1 /*
2 * Persistent Storage - platform driver interface parts.
3 *
4 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20 #include <linux/atomic.h>
21 #include <linux/types.h>
22 #include <linux/errno.h>
23 #include <linux/init.h>
24 #include <linux/kmsg_dump.h>
25 #include <linux/module.h>
26 #include <linux/pstore.h>
27 #include <linux/string.h>
28 #include <linux/timer.h>
29 #include <linux/slab.h>
30 #include <linux/uaccess.h>
31 #include <linux/hardirq.h>
32 #include <linux/workqueue.h>
33
34 #include "internal.h"
35
36 /*
37 * We defer making "oops" entries appear in pstore - see
38 * whether the system is actually still running well enough
39 * to let someone see the entry
40 */
41 #define PSTORE_INTERVAL (60 * HZ)
42
43 static int pstore_new_entry;
44
45 static void pstore_timefunc(unsigned long);
46 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
47
48 static void pstore_dowork(struct work_struct *);
49 static DECLARE_WORK(pstore_work, pstore_dowork);
50
51 /*
52 * pstore_lock just protects "psinfo" during
53 * calls to pstore_register()
54 */
55 static DEFINE_SPINLOCK(pstore_lock);
56 static struct pstore_info *psinfo;
57
58 static char *backend;
59
60 /* How much of the console log to snapshot */
61 static unsigned long kmsg_bytes = 10240;
62
pstore_set_kmsg_bytes(int bytes)63 void pstore_set_kmsg_bytes(int bytes)
64 {
65 kmsg_bytes = bytes;
66 }
67
68 /* Tag each group of saved records with a sequence number */
69 static int oopscount;
70
get_reason_str(enum kmsg_dump_reason reason)71 static const char *get_reason_str(enum kmsg_dump_reason reason)
72 {
73 switch (reason) {
74 case KMSG_DUMP_PANIC:
75 return "Panic";
76 case KMSG_DUMP_OOPS:
77 return "Oops";
78 case KMSG_DUMP_EMERG:
79 return "Emergency";
80 case KMSG_DUMP_RESTART:
81 return "Restart";
82 case KMSG_DUMP_HALT:
83 return "Halt";
84 case KMSG_DUMP_POWEROFF:
85 return "Poweroff";
86 default:
87 return "Unknown";
88 }
89 }
90
pstore_cannot_block_path(enum kmsg_dump_reason reason)91 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
92 {
93 /*
94 * In case of NMI path, pstore shouldn't be blocked
95 * regardless of reason.
96 */
97 if (in_nmi())
98 return true;
99
100 switch (reason) {
101 /* In panic case, other cpus are stopped by smp_send_stop(). */
102 case KMSG_DUMP_PANIC:
103 /* Emergency restart shouldn't be blocked by spin lock. */
104 case KMSG_DUMP_EMERG:
105 return true;
106 default:
107 return false;
108 }
109 }
110 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
111
112 /*
113 * callback from kmsg_dump. (s2,l2) has the most recently
114 * written bytes, older bytes are in (s1,l1). Save as much
115 * as we can from the end of the buffer.
116 */
pstore_dump(struct kmsg_dumper * dumper,enum kmsg_dump_reason reason,const char * s1,unsigned long l1,const char * s2,unsigned long l2)117 static void pstore_dump(struct kmsg_dumper *dumper,
118 enum kmsg_dump_reason reason,
119 const char *s1, unsigned long l1,
120 const char *s2, unsigned long l2)
121 {
122 unsigned long s1_start, s2_start;
123 unsigned long l1_cpy, l2_cpy;
124 unsigned long size, total = 0;
125 char *dst;
126 const char *why;
127 u64 id;
128 int hsize, ret;
129 unsigned int part = 1;
130 unsigned long flags = 0;
131 int is_locked = 0;
132
133 why = get_reason_str(reason);
134
135 if (pstore_cannot_block_path(reason)) {
136 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
137 if (!is_locked) {
138 pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
139 , in_nmi() ? "NMI" : why);
140 }
141 } else
142 spin_lock_irqsave(&psinfo->buf_lock, flags);
143 oopscount++;
144 while (total < kmsg_bytes) {
145 dst = psinfo->buf;
146 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
147 size = psinfo->bufsize - hsize;
148 dst += hsize;
149
150 l2_cpy = min(l2, size);
151 l1_cpy = min(l1, size - l2_cpy);
152
153 if (l1_cpy + l2_cpy == 0)
154 break;
155
156 s2_start = l2 - l2_cpy;
157 s1_start = l1 - l1_cpy;
158
159 memcpy(dst, s1 + s1_start, l1_cpy);
160 memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
161
162 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
163 hsize + l1_cpy + l2_cpy, psinfo);
164 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
165 pstore_new_entry = 1;
166 l1 -= l1_cpy;
167 l2 -= l2_cpy;
168 total += l1_cpy + l2_cpy;
169 part++;
170 }
171 if (pstore_cannot_block_path(reason)) {
172 if (is_locked)
173 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
174 } else
175 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
176 }
177
178 static struct kmsg_dumper pstore_dumper = {
179 .dump = pstore_dump,
180 };
181
182 /*
183 * platform specific persistent storage driver registers with
184 * us here. If pstore is already mounted, call the platform
185 * read function right away to populate the file system. If not
186 * then the pstore mount code will call us later to fill out
187 * the file system.
188 *
189 * Register with kmsg_dump to save last part of console log on panic.
190 */
pstore_register(struct pstore_info * psi)191 int pstore_register(struct pstore_info *psi)
192 {
193 struct module *owner = psi->owner;
194
195 spin_lock(&pstore_lock);
196 if (psinfo) {
197 spin_unlock(&pstore_lock);
198 return -EBUSY;
199 }
200
201 if (backend && strcmp(backend, psi->name)) {
202 spin_unlock(&pstore_lock);
203 return -EINVAL;
204 }
205
206 psinfo = psi;
207 mutex_init(&psinfo->read_mutex);
208 spin_unlock(&pstore_lock);
209
210 if (owner && !try_module_get(owner)) {
211 psinfo = NULL;
212 return -EINVAL;
213 }
214
215 if (pstore_is_mounted())
216 pstore_get_records(0);
217
218 kmsg_dump_register(&pstore_dumper);
219
220 pstore_timer.expires = jiffies + PSTORE_INTERVAL;
221 add_timer(&pstore_timer);
222
223 return 0;
224 }
225 EXPORT_SYMBOL_GPL(pstore_register);
226
227 /*
228 * Read all the records from the persistent store. Create
229 * files in our filesystem. Don't warn about -EEXIST errors
230 * when we are re-scanning the backing store looking to add new
231 * error records.
232 */
pstore_get_records(int quiet)233 void pstore_get_records(int quiet)
234 {
235 struct pstore_info *psi = psinfo;
236 char *buf = NULL;
237 ssize_t size;
238 u64 id;
239 enum pstore_type_id type;
240 struct timespec time;
241 int failed = 0, rc;
242
243 if (!psi)
244 return;
245
246 mutex_lock(&psi->read_mutex);
247 if (psi->open && psi->open(psi))
248 goto out;
249
250 while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
251 rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
252 time, psi);
253 kfree(buf);
254 buf = NULL;
255 if (rc && (rc != -EEXIST || !quiet))
256 failed++;
257 }
258 if (psi->close)
259 psi->close(psi);
260 out:
261 mutex_unlock(&psi->read_mutex);
262
263 if (failed)
264 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
265 failed, psi->name);
266 }
267
pstore_dowork(struct work_struct * work)268 static void pstore_dowork(struct work_struct *work)
269 {
270 pstore_get_records(1);
271 }
272
pstore_timefunc(unsigned long dummy)273 static void pstore_timefunc(unsigned long dummy)
274 {
275 if (pstore_new_entry) {
276 pstore_new_entry = 0;
277 schedule_work(&pstore_work);
278 }
279
280 mod_timer(&pstore_timer, jiffies + PSTORE_INTERVAL);
281 }
282
283 module_param(backend, charp, 0444);
284 MODULE_PARM_DESC(backend, "Pstore backend to use");
285