1/*
2 * Stacktrace support for Hexagon
3 *
4 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 and
8 * only version 2 as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18 * 02110-1301, USA.
19 */
20
21#include <linux/sched.h>
22#include <linux/stacktrace.h>
23#include <linux/thread_info.h>
24#include <linux/module.h>
25
26register unsigned long current_frame_pointer asm("r30");
27
28struct stackframe {
29	unsigned long fp;
30	unsigned long rets;
31};
32
33/*
34 * Save stack-backtrace addresses into a stack_trace buffer.
35 */
36void save_stack_trace(struct stack_trace *trace)
37{
38	unsigned long low, high;
39	unsigned long fp;
40	struct stackframe *frame;
41	int skip = trace->skip;
42
43	low = (unsigned long)task_stack_page(current);
44	high = low + THREAD_SIZE;
45	fp = current_frame_pointer;
46
47	while (fp >= low && fp <= (high - sizeof(*frame))) {
48		frame = (struct stackframe *)fp;
49
50		if (skip) {
51			skip--;
52		} else {
53			trace->entries[trace->nr_entries++] = frame->rets;
54			if (trace->nr_entries >= trace->max_entries)
55				break;
56		}
57
58		/*
59		 * The next frame must be at a higher address than the
60		 * current frame.
61		 */
62		low = fp + sizeof(*frame);
63		fp = frame->fp;
64	}
65}
66EXPORT_SYMBOL_GPL(save_stack_trace);
67