include/linux/pstore.h

   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*/