tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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{
33 unsigned long flags;
34 struct pstore_ftrace_record rec = {};
35
36 if (unlikely(oops_in_progress))
37 return;
38
39 local_irq_save(flags);
40
41 rec.ip = ip;
42 rec.parent_ip = parent_ip;
43 pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
44 psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec,
45 sizeof(rec), psinfo);
46
47 local_irq_restore(flags);
48}
49
50static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
51 .func = pstore_ftrace_call,
52};
53
54static DEFINE_MUTEX(pstore_ftrace_lock);
55static bool pstore_ftrace_enabled;
56
57static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
58 size_t count, loff_t *ppos)
59{
60 u8 on;
61 ssize_t ret;
62
63 ret = kstrtou8_from_user(buf, count, 2, &on);
64 if (ret)
65 return ret;
66
67 mutex_lock(&pstore_ftrace_lock);
68
69 if (!on ^ pstore_ftrace_enabled)
70 goto out;
71
72 if (on)
73 ret = register_ftrace_function(&pstore_ftrace_ops);
74 else
75 ret = unregister_ftrace_function(&pstore_ftrace_ops);
76 if (ret) {
77 pr_err("%s: unable to %sregister ftrace ops: %zd\n",
78 __func__, on ? "" : "un", ret);
79 goto err;
80 }
81
82 pstore_ftrace_enabled = on;
83out:
84 ret = count;
85err:
86 mutex_unlock(&pstore_ftrace_lock);
87
88 return ret;
89}
90
91static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
92 size_t count, loff_t *ppos)
93{
94 char val[] = { '0' + pstore_ftrace_enabled, '\n' };
95
96 return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
97}
98
99static const struct file_operations pstore_knob_fops = {
100 .open = simple_open,
101 .read = pstore_ftrace_knob_read,
102 .write = pstore_ftrace_knob_write,
103};
104
105void pstore_register_ftrace(void)
106{
107 struct dentry *dir;
108 struct dentry *file;
109
110 if (!psinfo->write_buf)
111 return;
112
113 dir = debugfs_create_dir("pstore", NULL);
114 if (!dir) {
115 pr_err("%s: unable to create pstore directory\n", __func__);
116 return;
117 }
118
119 file = debugfs_create_file("record_ftrace", 0600, dir, NULL,
120 &pstore_knob_fops);
121 if (!file) {
122 pr_err("%s: unable to create record_ftrace file\n", __func__);
123 goto err_file;
124 }
125
126 return;
127err_file:
128 debugfs_remove(dir);
129}