1 files changed, 81 insertions, 0 deletions
diff --git a/arch/avr32/oprofile/backtrace.c b/arch/avr32/oprofile/backtrace.c
new file mode 100644
index 00000000000..75d9ad6f99c
--- /dev/null
+++ b/arch/avr32/oprofile/backtrace.c
@@ -0,0 +1,81 @@
+/*
+ * AVR32 specific backtracing code for oprofile
+ *
+ * Copyright 2008 Weinmann GmbH
+ *
+ * Author: Nikolaus Voss <n.voss@weinmann.de>
+ *
+ * Based on i386 oprofile backtrace code by John Levon and David Smith
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/oprofile.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+
+/* The first two words of each frame on the stack look like this if we have
+ * frame pointers */
+struct frame_head {
+	unsigned long lr;
+	struct frame_head *fp;
+};
+
+/* copied from arch/avr32/kernel/process.c */
+static inline int valid_stack_ptr(struct thread_info *tinfo, unsigned long p)
+{
+	return (p > (unsigned long)tinfo)
+		&& (p < (unsigned long)tinfo + THREAD_SIZE - 3);
+}
+
+/* copied from arch/x86/oprofile/backtrace.c */
+static struct frame_head *dump_user_backtrace(struct frame_head *head)
+{
+	struct frame_head bufhead[2];
+
+	/* 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;
+
+	oprofile_add_trace(bufhead[0].lr);
+
+	/* frame pointers should strictly progress back up the stack
+	 * (towards higher addresses) */
+	if (bufhead[0].fp <= head)
+		return NULL;
+
+	return bufhead[0].fp;
+}
+
+void avr32_backtrace(struct pt_regs * const regs, unsigned int depth)
+{
+	/* Get first frame pointer */
+	struct frame_head *head = (struct frame_head *)(regs->r7);
+
+	if (!user_mode(regs)) {
+#ifdef CONFIG_FRAME_POINTER
+		/*
+		 * Traverse the kernel stack from frame to frame up to
+		 * "depth" steps.
+		 */
+		while (depth-- && valid_stack_ptr(task_thread_info(current),
+						  (unsigned long)head)) {
+			oprofile_add_trace(head->lr);
+			if (head->fp <= head)
+				break;
+			head = head->fp;
+		}
+#endif
+	} else {
+		/* Assume we have frame pointers in user mode process */
+		while (depth-- && head)
+			head = dump_user_backtrace(head);
+	}
+}
+
+