1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_RING_BUFFER_H 3 #define _LINUX_RING_BUFFER_H 4 5 #include <linux/kmemcheck.h> 6 #include <linux/mm.h> 7 #include <linux/seq_file.h> 8 #include <linux/poll.h> 9 10 struct ring_buffer; 11 struct ring_buffer_iter; 12 13 /* 14 * Don't refer to this struct directly, use functions below. 15 */ 16 struct ring_buffer_event { 17 kmemcheck_bitfield_begin(bitfield); 18 u32 type_len:5, time_delta:27; 19 kmemcheck_bitfield_end(bitfield); 20 21 u32 array[]; 22 }; 23 24 /** 25 * enum ring_buffer_type - internal ring buffer types 26 * 27 * @RINGBUF_TYPE_PADDING: Left over page padding or discarded event 28 * If time_delta is 0: 29 * array is ignored 30 * size is variable depending on how much 31 * padding is needed 32 * If time_delta is non zero: 33 * array[0] holds the actual length 34 * size = 4 + length (bytes) 35 * 36 * @RINGBUF_TYPE_TIME_EXTEND: Extend the time delta 37 * array[0] = time delta (28 .. 59) 38 * size = 8 bytes 39 * 40 * @RINGBUF_TYPE_TIME_STAMP: Sync time stamp with external clock 41 * array[0] = tv_nsec 42 * array[1..2] = tv_sec 43 * size = 16 bytes 44 * 45 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX: 46 * Data record 47 * If type_len is zero: 48 * array[0] holds the actual length 49 * array[1..(length+3)/4] holds data 50 * size = 4 + length (bytes) 51 * else 52 * length = type_len << 2 53 * array[0..(length+3)/4-1] holds data 54 * size = 4 + length (bytes) 55 */ 56 enum ring_buffer_type { 57 RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28, 58 RINGBUF_TYPE_PADDING, 59 RINGBUF_TYPE_TIME_EXTEND, 60 /* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */ 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 67 /* 68 * ring_buffer_discard_commit will remove an event that has not 69 * ben 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 ring_buffer *buffer, 82 struct ring_buffer_event *event); 83 84 /* 85 * size is in bytes for each per CPU buffer. 86 */ 87 struct ring_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 ring_buffer *buffer, int cpu, bool full); 102 int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu, 103 struct file *filp, poll_table *poll_table); 104 105 106 #define RING_BUFFER_ALL_CPUS -1 107 108 void ring_buffer_free(struct ring_buffer *buffer); 109 110 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu); 111 112 void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val); 113 114 struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer, 115 unsigned long length); 116 int ring_buffer_unlock_commit(struct ring_buffer *buffer, 117 struct ring_buffer_event *event); 118 int ring_buffer_write(struct ring_buffer *buffer, 119 unsigned long length, void *data); 120 121 struct ring_buffer_event * 122 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts, 123 unsigned long *lost_events); 124 struct ring_buffer_event * 125 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts, 126 unsigned long *lost_events); 127 128 struct ring_buffer_iter * 129 ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu); 130 void ring_buffer_read_prepare_sync(void); 131 void ring_buffer_read_start(struct ring_buffer_iter *iter); 132 void ring_buffer_read_finish(struct ring_buffer_iter *iter); 133 134 struct ring_buffer_event * 135 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts); 136 struct ring_buffer_event * 137 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts); 138 void ring_buffer_iter_reset(struct ring_buffer_iter *iter); 139 int ring_buffer_iter_empty(struct ring_buffer_iter *iter); 140 141 unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu); 142 143 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu); 144 void ring_buffer_reset(struct ring_buffer *buffer); 145 146 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP 147 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, 148 struct ring_buffer *buffer_b, int cpu); 149 #else 150 static inline int 151 ring_buffer_swap_cpu(struct ring_buffer *buffer_a, 152 struct ring_buffer *buffer_b, int cpu) 153 { 154 return -ENODEV; 155 } 156 #endif 157 158 bool ring_buffer_empty(struct ring_buffer *buffer); 159 bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu); 160 161 void ring_buffer_record_disable(struct ring_buffer *buffer); 162 void ring_buffer_record_enable(struct ring_buffer *buffer); 163 void ring_buffer_record_off(struct ring_buffer *buffer); 164 void ring_buffer_record_on(struct ring_buffer *buffer); 165 int ring_buffer_record_is_on(struct ring_buffer *buffer); 166 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu); 167 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu); 168 169 u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu); 170 unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu); 171 unsigned long ring_buffer_entries(struct ring_buffer *buffer); 172 unsigned long ring_buffer_overruns(struct ring_buffer *buffer); 173 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu); 174 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu); 175 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu); 176 unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu); 177 unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu); 178 179 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu); 180 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, 181 int cpu, u64 *ts); 182 void ring_buffer_set_clock(struct ring_buffer *buffer, 183 u64 (*clock)(void)); 184 185 size_t ring_buffer_page_len(void *page); 186 187 188 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu); 189 void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data); 190 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page, 191 size_t len, int cpu, int full); 192 193 struct trace_seq; 194 195 int ring_buffer_print_entry_header(struct trace_seq *s); 196 int ring_buffer_print_page_header(struct trace_seq *s); 197 198 enum ring_buffer_flags { 199 RB_FL_OVERWRITE = 1 << 0, 200 }; 201 202 #ifdef CONFIG_RING_BUFFER 203 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node); 204 #else 205 #define trace_rb_cpu_prepare NULL 206 #endif 207 208 #endif /* _LINUX_RING_BUFFER_H */ 209