1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_RING_BUFFER_H
3 #define _LINUX_RING_BUFFER_H
4 
5 #include <linux/mm.h>
6 #include <linux/seq_file.h>
7 #include <linux/poll.h>
8 
9 struct ring_buffer;
10 struct ring_buffer_iter;
11 
12 /*
13  * Don't refer to this struct directly, use functions below.
14  */
15 struct ring_buffer_event {
16 	u32		type_len:5, time_delta:27;
17 
18 	u32		array[];
19 };
20 
21 /**
22  * enum ring_buffer_type - internal ring buffer types
23  *
24  * @RINGBUF_TYPE_PADDING:	Left over page padding or discarded event
25  *				 If time_delta is 0:
26  *				  array is ignored
27  *				  size is variable depending on how much
28  *				  padding is needed
29  *				 If time_delta is non zero:
30  *				  array[0] holds the actual length
31  *				  size = 4 + length (bytes)
32  *
33  * @RINGBUF_TYPE_TIME_EXTEND:	Extend the time delta
34  *				 array[0] = time delta (28 .. 59)
35  *				 size = 8 bytes
36  *
37  * @RINGBUF_TYPE_TIME_STAMP:	Absolute timestamp
38  *				 Same format as TIME_EXTEND except that the
39  *				 value is an absolute timestamp, not a delta
40  *				 event.time_delta contains bottom 27 bits
41  *				 array[0] = top (28 .. 59) bits
42  *				 size = 8 bytes
43  *
44  * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
45  *				Data record
46  *				 If type_len is zero:
47  *				  array[0] holds the actual length
48  *				  array[1..(length+3)/4] holds data
49  *				  size = 4 + length (bytes)
50  *				 else
51  *				  length = type_len << 2
52  *				  array[0..(length+3)/4-1] holds data
53  *				  size = 4 + length (bytes)
54  */
55 enum ring_buffer_type {
56 	RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
57 	RINGBUF_TYPE_PADDING,
58 	RINGBUF_TYPE_TIME_EXTEND,
59 	RINGBUF_TYPE_TIME_STAMP,
60 };
61 
62 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
63 void *ring_buffer_event_data(struct ring_buffer_event *event);
64 u64 ring_buffer_event_time_stamp(struct ring_buffer_event *event);
65 
66 /*
67  * ring_buffer_discard_commit will remove an event that has not
68  *   been committed yet. If this is used, then ring_buffer_unlock_commit
69  *   must not be called on the discarded event. This function
70  *   will try to remove the event from the ring buffer completely
71  *   if another event has not been written after it.
72  *
73  * Example use:
74  *
75  *  if (some_condition)
76  *    ring_buffer_discard_commit(buffer, event);
77  *  else
78  *    ring_buffer_unlock_commit(buffer, event);
79  */
80 void ring_buffer_discard_commit(struct ring_buffer *buffer,
81 				struct ring_buffer_event *event);
82 
83 /*
84  * size is in bytes for each per CPU buffer.
85  */
86 struct ring_buffer *
87 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
88 
89 /*
90  * Because the ring buffer is generic, if other users of the ring buffer get
91  * traced by ftrace, it can produce lockdep warnings. We need to keep each
92  * ring buffer's lock class separate.
93  */
94 #define ring_buffer_alloc(size, flags)			\
95 ({							\
96 	static struct lock_class_key __key;		\
97 	__ring_buffer_alloc((size), (flags), &__key);	\
98 })
99 
100 int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full);
101 __poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
102 			  struct file *filp, poll_table *poll_table);
103 
104 
105 #define RING_BUFFER_ALL_CPUS -1
106 
107 void ring_buffer_free(struct ring_buffer *buffer);
108 
109 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);
110 
111 void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);
112 
113 struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
114 						   unsigned long length);
115 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
116 			      struct ring_buffer_event *event);
117 int ring_buffer_write(struct ring_buffer *buffer,
118 		      unsigned long length, void *data);
119 
120 void ring_buffer_nest_start(struct ring_buffer *buffer);
121 void ring_buffer_nest_end(struct ring_buffer *buffer);
122 
123 struct ring_buffer_event *
124 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
125 		 unsigned long *lost_events);
126 struct ring_buffer_event *
127 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
128 		    unsigned long *lost_events);
129 
130 struct ring_buffer_iter *
131 ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu, gfp_t flags);
132 void ring_buffer_read_prepare_sync(void);
133 void ring_buffer_read_start(struct ring_buffer_iter *iter);
134 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
135 
136 struct ring_buffer_event *
137 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
138 struct ring_buffer_event *
139 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
140 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
141 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
142 
143 unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);
144 
145 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
146 void ring_buffer_reset(struct ring_buffer *buffer);
147 
148 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
149 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
150 			 struct ring_buffer *buffer_b, int cpu);
151 #else
152 static inline int
ring_buffer_swap_cpu(struct ring_buffer * buffer_a,struct ring_buffer * buffer_b,int cpu)153 ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
154 		     struct ring_buffer *buffer_b, int cpu)
155 {
156 	return -ENODEV;
157 }
158 #endif
159 
160 bool ring_buffer_empty(struct ring_buffer *buffer);
161 bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
162 
163 void ring_buffer_record_disable(struct ring_buffer *buffer);
164 void ring_buffer_record_enable(struct ring_buffer *buffer);
165 void ring_buffer_record_off(struct ring_buffer *buffer);
166 void ring_buffer_record_on(struct ring_buffer *buffer);
167 bool ring_buffer_record_is_on(struct ring_buffer *buffer);
168 bool ring_buffer_record_is_set_on(struct ring_buffer *buffer);
169 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
170 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
171 
172 u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
173 unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
174 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
175 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
176 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
177 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
178 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
179 unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
180 unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);
181 
182 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
183 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
184 				      int cpu, u64 *ts);
185 void ring_buffer_set_clock(struct ring_buffer *buffer,
186 			   u64 (*clock)(void));
187 void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs);
188 bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer);
189 
190 size_t ring_buffer_page_len(void *page);
191 
192 
193 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
194 void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data);
195 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
196 			  size_t len, int cpu, int full);
197 
198 struct trace_seq;
199 
200 int ring_buffer_print_entry_header(struct trace_seq *s);
201 int ring_buffer_print_page_header(struct trace_seq *s);
202 
203 enum ring_buffer_flags {
204 	RB_FL_OVERWRITE		= 1 << 0,
205 };
206 
207 #ifdef CONFIG_RING_BUFFER
208 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
209 #else
210 #define trace_rb_cpu_prepare	NULL
211 #endif
212 
213 #endif /* _LINUX_RING_BUFFER_H */
214