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 	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
pstore_ftrace_encode_cpu(struct pstore_ftrace_record * rec,unsigned int cpu)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
pstore_ftrace_decode_cpu(struct pstore_ftrace_record * rec)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
pstore_ftrace_read_timestamp(struct pstore_ftrace_record * rec)252 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
253 {
254 	return rec->ts;
255 }
256 
257 static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record * rec,u64 val)258 pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
259 {
260 	rec->ts = val;
261 }
262 #else
263 static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record * rec,unsigned int cpu)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
pstore_ftrace_decode_cpu(struct pstore_ftrace_record * rec)271 pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
272 {
273 	return rec->ts & TS_CPU_MASK;
274 }
275 
276 static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record * rec)277 pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
278 {
279 	return rec->ts >> TS_CPU_SHIFT;
280 }
281 
282 static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record * rec,u64 val)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*/
290