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 typedef bool (*ring_buffer_cond_fn)(void *data); 102 int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full, 103 ring_buffer_cond_fn cond, void *data); 104 __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu, 105 struct file *filp, poll_table *poll_table, int full); 106 void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu); 107 108 #define RING_BUFFER_ALL_CPUS -1 109 110 void ring_buffer_free(struct trace_buffer *buffer); 111 112 int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu); 113 114 void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val); 115 116 struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer, 117 unsigned long length); 118 int ring_buffer_unlock_commit(struct trace_buffer *buffer); 119 int ring_buffer_write(struct trace_buffer *buffer, 120 unsigned long length, void *data); 121 122 void ring_buffer_nest_start(struct trace_buffer *buffer); 123 void ring_buffer_nest_end(struct trace_buffer *buffer); 124 125 struct ring_buffer_event * 126 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts, 127 unsigned long *lost_events); 128 struct ring_buffer_event * 129 ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts, 130 unsigned long *lost_events); 131 132 struct ring_buffer_iter * 133 ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags); 134 void ring_buffer_read_prepare_sync(void); 135 void ring_buffer_read_start(struct ring_buffer_iter *iter); 136 void ring_buffer_read_finish(struct ring_buffer_iter *iter); 137 138 struct ring_buffer_event * 139 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts); 140 void ring_buffer_iter_advance(struct ring_buffer_iter *iter); 141 void ring_buffer_iter_reset(struct ring_buffer_iter *iter); 142 int ring_buffer_iter_empty(struct ring_buffer_iter *iter); 143 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter); 144 145 unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu); 146 unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer); 147 148 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu); 149 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer); 150 void ring_buffer_reset(struct trace_buffer *buffer); 151 152 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP 153 int ring_buffer_swap_cpu(struct trace_buffer *buffer_a, 154 struct trace_buffer *buffer_b, int cpu); 155 #else 156 static inline int 157 ring_buffer_swap_cpu(struct trace_buffer *buffer_a, 158 struct trace_buffer *buffer_b, int cpu) 159 { 160 return -ENODEV; 161 } 162 #endif 163 164 bool ring_buffer_empty(struct trace_buffer *buffer); 165 bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu); 166 167 void ring_buffer_record_disable(struct trace_buffer *buffer); 168 void ring_buffer_record_enable(struct trace_buffer *buffer); 169 void ring_buffer_record_off(struct trace_buffer *buffer); 170 void ring_buffer_record_on(struct trace_buffer *buffer); 171 bool ring_buffer_record_is_on(struct trace_buffer *buffer); 172 bool ring_buffer_record_is_set_on(struct trace_buffer *buffer); 173 void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu); 174 void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu); 175 176 u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu); 177 unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu); 178 unsigned long ring_buffer_entries(struct trace_buffer *buffer); 179 unsigned long ring_buffer_overruns(struct trace_buffer *buffer); 180 unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu); 181 unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu); 182 unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu); 183 unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu); 184 unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu); 185 186 u64 ring_buffer_time_stamp(struct trace_buffer *buffer); 187 void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer, 188 int cpu, u64 *ts); 189 void ring_buffer_set_clock(struct trace_buffer *buffer, 190 u64 (*clock)(void)); 191 void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs); 192 bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer); 193 194 size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu); 195 size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu); 196 197 struct buffer_data_read_page; 198 struct buffer_data_read_page * 199 ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu); 200 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, 201 struct buffer_data_read_page *page); 202 int ring_buffer_read_page(struct trace_buffer *buffer, 203 struct buffer_data_read_page *data_page, 204 size_t len, int cpu, int full); 205 void *ring_buffer_read_page_data(struct buffer_data_read_page *page); 206 207 struct trace_seq; 208 209 int ring_buffer_print_entry_header(struct trace_seq *s); 210 int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s); 211 212 int ring_buffer_subbuf_order_get(struct trace_buffer *buffer); 213 int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order); 214 int ring_buffer_subbuf_size_get(struct trace_buffer *buffer); 215 216 enum ring_buffer_flags { 217 RB_FL_OVERWRITE = 1 << 0, 218 }; 219 220 #ifdef CONFIG_RING_BUFFER 221 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node); 222 #else 223 #define trace_rb_cpu_prepare NULL 224 #endif 225 226 #endif /* _LINUX_RING_BUFFER_H */ 227