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
21struct 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 */
28enum 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
46const char *pstore_type_to_name(enum pstore_type_id type);
47enum pstore_type_id pstore_name_to_type(const char *name);
48
49struct 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 */
72struct 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 */
181struct pstore_info {
182	struct module	*owner;
183	const char	*name;
184
185	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
210extern int pstore_register(struct pstore_info *);
211extern void pstore_unregister(struct pstore_info *);
212
213struct 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
239static inline void
240pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
241{
242	rec->ip |= cpu;
243}
244
245static inline unsigned int
246pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
247{
248	return rec->ip & PSTORE_CPU_IN_IP;
249}
250
251static inline u64
252pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
253{
254	return rec->ts;
255}
256
257static inline void
258pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
259{
260	rec->ts = val;
261}
262#else
263static inline void
264pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
265{
266	rec->ts &= ~(TS_CPU_MASK);
267	rec->ts |= cpu;
268}
269
270static inline unsigned int
271pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
272{
273	return rec->ts & TS_CPU_MASK;
274}
275
276static inline u64
277pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
278{
279	return rec->ts >> TS_CPU_SHIFT;
280}
281
282static inline void
283pstore_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*/
290