aboutsummaryrefslogtreecommitdiffstats
path: root/include/linux/pstore.h
blob: e779441e6d26cbaa576abe7f4f89d11e91bbaa19 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Persistent Storage - pstore.h
 *
 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
 *
 * This code is the generic layer to export data records from platform
 * level persistent storage via a file system.
 */
#ifndef _LINUX_PSTORE_H
#define _LINUX_PSTORE_H

#include <linux/compiler.h>
#include <linux/errno.h>
#include <linux/kmsg_dump.h>
#include <linux/mutex.h>
#include <linux/semaphore.h>
#include <linux/time.h>
#include <linux/types.h>

struct module;

/*
 * pstore record types (see fs/pstore/platform.c for pstore_type_names[])
 * These values may be written to storage (see EFI vars backend), so
 * they are kind of an ABI. Be careful changing the mappings.
 */
enum pstore_type_id {
	/* Frontend storage types */
	PSTORE_TYPE_DMESG	= 0,
	PSTORE_TYPE_MCE		= 1,
	PSTORE_TYPE_CONSOLE	= 2,
	PSTORE_TYPE_FTRACE	= 3,

	/* PPC64-specific partition types */
	PSTORE_TYPE_PPC_RTAS	= 4,
	PSTORE_TYPE_PPC_OF	= 5,
	PSTORE_TYPE_PPC_COMMON	= 6,
	PSTORE_TYPE_PMSG	= 7,
	PSTORE_TYPE_PPC_OPAL	= 8,

	/* End of the list */
	PSTORE_TYPE_MAX
};

const char *pstore_type_to_name(enum pstore_type_id type);
enum pstore_type_id pstore_name_to_type(const char *name);

struct pstore_info;
/**
 * struct pstore_record - details of a pstore record entry
 * @psi:	pstore backend driver information
 * @type:	pstore record type
 * @id:		per-type unique identifier for record
 * @time:	timestamp of the record
 * @buf:	pointer to record contents
 * @size:	size of @buf
 * @ecc_notice_size:
 *		ECC information for @buf
 *
 * Valid for PSTORE_TYPE_DMESG @type:
 *
 * @count:	Oops count since boot
 * @reason:	kdump reason for notification
 * @part:	position in a multipart record
 * @compressed:	whether the buffer is compressed
 *
 */
struct pstore_record {
	struct pstore_info	*psi;
	enum pstore_type_id	type;
	u64			id;
	struct timespec64	time;
	char			*buf;
	ssize_t			size;
	ssize_t			ecc_notice_size;

	int			count;
	enum kmsg_dump_reason	reason;
	unsigned int		part;
	bool			compressed;
};

/**
 * struct pstore_info - backend pstore driver structure
 *
 * @owner:	module which is responsible for this backend driver
 * @name:	name of the backend driver
 *
 * @buf_lock:	semaphore to serialize access to @buf
 * @buf:	preallocated crash dump buffer
 * @bufsize:	size of @buf available for crash dump bytes (must match
 *		smallest number of bytes available for writing to a
 *		backend entry, since compressed bytes don't take kindly
 *		to being truncated)
 *
 * @read_mutex:	serializes @open, @read, @close, and @erase callbacks
 * @flags:	bitfield of frontends the backend can accept writes for
 * @data:	backend-private pointer passed back during callbacks
 *
 * Callbacks:
 *
 * @open:
 *	Notify backend that pstore is starting a full read of backend
 *	records. Followed by one or more @read calls, and a final @close.
 *
 *	@psi:	in: pointer to the struct pstore_info for the backend
 *
 *	Returns 0 on success, and non-zero on error.
 *
 * @close:
 *	Notify backend that pstore has finished a full read of backend
 *	records. Always preceded by an @open call and one or more @read
 *	calls.
 *
 *	@psi:	in: pointer to the struct pstore_info for the backend
 *
 *	Returns 0 on success, and non-zero on error. (Though pstore will
 *	ignore the error.)
 *
 * @read:
 *	Read next available backend record. Called after a successful
 *	@open.
 *
 *	@record:
 *		pointer to record to populate. @buf should be allocated
 *		by the backend and filled. At least @type and @id should
 *		be populated, since these are used when creating pstorefs
 *		file names.
 *
 *	Returns record size on success, zero when no more records are
 *	available, or negative on error.
 *
 * @write:
 *	A newly generated record needs to be written to backend storage.
 *
 *	@record:
 *		pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
 *		@buf will be pointing to the preallocated @psi.buf, since
 *		memory allocation may be broken during an Oops. Regardless,
 *		@buf must be proccesed or copied before returning. The
 *		backend is also expected to write @id with something that
 *		can help identify this record to a future @erase callback.
 *		The @time field will be prepopulated with the current time,
 *		when available. The @size field will have the size of data
 *		in @buf.
 *
 *	Returns 0 on success, and non-zero on error.
 *
 * @write_user:
 *	Perform a frontend write to a backend record, using a specified
 *	buffer that is coming directly from userspace, instead of the
 *	@record @buf.
 *
 *	@record:	pointer to record metadata.
 *	@buf:		pointer to userspace contents to write to backend
 *
 *	Returns 0 on success, and non-zero on error.
 *
 * @erase:
 *	Delete a record from backend storage.  Different backends
 *	identify records differently, so entire original record is
 *	passed back to assist in identification of what the backend
 *	should remove from storage.
 *
 *	@record:	pointer to record metadata.
 *
 *	Returns 0 on success, and non-zero on error.
 *
 */
struct pstore_info {
	struct module	*owner;
	char		*name;

	struct semaphore buf_lock;
	char		*buf;
	size_t		bufsize;

	struct mutex	read_mutex;

	int		flags;
	void		*data;

	int		(*open)(struct pstore_info *psi);
	int		(*close)(struct pstore_info *psi);
	ssize_t		(*read)(struct pstore_record *record);
	int		(*write)(struct pstore_record *record);
	int		(*write_user)(struct pstore_record *record,
				      const char __user *buf);
	int		(*erase)(struct pstore_record *record);
};

/* Supported frontends */
#define PSTORE_FLAGS_DMESG	BIT(0)
#define PSTORE_FLAGS_CONSOLE	BIT(1)
#define PSTORE_FLAGS_FTRACE	BIT(2)
#define PSTORE_FLAGS_PMSG	BIT(3)

extern int pstore_register(struct pstore_info *);
extern void pstore_unregister(struct pstore_info *);

struct pstore_ftrace_record {
	unsigned long ip;
	unsigned long parent_ip;
	u64 ts;
};

/*
 * ftrace related stuff: Both backends and frontends need these so expose
 * them here.
 */

#if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
#define PSTORE_CPU_IN_IP 0x1
#elif NR_CPUS <= 4 && defined(CONFIG_ARM)
#define PSTORE_CPU_IN_IP 0x3
#endif

#define TS_CPU_SHIFT 8
#define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1)

/*
 * If CPU number can be stored in IP, store it there, otherwise store it in
 * the time stamp. This means more timestamp resolution is available when
 * the CPU can be stored in the IP.
 */
#ifdef PSTORE_CPU_IN_IP
static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
{
	rec->ip |= cpu;
}

static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
{
	return rec->ip & PSTORE_CPU_IN_IP;
}

static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
{
	return rec->ts;
}

static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
{
	rec->ts = val;
}
#else
static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
{
	rec->ts &= ~(TS_CPU_MASK);
	rec->ts |= cpu;
}

static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
{
	return rec->ts & TS_CPU_MASK;
}

static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
{
	return rec->ts >> TS_CPU_SHIFT;
}

static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
{
	rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT);
}
#endif

#endif /*_LINUX_PSTORE_H*/