2 * Persistent Storage - platform driver interface parts.
4 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
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.
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.
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
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>
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
41 #define PSTORE_INTERVAL (60 * HZ)
43 static int pstore_new_entry;
45 static void pstore_timefunc(unsigned long);
46 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
48 static void pstore_dowork(struct work_struct *);
49 static DECLARE_WORK(pstore_work, pstore_dowork);
52 * pstore_lock just protects "psinfo" during
53 * calls to pstore_register()
55 static DEFINE_SPINLOCK(pstore_lock);
56 static struct pstore_info *psinfo;
60 /* How much of the console log to snapshot */
61 static unsigned long kmsg_bytes = 10240;
63 void pstore_set_kmsg_bytes(int bytes)
68 /* Tag each group of saved records with a sequence number */
71 static char *reason_str[] = {
72 "Oops", "Panic", "Kexec", "Restart", "Halt", "Poweroff", "Emergency"
75 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
78 * In case of NMI path, pstore shouldn't be blocked
79 * regardless of reason.
85 /* In panic case, other cpus are stopped by smp_send_stop(). */
87 /* Emergency restart shouldn't be blocked by spin lock. */
94 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
97 * callback from kmsg_dump. (s2,l2) has the most recently
98 * written bytes, older bytes are in (s1,l1). Save as much
99 * as we can from the end of the buffer.
101 static void pstore_dump(struct kmsg_dumper *dumper,
102 enum kmsg_dump_reason reason,
103 const char *s1, unsigned long l1,
104 const char *s2, unsigned long l2)
106 unsigned long s1_start, s2_start;
107 unsigned long l1_cpy, l2_cpy;
108 unsigned long size, total = 0;
112 unsigned int part = 1;
113 unsigned long flags = 0;
116 if (reason < ARRAY_SIZE(reason_str))
117 why = reason_str[reason];
121 if (pstore_cannot_block_path(reason)) {
122 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
124 pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
125 , in_nmi() ? "NMI" : why);
128 spin_lock_irqsave(&psinfo->buf_lock, flags);
130 while (total < kmsg_bytes) {
132 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
133 size = psinfo->bufsize - hsize;
136 l2_cpy = min(l2, size);
137 l1_cpy = min(l1, size - l2_cpy);
139 if (l1_cpy + l2_cpy == 0)
142 s2_start = l2 - l2_cpy;
143 s1_start = l1 - l1_cpy;
145 memcpy(dst, s1 + s1_start, l1_cpy);
146 memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
148 ret = psinfo->write(PSTORE_TYPE_DMESG, &id, part,
149 hsize + l1_cpy + l2_cpy, psinfo);
150 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
151 pstore_new_entry = 1;
154 total += l1_cpy + l2_cpy;
157 if (pstore_cannot_block_path(reason)) {
159 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
161 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
164 static struct kmsg_dumper pstore_dumper = {
169 * platform specific persistent storage driver registers with
170 * us here. If pstore is already mounted, call the platform
171 * read function right away to populate the file system. If not
172 * then the pstore mount code will call us later to fill out
175 * Register with kmsg_dump to save last part of console log on panic.
177 int pstore_register(struct pstore_info *psi)
179 struct module *owner = psi->owner;
181 spin_lock(&pstore_lock);
183 spin_unlock(&pstore_lock);
187 if (backend && strcmp(backend, psi->name)) {
188 spin_unlock(&pstore_lock);
193 mutex_init(&psinfo->read_mutex);
194 spin_unlock(&pstore_lock);
196 if (owner && !try_module_get(owner)) {
201 if (pstore_is_mounted())
202 pstore_get_records(0);
204 kmsg_dump_register(&pstore_dumper);
206 pstore_timer.expires = jiffies + PSTORE_INTERVAL;
207 add_timer(&pstore_timer);
211 EXPORT_SYMBOL_GPL(pstore_register);
214 * Read all the records from the persistent store. Create
215 * files in our filesystem. Don't warn about -EEXIST errors
216 * when we are re-scanning the backing store looking to add new
219 void pstore_get_records(int quiet)
221 struct pstore_info *psi = psinfo;
225 enum pstore_type_id type;
226 struct timespec time;
232 mutex_lock(&psi->read_mutex);
237 while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
238 rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
242 if (rc && (rc != -EEXIST || !quiet))
247 mutex_unlock(&psi->read_mutex);
250 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
254 static void pstore_dowork(struct work_struct *work)
256 pstore_get_records(1);
259 static void pstore_timefunc(unsigned long dummy)
261 if (pstore_new_entry) {
262 pstore_new_entry = 0;
263 schedule_work(&pstore_work);
266 mod_timer(&pstore_timer, jiffies + PSTORE_INTERVAL);
270 * Call platform driver to write a record to the
273 int pstore_write(enum pstore_type_id type, char *buf, size_t size)
282 if (size > psinfo->bufsize)
285 spin_lock_irqsave(&psinfo->buf_lock, flags);
286 memcpy(psinfo->buf, buf, size);
287 ret = psinfo->write(type, &id, 0, size, psinfo);
288 if (ret == 0 && pstore_is_mounted())
289 pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
290 size, CURRENT_TIME, psinfo);
291 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
295 EXPORT_SYMBOL_GPL(pstore_write);
297 module_param(backend, charp, 0444);
298 MODULE_PARM_DESC(backend, "Pstore backend to use");