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. */
24 static u64 pstore_ftrace_stamp;
25
pstore_ftrace_call(unsigned long ip,unsigned long parent_ip,struct ftrace_ops * op,struct pt_regs * regs)26 static void notrace pstore_ftrace_call(unsigned long ip,
27 unsigned long parent_ip,
28 struct ftrace_ops *op,
29 struct pt_regs *regs)
30 {
31 unsigned long flags;
32 struct pstore_ftrace_record rec = {};
33 struct pstore_record record = {
34 .type = PSTORE_TYPE_FTRACE,
35 .buf = (char *)&rec,
36 .size = sizeof(rec),
37 .psi = psinfo,
38 };
39
40 if (unlikely(oops_in_progress))
41 return;
42
43 local_irq_save(flags);
44
45 rec.ip = ip;
46 rec.parent_ip = parent_ip;
47 pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
48 pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
49 psinfo->write(&record);
50
51 local_irq_restore(flags);
52 }
53
54 static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
55 .func = pstore_ftrace_call,
56 };
57
58 static DEFINE_MUTEX(pstore_ftrace_lock);
59 static bool pstore_ftrace_enabled;
60
pstore_ftrace_knob_write(struct file * f,const char __user * buf,size_t count,loff_t * ppos)61 static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
62 size_t count, loff_t *ppos)
63 {
64 u8 on;
65 ssize_t ret;
66
67 ret = kstrtou8_from_user(buf, count, 2, &on);
68 if (ret)
69 return ret;
70
71 mutex_lock(&pstore_ftrace_lock);
72
73 if (!on ^ pstore_ftrace_enabled)
74 goto out;
75
76 if (on) {
77 ftrace_ops_set_global_filter(&pstore_ftrace_ops);
78 ret = register_ftrace_function(&pstore_ftrace_ops);
79 } else {
80 ret = unregister_ftrace_function(&pstore_ftrace_ops);
81 }
82
83 if (ret) {
84 pr_err("%s: unable to %sregister ftrace ops: %zd\n",
85 __func__, on ? "" : "un", ret);
86 goto err;
87 }
88
89 pstore_ftrace_enabled = on;
90 out:
91 ret = count;
92 err:
93 mutex_unlock(&pstore_ftrace_lock);
94
95 return ret;
96 }
97
pstore_ftrace_knob_read(struct file * f,char __user * buf,size_t count,loff_t * ppos)98 static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
99 size_t count, loff_t *ppos)
100 {
101 char val[] = { '0' + pstore_ftrace_enabled, '\n' };
102
103 return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
104 }
105
106 static const struct file_operations pstore_knob_fops = {
107 .open = simple_open,
108 .read = pstore_ftrace_knob_read,
109 .write = pstore_ftrace_knob_write,
110 };
111
112 static struct dentry *pstore_ftrace_dir;
113
pstore_register_ftrace(void)114 void pstore_register_ftrace(void)
115 {
116 if (!psinfo->write)
117 return;
118
119 pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
120
121 debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
122 &pstore_knob_fops);
123 }
124
pstore_unregister_ftrace(void)125 void pstore_unregister_ftrace(void)
126 {
127 mutex_lock(&pstore_ftrace_lock);
128 if (pstore_ftrace_enabled) {
129 unregister_ftrace_function(&pstore_ftrace_ops);
130 pstore_ftrace_enabled = false;
131 }
132 mutex_unlock(&pstore_ftrace_lock);
133
134 debugfs_remove_recursive(pstore_ftrace_dir);
135 }
136
pstore_ftrace_combine_log(char ** dest_log,size_t * dest_log_size,const char * src_log,size_t src_log_size)137 ssize_t pstore_ftrace_combine_log(char **dest_log, size_t *dest_log_size,
138 const char *src_log, size_t src_log_size)
139 {
140 size_t dest_size, src_size, total, dest_off, src_off;
141 size_t dest_idx = 0, src_idx = 0, merged_idx = 0;
142 void *merged_buf;
143 struct pstore_ftrace_record *drec, *srec, *mrec;
144 size_t record_size = sizeof(struct pstore_ftrace_record);
145
146 dest_off = *dest_log_size % record_size;
147 dest_size = *dest_log_size - dest_off;
148
149 src_off = src_log_size % record_size;
150 src_size = src_log_size - src_off;
151
152 total = dest_size + src_size;
153 merged_buf = kmalloc(total, GFP_KERNEL);
154 if (!merged_buf)
155 return -ENOMEM;
156
157 drec = (struct pstore_ftrace_record *)(*dest_log + dest_off);
158 srec = (struct pstore_ftrace_record *)(src_log + src_off);
159 mrec = (struct pstore_ftrace_record *)(merged_buf);
160
161 while (dest_size > 0 && src_size > 0) {
162 if (pstore_ftrace_read_timestamp(&drec[dest_idx]) <
163 pstore_ftrace_read_timestamp(&srec[src_idx])) {
164 mrec[merged_idx++] = drec[dest_idx++];
165 dest_size -= record_size;
166 } else {
167 mrec[merged_idx++] = srec[src_idx++];
168 src_size -= record_size;
169 }
170 }
171
172 while (dest_size > 0) {
173 mrec[merged_idx++] = drec[dest_idx++];
174 dest_size -= record_size;
175 }
176
177 while (src_size > 0) {
178 mrec[merged_idx++] = srec[src_idx++];
179 src_size -= record_size;
180 }
181
182 kfree(*dest_log);
183 *dest_log = merged_buf;
184 *dest_log_size = total;
185
186 return 0;
187 }
188 EXPORT_SYMBOL_GPL(pstore_ftrace_combine_log);
189
