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 #include <uapi/linux/trace_mmap.h>
10
11 struct trace_buffer;
12 struct ring_buffer_iter;
13
14 /*
15 * Don't refer to this struct directly, use functions below.
16 */
17 struct ring_buffer_event {
18 u32 type_len:5, time_delta:27;
19
20 u32 array[];
21 };
22
23 /**
24 * enum ring_buffer_type - internal ring buffer types
25 *
26 * @RINGBUF_TYPE_PADDING: Left over page padding or discarded event
27 * If time_delta is 0:
28 * array is ignored
29 * size is variable depending on how much
30 * padding is needed
31 * If time_delta is non zero:
32 * array[0] holds the actual length
33 * size = 4 + length (bytes)
34 *
35 * @RINGBUF_TYPE_TIME_EXTEND: Extend the time delta
36 * array[0] = time delta (28 .. 59)
37 * size = 8 bytes
38 *
39 * @RINGBUF_TYPE_TIME_STAMP: Absolute timestamp
40 * Same format as TIME_EXTEND except that the
41 * value is an absolute timestamp, not a delta
42 * event.time_delta contains bottom 27 bits
43 * array[0] = top (28 .. 59) bits
44 * size = 8 bytes
45 *
46 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
47 * Data record
48 * If type_len is zero:
49 * array[0] holds the actual length
50 * array[1..(length+3)/4] holds data
51 * size = 4 + length (bytes)
52 * else
53 * length = type_len << 2
54 * array[0..(length+3)/4-1] holds data
55 * size = 4 + length (bytes)
56 */
57 enum ring_buffer_type {
58 RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
59 RINGBUF_TYPE_PADDING,
60 RINGBUF_TYPE_TIME_EXTEND,
61 RINGBUF_TYPE_TIME_STAMP,
62 };
63
64 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
65 void *ring_buffer_event_data(struct ring_buffer_event *event);
66 u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer,
67 struct ring_buffer_event *event);
68
69 /*
70 * ring_buffer_discard_commit will remove an event that has not
71 * been committed yet. If this is used, then ring_buffer_unlock_commit
72 * must not be called on the discarded event. This function
73 * will try to remove the event from the ring buffer completely
74 * if another event has not been written after it.
75 *
76 * Example use:
77 *
78 * if (some_condition)
79 * ring_buffer_discard_commit(buffer, event);
80 * else
81 * ring_buffer_unlock_commit(buffer, event);
82 */
83 void ring_buffer_discard_commit(struct trace_buffer *buffer,
84 struct ring_buffer_event *event);
85
86 /*
87 * size is in bytes for each per CPU buffer.
88 */
89 struct trace_buffer *
90 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
91
92 /*
93 * Because the ring buffer is generic, if other users of the ring buffer get
94 * traced by ftrace, it can produce lockdep warnings. We need to keep each
95 * ring buffer's lock class separate.
96 */
97 #define ring_buffer_alloc(size, flags) \
98 ({ \
99 static struct lock_class_key __key; \
100 __ring_buffer_alloc((size), (flags), &__key); \
101 })
102
103 typedef bool (*ring_buffer_cond_fn)(void *data);
104 int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full,
105 ring_buffer_cond_fn cond, void *data);
106 __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
107 struct file *filp, poll_table *poll_table, int full);
108 void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu);
109
110 #define RING_BUFFER_ALL_CPUS -1
111
112 void ring_buffer_free(struct trace_buffer *buffer);
113
114 int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu);
115
116 void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val);
117
118 struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer,
119 unsigned long length);
120 int ring_buffer_unlock_commit(struct trace_buffer *buffer);
121 int ring_buffer_write(struct trace_buffer *buffer,
122 unsigned long length, void *data);
123
124 void ring_buffer_nest_start(struct trace_buffer *buffer);
125 void ring_buffer_nest_end(struct trace_buffer *buffer);
126
127 struct ring_buffer_event *
128 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
129 unsigned long *lost_events);
130 struct ring_buffer_event *
131 ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
132 unsigned long *lost_events);
133
134 struct ring_buffer_iter *
135 ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags);
136 void ring_buffer_read_prepare_sync(void);
137 void ring_buffer_read_start(struct ring_buffer_iter *iter);
138 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
139
140 struct ring_buffer_event *
141 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
142 void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
143 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
144 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
145 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
146
147 unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
148 unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer);
149
150 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
151 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
152 void ring_buffer_reset(struct trace_buffer *buffer);
153
154 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
155 int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
156 struct trace_buffer *buffer_b, int cpu);
157 #else
158 static inline int
159 ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
160 struct trace_buffer *buffer_b, int cpu)
161 {
162 return -ENODEV;
163 }
164 #endif
165
166 bool ring_buffer_empty(struct trace_buffer *buffer);
167 bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);
168
169 void ring_buffer_record_disable(struct trace_buffer *buffer);
170 void ring_buffer_record_enable(struct trace_buffer *buffer);
171 void ring_buffer_record_off(struct trace_buffer *buffer);
172 void ring_buffer_record_on(struct trace_buffer *buffer);
173 bool ring_buffer_record_is_on(struct trace_buffer *buffer);
174 bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
175 void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
176 void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);
177
178 u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
179 unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
180 unsigned long ring_buffer_entries(struct trace_buffer *buffer);
181 unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
182 unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
183 unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
184 unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
185 unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
186 unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);
187
188 u64 ring_buffer_time_stamp(struct trace_buffer *buffer);
189 void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
190 int cpu, u64 *ts);
191 void ring_buffer_set_clock(struct trace_buffer *buffer,
192 u64 (*clock)(void));
193 void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
194 bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);
195
196 size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);
197
198 struct buffer_data_read_page;
199 struct buffer_data_read_page *
200 ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu);
201 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu,
202 struct buffer_data_read_page *page);
203 int ring_buffer_read_page(struct trace_buffer *buffer,
204 struct buffer_data_read_page *data_page,
205 size_t len, int cpu, int full);
206 void *ring_buffer_read_page_data(struct buffer_data_read_page *page);
207
208 struct trace_seq;
209
210 int ring_buffer_print_entry_header(struct trace_seq *s);
211 int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s);
212
213 int ring_buffer_subbuf_order_get(struct trace_buffer *buffer);
214 int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order);
215 int ring_buffer_subbuf_size_get(struct trace_buffer *buffer);
216
217 enum ring_buffer_flags {
218 RB_FL_OVERWRITE = 1 << 0,
219 };
220
221 #ifdef CONFIG_RING_BUFFER
222 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
223 #else
224 #define trace_rb_cpu_prepare NULL
225 #endif
226
227 int ring_buffer_map(struct trace_buffer *buffer, int cpu,
228 struct vm_area_struct *vma);
229 int ring_buffer_unmap(struct trace_buffer *buffer, int cpu);
230 int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu);
231 #endif /* _LINUX_RING_BUFFER_H */
232
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