xref: /openbmc/linux/fs/pstore/ftrace.c (revision a5d05b07)
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 ftrace_regs * fregs)26 static 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, pstore_ftrace_stamp++);
53 	pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
54 	psinfo->write(&record);
55 
56 	local_irq_restore(flags);
57 	ftrace_test_recursion_unlock(bit);
58 }
59 
60 static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
61 	.func	= pstore_ftrace_call,
62 };
63 
64 static DEFINE_MUTEX(pstore_ftrace_lock);
65 static bool pstore_ftrace_enabled;
66 
pstore_set_ftrace_enabled(bool on)67 static 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(&pstore_ftrace_ops);
76 		ret = register_ftrace_function(&pstore_ftrace_ops);
77 	} else {
78 		ret = unregister_ftrace_function(&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 
pstore_ftrace_knob_write(struct file * f,const char __user * buf,size_t count,loff_t * ppos)91 static 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(buf, count, 2, &on);
98 	if (ret)
99 		return ret;
100 
101 	mutex_lock(&pstore_ftrace_lock);
102 	ret = pstore_set_ftrace_enabled(on);
103 	mutex_unlock(&pstore_ftrace_lock);
104 
105 	if (ret == 0)
106 		ret = count;
107 
108 	return ret;
109 }
110 
pstore_ftrace_knob_read(struct file * f,char __user * buf,size_t count,loff_t * ppos)111 static 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(buf, count, ppos, val, sizeof(val));
117 }
118 
119 static 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 
125 static struct dentry *pstore_ftrace_dir;
126 
127 static bool record_ftrace;
128 module_param(record_ftrace, bool, 0400);
129 MODULE_PARM_DESC(record_ftrace,
130 		 "enable ftrace recording immediately (default: off)");
131 
pstore_register_ftrace(void)132 void pstore_register_ftrace(void)
133 {
134 	if (!psinfo->write)
135 		return;
136 
137 	pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
138 
139 	pstore_set_ftrace_enabled(record_ftrace);
140 
141 	debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
142 			    &pstore_knob_fops);
143 }
144 
pstore_unregister_ftrace(void)145 void pstore_unregister_ftrace(void)
146 {
147 	mutex_lock(&pstore_ftrace_lock);
148 	if (pstore_ftrace_enabled) {
149 		unregister_ftrace_function(&pstore_ftrace_ops);
150 		pstore_ftrace_enabled = false;
151 	}
152 	mutex_unlock(&pstore_ftrace_lock);
153 
154 	debugfs_remove_recursive(pstore_ftrace_dir);
155 }
156 
pstore_ftrace_combine_log(char ** dest_log,size_t * dest_log_size,const char * src_log,size_t src_log_size)157 ssize_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(&drec[dest_idx]) <
183 		    pstore_ftrace_read_timestamp(&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(*dest_log);
203 	*dest_log = merged_buf;
204 	*dest_log_size = total;
205 
206 	return 0;
207 }
208 EXPORT_SYMBOL_GPL(pstore_ftrace_combine_log);
209