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 /*
  36  * pstore record types (see fs/pstore/platform.c for pstore_type_names[])
  37  * These values may be written to storage (see EFI vars backend), so
  38  * they are kind of an ABI. Be careful changing the mappings.
  39  */
  40 enum pstore_type_id {
  41         /* Frontend storage types */
  42         PSTORE_TYPE_DMESG       = 0,
  43         PSTORE_TYPE_MCE         = 1,
  44         PSTORE_TYPE_CONSOLE     = 2,
  45         PSTORE_TYPE_FTRACE      = 3,
  46
  47         /* PPC64-specific partition types */
  48         PSTORE_TYPE_PPC_RTAS    = 4,
  49         PSTORE_TYPE_PPC_OF      = 5,
  50         PSTORE_TYPE_PPC_COMMON  = 6,
  51         PSTORE_TYPE_PMSG        = 7,
  52         PSTORE_TYPE_PPC_OPAL    = 8,
  53
  54         /* End of the list */
  55         PSTORE_TYPE_MAX
  56 };
  57
  58 const char *pstore_type_to_name(enum pstore_type_id type);
  59 enum pstore_type_id pstore_name_to_type(const char *name);
  60
  61 struct pstore_info;
  62 /**
  63  * struct pstore_record - details of a pstore record entry
  64  * @psi:        pstore backend driver information
  65  * @type:       pstore record type
  66  * @id:         per-type unique identifier for record
  67  * @time:       timestamp of the record
  68  * @buf:        pointer to record contents
  69  * @size:       size of @buf
  70  * @ecc_notice_size:
  71  *              ECC information for @buf
  72  *
  73  * Valid for PSTORE_TYPE_DMESG @type:
  74  *
  75  * @count:      Oops count since boot
  76  * @reason:     kdump reason for notification
  77  * @part:       position in a multipart record
  78  * @compressed: whether the buffer is compressed
  79  *
  80  */
  81 struct pstore_record {
  82         struct pstore_info      *psi;
  83         enum pstore_type_id     type;
  84         u64                     id;
  85         struct timespec64       time;
  86         char                    *buf;
  87         ssize_t                 size;
  88         ssize_t                 ecc_notice_size;
  89
  90         int                     count;
  91         enum kmsg_dump_reason   reason;
  92         unsigned int            part;
  93         bool                    compressed;
  94 };
  95
  96 /**
  97  * struct pstore_info - backend pstore driver structure
  98  *
  99  * @owner:      module which is responsible for this backend driver
 100  * @name:       name of the backend driver
 101  *
 102  * @buf_lock:   semaphore to serialize access to @buf
 103  * @buf:        preallocated crash dump buffer
 104  * @bufsize:    size of @buf available for crash dump bytes (must match
 105  *              smallest number of bytes available for writing to a
 106  *              backend entry, since compressed bytes don't take kindly
 107  *              to being truncated)
 108  *
 109  * @read_mutex: serializes @open, @read, @close, and @erase callbacks
 110  * @flags:      bitfield of frontends the backend can accept writes for
 111  * @data:       backend-private pointer passed back during callbacks
 112  *
 113  * Callbacks:
 114  *
 115  * @open:
 116  *      Notify backend that pstore is starting a full read of backend
 117  *      records. Followed by one or more @read calls, and a final @close.
 118  *
 119  *      @psi:   in: pointer to the struct pstore_info for the backend
 120  *
 121  *      Returns 0 on success, and non-zero on error.
 122  *
 123  * @close:
 124  *      Notify backend that pstore has finished a full read of backend
 125  *      records. Always preceded by an @open call and one or more @read
 126  *      calls.
 127  *
 128  *      @psi:   in: pointer to the struct pstore_info for the backend
 129  *
 130  *      Returns 0 on success, and non-zero on error. (Though pstore will
 131  *      ignore the error.)
 132  *
 133  * @read:
 134  *      Read next available backend record. Called after a successful
 135  *      @open.
 136  *
 137  *      @record:
 138  *              pointer to record to populate. @buf should be allocated
 139  *              by the backend and filled. At least @type and @id should
 140  *              be populated, since these are used when creating pstorefs
 141  *              file names.
 142  *
 143  *      Returns record size on success, zero when no more records are
 144  *      available, or negative on error.
 145  *
 146  * @write:
 147  *      A newly generated record needs to be written to backend storage.
 148  *
 149  *      @record:
 150  *              pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
 151  *              @buf will be pointing to the preallocated @psi.buf, since
 152  *              memory allocation may be broken during an Oops. Regardless,
 153  *              @buf must be proccesed or copied before returning. The
 154  *              backend is also expected to write @id with something that
 155  *              can help identify this record to a future @erase callback.
 156  *              The @time field will be prepopulated with the current time,
 157  *              when available. The @size field will have the size of data
 158  *              in @buf.
 159  *
 160  *      Returns 0 on success, and non-zero on error.
 161  *
 162  * @write_user:
 163  *      Perform a frontend write to a backend record, using a specified
 164  *      buffer that is coming directly from userspace, instead of the
 165  *      @record @buf.
 166  *
 167  *      @record:        pointer to record metadata.
 168  *      @buf:           pointer to userspace contents to write to backend
 169  *
 170  *      Returns 0 on success, and non-zero on error.
 171  *
 172  * @erase:
 173  *      Delete a record from backend storage.  Different backends
 174  *      identify records differently, so entire original record is
 175  *      passed back to assist in identification of what the backend
 176  *      should remove from storage.
 177  *
 178  *      @record:        pointer to record metadata.
 179  *
 180  *      Returns 0 on success, and non-zero on error.
 181  *
 182  */
 183 struct pstore_info {
 184         struct module   *owner;
 185         char            *name;
 186
 187         struct semaphore buf_lock;
 188         char            *buf;
 189         size_t          bufsize;
 190
 191         struct mutex    read_mutex;
 192
 193         int             flags;
 194         void            *data;
 195
 196         int             (*open)(struct pstore_info *psi);
 197         int             (*close)(struct pstore_info *psi);
 198         ssize_t         (*read)(struct pstore_record *record);
 199         int             (*write)(struct pstore_record *record);
 200         int             (*write_user)(struct pstore_record *record,
 201                                       const char __user *buf);
 202         int             (*erase)(struct pstore_record *record);
 203 };
 204
 205 /* Supported frontends */
 206 #define PSTORE_FLAGS_DMESG      BIT(0)
 207 #define PSTORE_FLAGS_CONSOLE    BIT(1)
 208 #define PSTORE_FLAGS_FTRACE     BIT(2)
 209 #define PSTORE_FLAGS_PMSG       BIT(3)
 210
 211 extern int pstore_register(struct pstore_info *);
 212 extern void pstore_unregister(struct pstore_info *);
 213
 214 struct pstore_ftrace_record {
 215         unsigned long ip;
 216         unsigned long parent_ip;
 217         u64 ts;
 218 };
 219
 220 /*
 221  * ftrace related stuff: Both backends and frontends need these so expose
 222  * them here.
 223  */
 224
 225 #if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
 226 #define PSTORE_CPU_IN_IP 0x1
 227 #elif NR_CPUS <= 4 && defined(CONFIG_ARM)
 228 #define PSTORE_CPU_IN_IP 0x3
 229 #endif
 230
 231 #define TS_CPU_SHIFT 8
 232 #define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1)
 233
 234 /*
 235  * If CPU number can be stored in IP, store it there, otherwise store it in
 236  * the time stamp. This means more timestamp resolution is available when
 237  * the CPU can be stored in the IP.
 238  */
 239 #ifdef PSTORE_CPU_IN_IP
 240 static inline void
 241 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
 242 {
 243         rec->ip |= cpu;
 244 }
 245
 246 static inline unsigned int
 247 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
 248 {
 249         return rec->ip & PSTORE_CPU_IN_IP;
 250 }
 251
 252 static inline u64
 253 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
 254 {
 255         return rec->ts;
 256 }
 257
 258 static inline void
 259 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
 260 {
 261         rec->ts = val;
 262 }
 263 #else
 264 static inline void
 265 pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
 266 {
 267         rec->ts &= ~(TS_CPU_MASK);
 268         rec->ts |= cpu;
 269 }
 270
 271 static inline unsigned int
 272 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
 273 {
 274         return rec->ts & TS_CPU_MASK;
 275 }
 276
 277 static inline u64
 278 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
 279 {
 280         return rec->ts >> TS_CPU_SHIFT;
 281 }
 282
 283 static inline void
 284 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
 285 {
 286         rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT);
 287 }
 288 #endif
 289
 290 #endif /*_LINUX_PSTORE_H*/