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/poll.h> 7 #include <linux/ring_buffer_types.h> 8 #include <linux/seq_file.h> 9 10 #include <uapi/linux/trace_mmap.h> 11 12 struct trace_buffer; 13 struct ring_buffer_iter; 14 15 /* 16 * Don't refer to this struct directly, use functions below. 17 */ 18 struct ring_buffer_event { 19 u32 type_len:5, time_delta:27; 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: Absolute timestamp 41 * Same format as TIME_EXTEND except that the 42 * value is an absolute timestamp, not a delta 43 * event.time_delta contains bottom 27 bits 44 * array[0] = top (28 .. 59) bits 45 * size = 8 bytes 46 * 47 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX: 48 * Data record 49 * If type_len is zero: 50 * array[0] holds the actual length 51 * array[1..(length+3)/4] holds data 52 * size = 4 + length (bytes) 53 * else 54 * length = type_len << 2 55 * array[0..(length+3)/4-1] holds data 56 * size = 4 + length (bytes) 57 */ 58 enum ring_buffer_type { 59 RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28, 60 RINGBUF_TYPE_PADDING, 61 RINGBUF_TYPE_TIME_EXTEND, 62 RINGBUF_TYPE_TIME_STAMP, 63 }; 64 65 unsigned ring_buffer_event_length(struct ring_buffer_event *event); 66 void *ring_buffer_event_data(struct ring_buffer_event *event); 67 u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer, 68 struct ring_buffer_event *event); 69 70 /* 71 * ring_buffer_discard_commit will remove an event that has not 72 * been committed yet. If this is used, then ring_buffer_unlock_commit 73 * must not be called on the discarded event. This function 74 * will try to remove the event from the ring buffer completely 75 * if another event has not been written after it. 76 * 77 * Example use: 78 * 79 * if (some_condition) 80 * ring_buffer_discard_commit(buffer, event); 81 * else 82 * ring_buffer_unlock_commit(buffer, event); 83 */ 84 void ring_buffer_discard_commit(struct trace_buffer *buffer, 85 struct ring_buffer_event *event); 86 87 /* 88 * size is in bytes for each per CPU buffer. 89 */ 90 struct trace_buffer * 91 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key); 92 93 struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flags, 94 int order, unsigned long start, 95 unsigned long range_size, 96 unsigned long scratch_size, 97 struct lock_class_key *key); 98 99 void *ring_buffer_meta_scratch(struct trace_buffer *buffer, unsigned int *size); 100 101 /* 102 * A minimum of 2 pages ensures we can always swap a page out of the ring 103 * buffer. This does not account for the reader page or any other page 104 * containing meta data used by static ring buffers. 105 */ 106 #define RING_BUFFER_MIN_NR_PAGES 2UL 107 108 /* 109 * Because the ring buffer is generic, if other users of the ring buffer get 110 * traced by ftrace, it can produce lockdep warnings. We need to keep each 111 * ring buffer's lock class separate. 112 */ 113 #define ring_buffer_alloc(size, flags) \ 114 ({ \ 115 static struct lock_class_key __key; \ 116 __ring_buffer_alloc((size), (flags), &__key); \ 117 }) 118 119 /* 120 * Because the ring buffer is generic, if other users of the ring buffer get 121 * traced by ftrace, it can produce lockdep warnings. We need to keep each 122 * ring buffer's lock class separate. 123 */ 124 #define ring_buffer_alloc_range(size, flags, order, start, range_size, s_size) \ 125 ({ \ 126 static struct lock_class_key __key; \ 127 __ring_buffer_alloc_range((size), (flags), (order), (start), \ 128 (range_size), (s_size), &__key); \ 129 }) 130 131 typedef bool (*ring_buffer_cond_fn)(void *data); 132 int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full, 133 ring_buffer_cond_fn cond, void *data); 134 __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu, 135 struct file *filp, poll_table *poll_table, int full); 136 void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu); 137 138 #define RING_BUFFER_ALL_CPUS -1 139 140 void ring_buffer_free(struct trace_buffer *buffer); 141 142 int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu); 143 144 void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val); 145 146 struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer, 147 unsigned long length); 148 int ring_buffer_unlock_commit(struct trace_buffer *buffer); 149 int ring_buffer_write(struct trace_buffer *buffer, 150 unsigned long length, void *data); 151 152 void ring_buffer_nest_start(struct trace_buffer *buffer); 153 void ring_buffer_nest_end(struct trace_buffer *buffer); 154 155 DEFINE_GUARD(ring_buffer_nest, struct trace_buffer *, 156 ring_buffer_nest_start(_T), ring_buffer_nest_end(_T)) 157 158 struct ring_buffer_event * 159 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts, 160 unsigned long *lost_events); 161 struct ring_buffer_event * 162 ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts, 163 unsigned long *lost_events); 164 165 struct ring_buffer_iter * 166 ring_buffer_read_start(struct trace_buffer *buffer, int cpu, gfp_t flags); 167 void ring_buffer_read_finish(struct ring_buffer_iter *iter); 168 169 struct ring_buffer_event * 170 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts); 171 void ring_buffer_iter_advance(struct ring_buffer_iter *iter); 172 void ring_buffer_iter_reset(struct ring_buffer_iter *iter); 173 int ring_buffer_iter_empty(struct ring_buffer_iter *iter); 174 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter); 175 176 unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu); 177 unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer); 178 179 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu); 180 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer); 181 void ring_buffer_reset(struct trace_buffer *buffer); 182 183 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP 184 int ring_buffer_swap_cpu(struct trace_buffer *buffer_a, 185 struct trace_buffer *buffer_b, int cpu); 186 #else 187 static inline int 188 ring_buffer_swap_cpu(struct trace_buffer *buffer_a, 189 struct trace_buffer *buffer_b, int cpu) 190 { 191 return -ENODEV; 192 } 193 #endif 194 195 bool ring_buffer_empty(struct trace_buffer *buffer); 196 bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu); 197 198 void ring_buffer_record_disable(struct trace_buffer *buffer); 199 void ring_buffer_record_enable(struct trace_buffer *buffer); 200 void ring_buffer_record_off(struct trace_buffer *buffer); 201 void ring_buffer_record_on(struct trace_buffer *buffer); 202 bool ring_buffer_record_is_on(struct trace_buffer *buffer); 203 bool ring_buffer_record_is_set_on(struct trace_buffer *buffer); 204 bool ring_buffer_record_is_on_cpu(struct trace_buffer *buffer, int cpu); 205 void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu); 206 void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu); 207 208 u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu); 209 unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu); 210 unsigned long ring_buffer_entries(struct trace_buffer *buffer); 211 unsigned long ring_buffer_overruns(struct trace_buffer *buffer); 212 unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu); 213 unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu); 214 unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu); 215 unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu); 216 unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu); 217 218 u64 ring_buffer_time_stamp(struct trace_buffer *buffer); 219 void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer, 220 int cpu, u64 *ts); 221 void ring_buffer_set_clock(struct trace_buffer *buffer, 222 u64 (*clock)(void)); 223 void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs); 224 bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer); 225 226 size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu); 227 228 struct buffer_data_read_page; 229 int ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu, 230 struct buffer_data_read_page **rpage); 231 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, 232 struct buffer_data_read_page *page); 233 int ring_buffer_read_page(struct trace_buffer *buffer, 234 struct buffer_data_read_page *data_page, 235 size_t len, int cpu, int full); 236 void *ring_buffer_read_page_data(struct buffer_data_read_page *page); 237 unsigned int ring_buffer_read_page_size(struct buffer_data_read_page *rpage); 238 239 struct trace_seq; 240 241 int ring_buffer_print_entry_header(struct trace_seq *s); 242 int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s); 243 244 int ring_buffer_subbuf_order_get(struct trace_buffer *buffer); 245 int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order); 246 int ring_buffer_subbuf_size_get(struct trace_buffer *buffer); 247 248 enum ring_buffer_flags { 249 RB_FL_OVERWRITE = 1 << 0, 250 RB_FL_TESTING = 1 << 1, 251 }; 252 253 #ifdef CONFIG_RING_BUFFER 254 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node); 255 #else 256 #define trace_rb_cpu_prepare NULL 257 #endif 258 259 int ring_buffer_map(struct trace_buffer *buffer, int cpu, 260 struct vm_area_struct *vma); 261 void ring_buffer_map_dup(struct trace_buffer *buffer, int cpu); 262 int ring_buffer_unmap(struct trace_buffer *buffer, int cpu); 263 int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu); 264 265 struct ring_buffer_desc { 266 int cpu; 267 unsigned int nr_page_va; /* excludes the meta page */ 268 unsigned long meta_va; 269 unsigned long page_va[] __counted_by(nr_page_va); 270 }; 271 272 struct trace_buffer_desc { 273 int nr_cpus; 274 size_t struct_len; 275 char __data[]; /* list of ring_buffer_desc */ 276 }; 277 278 static inline struct ring_buffer_desc *__next_ring_buffer_desc(struct ring_buffer_desc *desc) 279 { 280 size_t len = struct_size(desc, page_va, desc->nr_page_va); 281 282 return (struct ring_buffer_desc *)((void *)desc + len); 283 } 284 285 static inline struct ring_buffer_desc *__first_ring_buffer_desc(struct trace_buffer_desc *desc) 286 { 287 return (struct ring_buffer_desc *)(&desc->__data[0]); 288 } 289 290 /* 291 * Returns the number of pages for a ring_buffer_desc. The caller must ensure it 292 * does not overflow ring_buffer_desc::nr_page_va. 293 */ 294 static inline unsigned long __calc_nr_pages_ring_buffer_desc(size_t size) 295 { 296 /* Takes into account the reader page */ 297 return max(DIV_ROUND_UP(size, PAGE_SIZE - BUF_PAGE_HDR_SIZE), RING_BUFFER_MIN_NR_PAGES) + 1; 298 } 299 300 static inline size_t trace_buffer_desc_size(size_t buffer_size, unsigned int nr_cpus) 301 { 302 unsigned long nr_pages = __calc_nr_pages_ring_buffer_desc(buffer_size); 303 struct ring_buffer_desc *rbdesc; 304 305 /* Capped by ring_buffer_desc::nr_page_va */ 306 if (nr_pages > UINT_MAX) 307 return SIZE_MAX; 308 309 return size_add(offsetof(struct trace_buffer_desc, __data), 310 size_mul(nr_cpus, struct_size(rbdesc, page_va, nr_pages))); 311 } 312 313 #define for_each_ring_buffer_desc(__pdesc, __cpu, __trace_pdesc) \ 314 for (__pdesc = __first_ring_buffer_desc(__trace_pdesc), __cpu = 0; \ 315 (__cpu) < (__trace_pdesc)->nr_cpus; \ 316 (__cpu)++, __pdesc = __next_ring_buffer_desc(__pdesc)) 317 318 struct ring_buffer_remote { 319 struct trace_buffer_desc *desc; 320 int (*swap_reader_page)(unsigned int cpu, void *priv); 321 int (*reset)(unsigned int cpu, void *priv); 322 void *priv; 323 }; 324 325 int ring_buffer_poll_remote(struct trace_buffer *buffer, int cpu); 326 327 struct trace_buffer * 328 __ring_buffer_alloc_remote(struct ring_buffer_remote *remote, 329 struct lock_class_key *key); 330 331 #define ring_buffer_alloc_remote(remote) \ 332 ({ \ 333 static struct lock_class_key __key; \ 334 __ring_buffer_alloc_remote(remote, &__key); \ 335 }) 336 #endif /* _LINUX_RING_BUFFER_H */ 337