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