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060287b8 AV |
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> | |
65f8c95e AV |
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> | |
060287b8 AV |
27 | #include <asm/barrier.h> |
28 | #include "internal.h" | |
29 | ||
65f8c95e AV |
30 | static void notrace pstore_ftrace_call(unsigned long ip, |
31 | unsigned long parent_ip) | |
060287b8 | 32 | { |
65f8c95e | 33 | unsigned long flags; |
060287b8 AV |
34 | struct pstore_ftrace_record rec = {}; |
35 | ||
36 | if (unlikely(oops_in_progress)) | |
37 | return; | |
38 | ||
65f8c95e AV |
39 | local_irq_save(flags); |
40 | ||
060287b8 AV |
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); | |
65f8c95e AV |
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); | |
060287b8 | 129 | } |