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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