1/*
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
34/* if data isn't read by userspace after 5 minutes then delete it */
35#define DEVCD_TIMEOUT	(HZ * 60 * 5)
36
37struct devcd_entry {
38	struct device devcd_dev;
39	const void *data;
40	size_t datalen;
41	struct module *owner;
42	ssize_t (*read)(char *buffer, loff_t offset, size_t count,
43			const void *data, size_t datalen);
44	void (*free)(const void *data);
45	struct delayed_work del_wk;
46	struct device *failing_dev;
47};
48
49static struct devcd_entry *dev_to_devcd(struct device *dev)
50{
51	return container_of(dev, struct devcd_entry, devcd_dev);
52}
53
54static void devcd_dev_release(struct device *dev)
55{
56	struct devcd_entry *devcd = dev_to_devcd(dev);
57
58	devcd->free(devcd->data);
59	module_put(devcd->owner);
60
61	/*
62	 * this seems racy, but I don't see a notifier or such on
63	 * a struct device to know when it goes away?
64	 */
65	if (devcd->failing_dev->kobj.sd)
66		sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
67				  "devcoredump");
68
69	put_device(devcd->failing_dev);
70	kfree(devcd);
71}
72
73static void devcd_del(struct work_struct *wk)
74{
75	struct devcd_entry *devcd;
76
77	devcd = container_of(wk, struct devcd_entry, del_wk.work);
78
79	device_del(&devcd->devcd_dev);
80	put_device(&devcd->devcd_dev);
81}
82
83static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj,
84			       struct bin_attribute *bin_attr,
85			       char *buffer, loff_t offset, size_t count)
86{
87	struct device *dev = kobj_to_dev(kobj);
88	struct devcd_entry *devcd = dev_to_devcd(dev);
89
90	return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
91}
92
93static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
94				struct bin_attribute *bin_attr,
95				char *buffer, loff_t offset, size_t count)
96{
97	struct device *dev = kobj_to_dev(kobj);
98	struct devcd_entry *devcd = dev_to_devcd(dev);
99
100	mod_delayed_work(system_wq, &devcd->del_wk, 0);
101
102	return count;
103}
104
105static struct bin_attribute devcd_attr_data = {
106	.attr = { .name = "data", .mode = S_IRUSR | S_IWUSR, },
107	.size = 0,
108	.read = devcd_data_read,
109	.write = devcd_data_write,
110};
111
112static struct bin_attribute *devcd_dev_bin_attrs[] = {
113	&devcd_attr_data, NULL,
114};
115
116static const struct attribute_group devcd_dev_group = {
117	.bin_attrs = devcd_dev_bin_attrs,
118};
119
120static const struct attribute_group *devcd_dev_groups[] = {
121	&devcd_dev_group, NULL,
122};
123
124static struct class devcd_class = {
125	.name		= "devcoredump",
126	.owner		= THIS_MODULE,
127	.dev_release	= devcd_dev_release,
128	.dev_groups	= devcd_dev_groups,
129};
130
131static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
132			   const void *data, size_t datalen)
133{
134	if (offset > datalen)
135		return -EINVAL;
136
137	if (offset + count > datalen)
138		count = datalen - offset;
139
140	if (count)
141		memcpy(buffer, ((u8 *)data) + offset, count);
142
143	return count;
144}
145
146/**
147 * dev_coredumpv - create device coredump with vmalloc data
148 * @dev: the struct device for the crashed device
149 * @data: vmalloc data containing the device coredump
150 * @datalen: length of the data
151 * @gfp: allocation flags
152 *
153 * This function takes ownership of the vmalloc'ed data and will free
154 * it when it is no longer used. See dev_coredumpm() for more information.
155 */
156void dev_coredumpv(struct device *dev, const void *data, size_t datalen,
157		   gfp_t gfp)
158{
159	dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, vfree);
160}
161EXPORT_SYMBOL_GPL(dev_coredumpv);
162
163static int devcd_match_failing(struct device *dev, const void *failing)
164{
165	struct devcd_entry *devcd = dev_to_devcd(dev);
166
167	return devcd->failing_dev == failing;
168}
169
170/**
171 * dev_coredumpm - create device coredump with read/free methods
172 * @dev: the struct device for the crashed device
173 * @owner: the module that contains the read/free functions, use %THIS_MODULE
174 * @data: data cookie for the @read/@free functions
175 * @datalen: length of the data
176 * @gfp: allocation flags
177 * @read: function to read from the given buffer
178 * @free: function to free the given buffer
179 *
180 * Creates a new device coredump for the given device. If a previous one hasn't
181 * been read yet, the new coredump is discarded. The data lifetime is determined
182 * by the device coredump framework and when it is no longer needed the @free
183 * function will be called to free the data.
184 */
185void dev_coredumpm(struct device *dev, struct module *owner,
186		   const void *data, size_t datalen, gfp_t gfp,
187		   ssize_t (*read)(char *buffer, loff_t offset, size_t count,
188				   const void *data, size_t datalen),
189		   void (*free)(const void *data))
190{
191	static atomic_t devcd_count = ATOMIC_INIT(0);
192	struct devcd_entry *devcd;
193	struct device *existing;
194
195	existing = class_find_device(&devcd_class, NULL, dev,
196				     devcd_match_failing);
197	if (existing) {
198		put_device(existing);
199		goto free;
200	}
201
202	if (!try_module_get(owner))
203		goto free;
204
205	devcd = kzalloc(sizeof(*devcd), gfp);
206	if (!devcd)
207		goto put_module;
208
209	devcd->owner = owner;
210	devcd->data = data;
211	devcd->datalen = datalen;
212	devcd->read = read;
213	devcd->free = free;
214	devcd->failing_dev = get_device(dev);
215
216	device_initialize(&devcd->devcd_dev);
217
218	dev_set_name(&devcd->devcd_dev, "devcd%d",
219		     atomic_inc_return(&devcd_count));
220	devcd->devcd_dev.class = &devcd_class;
221
222	if (device_add(&devcd->devcd_dev))
223		goto put_device;
224
225	if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
226			      "failing_device"))
227		/* nothing - symlink will be missing */;
228
229	if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
230			      "devcoredump"))
231		/* nothing - symlink will be missing */;
232
233	INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
234	schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
235
236	return;
237 put_device:
238	put_device(&devcd->devcd_dev);
239 put_module:
240	module_put(owner);
241 free:
242	free(data);
243}
244EXPORT_SYMBOL_GPL(dev_coredumpm);
245
246static int __init devcoredump_init(void)
247{
248	return class_register(&devcd_class);
249}
250__initcall(devcoredump_init);
251
252static int devcd_free(struct device *dev, void *data)
253{
254	struct devcd_entry *devcd = dev_to_devcd(dev);
255
256	flush_delayed_work(&devcd->del_wk);
257	return 0;
258}
259
260static void __exit devcoredump_exit(void)
261{
262	class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
263	class_unregister(&devcd_class);
264}
265__exitcall(devcoredump_exit);
266