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
33struct 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 */
40enum 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
58const char *pstore_type_to_name(enum pstore_type_id type);
59enum pstore_type_id pstore_name_to_type(const char *name);
60
61struct 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 */
81struct 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 */
183struct 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
211extern int pstore_register(struct pstore_info *);
212extern void pstore_unregister(struct pstore_info *);
213
214struct 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
240static inline void
241pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
242{
243 rec->ip |= cpu;
244}
245
246static inline unsigned int
247pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
248{
249 return rec->ip & PSTORE_CPU_IN_IP;
250}
251
252static inline u64
253pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
254{
255 return rec->ts;
256}
257
258static inline void
259pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
260{
261 rec->ts = val;
262}
263#else
264static inline void
265pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
266{
267 rec->ts &= ~(TS_CPU_MASK);
268 rec->ts |= cpu;
269}
270
271static inline unsigned int
272pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
273{
274 return rec->ts & TS_CPU_MASK;
275}
276
277static inline u64
278pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
279{
280 return rec->ts >> TS_CPU_SHIFT;
281}
282
283static inline void
284pstore_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*/
291