From 2f0260371f428fd78ffc2287a5c5768ea8eeab97 Mon Sep 17 00:00:00 2001
From: Haavard Skinnemoen <hskinnemoen@atmel.com>
Date: Fri, 23 Nov 2007 20:01:59 +0100
Subject: [PATCH] [AVR32] Implement stacktrace support

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
---
 arch/avr32/Kconfig             |  3 +++
 arch/avr32/kernel/Makefile     |  1 +
 arch/avr32/kernel/stacktrace.c | 53 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+)
 create mode 100644 arch/avr32/kernel/stacktrace.c

diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig
index b108dd8..599ec16 100644
--- a/arch/avr32/Kconfig
+++ b/arch/avr32/Kconfig
@@ -24,6 +24,9 @@ config GENERIC_GPIO
 config GENERIC_HARDIRQS
 	def_bool y
 
+config STACKTRACE_SUPPORT
+	def_bool y
+
 config HARDIRQS_SW_RESEND
 	def_bool y
 
diff --git a/arch/avr32/kernel/Makefile b/arch/avr32/kernel/Makefile
index 989fcd1..2d6d48f 100644
--- a/arch/avr32/kernel/Makefile
+++ b/arch/avr32/kernel/Makefile
@@ -11,3 +11,4 @@ obj-y				+= signal.o sys_avr32.o process.o time.o
 obj-y				+= init_task.o switch_to.o cpu.o
 obj-$(CONFIG_MODULES)		+= module.o avr32_ksyms.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o
+obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
diff --git a/arch/avr32/kernel/stacktrace.c b/arch/avr32/kernel/stacktrace.c
new file mode 100644
index 0000000..9a68190
--- /dev/null
+++ b/arch/avr32/kernel/stacktrace.c
@@ -0,0 +1,53 @@
+/*
+ * Stack trace management functions
+ *
+ * Copyright (C) 2007 Atmel Corporation
+ *
+ * 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/sched.h>
+#include <linux/stacktrace.h>
+#include <linux/thread_info.h>
+
+register unsigned long current_frame_pointer asm("r7");
+
+struct stackframe {
+	unsigned long lr;
+	unsigned long fp;
+};
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ */
+void save_stack_trace(struct stack_trace *trace)
+{
+	unsigned long low, high;
+	unsigned long fp;
+	struct stackframe *frame;
+	int skip = trace->skip;
+
+	low = (unsigned long)task_stack_page(current);
+	high = low + THREAD_SIZE;
+	fp = current_frame_pointer;
+
+	while (fp >= low && fp <= (high - 8)) {
+		frame = (struct stackframe *)fp;
+
+		if (skip) {
+			skip--;
+		} else {
+			trace->entries[trace->nr_entries++] = frame->lr;
+			if (trace->nr_entries >= trace->max_entries)
+				break;
+		}
+
+		/*
+		 * The next frame must be at a higher address than the
+		 * current frame.
+		 */
+		low = fp + 8;
+		fp = frame->fp;
+	}
+}
-- 
2.7.4