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, 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
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(&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
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(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
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(buf, count, ppos, val, 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("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
145void 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
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(&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}
208EXPORT_SYMBOL_GPL(pstore_ftrace_combine_log);
209