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1 | /* SPDX-License-Identifier: GPL-2.0-only */ | |
2 | /* | |
3 | * Persistent Storage - pstore.h | |
4 | * | |
5 | * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com> | |
6 | * | |
7 | * This code is the generic layer to export data records from platform | |
8 | * level persistent storage via a file system. | |
9 | */ | |
10 | #ifndef _LINUX_PSTORE_H | |
11 | #define _LINUX_PSTORE_H | |
12 | ||
13 | #include <linux/compiler.h> | |
14 | #include <linux/errno.h> | |
15 | #include <linux/kmsg_dump.h> | |
16 | #include <linux/mutex.h> | |
17 | #include <linux/semaphore.h> | |
18 | #include <linux/time.h> | |
19 | #include <linux/types.h> | |
20 | ||
21 | struct module; | |
22 | ||
23 | /* | |
24 | * pstore record types (see fs/pstore/platform.c for pstore_type_names[]) | |
25 | * These values may be written to storage (see EFI vars backend), so | |
26 | * they are kind of an ABI. Be careful changing the mappings. | |
27 | */ | |
28 | enum pstore_type_id { | |
29 | /* Frontend storage types */ | |
30 | PSTORE_TYPE_DMESG = 0, | |
31 | PSTORE_TYPE_MCE = 1, | |
32 | PSTORE_TYPE_CONSOLE = 2, | |
33 | PSTORE_TYPE_FTRACE = 3, | |
34 | ||
35 | /* PPC64-specific partition types */ | |
36 | PSTORE_TYPE_PPC_RTAS = 4, | |
37 | PSTORE_TYPE_PPC_OF = 5, | |
38 | PSTORE_TYPE_PPC_COMMON = 6, | |
39 | PSTORE_TYPE_PMSG = 7, | |
40 | PSTORE_TYPE_PPC_OPAL = 8, | |
41 | ||
42 | /* End of the list */ | |
43 | PSTORE_TYPE_MAX | |
44 | }; | |
45 | ||
46 | const char *pstore_type_to_name(enum pstore_type_id type); | |
47 | enum pstore_type_id pstore_name_to_type(const char *name); | |
48 | ||
49 | struct pstore_info; | |
50 | /** | |
51 | * struct pstore_record - details of a pstore record entry | |
52 | * @psi: pstore backend driver information | |
53 | * @type: pstore record type | |
54 | * @id: per-type unique identifier for record | |
55 | * @time: timestamp of the record | |
56 | * @buf: pointer to record contents | |
57 | * @size: size of @buf | |
58 | * @ecc_notice_size: | |
59 | * ECC information for @buf | |
60 | * | |
61 | * Valid for PSTORE_TYPE_DMESG @type: | |
62 | * | |
63 | * @count: Oops count since boot | |
64 | * @reason: kdump reason for notification | |
65 | * @part: position in a multipart record | |
66 | * @compressed: whether the buffer is compressed | |
67 | * | |
68 | */ | |
69 | struct pstore_record { | |
70 | struct pstore_info *psi; | |
71 | enum pstore_type_id type; | |
72 | u64 id; | |
73 | struct timespec64 time; | |
74 | char *buf; | |
75 | ssize_t size; | |
76 | ssize_t ecc_notice_size; | |
77 | ||
78 | int count; | |
79 | enum kmsg_dump_reason reason; | |
80 | unsigned int part; | |
81 | bool compressed; | |
82 | }; | |
83 | ||
84 | /** | |
85 | * struct pstore_info - backend pstore driver structure | |
86 | * | |
87 | * @owner: module which is responsible for this backend driver | |
88 | * @name: name of the backend driver | |
89 | * | |
90 | * @buf_lock: semaphore to serialize access to @buf | |
91 | * @buf: preallocated crash dump buffer | |
92 | * @bufsize: size of @buf available for crash dump bytes (must match | |
93 | * smallest number of bytes available for writing to a | |
94 | * backend entry, since compressed bytes don't take kindly | |
95 | * to being truncated) | |
96 | * | |
97 | * @read_mutex: serializes @open, @read, @close, and @erase callbacks | |
98 | * @flags: bitfield of frontends the backend can accept writes for | |
99 | * @data: backend-private pointer passed back during callbacks | |
100 | * | |
101 | * Callbacks: | |
102 | * | |
103 | * @open: | |
104 | * Notify backend that pstore is starting a full read of backend | |
105 | * records. Followed by one or more @read calls, and a final @close. | |
106 | * | |
107 | * @psi: in: pointer to the struct pstore_info for the backend | |
108 | * | |
109 | * Returns 0 on success, and non-zero on error. | |
110 | * | |
111 | * @close: | |
112 | * Notify backend that pstore has finished a full read of backend | |
113 | * records. Always preceded by an @open call and one or more @read | |
114 | * calls. | |
115 | * | |
116 | * @psi: in: pointer to the struct pstore_info for the backend | |
117 | * | |
118 | * Returns 0 on success, and non-zero on error. (Though pstore will | |
119 | * ignore the error.) | |
120 | * | |
121 | * @read: | |
122 | * Read next available backend record. Called after a successful | |
123 | * @open. | |
124 | * | |
125 | * @record: | |
126 | * pointer to record to populate. @buf should be allocated | |
127 | * by the backend and filled. At least @type and @id should | |
128 | * be populated, since these are used when creating pstorefs | |
129 | * file names. | |
130 | * | |
131 | * Returns record size on success, zero when no more records are | |
132 | * available, or negative on error. | |
133 | * | |
134 | * @write: | |
135 | * A newly generated record needs to be written to backend storage. | |
136 | * | |
137 | * @record: | |
138 | * pointer to record metadata. When @type is PSTORE_TYPE_DMESG, | |
139 | * @buf will be pointing to the preallocated @psi.buf, since | |
140 | * memory allocation may be broken during an Oops. Regardless, | |
141 | * @buf must be proccesed or copied before returning. The | |
142 | * backend is also expected to write @id with something that | |
143 | * can help identify this record to a future @erase callback. | |
144 | * The @time field will be prepopulated with the current time, | |
145 | * when available. The @size field will have the size of data | |
146 | * in @buf. | |
147 | * | |
148 | * Returns 0 on success, and non-zero on error. | |
149 | * | |
150 | * @write_user: | |
151 | * Perform a frontend write to a backend record, using a specified | |
152 | * buffer that is coming directly from userspace, instead of the | |
153 | * @record @buf. | |
154 | * | |
155 | * @record: pointer to record metadata. | |
156 | * @buf: pointer to userspace contents to write to backend | |
157 | * | |
158 | * Returns 0 on success, and non-zero on error. | |
159 | * | |
160 | * @erase: | |
161 | * Delete a record from backend storage. Different backends | |
162 | * identify records differently, so entire original record is | |
163 | * passed back to assist in identification of what the backend | |
164 | * should remove from storage. | |
165 | * | |
166 | * @record: pointer to record metadata. | |
167 | * | |
168 | * Returns 0 on success, and non-zero on error. | |
169 | * | |
170 | */ | |
171 | struct pstore_info { | |
172 | struct module *owner; | |
173 | char *name; | |
174 | ||
175 | struct semaphore buf_lock; | |
176 | char *buf; | |
177 | size_t bufsize; | |
178 | ||
179 | struct mutex read_mutex; | |
180 | ||
181 | int flags; | |
182 | void *data; | |
183 | ||
184 | int (*open)(struct pstore_info *psi); | |
185 | int (*close)(struct pstore_info *psi); | |
186 | ssize_t (*read)(struct pstore_record *record); | |
187 | int (*write)(struct pstore_record *record); | |
188 | int (*write_user)(struct pstore_record *record, | |
189 | const char __user *buf); | |
190 | int (*erase)(struct pstore_record *record); | |
191 | }; | |
192 | ||
193 | /* Supported frontends */ | |
194 | #define PSTORE_FLAGS_DMESG BIT(0) | |
195 | #define PSTORE_FLAGS_CONSOLE BIT(1) | |
196 | #define PSTORE_FLAGS_FTRACE BIT(2) | |
197 | #define PSTORE_FLAGS_PMSG BIT(3) | |
198 | ||
199 | extern int pstore_register(struct pstore_info *); | |
200 | extern void pstore_unregister(struct pstore_info *); | |
201 | ||
202 | struct pstore_ftrace_record { | |
203 | unsigned long ip; | |
204 | unsigned long parent_ip; | |
205 | u64 ts; | |
206 | }; | |
207 | ||
208 | /* | |
209 | * ftrace related stuff: Both backends and frontends need these so expose | |
210 | * them here. | |
211 | */ | |
212 | ||
213 | #if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB) | |
214 | #define PSTORE_CPU_IN_IP 0x1 | |
215 | #elif NR_CPUS <= 4 && defined(CONFIG_ARM) | |
216 | #define PSTORE_CPU_IN_IP 0x3 | |
217 | #endif | |
218 | ||
219 | #define TS_CPU_SHIFT 8 | |
220 | #define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1) | |
221 | ||
222 | /* | |
223 | * If CPU number can be stored in IP, store it there, otherwise store it in | |
224 | * the time stamp. This means more timestamp resolution is available when | |
225 | * the CPU can be stored in the IP. | |
226 | */ | |
227 | #ifdef PSTORE_CPU_IN_IP | |
228 | static inline void | |
229 | pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu) | |
230 | { | |
231 | rec->ip |= cpu; | |
232 | } | |
233 | ||
234 | static inline unsigned int | |
235 | pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec) | |
236 | { | |
237 | return rec->ip & PSTORE_CPU_IN_IP; | |
238 | } | |
239 | ||
240 | static inline u64 | |
241 | pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec) | |
242 | { | |
243 | return rec->ts; | |
244 | } | |
245 | ||
246 | static inline void | |
247 | pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val) | |
248 | { | |
249 | rec->ts = val; | |
250 | } | |
251 | #else | |
252 | static inline void | |
253 | pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu) | |
254 | { | |
255 | rec->ts &= ~(TS_CPU_MASK); | |
256 | rec->ts |= cpu; | |
257 | } | |
258 | ||
259 | static inline unsigned int | |
260 | pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec) | |
261 | { | |
262 | return rec->ts & TS_CPU_MASK; | |
263 | } | |
264 | ||
265 | static inline u64 | |
266 | pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec) | |
267 | { | |
268 | return rec->ts >> TS_CPU_SHIFT; | |
269 | } | |
270 | ||
271 | static inline void | |
272 | pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val) | |
273 | { | |
274 | rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT); | |
275 | } | |
276 | #endif | |
277 | ||
278 | #endif /*_LINUX_PSTORE_H*/ |