1 /*
2 * Persistent Storage - platform driver interface parts.
3 *
4 * Copyright (C) 2007-2008 Google, Inc.
5 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21 #include <linux/atomic.h>
22 #include <linux/types.h>
23 #include <linux/errno.h>
24 #include <linux/init.h>
25 #include <linux/kmsg_dump.h>
26 #include <linux/console.h>
27 #include <linux/module.h>
28 #include <linux/pstore.h>
29 #include <linux/string.h>
30 #include <linux/timer.h>
31 #include <linux/slab.h>
32 #include <linux/uaccess.h>
33 #include <linux/hardirq.h>
34 #include <linux/jiffies.h>
35 #include <linux/workqueue.h>
36
37 #include "internal.h"
38
39 /*
40 * We defer making "oops" entries appear in pstore - see
41 * whether the system is actually still running well enough
42 * to let someone see the entry
43 */
44 static int pstore_update_ms = -1;
45 module_param_named(update_ms, pstore_update_ms, int, 0600);
46 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
47 "(default is -1, which means runtime updates are disabled; "
48 "enabling this option is not safe, it may lead to further "
49 "corruption on Oopses)");
50
51 static int pstore_new_entry;
52
53 static void pstore_timefunc(unsigned long);
54 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
55
56 static void pstore_dowork(struct work_struct *);
57 static DECLARE_WORK(pstore_work, pstore_dowork);
58
59 /*
60 * pstore_lock just protects "psinfo" during
61 * calls to pstore_register()
62 */
63 static DEFINE_SPINLOCK(pstore_lock);
64 struct pstore_info *psinfo;
65
66 static char *backend;
67
68 /* How much of the console log to snapshot */
69 static unsigned long kmsg_bytes = 10240;
70
pstore_set_kmsg_bytes(int bytes)71 void pstore_set_kmsg_bytes(int bytes)
72 {
73 kmsg_bytes = bytes;
74 }
75
76 /* Tag each group of saved records with a sequence number */
77 static int oopscount;
78
get_reason_str(enum kmsg_dump_reason reason)79 static const char *get_reason_str(enum kmsg_dump_reason reason)
80 {
81 switch (reason) {
82 case KMSG_DUMP_PANIC:
83 return "Panic";
84 case KMSG_DUMP_OOPS:
85 return "Oops";
86 case KMSG_DUMP_EMERG:
87 return "Emergency";
88 case KMSG_DUMP_RESTART:
89 return "Restart";
90 case KMSG_DUMP_HALT:
91 return "Halt";
92 case KMSG_DUMP_POWEROFF:
93 return "Poweroff";
94 default:
95 return "Unknown";
96 }
97 }
98
pstore_cannot_block_path(enum kmsg_dump_reason reason)99 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
100 {
101 /*
102 * In case of NMI path, pstore shouldn't be blocked
103 * regardless of reason.
104 */
105 if (in_nmi())
106 return true;
107
108 switch (reason) {
109 /* In panic case, other cpus are stopped by smp_send_stop(). */
110 case KMSG_DUMP_PANIC:
111 /* Emergency restart shouldn't be blocked by spin lock. */
112 case KMSG_DUMP_EMERG:
113 return true;
114 default:
115 return false;
116 }
117 }
118 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
119
120 /*
121 * callback from kmsg_dump. (s2,l2) has the most recently
122 * written bytes, older bytes are in (s1,l1). Save as much
123 * as we can from the end of the buffer.
124 */
pstore_dump(struct kmsg_dumper * dumper,enum kmsg_dump_reason reason)125 static void pstore_dump(struct kmsg_dumper *dumper,
126 enum kmsg_dump_reason reason)
127 {
128 unsigned long total = 0;
129 const char *why;
130 u64 id;
131 unsigned int part = 1;
132 unsigned long flags = 0;
133 int is_locked = 0;
134 int ret;
135
136 why = get_reason_str(reason);
137
138 if (pstore_cannot_block_path(reason)) {
139 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
140 if (!is_locked) {
141 pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
142 , in_nmi() ? "NMI" : why);
143 }
144 } else
145 spin_lock_irqsave(&psinfo->buf_lock, flags);
146 oopscount++;
147 while (total < kmsg_bytes) {
148 char *dst;
149 unsigned long size;
150 int hsize;
151 size_t len;
152
153 dst = psinfo->buf;
154 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
155 size = psinfo->bufsize - hsize;
156 dst += hsize;
157
158 if (!kmsg_dump_get_buffer(dumper, true, dst, size, &len))
159 break;
160
161 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
162 oopscount, hsize + len, psinfo);
163 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
164 pstore_new_entry = 1;
165
166 total += hsize + len;
167 part++;
168 }
169 if (pstore_cannot_block_path(reason)) {
170 if (is_locked)
171 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
172 } else
173 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
174 }
175
176 static struct kmsg_dumper pstore_dumper = {
177 .dump = pstore_dump,
178 };
179
180 #ifdef CONFIG_PSTORE_CONSOLE
pstore_console_write(struct console * con,const char * s,unsigned c)181 static void pstore_console_write(struct console *con, const char *s, unsigned c)
182 {
183 const char *e = s + c;
184
185 while (s < e) {
186 unsigned long flags;
187 u64 id;
188
189 if (c > psinfo->bufsize)
190 c = psinfo->bufsize;
191
192 if (oops_in_progress) {
193 if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
194 break;
195 } else {
196 spin_lock_irqsave(&psinfo->buf_lock, flags);
197 }
198 memcpy(psinfo->buf, s, c);
199 psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, c, psinfo);
200 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
201 s += c;
202 c = e - s;
203 }
204 }
205
206 static struct console pstore_console = {
207 .name = "pstore",
208 .write = pstore_console_write,
209 .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
210 .index = -1,
211 };
212
pstore_register_console(void)213 static void pstore_register_console(void)
214 {
215 register_console(&pstore_console);
216 }
217 #else
pstore_register_console(void)218 static void pstore_register_console(void) {}
219 #endif
220
pstore_write_compat(enum pstore_type_id type,enum kmsg_dump_reason reason,u64 * id,unsigned int part,int count,size_t size,struct pstore_info * psi)221 static int pstore_write_compat(enum pstore_type_id type,
222 enum kmsg_dump_reason reason,
223 u64 *id, unsigned int part, int count,
224 size_t size, struct pstore_info *psi)
225 {
226 return psi->write_buf(type, reason, id, part, psinfo->buf, size, psi);
227 }
228
pstore_write_buf_user_compat(enum pstore_type_id type,enum kmsg_dump_reason reason,u64 * id,unsigned int part,const char __user * buf,size_t size,struct pstore_info * psi)229 static int pstore_write_buf_user_compat(enum pstore_type_id type,
230 enum kmsg_dump_reason reason,
231 u64 *id, unsigned int part,
232 const char __user *buf,
233 size_t size,
234 struct pstore_info *psi)
235 {
236 unsigned long flags = 0;
237 size_t i, bufsize = size;
238 long ret = 0;
239
240 if (unlikely(!access_ok(VERIFY_READ, buf, size)))
241 return -EFAULT;
242 if (bufsize > psinfo->bufsize)
243 bufsize = psinfo->bufsize;
244 spin_lock_irqsave(&psinfo->buf_lock, flags);
245 for (i = 0; i < size; ) {
246 size_t c = min(size - i, bufsize);
247
248 ret = __copy_from_user(psinfo->buf, buf + i, c);
249 if (unlikely(ret != 0)) {
250 ret = -EFAULT;
251 break;
252 }
253 ret = psi->write_buf(type, reason, id, part, psinfo->buf,
254 c, psi);
255 if (unlikely(ret < 0))
256 break;
257 i += c;
258 }
259 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
260 return unlikely(ret < 0) ? ret : size;
261 }
262
263 /*
264 * platform specific persistent storage driver registers with
265 * us here. If pstore is already mounted, call the platform
266 * read function right away to populate the file system. If not
267 * then the pstore mount code will call us later to fill out
268 * the file system.
269 *
270 * Register with kmsg_dump to save last part of console log on panic.
271 */
pstore_register(struct pstore_info * psi)272 int pstore_register(struct pstore_info *psi)
273 {
274 struct module *owner = psi->owner;
275
276 spin_lock(&pstore_lock);
277 if (psinfo) {
278 spin_unlock(&pstore_lock);
279 return -EBUSY;
280 }
281
282 if (backend && strcmp(backend, psi->name)) {
283 spin_unlock(&pstore_lock);
284 return -EINVAL;
285 }
286
287 if (!psi->write)
288 psi->write = pstore_write_compat;
289 if (!psi->write_buf_user)
290 psi->write_buf_user = pstore_write_buf_user_compat;
291 psinfo = psi;
292 mutex_init(&psinfo->read_mutex);
293 spin_unlock(&pstore_lock);
294
295 if (owner && !try_module_get(owner)) {
296 psinfo = NULL;
297 return -EINVAL;
298 }
299
300 if (pstore_is_mounted())
301 pstore_get_records(0);
302
303 kmsg_dump_register(&pstore_dumper);
304 pstore_register_console();
305 pstore_register_ftrace();
306 pstore_register_pmsg();
307
308 if (pstore_update_ms >= 0) {
309 pstore_timer.expires = jiffies +
310 msecs_to_jiffies(pstore_update_ms);
311 add_timer(&pstore_timer);
312 }
313
314 return 0;
315 }
316 EXPORT_SYMBOL_GPL(pstore_register);
317
318 /*
319 * Read all the records from the persistent store. Create
320 * files in our filesystem. Don't warn about -EEXIST errors
321 * when we are re-scanning the backing store looking to add new
322 * error records.
323 */
pstore_get_records(int quiet)324 void pstore_get_records(int quiet)
325 {
326 struct pstore_info *psi = psinfo;
327 char *buf = NULL;
328 ssize_t size;
329 u64 id;
330 int count;
331 enum pstore_type_id type;
332 struct timespec time;
333 int failed = 0, rc;
334
335 if (!psi)
336 return;
337
338 mutex_lock(&psi->read_mutex);
339 if (psi->open && psi->open(psi))
340 goto out;
341
342 while ((size = psi->read(&id, &type, &count, &time, &buf, psi)) > 0) {
343 rc = pstore_mkfile(type, psi->name, id, count, buf,
344 (size_t)size, time, psi);
345 kfree(buf);
346 buf = NULL;
347 if (rc && (rc != -EEXIST || !quiet))
348 failed++;
349 }
350 if (psi->close)
351 psi->close(psi);
352 out:
353 mutex_unlock(&psi->read_mutex);
354
355 if (failed)
356 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
357 failed, psi->name);
358 }
359
pstore_dowork(struct work_struct * work)360 static void pstore_dowork(struct work_struct *work)
361 {
362 pstore_get_records(1);
363 }
364
pstore_timefunc(unsigned long dummy)365 static void pstore_timefunc(unsigned long dummy)
366 {
367 if (pstore_new_entry) {
368 pstore_new_entry = 0;
369 schedule_work(&pstore_work);
370 }
371
372 mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
373 }
374
375 module_param(backend, charp, 0444);
376 MODULE_PARM_DESC(backend, "Pstore backend to use");
377