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