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 <asm/setup.h>
22 #include "internal.h"
23
24 /* This doesn't need to be atomic: speed is chosen over correctness here. */
25 static u64 pstore_ftrace_stamp;
26
adjust_ip(unsigned long ip)27 static inline unsigned long adjust_ip(unsigned long ip)
28 {
29 #if defined(CONFIG_RANDOMIZE_BASE) && !defined(PSTORE_CPU_IN_IP) && IS_BUILTIN(CONFIG_PSTORE)
30 if (core_kernel_text(ip))
31 return ip - kaslr_offset();
32
33 __clear_bit(BITS_PER_LONG - 1, &ip);
34 #endif
35 return ip;
36 }
37
decode_ip(unsigned long ip)38 inline unsigned long decode_ip(unsigned long ip)
39 {
40 #if defined(CONFIG_RANDOMIZE_BASE) && !defined(PSTORE_CPU_IN_IP) && IS_BUILTIN(CONFIG_PSTORE)
41 if (test_bit(BITS_PER_LONG - 1, &ip))
42 return ip + kaslr_offset();
43
44 __set_bit(BITS_PER_LONG - 1, &ip);
45
46 #endif
47 return ip;
48 }
49
pstore_ftrace_call(unsigned long ip,unsigned long parent_ip,struct ftrace_ops * op,struct ftrace_regs * fregs)50 static void notrace pstore_ftrace_call(unsigned long ip,
51 unsigned long parent_ip,
52 struct ftrace_ops *op,
53 struct ftrace_regs *fregs)
54 {
55 int bit;
56 unsigned long flags;
57 struct pstore_ftrace_record rec = {};
58 struct pstore_record record = {
59 .type = PSTORE_TYPE_FTRACE,
60 .buf = (char *)&rec,
61 .size = sizeof(rec),
62 .psi = psinfo,
63 };
64
65 if (unlikely(oops_in_progress))
66 return;
67
68 bit = ftrace_test_recursion_trylock(ip, parent_ip);
69 if (bit < 0)
70 return;
71
72 local_irq_save(flags);
73
74 rec.ip = adjust_ip(ip);
75 rec.parent_ip = adjust_ip(parent_ip);
76 pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
77 pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
78 psinfo->write(&record);
79
80 local_irq_restore(flags);
81 ftrace_test_recursion_unlock(bit);
82 }
83
84 static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
85 .func = pstore_ftrace_call,
86 };
87
88 static DEFINE_MUTEX(pstore_ftrace_lock);
89 static bool record_ftrace;
90 module_param(record_ftrace, bool, 0400);
91 MODULE_PARM_DESC(record_ftrace,
92 "enable ftrace recording immediately (default: off)");
93
pstore_set_ftrace_enabled(bool on)94 static int pstore_set_ftrace_enabled(bool on)
95 {
96 ssize_t ret;
97
98 if (on == record_ftrace)
99 return 0;
100
101 if (on) {
102 ftrace_ops_set_global_filter(&pstore_ftrace_ops);
103 ret = register_ftrace_function(&pstore_ftrace_ops);
104 } else {
105 ret = unregister_ftrace_function(&pstore_ftrace_ops);
106 }
107
108 if (ret) {
109 pr_err("%s: unable to %sregister ftrace ops: %zd\n",
110 __func__, on ? "" : "un", ret);
111 } else {
112 record_ftrace = on;
113 }
114
115 return ret;
116 }
117
pstore_ftrace_knob_write(struct file * f,const char __user * buf,size_t count,loff_t * ppos)118 static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
119 size_t count, loff_t *ppos)
120 {
121 u8 on;
122 ssize_t ret;
123
124 ret = kstrtou8_from_user(buf, count, 2, &on);
125 if (ret)
126 return ret;
127
128 mutex_lock(&pstore_ftrace_lock);
129 ret = pstore_set_ftrace_enabled(on);
130 mutex_unlock(&pstore_ftrace_lock);
131
132 if (ret == 0)
133 ret = count;
134
135 return ret;
136 }
137
pstore_ftrace_knob_read(struct file * f,char __user * buf,size_t count,loff_t * ppos)138 static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
139 size_t count, loff_t *ppos)
140 {
141 char val[] = { '0' + record_ftrace, '\n' };
142
143 return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
144 }
145
146 static const struct file_operations pstore_knob_fops = {
147 .open = simple_open,
148 .read = pstore_ftrace_knob_read,
149 .write = pstore_ftrace_knob_write,
150 };
151
152 static struct dentry *pstore_ftrace_dir;
153
pstore_register_ftrace(void)154 void pstore_register_ftrace(void)
155 {
156 if (!psinfo->write)
157 return;
158
159 pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
160
161 pstore_set_ftrace_enabled(record_ftrace);
162
163 debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
164 &pstore_knob_fops);
165 }
166
pstore_unregister_ftrace(void)167 void pstore_unregister_ftrace(void)
168 {
169 mutex_lock(&pstore_ftrace_lock);
170 if (record_ftrace) {
171 unregister_ftrace_function(&pstore_ftrace_ops);
172 record_ftrace = false;
173 }
174 mutex_unlock(&pstore_ftrace_lock);
175
176 debugfs_remove_recursive(pstore_ftrace_dir);
177 }
178
pstore_ftrace_combine_log(char ** dest_log,size_t * dest_log_size,const char * src_log,size_t src_log_size)179 ssize_t pstore_ftrace_combine_log(char **dest_log, size_t *dest_log_size,
180 const char *src_log, size_t src_log_size)
181 {
182 size_t dest_size, src_size, total, dest_off, src_off;
183 size_t dest_idx = 0, src_idx = 0, merged_idx = 0;
184 void *merged_buf;
185 struct pstore_ftrace_record *drec, *srec, *mrec;
186 size_t record_size = sizeof(struct pstore_ftrace_record);
187
188 dest_off = *dest_log_size % record_size;
189 dest_size = *dest_log_size - dest_off;
190
191 src_off = src_log_size % record_size;
192 src_size = src_log_size - src_off;
193
194 total = dest_size + src_size;
195 merged_buf = kmalloc(total, GFP_KERNEL);
196 if (!merged_buf)
197 return -ENOMEM;
198
199 drec = (struct pstore_ftrace_record *)(*dest_log + dest_off);
200 srec = (struct pstore_ftrace_record *)(src_log + src_off);
201 mrec = (struct pstore_ftrace_record *)(merged_buf);
202
203 while (dest_size > 0 && src_size > 0) {
204 if (pstore_ftrace_read_timestamp(&drec[dest_idx]) <
205 pstore_ftrace_read_timestamp(&srec[src_idx])) {
206 mrec[merged_idx++] = drec[dest_idx++];
207 dest_size -= record_size;
208 } else {
209 mrec[merged_idx++] = srec[src_idx++];
210 src_size -= record_size;
211 }
212 }
213
214 while (dest_size > 0) {
215 mrec[merged_idx++] = drec[dest_idx++];
216 dest_size -= record_size;
217 }
218
219 while (src_size > 0) {
220 mrec[merged_idx++] = srec[src_idx++];
221 src_size -= record_size;
222 }
223
224 kfree(*dest_log);
225 *dest_log = merged_buf;
226 *dest_log_size = total;
227
228 return 0;
229 }
230 EXPORT_SYMBOL_GPL(pstore_ftrace_combine_log);
231