Merge tag 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik...
[~shefty/rdma-dev.git] / fs / pstore / ftrace.c
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
30 static 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
50 static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
51         .func   = pstore_ftrace_call,
52 };
53
54 static DEFINE_MUTEX(pstore_ftrace_lock);
55 static bool pstore_ftrace_enabled;
56
57 static 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;
83 out:
84         ret = count;
85 err:
86         mutex_unlock(&pstore_ftrace_lock);
87
88         return ret;
89 }
90
91 static 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
99 static 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
105 void 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;
127 err_file:
128         debugfs_remove(dir);
129 }