1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 * 26 * Portions Copyright (c) 2012 by Delphix. All rights reserved. 27 * Portions Copyright (c) 2016 by Joyent, Inc. 28 */ 29 30 #ifndef _SYS_DTRACE_IMPL_H 31 #define _SYS_DTRACE_IMPL_H 32 33 #ifdef __cplusplus 34 extern "C" { 35 #endif 36 37 /* 38 * DTrace Dynamic Tracing Software: Kernel Implementation Interfaces 39 * 40 * Note: The contents of this file are private to the implementation of the 41 * Solaris system and DTrace subsystem and are subject to change at any time 42 * without notice. Applications and drivers using these interfaces will fail 43 * to run on future releases. These interfaces should not be used for any 44 * purpose except those expressly outlined in dtrace(7D) and libdtrace(3LIB). 45 * Please refer to the "Solaris Dynamic Tracing Guide" for more information. 46 */ 47 48 #include <sys/dtrace.h> 49 #include <kern/kalloc.h> 50 51 /* 52 * DTrace Implementation Locks 53 */ 54 extern lck_attr_t dtrace_lck_attr; 55 extern lck_grp_t dtrace_lck_grp; 56 extern lck_mtx_t dtrace_procwaitfor_lock; 57 58 /* 59 * DTrace Implementation Constants and Typedefs 60 */ 61 #define DTRACE_MAXPROPLEN 128 62 #define DTRACE_DYNVAR_CHUNKSIZE 256 63 64 struct dtrace_probe; 65 struct dtrace_ecb; 66 struct dtrace_predicate; 67 struct dtrace_action; 68 struct dtrace_provider; 69 struct dtrace_state; 70 71 typedef struct dtrace_probe dtrace_probe_t; 72 typedef struct dtrace_ecb dtrace_ecb_t; 73 typedef struct dtrace_predicate dtrace_predicate_t; 74 typedef struct dtrace_action dtrace_action_t; 75 typedef struct dtrace_provider dtrace_provider_t; 76 typedef struct dtrace_meta dtrace_meta_t; 77 typedef struct dtrace_state dtrace_state_t; 78 typedef uint32_t dtrace_optid_t; 79 typedef uint32_t dtrace_specid_t; 80 typedef uint64_t dtrace_genid_t; 81 82 /* 83 * DTrace Probes 84 * 85 * The probe is the fundamental unit of the DTrace architecture. Probes are 86 * created by DTrace providers, and managed by the DTrace framework. A probe 87 * is identified by a unique <provider, module, function, name> tuple, and has 88 * a unique probe identifier assigned to it. (Some probes are not associated 89 * with a specific point in text; these are called _unanchored probes_ and have 90 * no module or function associated with them.) Probes are represented as a 91 * dtrace_probe structure. To allow quick lookups based on each element of the 92 * probe tuple, probes are hashed by each of provider, module, function and 93 * name. (If a lookup is performed based on a regular expression, a 94 * dtrace_probekey is prepared, and a linear search is performed.) Each probe 95 * is additionally pointed to by a linear array indexed by its identifier. The 96 * identifier is the provider's mechanism for indicating to the DTrace 97 * framework that a probe has fired: the identifier is passed as the first 98 * argument to dtrace_probe(), where it is then mapped into the corresponding 99 * dtrace_probe structure. From the dtrace_probe structure, dtrace_probe() can 100 * iterate over the probe's list of enabling control blocks; see "DTrace 101 * Enabling Control Blocks", below.) 102 */ 103 struct dtrace_probe { 104 dtrace_id_t dtpr_id; /* probe identifier */ 105 dtrace_ecb_t *dtpr_ecb; /* ECB list; see below */ 106 dtrace_ecb_t *dtpr_ecb_last; /* last ECB in list */ 107 void *dtpr_arg; /* provider argument */ 108 dtrace_cacheid_t dtpr_predcache; /* predicate cache ID */ 109 int dtpr_aframes; /* artificial frames */ 110 dtrace_provider_t *dtpr_provider; /* pointer to provider */ 111 char *dtpr_mod; /* probe's module name */ 112 char *dtpr_func; /* probe's function name */ 113 char *dtpr_name; /* probe's name */ 114 dtrace_probe_t *dtpr_nextprov; /* next in provider hash */ 115 dtrace_probe_t *dtpr_prevprov; /* previous in provider hash */ 116 dtrace_probe_t *dtpr_nextmod; /* next in module hash */ 117 dtrace_probe_t *dtpr_prevmod; /* previous in module hash */ 118 dtrace_probe_t *dtpr_nextfunc; /* next in function hash */ 119 dtrace_probe_t *dtpr_prevfunc; /* previous in function hash */ 120 dtrace_probe_t *dtpr_nextname; /* next in name hash */ 121 dtrace_probe_t *dtpr_prevname; /* previous in name hash */ 122 dtrace_genid_t dtpr_gen; /* probe generation ID */ 123 }; 124 125 typedef int dtrace_probekey_f(const char *, const char *, int); 126 127 typedef struct dtrace_probekey { 128 const char *dtpk_prov; /* provider name to match */ 129 dtrace_probekey_f *dtpk_pmatch; /* provider matching function */ 130 const char *dtpk_mod; /* module name to match */ 131 dtrace_probekey_f *dtpk_mmatch; /* module matching function */ 132 const char *dtpk_func; /* func name to match */ 133 dtrace_probekey_f *dtpk_fmatch; /* func matching function */ 134 const char *dtpk_name; /* name to match */ 135 dtrace_probekey_f *dtpk_nmatch; /* name matching function */ 136 dtrace_id_t dtpk_id; /* identifier to match */ 137 } dtrace_probekey_t; 138 139 typedef struct dtrace_hashbucket { 140 struct dtrace_hashbucket *dthb_next; /* next on hash chain */ 141 void *dthb_chain; /* chain of elements */ 142 int dthb_len; /* number of probes here */ 143 } dtrace_hashbucket_t; 144 145 typedef const char* dtrace_strkey_f(void*, uintptr_t); 146 147 typedef struct dtrace_hash { 148 dtrace_hashbucket_t **dth_tab; /* hash table */ 149 int dth_size; /* size of hash table */ 150 int dth_mask; /* mask to index into table */ 151 int dth_nbuckets; /* total number of buckets */ 152 uintptr_t dth_nextoffs; /* offset of next in element */ 153 uintptr_t dth_prevoffs; /* offset of prev in element */ 154 dtrace_strkey_f *dth_getstr; /* func to retrieve str in element */ 155 uintptr_t dth_stroffs; /* offset of str in element */ 156 } dtrace_hash_t; 157 158 /* 159 * DTrace Enabling Control Blocks 160 * 161 * When a provider wishes to fire a probe, it calls into dtrace_probe(), 162 * passing the probe identifier as the first argument. As described above, 163 * dtrace_probe() maps the identifier into a pointer to a dtrace_probe_t 164 * structure. This structure contains information about the probe, and a 165 * pointer to the list of Enabling Control Blocks (ECBs). Each ECB points to 166 * DTrace consumer state, and contains an optional predicate, and a list of 167 * actions. (Shown schematically below.) The ECB abstraction allows a single 168 * probe to be multiplexed across disjoint consumers, or across disjoint 169 * enablings of a single probe within one consumer. 170 * 171 * Enabling Control Block 172 * dtrace_ecb_t 173 * +------------------------+ 174 * | dtrace_epid_t ---------+--------------> Enabled Probe ID (EPID) 175 * | dtrace_state_t * ------+--------------> State associated with this ECB 176 * | dtrace_predicate_t * --+---------+ 177 * | dtrace_action_t * -----+----+ | 178 * | dtrace_ecb_t * ---+ | | | Predicate (if any) 179 * +-------------------+----+ | | dtrace_predicate_t 180 * | | +---> +--------------------+ 181 * | | | dtrace_difo_t * ---+----> DIFO 182 * | | +--------------------+ 183 * | | 184 * Next ECB | | Action 185 * (if any) | | dtrace_action_t 186 * : +--> +-------------------+ 187 * : | dtrace_actkind_t -+------> kind 188 * v | dtrace_difo_t * --+------> DIFO (if any) 189 * | dtrace_recdesc_t -+------> record descr. 190 * | dtrace_action_t * +------+ 191 * +-------------------+ | 192 * | Next action 193 * +-------------------------------+ (if any) 194 * | 195 * | Action 196 * | dtrace_action_t 197 * +--> +-------------------+ 198 * | dtrace_actkind_t -+------> kind 199 * | dtrace_difo_t * --+------> DIFO (if any) 200 * | dtrace_action_t * +------+ 201 * +-------------------+ | 202 * | Next action 203 * +-------------------------------+ (if any) 204 * | 205 * : 206 * v 207 * 208 * 209 * dtrace_probe() iterates over the ECB list. If the ECB needs less space 210 * than is available in the principal buffer, the ECB is processed: if the 211 * predicate is non-NULL, the DIF object is executed. If the result is 212 * non-zero, the action list is processed, with each action being executed 213 * accordingly. When the action list has been completely executed, processing 214 * advances to the next ECB. The ECB abstraction allows disjoint consumers 215 * to multiplex on single probes. 216 * 217 * Execution of the ECB results in consuming dte_size bytes in the buffer 218 * to record data. During execution, dte_needed bytes must be available in 219 * the buffer. This space is used for both recorded data and tuple data. 220 */ 221 struct dtrace_ecb { 222 dtrace_epid_t dte_epid; /* enabled probe ID */ 223 uint32_t dte_alignment; /* required alignment */ 224 size_t dte_needed; /* space needed for execution */ 225 size_t dte_size; /* size of recorded payload */ 226 dtrace_predicate_t *dte_predicate; /* predicate, if any */ 227 dtrace_action_t *dte_action; /* actions, if any */ 228 dtrace_ecb_t *dte_next; /* next ECB on probe */ 229 dtrace_state_t *dte_state; /* pointer to state */ 230 uint32_t dte_cond; /* security condition */ 231 dtrace_probe_t *dte_probe; /* pointer to probe */ 232 dtrace_action_t *dte_action_last; /* last action on ECB */ 233 uint64_t dte_uarg; /* library argument */ 234 }; 235 236 struct dtrace_predicate { 237 dtrace_difo_t *dtp_difo; /* DIF object */ 238 dtrace_cacheid_t dtp_cacheid; /* cache identifier */ 239 int dtp_refcnt; /* reference count */ 240 }; 241 242 struct dtrace_action { 243 dtrace_actkind_t dta_kind; /* kind of action */ 244 uint16_t dta_intuple; /* boolean: in aggregation */ 245 uint32_t dta_refcnt; /* reference count */ 246 dtrace_difo_t *dta_difo; /* pointer to DIFO */ 247 dtrace_recdesc_t dta_rec; /* record description */ 248 dtrace_action_t *dta_prev; /* previous action */ 249 dtrace_action_t *dta_next; /* next action */ 250 }; 251 252 typedef struct dtrace_aggregation { 253 dtrace_action_t dtag_action; /* action; must be first */ 254 dtrace_aggid_t dtag_id; /* identifier */ 255 dtrace_ecb_t *dtag_ecb; /* corresponding ECB */ 256 dtrace_action_t *dtag_first; /* first action in tuple */ 257 uint32_t dtag_base; /* base of aggregation */ 258 uint8_t dtag_hasarg; /* boolean: has argument */ 259 uint64_t dtag_initial; /* initial value */ 260 void (*dtag_aggregate)(uint64_t *, uint64_t, uint64_t); 261 } dtrace_aggregation_t; 262 263 /* 264 * DTrace Buffers 265 * 266 * Principal buffers, aggregation buffers, and speculative buffers are all 267 * managed with the dtrace_buffer structure. By default, this structure 268 * includes twin data buffers -- dtb_tomax and dtb_xamot -- that serve as the 269 * active and passive buffers, respectively. For speculative buffers, 270 * dtb_xamot will be NULL; for "ring" and "fill" buffers, dtb_xamot will point 271 * to a scratch buffer. For all buffer types, the dtrace_buffer structure is 272 * always allocated on a per-CPU basis; a single dtrace_buffer structure is 273 * never shared among CPUs. (That is, there is never true sharing of the 274 * dtrace_buffer structure; to prevent false sharing of the structure, it must 275 * always be aligned to the coherence granularity -- generally 64 bytes.) 276 * 277 * One of the critical design decisions of DTrace is that a given ECB always 278 * stores the same quantity and type of data. This is done to assure that the 279 * only metadata required for an ECB's traced data is the EPID. That is, from 280 * the EPID, the consumer can determine the data layout. (The data buffer 281 * layout is shown schematically below.) By assuring that one can determine 282 * data layout from the EPID, the metadata stream can be separated from the 283 * data stream -- simplifying the data stream enormously. The ECB always 284 * proceeds the recorded data as part of the dtrace_rechdr_t structure that 285 * includes the EPID and a high-resolution timestamp used for output ordering 286 * consistency. 287 * 288 * base of data buffer ---> +--------+--------------------+--------+ 289 * | rechdr | data | rechdr | 290 * +--------+------+--------+----+--------+ 291 * | data | rechdr | data | 292 * +---------------+--------+-------------+ 293 * | data, cont. | 294 * +--------+--------------------+--------+ 295 * | rechdr | data | | 296 * +--------+--------------------+ | 297 * | || | 298 * | || | 299 * | \/ | 300 * : : 301 * . . 302 * . . 303 * . . 304 * : : 305 * | | 306 * limit of data buffer ---> +--------------------------------------+ 307 * 308 * When evaluating an ECB, dtrace_probe() determines if the ECB's needs of the 309 * principal buffer (both scratch and payload) exceed the available space. If 310 * the ECB's needs exceed available space (and if the principal buffer policy 311 * is the default "switch" policy), the ECB is dropped, the buffer's drop count 312 * is incremented, and processing advances to the next ECB. If the ECB's needs 313 * can be met with the available space, the ECB is processed, but the offset in 314 * the principal buffer is only advanced if the ECB completes processing 315 * without error. 316 * 317 * When a buffer is to be switched (either because the buffer is the principal 318 * buffer with a "switch" policy or because it is an aggregation buffer), a 319 * cross call is issued to the CPU associated with the buffer. In the cross 320 * call context, interrupts are disabled, and the active and the inactive 321 * buffers are atomically switched. This involves switching the data pointers, 322 * copying the various state fields (offset, drops, errors, etc.) into their 323 * inactive equivalents, and clearing the state fields. Because interrupts are 324 * disabled during this procedure, the switch is guaranteed to appear atomic to 325 * dtrace_probe(). 326 * 327 * DTrace Ring Buffering 328 * 329 * To process a ring buffer correctly, one must know the oldest valid record. 330 * Processing starts at the oldest record in the buffer and continues until 331 * the end of the buffer is reached. Processing then resumes starting with 332 * the record stored at offset 0 in the buffer, and continues until the 333 * youngest record is processed. If trace records are of a fixed-length, 334 * determining the oldest record is trivial: 335 * 336 * - If the ring buffer has not wrapped, the oldest record is the record 337 * stored at offset 0. 338 * 339 * - If the ring buffer has wrapped, the oldest record is the record stored 340 * at the current offset. 341 * 342 * With variable length records, however, just knowing the current offset 343 * doesn't suffice for determining the oldest valid record: assuming that one 344 * allows for arbitrary data, one has no way of searching forward from the 345 * current offset to find the oldest valid record. (That is, one has no way 346 * of separating data from metadata.) It would be possible to simply refuse to 347 * process any data in the ring buffer between the current offset and the 348 * limit, but this leaves (potentially) an enormous amount of otherwise valid 349 * data unprocessed. 350 * 351 * To effect ring buffering, we track two offsets in the buffer: the current 352 * offset and the _wrapped_ offset. If a request is made to reserve some 353 * amount of data, and the buffer has wrapped, the wrapped offset is 354 * incremented until the wrapped offset minus the current offset is greater 355 * than or equal to the reserve request. This is done by repeatedly looking 356 * up the ECB corresponding to the EPID at the current wrapped offset, and 357 * incrementing the wrapped offset by the size of the data payload 358 * corresponding to that ECB. If this offset is greater than or equal to the 359 * limit of the data buffer, the wrapped offset is set to 0. Thus, the 360 * current offset effectively "chases" the wrapped offset around the buffer. 361 * Schematically: 362 * 363 * base of data buffer ---> +------+--------------------+------+ 364 * | EPID | data | EPID | 365 * +------+--------+------+----+------+ 366 * | data | EPID | data | 367 * +---------------+------+-----------+ 368 * | data, cont. | 369 * +------+---------------------------+ 370 * | EPID | data | 371 * current offset ---> +------+---------------------------+ 372 * | invalid data | 373 * wrapped offset ---> +------+--------------------+------+ 374 * | EPID | data | EPID | 375 * +------+--------+------+----+------+ 376 * | data | EPID | data | 377 * +---------------+------+-----------+ 378 * : : 379 * . . 380 * . ... valid data ... . 381 * . . 382 * : : 383 * +------+-------------+------+------+ 384 * | EPID | data | EPID | data | 385 * +------+------------++------+------+ 386 * | data, cont. | leftover | 387 * limit of data buffer ---> +-------------------+--------------+ 388 * 389 * If the amount of requested buffer space exceeds the amount of space 390 * available between the current offset and the end of the buffer: 391 * 392 * (1) all words in the data buffer between the current offset and the limit 393 * of the data buffer (marked "leftover", above) are set to 394 * DTRACE_EPIDNONE 395 * 396 * (2) the wrapped offset is set to zero 397 * 398 * (3) the iteration process described above occurs until the wrapped offset 399 * is greater than the amount of desired space. 400 * 401 * The wrapped offset is implemented by (re-)using the inactive offset. 402 * In a "switch" buffer policy, the inactive offset stores the offset in 403 * the inactive buffer; in a "ring" buffer policy, it stores the wrapped 404 * offset. 405 * 406 * DTrace Scratch Buffering 407 * 408 * Some ECBs may wish to allocate dynamically-sized temporary scratch memory. 409 * To accommodate such requests easily, scratch memory may be allocated in 410 * the buffer beyond the current offset plus the needed memory of the current 411 * ECB. If there isn't sufficient room in the buffer for the requested amount 412 * of scratch space, the allocation fails and an error is generated. Scratch 413 * memory is tracked in the dtrace_mstate_t and is automatically freed when 414 * the ECB ceases processing. Note that ring buffers cannot allocate their 415 * scratch from the principal buffer -- lest they needlessly overwrite older, 416 * valid data. Ring buffers therefore have their own dedicated scratch buffer 417 * from which scratch is allocated. 418 */ 419 #define DTRACEBUF_RING 0x0001 /* bufpolicy set to "ring" */ 420 #define DTRACEBUF_FILL 0x0002 /* bufpolicy set to "fill" */ 421 #define DTRACEBUF_NOSWITCH 0x0004 /* do not switch buffer */ 422 #define DTRACEBUF_WRAPPED 0x0008 /* ring buffer has wrapped */ 423 #define DTRACEBUF_DROPPED 0x0010 /* drops occurred */ 424 #define DTRACEBUF_ERROR 0x0020 /* errors occurred */ 425 #define DTRACEBUF_FULL 0x0040 /* "fill" buffer is full */ 426 #define DTRACEBUF_CONSUMED 0x0080 /* buffer has been consumed */ 427 #define DTRACEBUF_INACTIVE 0x0100 /* buffer is not yet active */ 428 429 typedef struct dtrace_buffer { 430 uint64_t dtb_offset; /* current offset in buffer */ 431 uint64_t dtb_cur_limit; /* current limit before signaling/dropping */ 432 uint64_t dtb_limit; /* limit before signaling */ 433 uint64_t dtb_size; /* size of buffer */ 434 uint32_t dtb_flags; /* flags */ 435 uint32_t dtb_drops; /* number of drops */ 436 caddr_t dtb_tomax; /* active buffer */ 437 caddr_t dtb_xamot; /* inactive buffer */ 438 uint32_t dtb_xamot_flags; /* inactive flags */ 439 uint32_t dtb_xamot_drops; /* drops in inactive buffer */ 440 uint64_t dtb_xamot_offset; /* offset in inactive buffer */ 441 uint32_t dtb_errors; /* number of errors */ 442 uint32_t dtb_xamot_errors; /* errors in inactive buffer */ 443 #ifndef _LP64 444 uint64_t dtb_pad1; 445 #endif 446 uint64_t dtb_switched; /* time of last switch */ 447 uint64_t dtb_interval; /* observed switch interval */ 448 uint64_t dtb_pad2[4]; /* pad to avoid false sharing */ 449 } dtrace_buffer_t; 450 451 /* 452 * DTrace Aggregation Buffers 453 * 454 * Aggregation buffers use much of the same mechanism as described above 455 * ("DTrace Buffers"). However, because an aggregation is fundamentally a 456 * hash, there exists dynamic metadata associated with an aggregation buffer 457 * that is not associated with other kinds of buffers. This aggregation 458 * metadata is _only_ relevant for the in-kernel implementation of 459 * aggregations; it is not actually relevant to user-level consumers. To do 460 * this, we allocate dynamic aggregation data (hash keys and hash buckets) 461 * starting below the _limit_ of the buffer, and we allocate data from the 462 * _base_ of the buffer. When the aggregation buffer is copied out, _only_ the 463 * data is copied out; the metadata is simply discarded. Schematically, 464 * aggregation buffers look like: 465 * 466 * base of data buffer ---> +-------+------+-----------+-------+ 467 * | aggid | key | value | aggid | 468 * +-------+------+-----------+-------+ 469 * | key | 470 * +-------+-------+-----+------------+ 471 * | value | aggid | key | value | 472 * +-------+------++-----+------+-----+ 473 * | aggid | key | value | | 474 * +-------+------+-------------+ | 475 * | || | 476 * | || | 477 * | \/ | 478 * : : 479 * . . 480 * . . 481 * . . 482 * : : 483 * | /\ | 484 * | || +------------+ 485 * | || | | 486 * +---------------------+ | 487 * | hash keys | 488 * | (dtrace_aggkey structures) | 489 * | | 490 * +----------------------------------+ 491 * | hash buckets | 492 * | (dtrace_aggbuffer structure) | 493 * | | 494 * limit of data buffer ---> +----------------------------------+ 495 * 496 * 497 * As implied above, just as we assure that ECBs always store a constant 498 * amount of data, we assure that a given aggregation -- identified by its 499 * aggregation ID -- always stores data of a constant quantity and type. 500 * As with EPIDs, this allows the aggregation ID to serve as the metadata for a 501 * given record. 502 * 503 * Note that the size of the dtrace_aggkey structure must be sizeof (uintptr_t) 504 * aligned. (If this the structure changes such that this becomes false, an 505 * assertion will fail in dtrace_aggregate().) 506 */ 507 typedef struct dtrace_aggkey { 508 uint32_t dtak_hashval; /* hash value */ 509 uint32_t dtak_action:4; /* action -- 4 bits */ 510 uint32_t dtak_size:28; /* size -- 28 bits */ 511 caddr_t dtak_data; /* data pointer */ 512 struct dtrace_aggkey *dtak_next; /* next in hash chain */ 513 } dtrace_aggkey_t; 514 515 typedef struct dtrace_aggbuffer { 516 uintptr_t dtagb_hashsize; /* number of buckets */ 517 uintptr_t dtagb_free; /* free list of keys */ 518 dtrace_aggkey_t **dtagb_hash; /* hash table */ 519 } dtrace_aggbuffer_t; 520 521 /* 522 * DTrace Speculations 523 * 524 * Speculations have a per-CPU buffer and a global state. Once a speculation 525 * buffer has been comitted or discarded, it cannot be reused until all CPUs 526 * have taken the same action (commit or discard) on their respective 527 * speculative buffer. However, because DTrace probes may execute in arbitrary 528 * context, other CPUs cannot simply be cross-called at probe firing time to 529 * perform the necessary commit or discard. The speculation states thus 530 * optimize for the case that a speculative buffer is only active on one CPU at 531 * the time of a commit() or discard() -- for if this is the case, other CPUs 532 * need not take action, and the speculation is immediately available for 533 * reuse. If the speculation is active on multiple CPUs, it must be 534 * asynchronously cleaned -- potentially leading to a higher rate of dirty 535 * speculative drops. The speculation states are as follows: 536 * 537 * DTRACESPEC_INACTIVE <= Initial state; inactive speculation 538 * DTRACESPEC_ACTIVE <= Allocated, but not yet speculatively traced to 539 * DTRACESPEC_ACTIVEONE <= Speculatively traced to on one CPU 540 * DTRACESPEC_ACTIVEMANY <= Speculatively traced to on more than one CPU 541 * DTRACESPEC_COMMITTING <= Currently being commited on one CPU 542 * DTRACESPEC_COMMITTINGMANY <= Currently being commited on many CPUs 543 * DTRACESPEC_DISCARDING <= Currently being discarded on many CPUs 544 * 545 * The state transition diagram is as follows: 546 * 547 * +----------------------------------------------------------+ 548 * | | 549 * | +------------+ | 550 * | +-------------------| COMMITTING |<-----------------+ | 551 * | | +------------+ | | 552 * | | copied spec. ^ commit() on | | discard() on 553 * | | into principal | active CPU | | active CPU 554 * | | | commit() | | 555 * V V | | | 556 * +----------+ +--------+ +-----------+ 557 * | INACTIVE |---------------->| ACTIVE |--------------->| ACTIVEONE | 558 * +----------+ speculation() +--------+ speculate() +-----------+ 559 * ^ ^ | | | 560 * | | | discard() | | 561 * | | asynchronously | discard() on | | speculate() 562 * | | cleaned V inactive CPU | | on inactive 563 * | | +------------+ | | CPU 564 * | +-------------------| DISCARDING |<-----------------+ | 565 * | +------------+ | 566 * | asynchronously ^ | 567 * | copied spec. | discard() | 568 * | into principal +------------------------+ | 569 * | | V 570 * +----------------+ commit() +------------+ 571 * | COMMITTINGMANY |<----------------------------------| ACTIVEMANY | 572 * +----------------+ +------------+ 573 */ 574 typedef enum dtrace_speculation_state { 575 DTRACESPEC_INACTIVE = 0, 576 DTRACESPEC_ACTIVE, 577 DTRACESPEC_ACTIVEONE, 578 DTRACESPEC_ACTIVEMANY, 579 DTRACESPEC_COMMITTING, 580 DTRACESPEC_COMMITTINGMANY, 581 DTRACESPEC_DISCARDING 582 } dtrace_speculation_state_t; 583 584 typedef struct dtrace_speculation { 585 dtrace_speculation_state_t dtsp_state; /* current speculation state */ 586 int dtsp_cleaning; /* non-zero if being cleaned */ 587 dtrace_buffer_t *dtsp_buffer; /* speculative buffer */ 588 } dtrace_speculation_t; 589 590 /* 591 * DTrace Dynamic Variables 592 * 593 * The dynamic variable problem is obviously decomposed into two subproblems: 594 * allocating new dynamic storage, and freeing old dynamic storage. The 595 * presence of the second problem makes the first much more complicated -- or 596 * rather, the absence of the second renders the first trivial. This is the 597 * case with aggregations, for which there is effectively no deallocation of 598 * dynamic storage. (Or more accurately, all dynamic storage is deallocated 599 * when a snapshot is taken of the aggregation.) As DTrace dynamic variables 600 * allow for both dynamic allocation and dynamic deallocation, the 601 * implementation of dynamic variables is quite a bit more complicated than 602 * that of their aggregation kin. 603 * 604 * We observe that allocating new dynamic storage is tricky only because the 605 * size can vary -- the allocation problem is much easier if allocation sizes 606 * are uniform. We further observe that in D, the size of dynamic variables is 607 * actually _not_ dynamic -- dynamic variable sizes may be determined by static 608 * analysis of DIF text. (This is true even of putatively dynamically-sized 609 * objects like strings and stacks, the sizes of which are dictated by the 610 * "stringsize" and "stackframes" variables, respectively.) We exploit this by 611 * performing this analysis on all DIF before enabling any probes. For each 612 * dynamic load or store, we calculate the dynamically-allocated size plus the 613 * size of the dtrace_dynvar structure plus the storage required to key the 614 * data. For all DIF, we take the largest value and dub it the _chunksize_. 615 * We then divide dynamic memory into two parts: a hash table that is wide 616 * enough to have every chunk in its own bucket, and a larger region of equal 617 * chunksize units. Whenever we wish to dynamically allocate a variable, we 618 * always allocate a single chunk of memory. Depending on the uniformity of 619 * allocation, this will waste some amount of memory -- but it eliminates the 620 * non-determinism inherent in traditional heap fragmentation. 621 * 622 * Dynamic objects are allocated by storing a non-zero value to them; they are 623 * deallocated by storing a zero value to them. Dynamic variables are 624 * complicated enormously by being shared between CPUs. In particular, 625 * consider the following scenario: 626 * 627 * CPU A CPU B 628 * +---------------------------------+ +---------------------------------+ 629 * | | | | 630 * | allocates dynamic object a[123] | | | 631 * | by storing the value 345 to it | | | 632 * | ---------> | 633 * | | | wishing to load from object | 634 * | | | a[123], performs lookup in | 635 * | | | dynamic variable space | 636 * | <--------- | 637 * | deallocates object a[123] by | | | 638 * | storing 0 to it | | | 639 * | | | | 640 * | allocates dynamic object b[567] | | performs load from a[123] | 641 * | by storing the value 789 to it | | | 642 * : : : : 643 * . . . . 644 * 645 * This is obviously a race in the D program, but there are nonetheless only 646 * two valid values for CPU B's load from a[123]: 345 or 0. Most importantly, 647 * CPU B may _not_ see the value 789 for a[123]. 648 * 649 * There are essentially two ways to deal with this: 650 * 651 * (1) Explicitly spin-lock variables. That is, if CPU B wishes to load 652 * from a[123], it needs to lock a[123] and hold the lock for the 653 * duration that it wishes to manipulate it. 654 * 655 * (2) Avoid reusing freed chunks until it is known that no CPU is referring 656 * to them. 657 * 658 * The implementation of (1) is rife with complexity, because it requires the 659 * user of a dynamic variable to explicitly decree when they are done using it. 660 * Were all variables by value, this perhaps wouldn't be debilitating -- but 661 * dynamic variables of non-scalar types are tracked by reference. That is, if 662 * a dynamic variable is, say, a string, and that variable is to be traced to, 663 * say, the principal buffer, the DIF emulation code returns to the main 664 * dtrace_probe() loop a pointer to the underlying storage, not the contents of 665 * the storage. Further, code calling on DIF emulation would have to be aware 666 * that the DIF emulation has returned a reference to a dynamic variable that 667 * has been potentially locked. The variable would have to be unlocked after 668 * the main dtrace_probe() loop is finished with the variable, and the main 669 * dtrace_probe() loop would have to be careful to not call any further DIF 670 * emulation while the variable is locked to avoid deadlock. More generally, 671 * if one were to implement (1), DIF emulation code dealing with dynamic 672 * variables could only deal with one dynamic variable at a time (lest deadlock 673 * result). To sum, (1) exports too much subtlety to the users of dynamic 674 * variables -- increasing maintenance burden and imposing serious constraints 675 * on future DTrace development. 676 * 677 * The implementation of (2) is also complex, but the complexity is more 678 * manageable. We need to be sure that when a variable is deallocated, it is 679 * not placed on a traditional free list, but rather on a _dirty_ list. Once a 680 * variable is on a dirty list, it cannot be found by CPUs performing a 681 * subsequent lookup of the variable -- but it may still be in use by other 682 * CPUs. To assure that all CPUs that may be seeing the old variable have 683 * cleared out of probe context, a dtrace_sync() can be issued. Once the 684 * dtrace_sync() has completed, it can be known that all CPUs are done 685 * manipulating the dynamic variable -- the dirty list can be atomically 686 * appended to the free list. Unfortunately, there's a slight hiccup in this 687 * mechanism: dtrace_sync() may not be issued from probe context. The 688 * dtrace_sync() must be therefore issued asynchronously from non-probe 689 * context. For this we rely on the DTrace cleaner, a cyclic that runs at the 690 * "cleanrate" frequency. To ease this implementation, we define several chunk 691 * lists: 692 * 693 * - Dirty. Deallocated chunks, not yet cleaned. Not available. 694 * 695 * - Rinsing. Formerly dirty chunks that are currently being asynchronously 696 * cleaned. Not available, but will be shortly. Dynamic variable 697 * allocation may not spin or block for availability, however. 698 * 699 * - Clean. Clean chunks, ready for allocation -- but not on the free list. 700 * 701 * - Free. Available for allocation. 702 * 703 * Moreover, to avoid absurd contention, _each_ of these lists is implemented 704 * on a per-CPU basis. This is only for performance, not correctness; chunks 705 * may be allocated from another CPU's free list. The algorithm for allocation 706 * then is this: 707 * 708 * (1) Attempt to atomically allocate from current CPU's free list. If list 709 * is non-empty and allocation is successful, allocation is complete. 710 * 711 * (2) If the clean list is non-empty, atomically move it to the free list, 712 * and reattempt (1). 713 * 714 * (3) If the dynamic variable space is in the CLEAN state, look for free 715 * and clean lists on other CPUs by setting the current CPU to the next 716 * CPU, and reattempting (1). If the next CPU is the current CPU (that 717 * is, if all CPUs have been checked), atomically switch the state of 718 * the dynamic variable space based on the following: 719 * 720 * - If no free chunks were found and no dirty chunks were found, 721 * atomically set the state to EMPTY. 722 * 723 * - If dirty chunks were found, atomically set the state to DIRTY. 724 * 725 * - If rinsing chunks were found, atomically set the state to RINSING. 726 * 727 * (4) Based on state of dynamic variable space state, increment appropriate 728 * counter to indicate dynamic drops (if in EMPTY state) vs. dynamic 729 * dirty drops (if in DIRTY state) vs. dynamic rinsing drops (if in 730 * RINSING state). Fail the allocation. 731 * 732 * The cleaning cyclic operates with the following algorithm: for all CPUs 733 * with a non-empty dirty list, atomically move the dirty list to the rinsing 734 * list. Perform a dtrace_sync(). For all CPUs with a non-empty rinsing list, 735 * atomically move the rinsing list to the clean list. Perform another 736 * dtrace_sync(). By this point, all CPUs have seen the new clean list; the 737 * state of the dynamic variable space can be restored to CLEAN. 738 * 739 * There exist two final races that merit explanation. The first is a simple 740 * allocation race: 741 * 742 * CPU A CPU B 743 * +---------------------------------+ +---------------------------------+ 744 * | | | | 745 * | allocates dynamic object a[123] | | allocates dynamic object a[123] | 746 * | by storing the value 345 to it | | by storing the value 567 to it | 747 * | | | | 748 * : : : : 749 * . . . . 750 * 751 * Again, this is a race in the D program. It can be resolved by having a[123] 752 * hold the value 345 or a[123] hold the value 567 -- but it must be true that 753 * a[123] have only _one_ of these values. (That is, the racing CPUs may not 754 * put the same element twice on the same hash chain.) This is resolved 755 * simply: before the allocation is undertaken, the start of the new chunk's 756 * hash chain is noted. Later, after the allocation is complete, the hash 757 * chain is atomically switched to point to the new element. If this fails 758 * (because of either concurrent allocations or an allocation concurrent with a 759 * deletion), the newly allocated chunk is deallocated to the dirty list, and 760 * the whole process of looking up (and potentially allocating) the dynamic 761 * variable is reattempted. 762 * 763 * The final race is a simple deallocation race: 764 * 765 * CPU A CPU B 766 * +---------------------------------+ +---------------------------------+ 767 * | | | | 768 * | deallocates dynamic object | | deallocates dynamic object | 769 * | a[123] by storing the value 0 | | a[123] by storing the value 0 | 770 * | to it | | to it | 771 * | | | | 772 * : : : : 773 * . . . . 774 * 775 * Once again, this is a race in the D program, but it is one that we must 776 * handle without corrupting the underlying data structures. Because 777 * deallocations require the deletion of a chunk from the middle of a hash 778 * chain, we cannot use a single-word atomic operation to remove it. For this, 779 * we add a spin lock to the hash buckets that is _only_ used for deallocations 780 * (allocation races are handled as above). Further, this spin lock is _only_ 781 * held for the duration of the delete; before control is returned to the DIF 782 * emulation code, the hash bucket is unlocked. 783 */ 784 typedef struct dtrace_key { 785 uint64_t dttk_value; /* data value or data pointer */ 786 uint64_t dttk_size; /* 0 if by-val, >0 if by-ref */ 787 } dtrace_key_t; 788 789 typedef struct dtrace_tuple { 790 uint32_t dtt_nkeys; /* number of keys in tuple */ 791 uint32_t dtt_pad; /* padding */ 792 dtrace_key_t dtt_key[1]; /* array of tuple keys */ 793 } dtrace_tuple_t; 794 795 typedef struct dtrace_dynvar { 796 uint64_t dtdv_hashval; /* hash value -- 0 if free */ 797 struct dtrace_dynvar *dtdv_next; /* next on list or hash chain */ 798 void *dtdv_data; /* pointer to data */ 799 dtrace_tuple_t dtdv_tuple; /* tuple key */ 800 } dtrace_dynvar_t; 801 802 typedef enum dtrace_dynvar_op { 803 DTRACE_DYNVAR_ALLOC, 804 DTRACE_DYNVAR_NOALLOC, 805 DTRACE_DYNVAR_DEALLOC 806 } dtrace_dynvar_op_t; 807 808 typedef struct dtrace_dynhash { 809 dtrace_dynvar_t *dtdh_chain; /* hash chain for this bucket */ 810 uintptr_t dtdh_lock; /* deallocation lock */ 811 #ifdef _LP64 812 uintptr_t dtdh_pad[6]; /* pad to avoid false sharing */ 813 #else 814 uintptr_t dtdh_pad[14]; /* pad to avoid false sharing */ 815 #endif 816 } dtrace_dynhash_t; 817 818 typedef struct dtrace_dstate_percpu { 819 dtrace_dynvar_t *dtdsc_free; /* free list for this CPU */ 820 dtrace_dynvar_t *dtdsc_dirty; /* dirty list for this CPU */ 821 dtrace_dynvar_t *dtdsc_rinsing; /* rinsing list for this CPU */ 822 dtrace_dynvar_t *dtdsc_clean; /* clean list for this CPU */ 823 uint64_t dtdsc_drops; /* number of capacity drops */ 824 uint64_t dtdsc_dirty_drops; /* number of dirty drops */ 825 uint64_t dtdsc_rinsing_drops; /* number of rinsing drops */ 826 } dtrace_dstate_percpu_t; 827 828 typedef enum dtrace_dstate_state { 829 DTRACE_DSTATE_CLEAN = 0, 830 DTRACE_DSTATE_EMPTY, 831 DTRACE_DSTATE_DIRTY, 832 DTRACE_DSTATE_RINSING 833 } dtrace_dstate_state_t; 834 835 typedef struct dtrace_dstate { 836 void *dtds_base; /* base of dynamic var. space */ 837 size_t dtds_size; /* size of dynamic var. space */ 838 size_t dtds_hashsize; /* number of buckets in hash */ 839 size_t dtds_chunksize; /* size of each chunk */ 840 dtrace_dynhash_t *dtds_hash; /* pointer to hash table */ 841 dtrace_dstate_state_t dtds_state; /* current dynamic var. state */ 842 dtrace_dstate_percpu_t *__zpercpu dtds_percpu; /* per-CPU dyn. var. state */ 843 } dtrace_dstate_t; 844 845 /* 846 * DTrace Variable State 847 * 848 * The DTrace variable state tracks user-defined variables in its dtrace_vstate 849 * structure. Each DTrace consumer has exactly one dtrace_vstate structure, 850 * but some dtrace_vstate structures may exist without a corresponding DTrace 851 * consumer (see "DTrace Helpers", below). As described in <sys/dtrace.h>, 852 * user-defined variables can have one of three scopes: 853 * 854 * DIFV_SCOPE_GLOBAL => global scope 855 * DIFV_SCOPE_THREAD => thread-local scope (i.e. "self->" variables) 856 * DIFV_SCOPE_LOCAL => clause-local scope (i.e. "this->" variables) 857 * 858 * The variable state tracks variables by both their scope and their allocation 859 * type: 860 * 861 * - The dtvs_globals and dtvs_locals members each point to an array of 862 * dtrace_statvar structures. These structures contain both the variable 863 * metadata (dtrace_difv structures) and the underlying storage for all 864 * statically allocated variables, including statically allocated 865 * DIFV_SCOPE_GLOBAL variables and all DIFV_SCOPE_LOCAL variables. 866 * 867 * - The dtvs_tlocals member points to an array of dtrace_difv structures for 868 * DIFV_SCOPE_THREAD variables. As such, this array tracks _only_ the 869 * variable metadata for DIFV_SCOPE_THREAD variables; the underlying storage 870 * is allocated out of the dynamic variable space. 871 * 872 * - The dtvs_dynvars member is the dynamic variable state associated with the 873 * variable state. The dynamic variable state (described in "DTrace Dynamic 874 * Variables", above) tracks all DIFV_SCOPE_THREAD variables and all 875 * dynamically-allocated DIFV_SCOPE_GLOBAL variables. 876 */ 877 typedef struct dtrace_statvar { 878 uint64_t dtsv_data; /* data or pointer to it */ 879 size_t dtsv_size; /* size of pointed-to data */ 880 int dtsv_refcnt; /* reference count */ 881 dtrace_difv_t dtsv_var; /* variable metadata */ 882 } dtrace_statvar_t; 883 884 typedef struct dtrace_vstate { 885 dtrace_state_t *dtvs_state; /* back pointer to state */ 886 dtrace_statvar_t **dtvs_globals; /* statically-allocated glbls */ 887 int dtvs_nglobals; /* number of globals */ 888 dtrace_difv_t *dtvs_tlocals; /* thread-local metadata */ 889 int dtvs_ntlocals; /* number of thread-locals */ 890 dtrace_statvar_t **dtvs_locals; /* clause-local data */ 891 int dtvs_nlocals; /* number of clause-locals */ 892 dtrace_dstate_t dtvs_dynvars; /* dynamic variable state */ 893 } dtrace_vstate_t; 894 895 /* 896 * DTrace Machine State 897 * 898 * In the process of processing a fired probe, DTrace needs to track and/or 899 * cache some per-CPU state associated with that particular firing. This is 900 * state that is always discarded after the probe firing has completed, and 901 * much of it is not specific to any DTrace consumer, remaining valid across 902 * all ECBs. This state is tracked in the dtrace_mstate structure. 903 */ 904 #define DTRACE_MSTATE_ARGS 0x00000001 905 #define DTRACE_MSTATE_PROBE 0x00000002 906 #define DTRACE_MSTATE_EPID 0x00000004 907 #define DTRACE_MSTATE_TIMESTAMP 0x00000008 908 #define DTRACE_MSTATE_STACKDEPTH 0x00000010 909 #define DTRACE_MSTATE_CALLER 0x00000020 910 #define DTRACE_MSTATE_IPL 0x00000040 911 #define DTRACE_MSTATE_FLTOFFS 0x00000080 912 #define DTRACE_MSTATE_WALLTIMESTAMP 0x00000100 913 #define DTRACE_MSTATE_USTACKDEPTH 0x00000200 914 #define DTRACE_MSTATE_UCALLER 0x00000400 915 #define DTRACE_MSTATE_MACHTIMESTAMP 0x00000800 916 #define DTRACE_MSTATE_MACHCTIMESTAMP 0x00001000 917 918 typedef struct dtrace_mstate { 919 uintptr_t dtms_scratch_base; /* base of scratch space */ 920 uintptr_t dtms_scratch_ptr; /* current scratch pointer */ 921 size_t dtms_scratch_size; /* scratch size */ 922 uint32_t dtms_present; /* variables that are present */ 923 uint64_t dtms_arg[5]; /* cached arguments */ 924 dtrace_epid_t dtms_epid; /* current EPID */ 925 uint64_t dtms_timestamp; /* cached timestamp */ 926 hrtime_t dtms_walltimestamp; /* cached wall timestamp */ 927 uint64_t dtms_machtimestamp; /* cached mach absolute timestamp */ 928 uint64_t dtms_machctimestamp; /* cached mach continuous timestamp */ 929 int dtms_stackdepth; /* cached stackdepth */ 930 int dtms_ustackdepth; /* cached ustackdepth */ 931 struct dtrace_probe *dtms_probe; /* current probe */ 932 uintptr_t dtms_caller; /* cached caller */ 933 uint64_t dtms_ucaller; /* cached user-level caller */ 934 int dtms_ipl; /* cached interrupt pri lev */ 935 int dtms_fltoffs; /* faulting DIFO offset */ 936 uintptr_t dtms_strtok; /* saved strtok() pointer */ 937 uintptr_t dtms_strtok_limit; /* upper bound of strtok ptr */ 938 uint32_t dtms_access; /* memory access rights */ 939 dtrace_difo_t *dtms_difo; /* current dif object */ 940 } dtrace_mstate_t; 941 942 #define DTRACE_COND_OWNER 0x1 943 #define DTRACE_COND_USERMODE 0x2 944 #define DTRACE_COND_ZONEOWNER 0x4 945 946 #define DTRACE_PROBEKEY_MAXDEPTH 8 /* max glob recursion depth */ 947 948 /* 949 * Access flag used by dtrace_mstate.dtms_access. 950 */ 951 #define DTRACE_ACCESS_KERNEL 0x1 /* the priv to read kmem */ 952 953 954 /* 955 * DTrace Activity 956 * 957 * Each DTrace consumer is in one of several states, which (for purposes of 958 * avoiding yet-another overloading of the noun "state") we call the current 959 * _activity_. The activity transitions on dtrace_go() (from DTRACIOCGO), on 960 * dtrace_stop() (from DTRACIOCSTOP) and on the exit() action. Activities may 961 * only transition in one direction; the activity transition diagram is a 962 * directed acyclic graph. The activity transition diagram is as follows: 963 * 964 * 965 * 966 * +----------+ +--------+ +--------+ 967 * | INACTIVE |------------------>| WARMUP |------------------>| ACTIVE | 968 * +----------+ dtrace_go(), +--------+ dtrace_go(), +--------+ 969 * before BEGIN | after BEGIN | | | 970 * | | | | 971 * exit() action | | | | 972 * from BEGIN ECB | | | | 973 * | | | | 974 * v | | | 975 * +----------+ exit() action | | | 976 * +-----------------------------| DRAINING |<-------------------+ | | 977 * | +----------+ | | 978 * | | | | 979 * | dtrace_stop(), | | | 980 * | before END | | | 981 * | | | | 982 * | v | | 983 * | +---------+ +----------+ | | 984 * | | STOPPED |<----------------| COOLDOWN |<----------------------+ | 985 * | +---------+ dtrace_stop(), +----------+ dtrace_stop(), | 986 * | after END before END | 987 * | | 988 * | +--------+ | 989 * +----------------------------->| KILLED |<--------------------------+ 990 * deadman timeout or +--------+ deadman timeout or 991 * killed consumer killed consumer 992 * 993 * Note that once a DTrace consumer has stopped tracing, there is no way to 994 * restart it; if a DTrace consumer wishes to restart tracing, it must reopen 995 * the DTrace pseudodevice. 996 */ 997 typedef enum dtrace_activity { 998 DTRACE_ACTIVITY_INACTIVE = 0, /* not yet running */ 999 DTRACE_ACTIVITY_WARMUP, /* while starting */ 1000 DTRACE_ACTIVITY_ACTIVE, /* running */ 1001 DTRACE_ACTIVITY_DRAINING, /* before stopping */ 1002 DTRACE_ACTIVITY_COOLDOWN, /* while stopping */ 1003 DTRACE_ACTIVITY_STOPPED, /* after stopping */ 1004 DTRACE_ACTIVITY_KILLED /* killed */ 1005 } dtrace_activity_t; 1006 1007 1008 /* 1009 * APPLE NOTE: DTrace dof modes implementation 1010 * 1011 * DTrace has four "dof modes". They are: 1012 * 1013 * DTRACE_DOF_MODE_NEVER Never load any dof, period. 1014 * DTRACE_DOF_MODE_LAZY_ON Defer loading dof until later 1015 * DTRACE_DOF_MODE_LAZY_OFF Load all deferred dof now, and any new dof 1016 * DTRACE_DOF_MODE_NON_LAZY Load all dof immediately. 1017 * 1018 * It is legal to transition between the two lazy modes. The NEVER and 1019 * NON_LAZY modes are permanent, and must not change once set. 1020 * 1021 * The current dof mode is kept in dtrace_dof_mode, which is protected by the 1022 * dtrace_dof_mode_lock. This is a RW lock, reads require shared access, writes 1023 * require exclusive access. Because NEVER and NON_LAZY are permanent states, 1024 * it is legal to test for those modes without holding the dof mode lock. 1025 * 1026 * Lock ordering is dof mode lock before any dtrace lock, and before the 1027 * process p_dtrace_sprlock. In general, other locks should not be held when 1028 * taking the dof mode lock. Acquiring the dof mode lock in exclusive mode 1029 * will block process fork, exec, and exit, so it should be held exclusive 1030 * for as short a time as possible. 1031 */ 1032 1033 #define DTRACE_DOF_MODE_NEVER 0 1034 #define DTRACE_DOF_MODE_LAZY_ON 1 1035 #define DTRACE_DOF_MODE_LAZY_OFF 2 1036 #define DTRACE_DOF_MODE_NON_LAZY 3 1037 1038 /* 1039 * dtrace kernel symbol modes are used to control when the kernel may dispose of 1040 * symbol information used by the fbt/sdt provider. The kernel itself, as well as 1041 * every kext, has symbol table/nlist info that has historically been preserved 1042 * for dtrace's use. This allowed dtrace to be lazy about allocating fbt/sdt probes, 1043 * at the expense of keeping the symbol info in the kernel permanently. 1044 * 1045 * Starting in 10.7+, fbt probes may be created from userspace, in the same 1046 * fashion as pid probes. The kernel allows dtrace "first right of refusal" 1047 * whenever symbol data becomes available (such as a kext load). If dtrace is 1048 * active, it will immediately read/copy the needed data, and then the kernel 1049 * may free it. If dtrace is not active, it returns immediately, having done 1050 * no work or allocations, and the symbol data is freed. Should dtrace need 1051 * this data later, it is expected that the userspace client will push the 1052 * data into the kernel via ioctl calls. 1053 * 1054 * The kernel symbol modes are used to control what dtrace does with symbol data: 1055 * 1056 * DTRACE_KERNEL_SYMBOLS_NEVER Effectively disables fbt/sdt 1057 * DTRACE_KERNEL_SYMBOLS_FROM_KERNEL Immediately read/copy symbol data 1058 * DTRACE_KERNEL_SYMBOLS_FROM_USERSPACE Wait for symbols from userspace 1059 * DTRACE_KERNEL_SYMBOLS_ALWAYS_FROM_KERNEL Immediately read/copy symbol data 1060 * 1061 * It is legal to transition between DTRACE_KERNEL_SYMBOLS_FROM_KERNEL and 1062 * DTRACE_KERNEL_SYMBOLS_FROM_USERSPACE. The DTRACE_KERNEL_SYMBOLS_NEVER and 1063 * DTRACE_KERNEL_SYMBOLS_ALWAYS_FROM_KERNEL are permanent modes, intended to 1064 * disable fbt probes entirely, or prevent any symbols being loaded from 1065 * userspace. 1066 * 1067 * The kernel symbol mode is kept in dtrace_kernel_symbol_mode, which is protected 1068 * by the dtrace_lock. 1069 */ 1070 1071 #define DTRACE_KERNEL_SYMBOLS_NEVER 0 1072 #define DTRACE_KERNEL_SYMBOLS_FROM_KERNEL 1 1073 #define DTRACE_KERNEL_SYMBOLS_FROM_USERSPACE 2 1074 #define DTRACE_KERNEL_SYMBOLS_ALWAYS_FROM_KERNEL 3 1075 1076 1077 /* 1078 * DTrace Helper Implementation 1079 * 1080 * A description of the helper architecture may be found in <sys/dtrace.h>. 1081 * Each process contains a pointer to its helpers in its p_dtrace_helpers 1082 * member. This is a pointer to a dtrace_helpers structure, which contains an 1083 * array of pointers to dtrace_helper structures, helper variable state (shared 1084 * among a process's helpers) and a generation count. (The generation count is 1085 * used to provide an identifier when a helper is added so that it may be 1086 * subsequently removed.) The dtrace_helper structure is self-explanatory, 1087 * containing pointers to the objects needed to execute the helper. Note that 1088 * helpers are _duplicated_ across fork(2), and destroyed on exec(2). No more 1089 * than dtrace_helpers_max are allowed per-process. 1090 */ 1091 #define DTRACE_HELPER_ACTION_USTACK 0 1092 #define DTRACE_NHELPER_ACTIONS 1 1093 1094 typedef struct dtrace_helper_action { 1095 int dtha_generation; /* helper action generation */ 1096 int dtha_nactions; /* number of actions */ 1097 dtrace_difo_t *dtha_predicate; /* helper action predicate */ 1098 dtrace_difo_t **dtha_actions; /* array of actions */ 1099 struct dtrace_helper_action *dtha_next; /* next helper action */ 1100 } dtrace_helper_action_t; 1101 1102 typedef struct dtrace_helper_provider { 1103 int dthp_generation; /* helper provider generation */ 1104 uint32_t dthp_ref; /* reference count */ 1105 dof_helper_t dthp_prov; /* DOF w/ provider and probes */ 1106 } dtrace_helper_provider_t; 1107 1108 typedef struct dtrace_helpers { 1109 dtrace_helper_action_t **dthps_actions; /* array of helper actions */ 1110 dtrace_vstate_t dthps_vstate; /* helper action var. state */ 1111 dtrace_helper_provider_t **dthps_provs; /* array of providers */ 1112 uint_t dthps_nprovs; /* count of providers */ 1113 uint_t dthps_maxprovs; /* provider array size */ 1114 int dthps_generation; /* current generation */ 1115 pid_t dthps_pid; /* pid of associated proc */ 1116 int dthps_deferred; /* helper in deferred list */ 1117 struct dtrace_helpers *dthps_next; /* next pointer */ 1118 struct dtrace_helpers *dthps_prev; /* prev pointer */ 1119 } dtrace_helpers_t; 1120 1121 /* 1122 * DTrace Helper Action Tracing 1123 * 1124 * Debugging helper actions can be arduous. To ease the development and 1125 * debugging of helpers, DTrace contains a tracing-framework-within-a-tracing- 1126 * framework: helper tracing. If dtrace_helptrace_enabled is non-zero (which 1127 * it is by default on DEBUG kernels), all helper activity will be traced to a 1128 * global, in-kernel ring buffer. Each entry includes a pointer to the specific 1129 * helper, the location within the helper, and a trace of all local variables. 1130 * The ring buffer may be displayed in a human-readable format with the 1131 * ::dtrace_helptrace mdb(1) dcmd. 1132 */ 1133 #define DTRACE_HELPTRACE_NEXT (-1) 1134 #define DTRACE_HELPTRACE_DONE (-2) 1135 #define DTRACE_HELPTRACE_ERR (-3) 1136 1137 1138 typedef struct dtrace_helptrace { 1139 dtrace_helper_action_t *dtht_helper; /* helper action */ 1140 int dtht_where; /* where in helper action */ 1141 int dtht_nlocals; /* number of locals */ 1142 int dtht_fault; /* type of fault (if any) */ 1143 int dtht_fltoffs; /* DIF offset */ 1144 uint64_t dtht_illval; /* faulting value */ 1145 uint64_t dtht_locals[1]; /* local variables */ 1146 } dtrace_helptrace_t; 1147 1148 /* 1149 * DTrace Credentials 1150 * 1151 * In probe context, we have limited flexibility to examine the credentials 1152 * of the DTrace consumer that created a particular enabling. We use 1153 * the Least Privilege interfaces to cache the consumer's cred pointer and 1154 * some facts about that credential in a dtrace_cred_t structure. These 1155 * can limit the consumer's breadth of visibility and what actions the 1156 * consumer may take. 1157 */ 1158 #define DTRACE_CRV_ALLPROC 0x01 1159 #define DTRACE_CRV_KERNEL 0x02 1160 #define DTRACE_CRV_ALLZONE 0x04 1161 1162 #define DTRACE_CRV_ALL (DTRACE_CRV_ALLPROC | DTRACE_CRV_KERNEL | \ 1163 DTRACE_CRV_ALLZONE) 1164 1165 #define DTRACE_CRA_PROC 0x0001 1166 #define DTRACE_CRA_PROC_CONTROL 0x0002 1167 #define DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER 0x0004 1168 #define DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE 0x0008 1169 #define DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG 0x0010 1170 #define DTRACE_CRA_KERNEL 0x0020 1171 #define DTRACE_CRA_KERNEL_DESTRUCTIVE 0x0040 1172 1173 #define DTRACE_CRA_ALL (DTRACE_CRA_PROC | \ 1174 DTRACE_CRA_PROC_CONTROL | \ 1175 DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER | \ 1176 DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE | \ 1177 DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG | \ 1178 DTRACE_CRA_KERNEL | \ 1179 DTRACE_CRA_KERNEL_DESTRUCTIVE) 1180 1181 typedef struct dtrace_cred { 1182 cred_t *dcr_cred; 1183 uint8_t dcr_destructive; 1184 uint8_t dcr_visible; 1185 uint16_t dcr_action; 1186 } dtrace_cred_t; 1187 1188 typedef struct dtrace_format { 1189 uint64_t dtf_refcount; 1190 char dtf_str[]; 1191 } dtrace_format_t; 1192 1193 #define DTRACE_FORMAT_SIZE(fmt) (strlen(fmt->dtf_str) + 1 + sizeof(dtrace_format_t)) 1194 1195 /* 1196 * DTrace Consumer State 1197 * 1198 * Each DTrace consumer has an associated dtrace_state structure that contains 1199 * its in-kernel DTrace state -- including options, credentials, statistics and 1200 * pointers to ECBs, buffers, speculations and formats. A dtrace_state 1201 * structure is also allocated for anonymous enablings. When anonymous state 1202 * is grabbed, the grabbing consumers dts_anon pointer is set to the grabbed 1203 * dtrace_state structure. 1204 */ 1205 struct dtrace_state { 1206 dev_t dts_dev; /* device */ 1207 int dts_necbs; /* total number of ECBs */ 1208 dtrace_ecb_t **dts_ecbs; /* array of ECBs */ 1209 dtrace_epid_t dts_epid; /* next EPID to allocate */ 1210 size_t dts_needed; /* greatest needed space */ 1211 struct dtrace_state *dts_anon; /* anon. state, if grabbed */ 1212 dtrace_activity_t dts_activity; /* current activity */ 1213 dtrace_vstate_t dts_vstate; /* variable state */ 1214 dtrace_buffer_t *dts_buffer; /* principal buffer */ 1215 dtrace_buffer_t *dts_aggbuffer; /* aggregation buffer */ 1216 dtrace_speculation_t *dts_speculations; /* speculation array */ 1217 int dts_nspeculations; /* number of speculations */ 1218 int dts_naggregations; /* number of aggregations */ 1219 dtrace_aggregation_t **dts_aggregations; /* aggregation array */ 1220 vmem_t *dts_aggid_arena; /* arena for aggregation IDs */ 1221 uint64_t dts_errors; /* total number of errors */ 1222 uint32_t dts_speculations_busy; /* number of spec. busy */ 1223 uint32_t dts_speculations_unavail; /* number of spec unavail */ 1224 uint32_t dts_stkstroverflows; /* stack string tab overflows */ 1225 uint32_t dts_dblerrors; /* errors in ERROR probes */ 1226 uint32_t dts_reserve; /* space reserved for END */ 1227 hrtime_t dts_laststatus; /* time of last status */ 1228 cyclic_id_t dts_cleaner; /* cleaning cyclic */ 1229 cyclic_id_t dts_deadman; /* deadman cyclic */ 1230 hrtime_t dts_alive; /* time last alive */ 1231 char dts_speculates; /* boolean: has speculations */ 1232 char dts_destructive; /* boolean: has dest. actions */ 1233 int dts_nformats; /* number of formats */ 1234 dtrace_format_t **dts_formats; /* format string array */ 1235 dtrace_optval_t dts_options[DTRACEOPT_MAX]; /* options */ 1236 dtrace_cred_t dts_cred; /* credentials */ 1237 size_t dts_nretained; /* number of retained enabs */ 1238 uint64_t dts_arg_error_illval; 1239 uint32_t dts_buf_over_limit; /* number of bufs over dtb_limit */ 1240 uint64_t **dts_rstate; /* per-CPU random state */ 1241 }; 1242 1243 struct dtrace_provider { 1244 dtrace_pattr_t dtpv_attr; /* provider attributes */ 1245 dtrace_ppriv_t dtpv_priv; /* provider privileges */ 1246 dtrace_pops_t dtpv_pops; /* provider operations */ 1247 char *dtpv_name; /* provider name */ 1248 void *dtpv_arg; /* provider argument */ 1249 uint_t dtpv_defunct; /* boolean: defunct provider */ 1250 struct dtrace_provider *dtpv_next; /* next provider */ 1251 uint64_t dtpv_probe_count; /* number of associated probes */ 1252 uint64_t dtpv_ecb_count; /* number of associated enabled ECBs */ 1253 }; 1254 1255 struct dtrace_meta { 1256 dtrace_mops_t dtm_mops; /* meta provider operations */ 1257 char *dtm_name; /* meta provider name */ 1258 void *dtm_arg; /* meta provider user arg */ 1259 uint64_t dtm_count; /* number of associated providers */ 1260 }; 1261 1262 /* 1263 * DTrace Enablings 1264 * 1265 * A dtrace_enabling structure is used to track a collection of ECB 1266 * descriptions -- before they have been turned into actual ECBs. This is 1267 * created as a result of DOF processing, and is generally used to generate 1268 * ECBs immediately thereafter. However, enablings are also generally 1269 * retained should the probes they describe be created at a later time; as 1270 * each new module or provider registers with the framework, the retained 1271 * enablings are reevaluated, with any new match resulting in new ECBs. To 1272 * prevent probes from being matched more than once, the enabling tracks the 1273 * last probe generation matched, and only matches probes from subsequent 1274 * generations. 1275 */ 1276 typedef struct dtrace_enabling { 1277 dtrace_ecbdesc_t **dten_desc; /* all ECB descriptions */ 1278 int dten_ndesc; /* number of ECB descriptions */ 1279 int dten_maxdesc; /* size of ECB array */ 1280 dtrace_vstate_t *dten_vstate; /* associated variable state */ 1281 dtrace_genid_t dten_probegen; /* matched probe generation */ 1282 dtrace_ecbdesc_t *dten_current; /* current ECB description */ 1283 int dten_error; /* current error value */ 1284 int dten_primed; /* boolean: set if primed */ 1285 struct dtrace_enabling *dten_prev; /* previous enabling */ 1286 struct dtrace_enabling *dten_next; /* next enabling */ 1287 } dtrace_enabling_t; 1288 1289 /* 1290 * DTrace Anonymous Enablings 1291 * 1292 * Anonymous enablings are DTrace enablings that are not associated with a 1293 * controlling process, but rather derive their enabling from DOF stored as 1294 * properties in the dtrace.conf file. If there is an anonymous enabling, a 1295 * DTrace consumer state and enabling are created on attach. The state may be 1296 * subsequently grabbed by the first consumer specifying the "grabanon" 1297 * option. As long as an anonymous DTrace enabling exists, dtrace(7D) will 1298 * refuse to unload. 1299 */ 1300 typedef struct dtrace_anon { 1301 dtrace_state_t *dta_state; /* DTrace consumer state */ 1302 dtrace_enabling_t *dta_enabling; /* pointer to enabling */ 1303 processorid_t dta_beganon; /* which CPU BEGIN ran on */ 1304 } dtrace_anon_t; 1305 1306 /* 1307 * DTrace Error Debugging 1308 */ 1309 #if DEBUG 1310 #define DTRACE_ERRDEBUG 1311 #endif 1312 1313 #ifdef DTRACE_ERRDEBUG 1314 1315 typedef struct dtrace_errhash { 1316 const char *dter_msg; /* error message */ 1317 int dter_count; /* number of times seen */ 1318 } dtrace_errhash_t; 1319 1320 #define DTRACE_ERRHASHSZ 256 /* must be > number of err msgs */ 1321 1322 #endif /* DTRACE_ERRDEBUG */ 1323 1324 typedef struct dtrace_string dtrace_string_t; 1325 1326 typedef struct dtrace_string { 1327 dtrace_string_t *dtst_next; 1328 dtrace_string_t *dtst_prev; 1329 uint32_t dtst_refcount; 1330 char dtst_str[]; 1331 } dtrace_string_t; 1332 1333 /** 1334 * DTrace Matching pre-conditions 1335 * 1336 * Used when matching new probes to discard matching of enablings that 1337 * doesn't match the condition tested by dmc_func 1338 */ 1339 typedef struct dtrace_match_cond { 1340 int (*dmc_func)(dtrace_probedesc_t*, void*); 1341 void *dmc_data; 1342 } dtrace_match_cond_t; 1343 1344 1345 /* 1346 * DTrace Toxic Ranges 1347 * 1348 * DTrace supports safe loads from probe context; if the address turns out to 1349 * be invalid, a bit will be set by the kernel indicating that DTrace 1350 * encountered a memory error, and DTrace will propagate the error to the user 1351 * accordingly. However, there may exist some regions of memory in which an 1352 * arbitrary load can change system state, and from which it is impossible to 1353 * recover from such a load after it has been attempted. Examples of this may 1354 * include memory in which programmable I/O registers are mapped (for which a 1355 * read may have some implications for the device) or (in the specific case of 1356 * UltraSPARC-I and -II) the virtual address hole. The platform is required 1357 * to make DTrace aware of these toxic ranges; DTrace will then check that 1358 * target addresses are not in a toxic range before attempting to issue a 1359 * safe load. 1360 */ 1361 typedef struct dtrace_toxrange { 1362 uintptr_t dtt_base; /* base of toxic range */ 1363 uintptr_t dtt_limit; /* limit of toxic range */ 1364 } dtrace_toxrange_t; 1365 1366 extern uint64_t dtrace_getarg(int, int, dtrace_mstate_t*, dtrace_vstate_t*); 1367 extern int dtrace_getipl(void); 1368 extern uintptr_t dtrace_caller(int); 1369 extern uint32_t dtrace_cas32(uint32_t *, uint32_t, uint32_t); 1370 extern void *dtrace_casptr(void *, void *, void *); 1371 extern void dtrace_copyin(user_addr_t, uintptr_t, size_t, volatile uint16_t *); 1372 extern void dtrace_copyinstr(user_addr_t, uintptr_t, size_t, volatile uint16_t *); 1373 extern void dtrace_copyout(uintptr_t, user_addr_t, size_t, volatile uint16_t *); 1374 extern void dtrace_copyoutstr(uintptr_t, user_addr_t, size_t, volatile uint16_t *); 1375 extern void dtrace_getpcstack(pc_t *, int, int, uint32_t *); 1376 extern uint64_t dtrace_load64(uintptr_t); 1377 extern int dtrace_canload(uint64_t, size_t, dtrace_mstate_t*, dtrace_vstate_t*); 1378 1379 extern uint64_t dtrace_getreg(struct regs *, uint_t); 1380 extern uint64_t dtrace_getvmreg(uint_t); 1381 extern int dtrace_getstackdepth(int); 1382 extern void dtrace_getupcstack(uint64_t *, int); 1383 extern void dtrace_getufpstack(uint64_t *, uint64_t *, int); 1384 extern int dtrace_getustackdepth(void); 1385 extern uintptr_t dtrace_fulword(void *); 1386 extern uint8_t dtrace_fuword8(user_addr_t); 1387 extern uint16_t dtrace_fuword16(user_addr_t); 1388 extern uint32_t dtrace_fuword32(user_addr_t); 1389 extern uint64_t dtrace_fuword64(user_addr_t); 1390 extern int dtrace_proc_waitfor(dtrace_procdesc_t*); 1391 extern void dtrace_probe_error(dtrace_state_t *, dtrace_epid_t, int, int, 1392 int, uint64_t); 1393 extern int dtrace_assfail(const char *, const char *, int); 1394 extern int dtrace_attached(void); 1395 extern hrtime_t dtrace_gethrestime(void); 1396 1397 extern void dtrace_flush_caches(void); 1398 1399 extern void dtrace_copy(uintptr_t, uintptr_t, size_t); 1400 extern void dtrace_copystr(uintptr_t, uintptr_t, size_t, volatile uint16_t *); 1401 1402 extern void* dtrace_ptrauth_strip(void*, uint64_t); 1403 extern int dtrace_is_valid_ptrauth_key(uint64_t); 1404 1405 extern uint64_t dtrace_physmem_read(uint64_t, size_t); 1406 extern void dtrace_physmem_write(uint64_t, uint64_t, size_t); 1407 1408 extern void dtrace_livedump(char *, size_t); 1409 1410 /* 1411 * DTrace state handling 1412 */ 1413 extern minor_t dtrace_state_reserve(void); 1414 extern dtrace_state_t* dtrace_state_allocate(minor_t minor); 1415 extern dtrace_state_t* dtrace_state_get(minor_t minor); 1416 extern void dtrace_state_free(minor_t minor); 1417 1418 /* 1419 * DTrace restriction checks 1420 */ 1421 extern void dtrace_restriction_policy_load(void); 1422 extern boolean_t dtrace_is_restricted(void); 1423 extern boolean_t dtrace_are_restrictions_relaxed(void); 1424 extern boolean_t dtrace_fbt_probes_restricted(void); 1425 extern boolean_t dtrace_sdt_probes_restricted(void); 1426 extern boolean_t dtrace_can_attach_to_proc(proc_t); 1427 1428 /* 1429 * DTrace Assertions 1430 * 1431 * DTrace calls ASSERT and VERIFY from probe context. To assure that a failed 1432 * ASSERT or VERIFYdoes not induce a markedly more catastrophic failure (e.g., 1433 * one from which a dump cannot be gleaned), DTrace must define its own ASSERT 1434 * and VERIFY macros to be ones that may safely be called from probe context. 1435 * This header file must thus be included by any DTrace component that calls 1436 * ASSERT and/or VERIFY from probe context, and _only_ by those components. 1437 * (The only exception to this is kernel debugging infrastructure at user-level 1438 * that doesn't depend on calling ASSERT.) 1439 */ 1440 #undef ASSERT 1441 #undef VERIFY 1442 1443 #define VERIFY(EX) ((void)((EX) || \ 1444 dtrace_assfail(#EX, __FILE__, __LINE__))) 1445 1446 #if DEBUG 1447 #define ASSERT(EX) ((void)((EX) || \ 1448 dtrace_assfail(#EX, __FILE__, __LINE__))) 1449 #else 1450 #define ASSERT(X) ((void)0) 1451 #endif 1452 1453 #ifdef __cplusplus 1454 } 1455 #endif 1456 1457 #endif /* _SYS_DTRACE_IMPL_H */ 1458 1459