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 trace_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 trace_buffer *buffer, 65 struct ring_buffer_event *event); 66 67 /* 68 * ring_buffer_discard_commit will remove an event that has not 69 * been committed yet. If this is used, then ring_buffer_unlock_commit 70 * must not be called on the discarded event. This function 71 * will try to remove the event from the ring buffer completely 72 * if another event has not been written after it. 73 * 74 * Example use: 75 * 76 * if (some_condition) 77 * ring_buffer_discard_commit(buffer, event); 78 * else 79 * ring_buffer_unlock_commit(buffer, event); 80 */ 81 void ring_buffer_discard_commit(struct trace_buffer *buffer, 82 struct ring_buffer_event *event); 83 84 /* 85 * size is in bytes for each per CPU buffer. 86 */ 87 struct trace_buffer * 88 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key); 89 90 /* 91 * Because the ring buffer is generic, if other users of the ring buffer get 92 * traced by ftrace, it can produce lockdep warnings. We need to keep each 93 * ring buffer's lock class separate. 94 */ 95 #define ring_buffer_alloc(size, flags) \ 96 ({ \ 97 static struct lock_class_key __key; \ 98 __ring_buffer_alloc((size), (flags), &__key); \ 99 }) 100 101 int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full); 102 __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu, 103 struct file *filp, poll_table *poll_table, int full); 104 void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu); 105 106 #define RING_BUFFER_ALL_CPUS -1 107 108 void ring_buffer_free(struct trace_buffer *buffer); 109 110 int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu); 111 112 void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val); 113 114 struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer, 115 unsigned long length); 116 int ring_buffer_unlock_commit(struct trace_buffer *buffer); 117 int ring_buffer_write(struct trace_buffer *buffer, 118 unsigned long length, void *data); 119 120 void ring_buffer_nest_start(struct trace_buffer *buffer); 121 void ring_buffer_nest_end(struct trace_buffer *buffer); 122 123 struct ring_buffer_event * 124 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts, 125 unsigned long *lost_events); 126 struct ring_buffer_event * 127 ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts, 128 unsigned long *lost_events); 129 130 struct ring_buffer_iter * 131 ring_buffer_read_prepare(struct trace_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 void ring_buffer_iter_advance(struct ring_buffer_iter *iter); 139 void ring_buffer_iter_reset(struct ring_buffer_iter *iter); 140 int ring_buffer_iter_empty(struct ring_buffer_iter *iter); 141 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter); 142 143 unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu); 144 145 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu); 146 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer); 147 void ring_buffer_reset(struct trace_buffer *buffer); 148 149 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP 150 int ring_buffer_swap_cpu(struct trace_buffer *buffer_a, 151 struct trace_buffer *buffer_b, int cpu); 152 #else 153 static inline int 154 ring_buffer_swap_cpu(struct trace_buffer *buffer_a, 155 struct trace_buffer *buffer_b, int cpu) 156 { 157 return -ENODEV; 158 } 159 #endif 160 161 bool ring_buffer_empty(struct trace_buffer *buffer); 162 bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu); 163 164 void ring_buffer_record_disable(struct trace_buffer *buffer); 165 void ring_buffer_record_enable(struct trace_buffer *buffer); 166 void ring_buffer_record_off(struct trace_buffer *buffer); 167 void ring_buffer_record_on(struct trace_buffer *buffer); 168 bool ring_buffer_record_is_on(struct trace_buffer *buffer); 169 bool ring_buffer_record_is_set_on(struct trace_buffer *buffer); 170 void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu); 171 void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu); 172 173 u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu); 174 unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu); 175 unsigned long ring_buffer_entries(struct trace_buffer *buffer); 176 unsigned long ring_buffer_overruns(struct trace_buffer *buffer); 177 unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu); 178 unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu); 179 unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu); 180 unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu); 181 unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu); 182 183 u64 ring_buffer_time_stamp(struct trace_buffer *buffer); 184 void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer, 185 int cpu, u64 *ts); 186 void ring_buffer_set_clock(struct trace_buffer *buffer, 187 u64 (*clock)(void)); 188 void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs); 189 bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer); 190 191 size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu); 192 size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu); 193 194 void *ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu); 195 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data); 196 int ring_buffer_read_page(struct trace_buffer *buffer, void **data_page, 197 size_t len, int cpu, int full); 198 199 struct trace_seq; 200 201 int ring_buffer_print_entry_header(struct trace_seq *s); 202 int ring_buffer_print_page_header(struct trace_seq *s); 203 204 enum ring_buffer_flags { 205 RB_FL_OVERWRITE = 1 << 0, 206 }; 207 208 #ifdef CONFIG_RING_BUFFER 209 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node); 210 #else 211 #define trace_rb_cpu_prepare NULL 212 #endif 213 214 #endif /* _LINUX_RING_BUFFER_H */ 215