1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2012 Google, Inc.
4 */
5
6 #include <linux/kernel.h>
7 #include <linux/compiler.h>
8 #include <linux/irqflags.h>
9 #include <linux/percpu.h>
10 #include <linux/smp.h>
11 #include <linux/atomic.h>
12 #include <linux/types.h>
13 #include <linux/mutex.h>
14 #include <linux/ftrace.h>
15 #include <linux/fs.h>
16 #include <linux/debugfs.h>
17 #include <linux/err.h>
18 #include <linux/cache.h>
19 #include <asm/barrier.h>
20 #include "internal.h"
21
22 /* This doesn't need to be atomic: speed is chosen over correctness here. */
23 static u64 pstore_ftrace_stamp;
24
pstore_ftrace_call(unsigned long ip,unsigned long parent_ip,struct ftrace_ops * op,struct pt_regs * regs)25 static void notrace pstore_ftrace_call(unsigned long ip,
26 unsigned long parent_ip,
27 struct ftrace_ops *op,
28 struct pt_regs *regs)
29 {
30 unsigned long flags;
31 struct pstore_ftrace_record rec = {};
32 struct pstore_record record = {
33 .type = PSTORE_TYPE_FTRACE,
34 .buf = (char *)&rec,
35 .size = sizeof(rec),
36 .psi = psinfo,
37 };
38
39 if (unlikely(oops_in_progress))
40 return;
41
42 local_irq_save(flags);
43
44 rec.ip = ip;
45 rec.parent_ip = parent_ip;
46 pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
47 pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
48 psinfo->write(&record);
49
50 local_irq_restore(flags);
51 }
52
53 static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
54 .func = pstore_ftrace_call,
55 };
56
57 static DEFINE_MUTEX(pstore_ftrace_lock);
58 static bool pstore_ftrace_enabled;
59
pstore_ftrace_knob_write(struct file * f,const char __user * buf,size_t count,loff_t * ppos)60 static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
61 size_t count, loff_t *ppos)
62 {
63 u8 on;
64 ssize_t ret;
65
66 ret = kstrtou8_from_user(buf, count, 2, &on);
67 if (ret)
68 return ret;
69
70 mutex_lock(&pstore_ftrace_lock);
71
72 if (!on ^ pstore_ftrace_enabled)
73 goto out;
74
75 if (on) {
76 ftrace_ops_set_global_filter(&pstore_ftrace_ops);
77 ret = register_ftrace_function(&pstore_ftrace_ops);
78 } else {
79 ret = unregister_ftrace_function(&pstore_ftrace_ops);
80 }
81
82 if (ret) {
83 pr_err("%s: unable to %sregister ftrace ops: %zd\n",
84 __func__, on ? "" : "un", ret);
85 goto err;
86 }
87
88 pstore_ftrace_enabled = on;
89 out:
90 ret = count;
91 err:
92 mutex_unlock(&pstore_ftrace_lock);
93
94 return ret;
95 }
96
pstore_ftrace_knob_read(struct file * f,char __user * buf,size_t count,loff_t * ppos)97 static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
98 size_t count, loff_t *ppos)
99 {
100 char val[] = { '0' + pstore_ftrace_enabled, '\n' };
101
102 return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
103 }
104
105 static const struct file_operations pstore_knob_fops = {
106 .open = simple_open,
107 .read = pstore_ftrace_knob_read,
108 .write = pstore_ftrace_knob_write,
109 };
110
111 static struct dentry *pstore_ftrace_dir;
112
pstore_register_ftrace(void)113 void pstore_register_ftrace(void)
114 {
115 if (!psinfo->write)
116 return;
117
118 pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
119
120 debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
121 &pstore_knob_fops);
122 }
123
pstore_unregister_ftrace(void)124 void pstore_unregister_ftrace(void)
125 {
126 mutex_lock(&pstore_ftrace_lock);
127 if (pstore_ftrace_enabled) {
128 unregister_ftrace_function(&pstore_ftrace_ops);
129 pstore_ftrace_enabled = false;
130 }
131 mutex_unlock(&pstore_ftrace_lock);
132
133 debugfs_remove_recursive(pstore_ftrace_dir);
134 }
135