1 /*
2 * Persistent Storage - pstore.h
3 *
4 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
5 *
6 * This code is the generic layer to export data records from platform
7 * level persistent storage via a file system.
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 */
22 #ifndef _LINUX_PSTORE_H
23 #define _LINUX_PSTORE_H
24
25 #include <linux/compiler.h>
26 #include <linux/errno.h>
27 #include <linux/kmsg_dump.h>
28 #include <linux/mutex.h>
29 #include <linux/semaphore.h>
30 #include <linux/time.h>
31 #include <linux/types.h>
32
33 struct module;
34
35 /* pstore record types (see fs/pstore/inode.c for filename templates) */
36 enum pstore_type_id {
37 PSTORE_TYPE_DMESG = 0,
38 PSTORE_TYPE_MCE = 1,
39 PSTORE_TYPE_CONSOLE = 2,
40 PSTORE_TYPE_FTRACE = 3,
41 /* PPC64 partition types */
42 PSTORE_TYPE_PPC_RTAS = 4,
43 PSTORE_TYPE_PPC_OF = 5,
44 PSTORE_TYPE_PPC_COMMON = 6,
45 PSTORE_TYPE_PMSG = 7,
46 PSTORE_TYPE_PPC_OPAL = 8,
47 PSTORE_TYPE_UNKNOWN = 255
48 };
49
50 struct pstore_info;
51 /**
52 * struct pstore_record - details of a pstore record entry
53 * @psi: pstore backend driver information
54 * @type: pstore record type
55 * @id: per-type unique identifier for record
56 * @time: timestamp of the record
57 * @buf: pointer to record contents
58 * @size: size of @buf
59 * @ecc_notice_size:
60 * ECC information for @buf
61 *
62 * Valid for PSTORE_TYPE_DMESG @type:
63 *
64 * @count: Oops count since boot
65 * @reason: kdump reason for notification
66 * @part: position in a multipart record
67 * @compressed: whether the buffer is compressed
68 *
69 */
70 struct pstore_record {
71 struct pstore_info *psi;
72 enum pstore_type_id type;
73 u64 id;
74 struct timespec64 time;
75 char *buf;
76 ssize_t size;
77 ssize_t ecc_notice_size;
78
79 int count;
80 enum kmsg_dump_reason reason;
81 unsigned int part;
82 bool compressed;
83 };
84
85 /**
86 * struct pstore_info - backend pstore driver structure
87 *
88 * @owner: module which is repsonsible for this backend driver
89 * @name: name of the backend driver
90 *
91 * @buf_lock: semaphore to serialize access to @buf
92 * @buf: preallocated crash dump buffer
93 * @bufsize: size of @buf available for crash dump bytes (must match
94 * smallest number of bytes available for writing to a
95 * backend entry, since compressed bytes don't take kindly
96 * to being truncated)
97 *
98 * @read_mutex: serializes @open, @read, @close, and @erase callbacks
99 * @flags: bitfield of frontends the backend can accept writes for
100 * @data: backend-private pointer passed back during callbacks
101 *
102 * Callbacks:
103 *
104 * @open:
105 * Notify backend that pstore is starting a full read of backend
106 * records. Followed by one or more @read calls, and a final @close.
107 *
108 * @psi: in: pointer to the struct pstore_info for the backend
109 *
110 * Returns 0 on success, and non-zero on error.
111 *
112 * @close:
113 * Notify backend that pstore has finished a full read of backend
114 * records. Always preceded by an @open call and one or more @read
115 * calls.
116 *
117 * @psi: in: pointer to the struct pstore_info for the backend
118 *
119 * Returns 0 on success, and non-zero on error. (Though pstore will
120 * ignore the error.)
121 *
122 * @read:
123 * Read next available backend record. Called after a successful
124 * @open.
125 *
126 * @record:
127 * pointer to record to populate. @buf should be allocated
128 * by the backend and filled. At least @type and @id should
129 * be populated, since these are used when creating pstorefs
130 * file names.
131 *
132 * Returns record size on success, zero when no more records are
133 * available, or negative on error.
134 *
135 * @write:
136 * A newly generated record needs to be written to backend storage.
137 *
138 * @record:
139 * pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
140 * @buf will be pointing to the preallocated @psi.buf, since
141 * memory allocation may be broken during an Oops. Regardless,
142 * @buf must be proccesed or copied before returning. The
143 * backend is also expected to write @id with something that
144 * can help identify this record to a future @erase callback.
145 * The @time field will be prepopulated with the current time,
146 * when available. The @size field will have the size of data
147 * in @buf.
148 *
149 * Returns 0 on success, and non-zero on error.
150 *
151 * @write_user:
152 * Perform a frontend write to a backend record, using a specified
153 * buffer that is coming directly from userspace, instead of the
154 * @record @buf.
155 *
156 * @record: pointer to record metadata.
157 * @buf: pointer to userspace contents to write to backend
158 *
159 * Returns 0 on success, and non-zero on error.
160 *
161 * @erase:
162 * Delete a record from backend storage. Different backends
163 * identify records differently, so entire original record is
164 * passed back to assist in identification of what the backend
165 * should remove from storage.
166 *
167 * @record: pointer to record metadata.
168 *
169 * Returns 0 on success, and non-zero on error.
170 *
171 */
172 struct pstore_info {
173 struct module *owner;
174 char *name;
175
176 struct semaphore buf_lock;
177 char *buf;
178 size_t bufsize;
179
180 struct mutex read_mutex;
181
182 int flags;
183 void *data;
184
185 int (*open)(struct pstore_info *psi);
186 int (*close)(struct pstore_info *psi);
187 ssize_t (*read)(struct pstore_record *record);
188 int (*write)(struct pstore_record *record);
189 int (*write_user)(struct pstore_record *record,
190 const char __user *buf);
191 int (*erase)(struct pstore_record *record);
192 };
193
194 /* Supported frontends */
195 #define PSTORE_FLAGS_DMESG (1 << 0)
196 #define PSTORE_FLAGS_CONSOLE (1 << 1)
197 #define PSTORE_FLAGS_FTRACE (1 << 2)
198 #define PSTORE_FLAGS_PMSG (1 << 3)
199
200 extern int pstore_register(struct pstore_info *);
201 extern void pstore_unregister(struct pstore_info *);
202
203 struct pstore_ftrace_record {
204 unsigned long ip;
205 unsigned long parent_ip;
206 u64 ts;
207 };
208
209 /*
210 * ftrace related stuff: Both backends and frontends need these so expose
211 * them here.
212 */
213
214 #if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
215 #define PSTORE_CPU_IN_IP 0x1
216 #elif NR_CPUS <= 4 && defined(CONFIG_ARM)
217 #define PSTORE_CPU_IN_IP 0x3
218 #endif
219
220 #define TS_CPU_SHIFT 8
221 #define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1)
222
223 /*
224 * If CPU number can be stored in IP, store it there, otherwise store it in
225 * the time stamp. This means more timestamp resolution is available when
226 * the CPU can be stored in the IP.
227 */
228 #ifdef PSTORE_CPU_IN_IP
229 static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record * rec,unsigned int cpu)230 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
231 {
232 rec->ip |= cpu;
233 }
234
235 static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record * rec)236 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
237 {
238 return rec->ip & PSTORE_CPU_IN_IP;
239 }
240
241 static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record * rec)242 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
243 {
244 return rec->ts;
245 }
246
247 static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record * rec,u64 val)248 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
249 {
250 rec->ts = val;
251 }
252 #else
253 static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record * rec,unsigned int cpu)254 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
255 {
256 rec->ts &= ~(TS_CPU_MASK);
257 rec->ts |= cpu;
258 }
259
260 static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record * rec)261 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
262 {
263 return rec->ts & TS_CPU_MASK;
264 }
265
266 static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record * rec)267 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
268 {
269 return rec->ts >> TS_CPU_SHIFT;
270 }
271
272 static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record * rec,u64 val)273 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
274 {
275 rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT);
276 }
277 #endif
278
279 #endif /*_LINUX_PSTORE_H*/
280