From d4e28c48a98ab8461dc1d97674107d107fc0f9fb Mon Sep 17 00:00:00 2001
From: Jiri Olsa <jolsa@redhat.com>
Date: Wed, 29 Sep 2010 10:46:47 -0400
Subject: [PATCH] --- yaml --- r: 211908 b: refs/heads/master c:
 f6dedecc37164a58bb80ae2ed9d204669ffc4850 h: refs/heads/master v: v3

---
 [refs]                              |  2 +-
 trunk/arch/x86/oprofile/backtrace.c | 53 +++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 3fa35b8ff1da..6e2c79de9037 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 40c6b3cb64cd1d02322df5f729cca25084580f40
+refs/heads/master: f6dedecc37164a58bb80ae2ed9d204669ffc4850
diff --git a/trunk/arch/x86/oprofile/backtrace.c b/trunk/arch/x86/oprofile/backtrace.c
index d640a86198b1..2d49d4e19a36 100644
--- a/trunk/arch/x86/oprofile/backtrace.c
+++ b/trunk/arch/x86/oprofile/backtrace.c
@@ -14,6 +14,7 @@
 #include <asm/ptrace.h>
 #include <asm/uaccess.h>
 #include <asm/stacktrace.h>
+#include <linux/compat.h>
 
 static void backtrace_warning_symbol(void *data, char *msg,
 				     unsigned long symbol)
@@ -48,6 +49,55 @@ static struct stacktrace_ops backtrace_ops = {
 	.walk_stack	= print_context_stack,
 };
 
+#ifdef CONFIG_COMPAT
+static struct stack_frame_ia32 *
+dump_user_backtrace_32(struct stack_frame_ia32 *head)
+{
+	struct stack_frame_ia32 bufhead[2];
+	struct stack_frame_ia32 *fp;
+
+	/* Also check accessibility of one struct frame_head beyond */
+	if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
+		return NULL;
+	if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
+		return NULL;
+
+	fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);
+
+	oprofile_add_trace(bufhead[0].return_address);
+
+	/* frame pointers should strictly progress back up the stack
+	* (towards higher addresses) */
+	if (head >= fp)
+		return NULL;
+
+	return fp;
+}
+
+static inline int
+x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
+{
+	struct stack_frame_ia32 *head;
+
+	/* User process is 32-bit */
+	if (!current || !test_thread_flag(TIF_IA32))
+		return 0;
+
+	head = (struct stack_frame_ia32 *) regs->bp;
+	while (depth-- && head)
+		head = dump_user_backtrace_32(head);
+
+	return 1;
+}
+
+#else
+static inline int
+x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
+{
+	return 0;
+}
+#endif /* CONFIG_COMPAT */
+
 static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
 {
 	struct stack_frame bufhead[2];
@@ -81,6 +131,9 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
 		return;
 	}
 
+	if (x86_backtrace_32(regs, depth))
+		return;
+
 	while (depth-- && head)
 		head = dump_user_backtrace(head);
 }