From 8f5937b10fc3afba10102b04a5242edb9b0ea27b Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 12 May 2008 21:20:48 +0200
Subject: [PATCH] --- yaml --- r: 100631 b: refs/heads/master c:
 9f6b4e3f4a24f2590f1c96f117fc45fbea9b0fa4 h: refs/heads/master i:   100629:
 cb21c75981015f46614a77fc2b0f110e119e9c7b   100627:
 a1ed7a193c8001e93f66802188e5a07abe60ba0d   100623:
 47a197d549528ee63c9c2e9f20001e7db8a2f858 v: v3

---
 [refs]                             |  2 +-
 trunk/kernel/trace/trace_sysprof.c | 28 +++++++++++++++++++---------
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/[refs] b/[refs]
index 5a792c5b3124..7345bbb64625 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ef4ab15ff34fd9c65e92bee70f58e7179da881c5
+refs/heads/master: 9f6b4e3f4a24f2590f1c96f117fc45fbea9b0fa4
diff --git a/trunk/kernel/trace/trace_sysprof.c b/trunk/kernel/trace/trace_sysprof.c
index 7f6fcccffb88..f9a09fe705b0 100644
--- a/trunk/kernel/trace/trace_sysprof.c
+++ b/trunk/kernel/trace/trace_sysprof.c
@@ -37,21 +37,26 @@ struct stack_frame {
 
 static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
 {
+	int ret;
+
 	if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
 		return 0;
 
-	if (__copy_from_user_inatomic(frame, frame_pointer, sizeof(*frame)))
-		return 0;
+	ret = 1;
+	pagefault_disable();
+	if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
+		ret = 0;
+	pagefault_enable();
 
-	return 1;
+	return ret;
 }
 
 static void timer_notify(struct pt_regs *regs, int cpu)
 {
-	const void __user *frame_pointer;
 	struct trace_array_cpu *data;
 	struct stack_frame frame;
 	struct trace_array *tr;
+	const void __user *fp;
 	int is_user;
 	int i;
 
@@ -77,21 +82,26 @@ static void timer_notify(struct pt_regs *regs, int cpu)
 
 	trace_special(tr, data, 0, current->pid, regs->ip);
 
-	frame_pointer = (void __user *)regs->bp;
+	fp = (void __user *)regs->bp;
 
 	for (i = 0; i < sample_max_depth; i++) {
-		if (!copy_stack_frame(frame_pointer, &frame))
+		frame.next_fp = 0;
+		frame.return_address = 0;
+		if (!copy_stack_frame(fp, &frame))
 			break;
-		if ((unsigned long)frame_pointer < regs->sp)
+		if ((unsigned long)fp < regs->sp)
 			break;
 
 		trace_special(tr, data, 1, frame.return_address,
-			      (unsigned long)frame_pointer);
-		frame_pointer = frame.next_fp;
+			      (unsigned long)fp);
+		fp = frame.next_fp;
 	}
 
 	trace_special(tr, data, 2, current->pid, i);
 
+	/*
+	 * Special trace entry if we overflow the max depth:
+	 */
 	if (i == sample_max_depth)
 		trace_special(tr, data, -1, -1, -1);
 }