xref: /openbmc/linux/fs/pstore/platform.c (revision 565d76cb)
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/slab.h>
29 #include <linux/uaccess.h>
30 
31 #include "internal.h"
32 
33 /*
34  * pstore_lock just protects "psinfo" during
35  * calls to pstore_register()
36  */
37 static DEFINE_SPINLOCK(pstore_lock);
38 static struct pstore_info *psinfo;
39 
40 /* How much of the console log to snapshot */
41 static unsigned long kmsg_bytes = 10240;
42 
43 void pstore_set_kmsg_bytes(int bytes)
44 {
45 	kmsg_bytes = bytes;
46 }
47 
48 /* Tag each group of saved records with a sequence number */
49 static int	oopscount;
50 
51 /*
52  * callback from kmsg_dump. (s2,l2) has the most recently
53  * written bytes, older bytes are in (s1,l1). Save as much
54  * as we can from the end of the buffer.
55  */
56 static void pstore_dump(struct kmsg_dumper *dumper,
57 	    enum kmsg_dump_reason reason,
58 	    const char *s1, unsigned long l1,
59 	    const char *s2, unsigned long l2)
60 {
61 	unsigned long	s1_start, s2_start;
62 	unsigned long	l1_cpy, l2_cpy;
63 	unsigned long	size, total = 0;
64 	char		*dst;
65 	u64		id;
66 	int		hsize, part = 1;
67 
68 	mutex_lock(&psinfo->buf_mutex);
69 	oopscount++;
70 	while (total < kmsg_bytes) {
71 		dst = psinfo->buf;
72 		hsize = sprintf(dst, "Oops#%d Part%d\n", oopscount, part++);
73 		size = psinfo->bufsize - hsize;
74 		dst += hsize;
75 
76 		l2_cpy = min(l2, size);
77 		l1_cpy = min(l1, size - l2_cpy);
78 
79 		if (l1_cpy + l2_cpy == 0)
80 			break;
81 
82 		s2_start = l2 - l2_cpy;
83 		s1_start = l1 - l1_cpy;
84 
85 		memcpy(dst, s1 + s1_start, l1_cpy);
86 		memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
87 
88 		id = psinfo->write(PSTORE_TYPE_DMESG, hsize + l1_cpy + l2_cpy);
89 		if (pstore_is_mounted())
90 			pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id,
91 				      psinfo->buf, hsize + l1_cpy + l2_cpy,
92 				      CURRENT_TIME, psinfo->erase);
93 		l1 -= l1_cpy;
94 		l2 -= l2_cpy;
95 		total += l1_cpy + l2_cpy;
96 	}
97 	mutex_unlock(&psinfo->buf_mutex);
98 }
99 
100 static struct kmsg_dumper pstore_dumper = {
101 	.dump = pstore_dump,
102 };
103 
104 /*
105  * platform specific persistent storage driver registers with
106  * us here. If pstore is already mounted, call the platform
107  * read function right away to populate the file system. If not
108  * then the pstore mount code will call us later to fill out
109  * the file system.
110  *
111  * Register with kmsg_dump to save last part of console log on panic.
112  */
113 int pstore_register(struct pstore_info *psi)
114 {
115 	struct module *owner = psi->owner;
116 
117 	spin_lock(&pstore_lock);
118 	if (psinfo) {
119 		spin_unlock(&pstore_lock);
120 		return -EBUSY;
121 	}
122 	psinfo = psi;
123 	spin_unlock(&pstore_lock);
124 
125 	if (owner && !try_module_get(owner)) {
126 		psinfo = NULL;
127 		return -EINVAL;
128 	}
129 
130 	if (pstore_is_mounted())
131 		pstore_get_records();
132 
133 	kmsg_dump_register(&pstore_dumper);
134 
135 	return 0;
136 }
137 EXPORT_SYMBOL_GPL(pstore_register);
138 
139 /*
140  * Read all the records from the persistent store. Create and
141  * file files in our filesystem.
142  */
143 void pstore_get_records(void)
144 {
145 	struct pstore_info *psi = psinfo;
146 	size_t			size;
147 	u64			id;
148 	enum pstore_type_id	type;
149 	struct timespec		time;
150 	int			failed = 0;
151 
152 	if (!psi)
153 		return;
154 
155 	mutex_lock(&psinfo->buf_mutex);
156 	while ((size = psi->read(&id, &type, &time)) > 0) {
157 		if (pstore_mkfile(type, psi->name, id, psi->buf, size,
158 				  time, psi->erase))
159 			failed++;
160 	}
161 	mutex_unlock(&psinfo->buf_mutex);
162 
163 	if (failed)
164 		printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
165 		       failed, psi->name);
166 }
167 
168 /*
169  * Call platform driver to write a record to the
170  * persistent store.
171  */
172 int pstore_write(enum pstore_type_id type, char *buf, size_t size)
173 {
174 	u64	id;
175 
176 	if (!psinfo)
177 		return -ENODEV;
178 
179 	if (size > psinfo->bufsize)
180 		return -EFBIG;
181 
182 	mutex_lock(&psinfo->buf_mutex);
183 	memcpy(psinfo->buf, buf, size);
184 	id = psinfo->write(type, size);
185 	if (pstore_is_mounted())
186 		pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
187 			      size, CURRENT_TIME, psinfo->erase);
188 	mutex_unlock(&psinfo->buf_mutex);
189 
190 	return 0;
191 }
192 EXPORT_SYMBOL_GPL(pstore_write);
193