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 <linux/slab.h>
20#include <asm/barrier.h>
21#include "internal.h"
22
23/* This doesn't need to be atomic: speed is chosen over correctness here. */
24static u64 pstore_ftrace_stamp;
25
26static void notrace pstore_ftrace_call(unsigned long ip,
27 unsigned long parent_ip,
28 struct ftrace_ops *op,
29 struct ftrace_regs *fregs)
30{
31 int bit;
32 unsigned long flags;
33 struct pstore_ftrace_record rec = {};
34 struct pstore_record record = {
35 .type = PSTORE_TYPE_FTRACE,
36 .buf = (char *)&rec,
37 .size = sizeof(rec),
38 .psi = psinfo,
39 };
40
41 if (unlikely(oops_in_progress))
42 return;
43
44 bit = ftrace_test_recursion_trylock(ip, parent_ip);
45 if (bit < 0)
46 return;
47
48 local_irq_save(flags);
49
50 rec.ip = ip;
51 rec.parent_ip = parent_ip;
52 pstore_ftrace_write_timestamp(rec: &rec, val: pstore_ftrace_stamp++);
53 pstore_ftrace_encode_cpu(rec: &rec, raw_smp_processor_id());
54 psinfo->write(&record);
55
56 local_irq_restore(flags);
57 ftrace_test_recursion_unlock(bit);
58}
59
60static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
61 .func = pstore_ftrace_call,
62};
63
64static DEFINE_MUTEX(pstore_ftrace_lock);
65static bool pstore_ftrace_enabled;
66
67static int pstore_set_ftrace_enabled(bool on)
68{
69 ssize_t ret;
70
71 if (on == pstore_ftrace_enabled)
72 return 0;
73
74 if (on) {
75 ftrace_ops_set_global_filter(ops: &pstore_ftrace_ops);
76 ret = register_ftrace_function(ops: &pstore_ftrace_ops);
77 } else {
78 ret = unregister_ftrace_function(ops: &pstore_ftrace_ops);
79 }
80
81 if (ret) {
82 pr_err("%s: unable to %sregister ftrace ops: %zd\n",
83 __func__, on ? "" : "un", ret);
84 } else {
85 pstore_ftrace_enabled = on;
86 }
87
88 return ret;
89}
90
91static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
92 size_t count, loff_t *ppos)
93{
94 u8 on;
95 ssize_t ret;
96
97 ret = kstrtou8_from_user(s: buf, count, base: 2, res: &on);
98 if (ret)
99 return ret;
100
101 mutex_lock(&pstore_ftrace_lock);
102 ret = pstore_set_ftrace_enabled(on);
103 mutex_unlock(lock: &pstore_ftrace_lock);
104
105 if (ret == 0)
106 ret = count;
107
108 return ret;
109}
110
111static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
112 size_t count, loff_t *ppos)
113{
114 char val[] = { '0' + pstore_ftrace_enabled, '\n' };
115
116 return simple_read_from_buffer(to: buf, count, ppos, from: val, available: sizeof(val));
117}
118
119static const struct file_operations pstore_knob_fops = {
120 .open = simple_open,
121 .read = pstore_ftrace_knob_read,
122 .write = pstore_ftrace_knob_write,
123};
124
125static struct dentry *pstore_ftrace_dir;
126
127static bool record_ftrace;
128module_param(record_ftrace, bool, 0400);
129MODULE_PARM_DESC(record_ftrace,
130 "enable ftrace recording immediately (default: off)");
131
132void pstore_register_ftrace(void)
133{
134 if (!psinfo->write)
135 return;
136
137 pstore_ftrace_dir = debugfs_create_dir(name: "pstore", NULL);
138
139 pstore_set_ftrace_enabled(on: record_ftrace);
140
141 debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
142 &pstore_knob_fops);
143}
144
145void pstore_unregister_ftrace(void)
146{
147 mutex_lock(&pstore_ftrace_lock);
148 if (pstore_ftrace_enabled) {
149 unregister_ftrace_function(ops: &pstore_ftrace_ops);
150 pstore_ftrace_enabled = false;
151 }
152 mutex_unlock(lock: &pstore_ftrace_lock);
153
154 debugfs_remove_recursive(dentry: pstore_ftrace_dir);
155}
156
157ssize_t pstore_ftrace_combine_log(char **dest_log, size_t *dest_log_size,
158 const char *src_log, size_t src_log_size)
159{
160 size_t dest_size, src_size, total, dest_off, src_off;
161 size_t dest_idx = 0, src_idx = 0, merged_idx = 0;
162 void *merged_buf;
163 struct pstore_ftrace_record *drec, *srec, *mrec;
164 size_t record_size = sizeof(struct pstore_ftrace_record);
165
166 dest_off = *dest_log_size % record_size;
167 dest_size = *dest_log_size - dest_off;
168
169 src_off = src_log_size % record_size;
170 src_size = src_log_size - src_off;
171
172 total = dest_size + src_size;
173 merged_buf = kmalloc(total, GFP_KERNEL);
174 if (!merged_buf)
175 return -ENOMEM;
176
177 drec = (struct pstore_ftrace_record *)(*dest_log + dest_off);
178 srec = (struct pstore_ftrace_record *)(src_log + src_off);
179 mrec = (struct pstore_ftrace_record *)(merged_buf);
180
181 while (dest_size > 0 && src_size > 0) {
182 if (pstore_ftrace_read_timestamp(rec: &drec[dest_idx]) <
183 pstore_ftrace_read_timestamp(rec: &srec[src_idx])) {
184 mrec[merged_idx++] = drec[dest_idx++];
185 dest_size -= record_size;
186 } else {
187 mrec[merged_idx++] = srec[src_idx++];
188 src_size -= record_size;
189 }
190 }
191
192 while (dest_size > 0) {
193 mrec[merged_idx++] = drec[dest_idx++];
194 dest_size -= record_size;
195 }
196
197 while (src_size > 0) {
198 mrec[merged_idx++] = srec[src_idx++];
199 src_size -= record_size;
200 }
201
202 kfree(objp: *dest_log);
203 *dest_log = merged_buf;
204 *dest_log_size = total;
205
206 return 0;
207}
208EXPORT_SYMBOL_GPL(pstore_ftrace_combine_log);
209

source code of linux/fs/pstore/ftrace.c