1/*
2 * Copyright 2012  Google, Inc.
3 *
4 * This software is licensed under the terms of the GNU General Public
5 * License version 2, as published by the Free Software Foundation, and
6 * may be copied, distributed, and modified under those terms.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11 * GNU General Public License for more details.
12 */
13
14#include <linux/kernel.h>
15#include <linux/compiler.h>
16#include <linux/irqflags.h>
17#include <linux/percpu.h>
18#include <linux/smp.h>
19#include <linux/atomic.h>
20#include <linux/types.h>
21#include <linux/mutex.h>
22#include <linux/ftrace.h>
23#include <linux/fs.h>
24#include <linux/debugfs.h>
25#include <linux/err.h>
26#include <linux/cache.h>
27#include <asm/barrier.h>
28#include "internal.h"
29
30static void notrace pstore_ftrace_call(unsigned long ip,
31				       unsigned long parent_ip,
32				       struct ftrace_ops *op,
33				       struct pt_regs *regs)
34{
35	unsigned long flags;
36	struct pstore_ftrace_record rec = {};
37
38	if (unlikely(oops_in_progress))
39		return;
40
41	local_irq_save(flags);
42
43	rec.ip = ip;
44	rec.parent_ip = parent_ip;
45	pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
46	psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec,
47			  0, sizeof(rec), psinfo);
48
49	local_irq_restore(flags);
50}
51
52static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
53	.func	= pstore_ftrace_call,
54};
55
56static DEFINE_MUTEX(pstore_ftrace_lock);
57static bool pstore_ftrace_enabled;
58
59static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
60					size_t count, loff_t *ppos)
61{
62	u8 on;
63	ssize_t ret;
64
65	ret = kstrtou8_from_user(buf, count, 2, &on);
66	if (ret)
67		return ret;
68
69	mutex_lock(&pstore_ftrace_lock);
70
71	if (!on ^ pstore_ftrace_enabled)
72		goto out;
73
74	if (on)
75		ret = register_ftrace_function(&pstore_ftrace_ops);
76	else
77		ret = unregister_ftrace_function(&pstore_ftrace_ops);
78	if (ret) {
79		pr_err("%s: unable to %sregister ftrace ops: %zd\n",
80		       __func__, on ? "" : "un", ret);
81		goto err;
82	}
83
84	pstore_ftrace_enabled = on;
85out:
86	ret = count;
87err:
88	mutex_unlock(&pstore_ftrace_lock);
89
90	return ret;
91}
92
93static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
94				       size_t count, loff_t *ppos)
95{
96	char val[] = { '0' + pstore_ftrace_enabled, '\n' };
97
98	return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
99}
100
101static const struct file_operations pstore_knob_fops = {
102	.open	= simple_open,
103	.read	= pstore_ftrace_knob_read,
104	.write	= pstore_ftrace_knob_write,
105};
106
107void pstore_register_ftrace(void)
108{
109	struct dentry *dir;
110	struct dentry *file;
111
112	if (!psinfo->write_buf)
113		return;
114
115	dir = debugfs_create_dir("pstore", NULL);
116	if (!dir) {
117		pr_err("%s: unable to create pstore directory\n", __func__);
118		return;
119	}
120
121	file = debugfs_create_file("record_ftrace", 0600, dir, NULL,
122				   &pstore_knob_fops);
123	if (!file) {
124		pr_err("%s: unable to create record_ftrace file\n", __func__);
125		goto err_file;
126	}
127
128	return;
129err_file:
130	debugfs_remove(dir);
131}
132