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TOMOYO Linux Cross Reference
Linux/include/linux/pstore.h

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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*/
279 

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