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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 | 30 | static void notrace pstore_ftrace_call(unsigned long ip, |
ebacfd1e AV |
31 | unsigned long parent_ip, |
32 | struct ftrace_ops *op, | |
33 | struct pt_regs *regs) | |
060287b8 | 34 | { |
65f8c95e | 35 | unsigned long flags; |
060287b8 AV |
36 | struct pstore_ftrace_record rec = {}; |
37 | ||
38 | if (unlikely(oops_in_progress)) | |
39 | return; | |
40 | ||
65f8c95e AV |
41 | local_irq_save(flags); |
42 | ||
060287b8 AV |
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 | sizeof(rec), psinfo); | |
65f8c95e AV |
48 | |
49 | local_irq_restore(flags); | |
50 | } | |
51 | ||
52 | static struct ftrace_ops pstore_ftrace_ops __read_mostly = { | |
53 | .func = pstore_ftrace_call, | |
54 | }; | |
55 | ||
56 | static DEFINE_MUTEX(pstore_ftrace_lock); | |
57 | static bool pstore_ftrace_enabled; | |
58 | ||
59 | static 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; | |
85 | out: | |
86 | ret = count; | |
87 | err: | |
88 | mutex_unlock(&pstore_ftrace_lock); | |
89 | ||
90 | return ret; | |
91 | } | |
92 | ||
93 | static 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 | ||
101 | static 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 | ||
107 | void 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; | |
129 | err_file: | |
130 | debugfs_remove(dir); | |
060287b8 | 131 | } |