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 PSTORE_TYPE_BLACKBOX = 9,
43
44 /* End of the list */
45 PSTORE_TYPE_MAX
46 };
47
48 const char *pstore_type_to_name(enum pstore_type_id type);
49 enum pstore_type_id pstore_name_to_type(const char *name);
50
51 struct pstore_info;
52 /**
53 * struct pstore_record - details of a pstore record entry
54 * @psi: pstore backend driver information
55 * @type: pstore record type
56 * @id: per-type unique identifier for record
57 * @time: timestamp of the record
58 * @buf: pointer to record contents
59 * @size: size of @buf
60 * @ecc_notice_size:
61 * ECC information for @buf
62 *
63 * Valid for PSTORE_TYPE_DMESG @type:
64 *
65 * @count: Oops count since boot
66 * @reason: kdump reason for notification
67 * @part: position in a multipart record
68 * @compressed: whether the buffer is compressed
69 *
70 */
71 struct pstore_record {
72 struct pstore_info *psi;
73 enum pstore_type_id type;
74 u64 id;
75 struct timespec64 time;
76 char *buf;
77 ssize_t size;
78 ssize_t ecc_notice_size;
79
80 int count;
81 enum kmsg_dump_reason reason;
82 unsigned int part;
83 bool compressed;
84 };
85
86 /**
87 * struct pstore_info - backend pstore driver structure
88 *
89 * @owner: module which is responsible for this backend driver
90 * @name: name of the backend driver
91 *
92 * @buf_lock: spinlock to serialize access to @buf
93 * @buf: preallocated crash dump buffer
94 * @bufsize: size of @buf available for crash dump bytes (must match
95 * smallest number of bytes available for writing to a
96 * backend entry, since compressed bytes don't take kindly
97 * to being truncated)
98 *
99 * @read_mutex: serializes @open, @read, @close, and @erase callbacks
100 * @flags: bitfield of frontends the backend can accept writes for
101 * @max_reason: Used when PSTORE_FLAGS_DMESG is set. Contains the
102 * kmsg_dump_reason enum value. KMSG_DUMP_UNDEF means
103 * "use existing kmsg_dump() filtering, based on the
104 * printk.always_kmsg_dump boot param" (which is either
105 * KMSG_DUMP_OOPS when false, or KMSG_DUMP_MAX when
106 * true); see printk.always_kmsg_dump for more details.
107 * @data: backend-private pointer passed back during callbacks
108 *
109 * Callbacks:
110 *
111 * @open:
112 * Notify backend that pstore is starting a full read of backend
113 * records. Followed by one or more @read calls, and a final @close.
114 *
115 * @psi: in: pointer to the struct pstore_info for the backend
116 *
117 * Returns 0 on success, and non-zero on error.
118 *
119 * @close:
120 * Notify backend that pstore has finished a full read of backend
121 * records. Always preceded by an @open call and one or more @read
122 * calls.
123 *
124 * @psi: in: pointer to the struct pstore_info for the backend
125 *
126 * Returns 0 on success, and non-zero on error. (Though pstore will
127 * ignore the error.)
128 *
129 * @read:
130 * Read next available backend record. Called after a successful
131 * @open.
132 *
133 * @record:
134 * pointer to record to populate. @buf should be allocated
135 * by the backend and filled. At least @type and @id should
136 * be populated, since these are used when creating pstorefs
137 * file names.
138 *
139 * Returns record size on success, zero when no more records are
140 * available, or negative on error.
141 *
142 * @write:
143 * A newly generated record needs to be written to backend storage.
144 *
145 * @record:
146 * pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
147 * @buf will be pointing to the preallocated @psi.buf, since
148 * memory allocation may be broken during an Oops. Regardless,
149 * @buf must be proccesed or copied before returning. The
150 * backend is also expected to write @id with something that
151 * can help identify this record to a future @erase callback.
152 * The @time field will be prepopulated with the current time,
153 * when available. The @size field will have the size of data
154 * in @buf.
155 *
156 * Returns 0 on success, and non-zero on error.
157 *
158 * @write_user:
159 * Perform a frontend write to a backend record, using a specified
160 * buffer that is coming directly from userspace, instead of the
161 * @record @buf.
162 *
163 * @record: pointer to record metadata.
164 * @buf: pointer to userspace contents to write to backend
165 *
166 * Returns 0 on success, and non-zero on error.
167 *
168 * @erase:
169 * Delete a record from backend storage. Different backends
170 * identify records differently, so entire original record is
171 * passed back to assist in identification of what the backend
172 * should remove from storage.
173 *
174 * @record: pointer to record metadata.
175 *
176 * Returns 0 on success, and non-zero on error.
177 *
178 */
179 struct pstore_info {
180 struct module *owner;
181 const char *name;
182
183 spinlock_t buf_lock;
184 char *buf;
185 size_t bufsize;
186
187 struct mutex read_mutex;
188
189 int flags;
190 int max_reason;
191 void *data;
192
193 int (*open)(struct pstore_info *psi);
194 int (*close)(struct pstore_info *psi);
195 ssize_t (*read)(struct pstore_record *record);
196 int (*write)(struct pstore_record *record);
197 int (*write_user)(struct pstore_record *record,
198 const char __user *buf);
199 int (*erase)(struct pstore_record *record);
200 };
201
202 /* Supported frontends */
203 #define PSTORE_FLAGS_DMESG BIT(0)
204 #define PSTORE_FLAGS_CONSOLE BIT(1)
205 #define PSTORE_FLAGS_FTRACE BIT(2)
206 #define PSTORE_FLAGS_PMSG BIT(3)
207 #define PSTORE_FLAGS_BLACKBOX BIT(4)
208
209 extern int pstore_register(struct pstore_info *);
210 extern void pstore_unregister(struct pstore_info *);
211
212 struct pstore_ftrace_record {
213 unsigned long ip;
214 unsigned long parent_ip;
215 u64 ts;
216 };
217
218 /*
219 * ftrace related stuff: Both backends and frontends need these so expose
220 * them here.
221 */
222
223 #if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
224 #define PSTORE_CPU_IN_IP 0x1
225 #elif NR_CPUS <= 4 && defined(CONFIG_ARM)
226 #define PSTORE_CPU_IN_IP 0x3
227 #endif
228
229 #define TS_CPU_SHIFT 8
230 #define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1)
231
232 /*
233 * If CPU number can be stored in IP, store it there, otherwise store it in
234 * the time stamp. This means more timestamp resolution is available when
235 * the CPU can be stored in the IP.
236 */
237 #ifdef PSTORE_CPU_IN_IP
238 static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record * rec,unsigned int cpu)239 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
240 {
241 rec->ip |= cpu;
242 }
243
244 static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record * rec)245 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
246 {
247 return rec->ip & PSTORE_CPU_IN_IP;
248 }
249
250 static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record * rec)251 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
252 {
253 return rec->ts;
254 }
255
256 static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record * rec,u64 val)257 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
258 {
259 rec->ts = val;
260 }
261 #else
262 static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record * rec,unsigned int cpu)263 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
264 {
265 rec->ts &= ~(TS_CPU_MASK);
266 rec->ts |= cpu;
267 }
268
269 static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record * rec)270 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
271 {
272 return rec->ts & TS_CPU_MASK;
273 }
274
275 static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record * rec)276 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
277 {
278 return rec->ts >> TS_CPU_SHIFT;
279 }
280
281 static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record * rec,u64 val)282 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
283 {
284 rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT);
285 }
286 #endif
287
288 #ifdef CONFIG_PSTORE_BLACKBOX
289 extern void pstore_blackbox_dump(struct kmsg_dumper *dumper,
290 enum kmsg_dump_reason reason);
291 #endif
292
293 #endif /*_LINUX_PSTORE_H*/
294