blob: 1bd120a0b084195df0a1d1bfe532f7e34874e946 [file] [log] [blame]
Johannes Berg833c9542014-09-12 09:01:56 +02001/*
2 * This file is provided under the GPLv2 license.
3 *
4 * GPL LICENSE SUMMARY
5 *
6 * Copyright(c) 2014 Intel Mobile Communications GmbH
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of version 2 of the GNU General Public License as
10 * published by the Free Software Foundation.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
16 *
17 * The full GNU General Public License is included in this distribution
18 * in the file called COPYING.
19 *
20 * Contact Information:
21 * Intel Linux Wireless <ilw@linux.intel.com>
22 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
23 *
24 * Author: Johannes Berg <johannes@sipsolutions.net>
25 */
26#include <linux/module.h>
27#include <linux/device.h>
28#include <linux/devcoredump.h>
29#include <linux/list.h>
30#include <linux/slab.h>
31#include <linux/fs.h>
32#include <linux/workqueue.h>
33
Johannes Bergd4533322014-11-13 22:16:29 +010034static struct class devcd_class;
35
36/* global disable flag, for security purposes */
37static bool devcd_disabled;
38
Johannes Berg833c9542014-09-12 09:01:56 +020039/* if data isn't read by userspace after 5 minutes then delete it */
40#define DEVCD_TIMEOUT (HZ * 60 * 5)
41
42struct devcd_entry {
43 struct device devcd_dev;
44 const void *data;
45 size_t datalen;
46 struct module *owner;
47 ssize_t (*read)(char *buffer, loff_t offset, size_t count,
48 const void *data, size_t datalen);
49 void (*free)(const void *data);
50 struct delayed_work del_wk;
51 struct device *failing_dev;
52};
53
54static struct devcd_entry *dev_to_devcd(struct device *dev)
55{
56 return container_of(dev, struct devcd_entry, devcd_dev);
57}
58
59static void devcd_dev_release(struct device *dev)
60{
61 struct devcd_entry *devcd = dev_to_devcd(dev);
62
63 devcd->free(devcd->data);
64 module_put(devcd->owner);
65
66 /*
67 * this seems racy, but I don't see a notifier or such on
68 * a struct device to know when it goes away?
69 */
70 if (devcd->failing_dev->kobj.sd)
71 sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
72 "devcoredump");
73
74 put_device(devcd->failing_dev);
75 kfree(devcd);
76}
77
78static void devcd_del(struct work_struct *wk)
79{
80 struct devcd_entry *devcd;
81
82 devcd = container_of(wk, struct devcd_entry, del_wk.work);
83
84 device_del(&devcd->devcd_dev);
85 put_device(&devcd->devcd_dev);
86}
87
88static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj,
89 struct bin_attribute *bin_attr,
90 char *buffer, loff_t offset, size_t count)
91{
92 struct device *dev = kobj_to_dev(kobj);
93 struct devcd_entry *devcd = dev_to_devcd(dev);
94
95 return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
96}
97
98static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
99 struct bin_attribute *bin_attr,
100 char *buffer, loff_t offset, size_t count)
101{
102 struct device *dev = kobj_to_dev(kobj);
103 struct devcd_entry *devcd = dev_to_devcd(dev);
104
105 mod_delayed_work(system_wq, &devcd->del_wk, 0);
106
107 return count;
108}
109
110static struct bin_attribute devcd_attr_data = {
111 .attr = { .name = "data", .mode = S_IRUSR | S_IWUSR, },
112 .size = 0,
113 .read = devcd_data_read,
114 .write = devcd_data_write,
115};
116
117static struct bin_attribute *devcd_dev_bin_attrs[] = {
118 &devcd_attr_data, NULL,
119};
120
121static const struct attribute_group devcd_dev_group = {
122 .bin_attrs = devcd_dev_bin_attrs,
123};
124
125static const struct attribute_group *devcd_dev_groups[] = {
126 &devcd_dev_group, NULL,
127};
128
Johannes Bergd4533322014-11-13 22:16:29 +0100129static int devcd_free(struct device *dev, void *data)
130{
131 struct devcd_entry *devcd = dev_to_devcd(dev);
132
133 flush_delayed_work(&devcd->del_wk);
134 return 0;
135}
136
137static ssize_t disabled_show(struct class *class, struct class_attribute *attr,
138 char *buf)
139{
140 return sprintf(buf, "%d\n", devcd_disabled);
141}
142
143static ssize_t disabled_store(struct class *class, struct class_attribute *attr,
144 const char *buf, size_t count)
145{
146 long tmp = simple_strtol(buf, NULL, 10);
147
148 /*
149 * This essentially makes the attribute write-once, since you can't
150 * go back to not having it disabled. This is intentional, it serves
151 * as a system lockdown feature.
152 */
153 if (tmp != 1)
154 return -EINVAL;
155
156 devcd_disabled = true;
157
158 class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
159
160 return count;
161}
162
163static struct class_attribute devcd_class_attrs[] = {
164 __ATTR_RW(disabled),
165 __ATTR_NULL
166};
167
Johannes Berg833c9542014-09-12 09:01:56 +0200168static struct class devcd_class = {
169 .name = "devcoredump",
170 .owner = THIS_MODULE,
171 .dev_release = devcd_dev_release,
172 .dev_groups = devcd_dev_groups,
Johannes Bergd4533322014-11-13 22:16:29 +0100173 .class_attrs = devcd_class_attrs,
Johannes Berg833c9542014-09-12 09:01:56 +0200174};
175
176static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
177 const void *data, size_t datalen)
178{
179 if (offset > datalen)
180 return -EINVAL;
181
182 if (offset + count > datalen)
183 count = datalen - offset;
184
185 if (count)
186 memcpy(buffer, ((u8 *)data) + offset, count);
187
188 return count;
189}
190
191/**
192 * dev_coredumpv - create device coredump with vmalloc data
193 * @dev: the struct device for the crashed device
194 * @data: vmalloc data containing the device coredump
195 * @datalen: length of the data
196 * @gfp: allocation flags
197 *
198 * This function takes ownership of the vmalloc'ed data and will free
199 * it when it is no longer used. See dev_coredumpm() for more information.
200 */
201void dev_coredumpv(struct device *dev, const void *data, size_t datalen,
202 gfp_t gfp)
203{
204 dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, vfree);
205}
206EXPORT_SYMBOL_GPL(dev_coredumpv);
207
208static int devcd_match_failing(struct device *dev, const void *failing)
209{
210 struct devcd_entry *devcd = dev_to_devcd(dev);
211
212 return devcd->failing_dev == failing;
213}
214
215/**
216 * dev_coredumpm - create device coredump with read/free methods
217 * @dev: the struct device for the crashed device
218 * @owner: the module that contains the read/free functions, use %THIS_MODULE
219 * @data: data cookie for the @read/@free functions
220 * @datalen: length of the data
221 * @gfp: allocation flags
222 * @read: function to read from the given buffer
223 * @free: function to free the given buffer
224 *
225 * Creates a new device coredump for the given device. If a previous one hasn't
226 * been read yet, the new coredump is discarded. The data lifetime is determined
227 * by the device coredump framework and when it is no longer needed the @free
228 * function will be called to free the data.
229 */
230void dev_coredumpm(struct device *dev, struct module *owner,
231 const void *data, size_t datalen, gfp_t gfp,
232 ssize_t (*read)(char *buffer, loff_t offset, size_t count,
233 const void *data, size_t datalen),
234 void (*free)(const void *data))
235{
236 static atomic_t devcd_count = ATOMIC_INIT(0);
237 struct devcd_entry *devcd;
238 struct device *existing;
239
Johannes Bergd4533322014-11-13 22:16:29 +0100240 if (devcd_disabled)
241 goto free;
242
Johannes Berg833c9542014-09-12 09:01:56 +0200243 existing = class_find_device(&devcd_class, NULL, dev,
244 devcd_match_failing);
245 if (existing) {
246 put_device(existing);
247 goto free;
248 }
249
250 if (!try_module_get(owner))
251 goto free;
252
253 devcd = kzalloc(sizeof(*devcd), gfp);
254 if (!devcd)
255 goto put_module;
256
257 devcd->owner = owner;
258 devcd->data = data;
259 devcd->datalen = datalen;
260 devcd->read = read;
261 devcd->free = free;
262 devcd->failing_dev = get_device(dev);
263
264 device_initialize(&devcd->devcd_dev);
265
266 dev_set_name(&devcd->devcd_dev, "devcd%d",
267 atomic_inc_return(&devcd_count));
268 devcd->devcd_dev.class = &devcd_class;
269
270 if (device_add(&devcd->devcd_dev))
271 goto put_device;
272
273 if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
274 "failing_device"))
275 /* nothing - symlink will be missing */;
276
277 if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
278 "devcoredump"))
279 /* nothing - symlink will be missing */;
280
281 INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
282 schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
283
284 return;
285 put_device:
286 put_device(&devcd->devcd_dev);
287 put_module:
288 module_put(owner);
289 free:
290 free(data);
291}
292EXPORT_SYMBOL_GPL(dev_coredumpm);
293
294static int __init devcoredump_init(void)
295{
296 return class_register(&devcd_class);
297}
298__initcall(devcoredump_init);
299
Johannes Berg833c9542014-09-12 09:01:56 +0200300static void __exit devcoredump_exit(void)
301{
302 class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
303 class_unregister(&devcd_class);
304}
305__exitcall(devcoredump_exit);