag(TIF_NOTIFY_RESUME);
+		tracehook_notify_resume(regs);
+	}
+}
+
 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 		unsigned long r5, unsigned long r6, unsigned long r7,
 		unsigned long r8, struct pt_regs *regs)