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 #ifdef CONFIG_PSTORE_BOOT_LOG
42 PSTORE_TYPE_BOOT_LOG = 9,
43 #endif
44
45 /* End of the list */
46 PSTORE_TYPE_MAX
47 };
48
49 const char *pstore_type_to_name(enum pstore_type_id type);
50 enum pstore_type_id pstore_name_to_type(const char *name);
51
52 struct pstore_info;
53 /**
54 * struct pstore_record - details of a pstore record entry
55 * @psi: pstore backend driver information
56 * @type: pstore record type
57 * @id: per-type unique identifier for record
58 * @time: timestamp of the record
59 * @buf: pointer to record contents
60 * @size: size of @buf
61 * @ecc_notice_size:
62 * ECC information for @buf
63 *
64 * Valid for PSTORE_TYPE_DMESG @type:
65 *
66 * @count: Oops count since boot
67 * @reason: kdump reason for notification
68 * @part: position in a multipart record
69 * @compressed: whether the buffer is compressed
70 *
71 */
72 struct pstore_record {
73 struct pstore_info *psi;
74 enum pstore_type_id type;
75 u64 id;
76 struct timespec64 time;
77 char *buf;
78 ssize_t size;
79 ssize_t ecc_notice_size;
80
81 int count;
82 enum kmsg_dump_reason reason;
83 unsigned int part;
84 bool compressed;
85 };
86
87 /**
88 * struct pstore_info - backend pstore driver structure
89 *
90 * @owner: module which is responsible for this backend driver
91 * @name: name of the backend driver
92 *
93 * @buf_lock: semaphore to serialize access to @buf
94 * @buf: preallocated crash dump buffer
95 * @bufsize: size of @buf available for crash dump bytes (must match
96 * smallest number of bytes available for writing to a
97 * backend entry, since compressed bytes don't take kindly
98 * to being truncated)
99 *
100 * @read_mutex: serializes @open, @read, @close, and @erase callbacks
101 * @flags: bitfield of frontends the backend can accept writes for
102 * @max_reason: Used when PSTORE_FLAGS_DMESG is set. Contains the
103 * kmsg_dump_reason enum value. KMSG_DUMP_UNDEF means
104 * "use existing kmsg_dump() filtering, based on the
105 * printk.always_kmsg_dump boot param" (which is either
106 * KMSG_DUMP_OOPS when false, or KMSG_DUMP_MAX when
107 * true); see printk.always_kmsg_dump for more details.
108 * @data: backend-private pointer passed back during callbacks
109 *
110 * Callbacks:
111 *
112 * @open:
113 * Notify backend that pstore is starting a full read of backend
114 * records. Followed by one or more @read calls, and a final @close.
115 *
116 * @psi: in: pointer to the struct pstore_info for the backend
117 *
118 * Returns 0 on success, and non-zero on error.
119 *
120 * @close:
121 * Notify backend that pstore has finished a full read of backend
122 * records. Always preceded by an @open call and one or more @read
123 * calls.
124 *
125 * @psi: in: pointer to the struct pstore_info for the backend
126 *
127 * Returns 0 on success, and non-zero on error. (Though pstore will
128 * ignore the error.)
129 *
130 * @read:
131 * Read next available backend record. Called after a successful
132 * @open.
133 *
134 * @record:
135 * pointer to record to populate. @buf should be allocated
136 * by the backend and filled. At least @type and @id should
137 * be populated, since these are used when creating pstorefs
138 * file names.
139 *
140 * Returns record size on success, zero when no more records are
141 * available, or negative on error.
142 *
143 * @write:
144 * A newly generated record needs to be written to backend storage.
145 *
146 * @record:
147 * pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
148 * @buf will be pointing to the preallocated @psi.buf, since
149 * memory allocation may be broken during an Oops. Regardless,
150 * @buf must be proccesed or copied before returning. The
151 * backend is also expected to write @id with something that
152 * can help identify this record to a future @erase callback.
153 * The @time field will be prepopulated with the current time,
154 * when available. The @size field will have the size of data
155 * in @buf.
156 *
157 * Returns 0 on success, and non-zero on error.
158 *
159 * @write_user:
160 * Perform a frontend write to a backend record, using a specified
161 * buffer that is coming directly from userspace, instead of the
162 * @record @buf.
163 *
164 * @record: pointer to record metadata.
165 * @buf: pointer to userspace contents to write to backend
166 *
167 * Returns 0 on success, and non-zero on error.
168 *
169 * @erase:
170 * Delete a record from backend storage. Different backends
171 * identify records differently, so entire original record is
172 * passed back to assist in identification of what the backend
173 * should remove from storage.
174 *
175 * @record: pointer to record metadata.
176 *
177 * Returns 0 on success, and non-zero on error.
178 *
179 */
180 struct pstore_info {
181 struct module *owner;
182 const char *name;
183
184 struct semaphore buf_lock;
185 char *buf;
186 size_t bufsize;
187
188 struct mutex read_mutex;
189
190 int flags;
191 int max_reason;
192 void *data;
193
194 int (*open)(struct pstore_info *psi);
195 int (*close)(struct pstore_info *psi);
196 ssize_t (*read)(struct pstore_record *record);
197 int (*write)(struct pstore_record *record);
198 int (*write_user)(struct pstore_record *record,
199 const char __user *buf);
200 int (*erase)(struct pstore_record *record);
201 };
202
203 /* Supported frontends */
204 #define PSTORE_FLAGS_DMESG BIT(0)
205 #define PSTORE_FLAGS_CONSOLE BIT(1)
206 #define PSTORE_FLAGS_FTRACE BIT(2)
207 #define PSTORE_FLAGS_PMSG BIT(3)
208 #ifdef CONFIG_PSTORE_BOOT_LOG
209 #define PSTORE_FLAGS_BOOT_LOG BIT(4)
210 #endif
211
212 extern int pstore_register(struct pstore_info *);
213 extern void pstore_unregister(struct pstore_info *);
214
215 struct pstore_ftrace_record {
216 unsigned long ip;
217 unsigned long parent_ip;
218 u64 ts;
219 };
220
221 /*
222 * ftrace related stuff: Both backends and frontends need these so expose
223 * them here.
224 */
225
226 #if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
227 #define PSTORE_CPU_IN_IP 0x1
228 #elif NR_CPUS <= 4 && defined(CONFIG_ARM)
229 #define PSTORE_CPU_IN_IP 0x3
230 #endif
231
232 #define TS_CPU_SHIFT 8
233 #define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1)
234
235 /*
236 * If CPU number can be stored in IP, store it there, otherwise store it in
237 * the time stamp. This means more timestamp resolution is available when
238 * the CPU can be stored in the IP.
239 */
240 #ifdef PSTORE_CPU_IN_IP
241 static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record * rec,unsigned int cpu)242 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
243 {
244 rec->ip |= cpu;
245 }
246
247 static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record * rec)248 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
249 {
250 return rec->ip & PSTORE_CPU_IN_IP;
251 }
252
253 static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record * rec)254 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
255 {
256 return rec->ts;
257 }
258
259 static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record * rec,u64 val)260 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
261 {
262 rec->ts = val;
263 }
264 #else
265 static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record * rec,unsigned int cpu)266 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
267 {
268 rec->ts &= ~(TS_CPU_MASK);
269 rec->ts |= cpu;
270 }
271
272 static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record * rec)273 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
274 {
275 return rec->ts & TS_CPU_MASK;
276 }
277
278 static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record * rec)279 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
280 {
281 return rec->ts >> TS_CPU_SHIFT;
282 }
283
284 static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record * rec,u64 val)285 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
286 {
287 rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT);
288 }
289 #endif
290
291 #endif /*_LINUX_PSTORE_H*/
292