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