include/linux/pstore.h

   1 /*
   2  * Persistent Storage - pstore.h
   3  *
   4  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   5  *
   6  * This code is the generic layer to export data records from platform
   7  * level persistent storage via a file system.
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2 as
  11  *  published by the Free Software Foundation.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to the Free Software
  20  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  */
  22 #ifndef _LINUX_PSTORE_H
  23 #define _LINUX_PSTORE_H
  24
  25 #include <linux/compiler.h>
  26 #include <linux/errno.h>
  27 #include <linux/kmsg_dump.h>
  28 #include <linux/mutex.h>
  29 #include <linux/semaphore.h>
  30 #include <linux/time.h>
  31 #include <linux/types.h>
  32
  33 struct module;
  34
  35 /* pstore record types (see fs/pstore/inode.c for filename templates) */
  36 enum pstore_type_id {
  37         PSTORE_TYPE_DMESG       = 0,
  38         PSTORE_TYPE_MCE         = 1,
  39         PSTORE_TYPE_CONSOLE     = 2,
  40         PSTORE_TYPE_FTRACE      = 3,
  41         /* PPC64 partition types */
  42         PSTORE_TYPE_PPC_RTAS    = 4,
  43         PSTORE_TYPE_PPC_OF      = 5,
  44         PSTORE_TYPE_PPC_COMMON  = 6,
  45         PSTORE_TYPE_PMSG        = 7,
  46         PSTORE_TYPE_PPC_OPAL    = 8,
  47         PSTORE_TYPE_UNKNOWN     = 255
  48 };
  49
  50 struct pstore_info;
  51 /**
  52  * struct pstore_record - details of a pstore record entry
  53  * @psi:        pstore backend driver information
  54  * @type:       pstore record type
  55  * @id:         per-type unique identifier for record
  56  * @time:       timestamp of the record
  57  * @buf:        pointer to record contents
  58  * @size:       size of @buf
  59  * @ecc_notice_size:
  60  *              ECC information for @buf
  61  *
  62  * Valid for PSTORE_TYPE_DMESG @type:
  63  *
  64  * @count:      Oops count since boot
  65  * @reason:     kdump reason for notification
  66  * @part:       position in a multipart record
  67  * @compressed: whether the buffer is compressed
  68  *
  69  */
  70 struct pstore_record {
  71         struct pstore_info      *psi;
  72         enum pstore_type_id     type;
  73         u64                     id;
  74         struct timespec         time;
  75         char                    *buf;
  76         ssize_t                 size;
  77         ssize_t                 ecc_notice_size;
  78
  79         int                     count;
  80         enum kmsg_dump_reason   reason;
  81         unsigned int            part;
  82         bool                    compressed;
  83 };
  84
  85 /**
  86  * struct pstore_info - backend pstore driver structure
  87  *
  88  * @owner:      module which is repsonsible for this backend driver
  89  * @name:       name of the backend driver
  90  *
  91  * @buf_lock:   semaphore to serialize access to @buf
  92  * @buf:        preallocated crash dump buffer
  93  * @bufsize:    size of @buf available for crash dump bytes (must match
  94  *              smallest number of bytes available for writing to a
  95  *              backend entry, since compressed bytes don't take kindly
  96  *              to being truncated)
  97  *
  98  * @read_mutex: serializes @open, @read, @close, and @erase callbacks
  99  * @flags:      bitfield of frontends the backend can accept writes for
 100  * @data:       backend-private pointer passed back during callbacks
 101  *
 102  * Callbacks:
 103  *
 104  * @open:
 105  *      Notify backend that pstore is starting a full read of backend
 106  *      records. Followed by one or more @read calls, and a final @close.
 107  *
 108  *      @psi:   in: pointer to the struct pstore_info for the backend
 109  *
 110  *      Returns 0 on success, and non-zero on error.
 111  *
 112  * @close:
 113  *      Notify backend that pstore has finished a full read of backend
 114  *      records. Always preceded by an @open call and one or more @read
 115  *      calls.
 116  *
 117  *      @psi:   in: pointer to the struct pstore_info for the backend
 118  *
 119  *      Returns 0 on success, and non-zero on error. (Though pstore will
 120  *      ignore the error.)
 121  *
 122  * @read:
 123  *      Read next available backend record. Called after a successful
 124  *      @open.
 125  *
 126  *      @record:
 127  *              pointer to record to populate. @buf should be allocated
 128  *              by the backend and filled. At least @type and @id should
 129  *              be populated, since these are used when creating pstorefs
 130  *              file names.
 131  *
 132  *      Returns record size on success, zero when no more records are
 133  *      available, or negative on error.
 134  *
 135  * @write:
 136  *      A newly generated record needs to be written to backend storage.
 137  *
 138  *      @record:
 139  *              pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
 140  *              @buf will be pointing to the preallocated @psi.buf, since
 141  *              memory allocation may be broken during an Oops. Regardless,
 142  *              @buf must be proccesed or copied before returning. The
 143  *              backend is also expected to write @id with something that
 144  *              can help identify this record to a future @erase callback.
 145  *              The @time field will be prepopulated with the current time,
 146  *              when available. The @size field will have the size of data
 147  *              in @buf.
 148  *
 149  *      Returns 0 on success, and non-zero on error.
 150  *
 151  * @write_user:
 152  *      Perform a frontend write to a backend record, using a specified
 153  *      buffer that is coming directly from userspace, instead of the
 154  *      @record @buf.
 155  *
 156  *      @record:        pointer to record metadata.
 157  *      @buf:           pointer to userspace contents to write to backend
 158  *
 159  *      Returns 0 on success, and non-zero on error.
 160  *
 161  * @erase:
 162  *      Delete a record from backend storage.  Different backends
 163  *      identify records differently, so entire original record is
 164  *      passed back to assist in identification of what the backend
 165  *      should remove from storage.
 166  *
 167  *      @record:        pointer to record metadata.
 168  *
 169  *      Returns 0 on success, and non-zero on error.
 170  *
 171  */
 172 struct pstore_info {
 173         struct module   *owner;
 174         char            *name;
 175
 176         struct semaphore buf_lock;
 177         char            *buf;
 178         size_t          bufsize;
 179
 180         struct mutex    read_mutex;
 181
 182         int             flags;
 183         void            *data;
 184
 185         int             (*open)(struct pstore_info *psi);
 186         int             (*close)(struct pstore_info *psi);
 187         ssize_t         (*read)(struct pstore_record *record);
 188         int             (*write)(struct pstore_record *record);
 189         int             (*write_user)(struct pstore_record *record,
 190                                       const char __user *buf);
 191         int             (*erase)(struct pstore_record *record);
 192 };
 193
 194 /* Supported frontends */
 195 #define PSTORE_FLAGS_DMESG      (1 << 0)
 196 #define PSTORE_FLAGS_CONSOLE    (1 << 1)
 197 #define PSTORE_FLAGS_FTRACE     (1 << 2)
 198 #define PSTORE_FLAGS_PMSG       (1 << 3)
 199
 200 extern int pstore_register(struct pstore_info *);
 201 extern void pstore_unregister(struct pstore_info *);
 202
 203 struct pstore_ftrace_record {
 204         unsigned long ip;
 205         unsigned long parent_ip;
 206         u64 ts;
 207 };
 208
 209 /*
 210  * ftrace related stuff: Both backends and frontends need these so expose
 211  * them here.
 212  */
 213
 214 #if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
 215 #define PSTORE_CPU_IN_IP 0x1
 216 #elif NR_CPUS <= 4 && defined(CONFIG_ARM)
 217 #define PSTORE_CPU_IN_IP 0x3
 218 #endif
 219
 220 #define TS_CPU_SHIFT 8
 221 #define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1)
 222
 223 /*
 224  * If CPU number can be stored in IP, store it there, otherwise store it in
 225  * the time stamp. This means more timestamp resolution is available when
 226  * the CPU can be stored in the IP.
 227  */
 228 #ifdef PSTORE_CPU_IN_IP
 229 static inline void
 230 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
 231 {
 232         rec->ip |= cpu;
 233 }
 234
 235 static inline unsigned int
 236 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
 237 {
 238         return rec->ip & PSTORE_CPU_IN_IP;
 239 }
 240
 241 static inline u64
 242 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
 243 {
 244         return rec->ts;
 245 }
 246
 247 static inline void
 248 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
 249 {
 250         rec->ts = val;
 251 }
 252 #else
 253 static inline void
 254 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
 255 {
 256         rec->ts &= ~(TS_CPU_MASK);
 257         rec->ts |= cpu;
 258 }
 259
 260 static inline unsigned int
 261 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
 262 {
 263         return rec->ts & TS_CPU_MASK;
 264 }
 265
 266 static inline u64
 267 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
 268 {
 269         return rec->ts >> TS_CPU_SHIFT;
 270 }
 271
 272 static inline void
 273 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
 274 {
 275         rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT);
 276 }
 277 #endif
 278
 279 #endif /*_LINUX_PSTORE_H*/