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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
Aviya Erenfeld52256632016-04-14 11:59:31 +02007 * Copyright(c) 2015 Intel Deutschland GmbH
Johannes Berg833c9542014-09-12 09:01:56 +02008 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of version 2 of the GNU General Public License as
11 * published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
17 *
18 * The full GNU General Public License is included in this distribution
19 * in the file called COPYING.
20 *
21 * Contact Information:
22 * Intel Linux Wireless <ilw@linux.intel.com>
23 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
24 *
25 * Author: Johannes Berg <johannes@sipsolutions.net>
26 */
27#include <linux/module.h>
28#include <linux/device.h>
29#include <linux/devcoredump.h>
30#include <linux/list.h>
31#include <linux/slab.h>
32#include <linux/fs.h>
33#include <linux/workqueue.h>
34
Johannes Bergd4533322014-11-13 22:16:29 +010035static struct class devcd_class;
36
37/* global disable flag, for security purposes */
38static bool devcd_disabled;
39
Johannes Berg833c9542014-09-12 09:01:56 +020040/* if data isn't read by userspace after 5 minutes then delete it */
41#define DEVCD_TIMEOUT (HZ * 60 * 5)
42
43struct devcd_entry {
44 struct device devcd_dev;
Aviya Erenfeld52256632016-04-14 11:59:31 +020045 void *data;
Johannes Berg833c9542014-09-12 09:01:56 +020046 size_t datalen;
47 struct module *owner;
48 ssize_t (*read)(char *buffer, loff_t offset, size_t count,
Aviya Erenfeld52256632016-04-14 11:59:31 +020049 void *data, size_t datalen);
50 void (*free)(void *data);
Johannes Berg833c9542014-09-12 09:01:56 +020051 struct delayed_work del_wk;
52 struct device *failing_dev;
53};
54
55static struct devcd_entry *dev_to_devcd(struct device *dev)
56{
57 return container_of(dev, struct devcd_entry, devcd_dev);
58}
59
60static void devcd_dev_release(struct device *dev)
61{
62 struct devcd_entry *devcd = dev_to_devcd(dev);
63
64 devcd->free(devcd->data);
65 module_put(devcd->owner);
66
67 /*
68 * this seems racy, but I don't see a notifier or such on
69 * a struct device to know when it goes away?
70 */
71 if (devcd->failing_dev->kobj.sd)
72 sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
73 "devcoredump");
74
75 put_device(devcd->failing_dev);
76 kfree(devcd);
77}
78
79static void devcd_del(struct work_struct *wk)
80{
81 struct devcd_entry *devcd;
82
83 devcd = container_of(wk, struct devcd_entry, del_wk.work);
84
85 device_del(&devcd->devcd_dev);
86 put_device(&devcd->devcd_dev);
87}
88
89static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj,
90 struct bin_attribute *bin_attr,
91 char *buffer, loff_t offset, size_t count)
92{
93 struct device *dev = kobj_to_dev(kobj);
94 struct devcd_entry *devcd = dev_to_devcd(dev);
95
96 return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
97}
98
99static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
100 struct bin_attribute *bin_attr,
101 char *buffer, loff_t offset, size_t count)
102{
103 struct device *dev = kobj_to_dev(kobj);
104 struct devcd_entry *devcd = dev_to_devcd(dev);
105
106 mod_delayed_work(system_wq, &devcd->del_wk, 0);
107
108 return count;
109}
110
111static struct bin_attribute devcd_attr_data = {
112 .attr = { .name = "data", .mode = S_IRUSR | S_IWUSR, },
113 .size = 0,
114 .read = devcd_data_read,
115 .write = devcd_data_write,
116};
117
118static struct bin_attribute *devcd_dev_bin_attrs[] = {
119 &devcd_attr_data, NULL,
120};
121
122static const struct attribute_group devcd_dev_group = {
123 .bin_attrs = devcd_dev_bin_attrs,
124};
125
126static const struct attribute_group *devcd_dev_groups[] = {
127 &devcd_dev_group, NULL,
128};
129
Johannes Bergd4533322014-11-13 22:16:29 +0100130static int devcd_free(struct device *dev, void *data)
131{
132 struct devcd_entry *devcd = dev_to_devcd(dev);
133
134 flush_delayed_work(&devcd->del_wk);
135 return 0;
136}
137
138static ssize_t disabled_show(struct class *class, struct class_attribute *attr,
139 char *buf)
140{
141 return sprintf(buf, "%d\n", devcd_disabled);
142}
143
144static ssize_t disabled_store(struct class *class, struct class_attribute *attr,
145 const char *buf, size_t count)
146{
147 long tmp = simple_strtol(buf, NULL, 10);
148
149 /*
150 * This essentially makes the attribute write-once, since you can't
151 * go back to not having it disabled. This is intentional, it serves
152 * as a system lockdown feature.
153 */
154 if (tmp != 1)
155 return -EINVAL;
156
157 devcd_disabled = true;
158
159 class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
160
161 return count;
162}
163
164static struct class_attribute devcd_class_attrs[] = {
165 __ATTR_RW(disabled),
166 __ATTR_NULL
167};
168
Johannes Berg833c9542014-09-12 09:01:56 +0200169static struct class devcd_class = {
170 .name = "devcoredump",
171 .owner = THIS_MODULE,
172 .dev_release = devcd_dev_release,
173 .dev_groups = devcd_dev_groups,
Johannes Bergd4533322014-11-13 22:16:29 +0100174 .class_attrs = devcd_class_attrs,
Johannes Berg833c9542014-09-12 09:01:56 +0200175};
176
177static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
Aviya Erenfeld52256632016-04-14 11:59:31 +0200178 void *data, size_t datalen)
Johannes Berg833c9542014-09-12 09:01:56 +0200179{
180 if (offset > datalen)
181 return -EINVAL;
182
183 if (offset + count > datalen)
184 count = datalen - offset;
185
186 if (count)
187 memcpy(buffer, ((u8 *)data) + offset, count);
188
189 return count;
190}
191
Aviya Erenfeld52256632016-04-14 11:59:31 +0200192static void devcd_freev(void *data)
193{
194 vfree(data);
195}
196
Johannes Berg833c9542014-09-12 09:01:56 +0200197/**
198 * dev_coredumpv - create device coredump with vmalloc data
199 * @dev: the struct device for the crashed device
200 * @data: vmalloc data containing the device coredump
201 * @datalen: length of the data
202 * @gfp: allocation flags
203 *
204 * This function takes ownership of the vmalloc'ed data and will free
205 * it when it is no longer used. See dev_coredumpm() for more information.
206 */
Aviya Erenfeld52256632016-04-14 11:59:31 +0200207void dev_coredumpv(struct device *dev, void *data, size_t datalen,
Johannes Berg833c9542014-09-12 09:01:56 +0200208 gfp_t gfp)
209{
Aviya Erenfeld52256632016-04-14 11:59:31 +0200210 dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, devcd_freev);
Johannes Berg833c9542014-09-12 09:01:56 +0200211}
212EXPORT_SYMBOL_GPL(dev_coredumpv);
213
214static int devcd_match_failing(struct device *dev, const void *failing)
215{
216 struct devcd_entry *devcd = dev_to_devcd(dev);
217
218 return devcd->failing_dev == failing;
219}
220
221/**
Aviya Erenfeld52256632016-04-14 11:59:31 +0200222 * devcd_free_sgtable - free all the memory of the given scatterlist table
223 * (i.e. both pages and scatterlist instances)
224 * NOTE: if two tables allocated with devcd_alloc_sgtable and then chained
225 * using the sg_chain function then that function should be called only once
226 * on the chained table
227 * @table: pointer to sg_table to free
228 */
229static void devcd_free_sgtable(void *data)
230{
231 _devcd_free_sgtable(data);
232}
233
234/**
235 * devcd_read_from_table - copy data from sg_table to a given buffer
236 * and return the number of bytes read
237 * @buffer: the buffer to copy the data to it
238 * @buf_len: the length of the buffer
239 * @data: the scatterlist table to copy from
240 * @offset: start copy from @offset@ bytes from the head of the data
241 * in the given scatterlist
242 * @data_len: the length of the data in the sg_table
243 */
244static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
245 size_t buf_len, void *data,
246 size_t data_len)
247{
248 struct scatterlist *table = data;
249
250 if (offset > data_len)
251 return -EINVAL;
252
253 if (offset + buf_len > data_len)
254 buf_len = data_len - offset;
255 return sg_pcopy_to_buffer(table, sg_nents(table), buffer, buf_len,
256 offset);
257}
258
259/**
Johannes Berg833c9542014-09-12 09:01:56 +0200260 * dev_coredumpm - create device coredump with read/free methods
261 * @dev: the struct device for the crashed device
262 * @owner: the module that contains the read/free functions, use %THIS_MODULE
263 * @data: data cookie for the @read/@free functions
264 * @datalen: length of the data
265 * @gfp: allocation flags
266 * @read: function to read from the given buffer
267 * @free: function to free the given buffer
268 *
269 * Creates a new device coredump for the given device. If a previous one hasn't
270 * been read yet, the new coredump is discarded. The data lifetime is determined
271 * by the device coredump framework and when it is no longer needed the @free
272 * function will be called to free the data.
273 */
274void dev_coredumpm(struct device *dev, struct module *owner,
Aviya Erenfeld52256632016-04-14 11:59:31 +0200275 void *data, size_t datalen, gfp_t gfp,
Johannes Berg833c9542014-09-12 09:01:56 +0200276 ssize_t (*read)(char *buffer, loff_t offset, size_t count,
Aviya Erenfeld52256632016-04-14 11:59:31 +0200277 void *data, size_t datalen),
278 void (*free)(void *data))
Johannes Berg833c9542014-09-12 09:01:56 +0200279{
280 static atomic_t devcd_count = ATOMIC_INIT(0);
281 struct devcd_entry *devcd;
282 struct device *existing;
283
Johannes Bergd4533322014-11-13 22:16:29 +0100284 if (devcd_disabled)
285 goto free;
286
Johannes Berg833c9542014-09-12 09:01:56 +0200287 existing = class_find_device(&devcd_class, NULL, dev,
288 devcd_match_failing);
289 if (existing) {
290 put_device(existing);
291 goto free;
292 }
293
294 if (!try_module_get(owner))
295 goto free;
296
297 devcd = kzalloc(sizeof(*devcd), gfp);
298 if (!devcd)
299 goto put_module;
300
301 devcd->owner = owner;
302 devcd->data = data;
303 devcd->datalen = datalen;
304 devcd->read = read;
305 devcd->free = free;
306 devcd->failing_dev = get_device(dev);
307
308 device_initialize(&devcd->devcd_dev);
309
310 dev_set_name(&devcd->devcd_dev, "devcd%d",
311 atomic_inc_return(&devcd_count));
312 devcd->devcd_dev.class = &devcd_class;
313
314 if (device_add(&devcd->devcd_dev))
315 goto put_device;
316
317 if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
318 "failing_device"))
319 /* nothing - symlink will be missing */;
320
321 if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
322 "devcoredump"))
323 /* nothing - symlink will be missing */;
324
325 INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
326 schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
327
328 return;
329 put_device:
330 put_device(&devcd->devcd_dev);
331 put_module:
332 module_put(owner);
333 free:
334 free(data);
335}
336EXPORT_SYMBOL_GPL(dev_coredumpm);
337
Aviya Erenfeld52256632016-04-14 11:59:31 +0200338/**
339 * dev_coredumpmsg - create device coredump that uses scatterlist as data
340 * parameter
341 * @dev: the struct device for the crashed device
342 * @table: the dump data
343 * @datalen: length of the data
344 * @gfp: allocation flags
345 *
346 * Creates a new device coredump for the given device. If a previous one hasn't
347 * been read yet, the new coredump is discarded. The data lifetime is determined
348 * by the device coredump framework and when it is no longer needed
349 * it will free the data.
350 */
351void dev_coredumpsg(struct device *dev, struct scatterlist *table,
352 size_t datalen, gfp_t gfp)
353{
354 dev_coredumpm(dev, NULL, table, datalen, gfp, devcd_read_from_sgtable,
355 devcd_free_sgtable);
356}
357EXPORT_SYMBOL_GPL(dev_coredumpsg);
358
Johannes Berg833c9542014-09-12 09:01:56 +0200359static int __init devcoredump_init(void)
360{
361 return class_register(&devcd_class);
362}
363__initcall(devcoredump_init);
364
Johannes Berg833c9542014-09-12 09:01:56 +0200365static void __exit devcoredump_exit(void)
366{
367 class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
368 class_unregister(&devcd_class);
369}
370__exitcall(devcoredump_exit);