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 27 /* 28 * Copyright (c) 2011, Joyent, Inc. All rights reserved. 29 */ 30 31 #ifndef _SYS_DTRACE_IMPL_H 32 #define _SYS_DTRACE_IMPL_H 33 34 #ifdef __cplusplus 35 extern "C" { 36 #endif 37 38 /* 39 * DTrace Dynamic Tracing Software: Kernel Implementation Interfaces 40 * 41 * Note: The contents of this file are private to the implementation of the 42 * Solaris system and DTrace subsystem and are subject to change at any time 43 * without notice. Applications and drivers using these interfaces will fail 44 * to run on future releases. These interfaces should not be used for any 45 * purpose except those expressly outlined in dtrace(7D) and libdtrace(3LIB). 46 * Please refer to the "Solaris Dynamic Tracing Guide" for more information. 47 */ 48 49 #include <sys/dtrace.h> 50 51 /* 52 * DTrace Implementation Constants and Typedefs 53 */ 54 #define DTRACE_MAXPROPLEN 128 55 #define DTRACE_DYNVAR_CHUNKSIZE 256 56 57 struct dtrace_probe; 58 struct dtrace_ecb; 59 struct dtrace_predicate; 60 struct dtrace_action; 61 struct dtrace_provider; 62 struct dtrace_state; 63 64 typedef struct dtrace_probe dtrace_probe_t; 65 typedef struct dtrace_ecb dtrace_ecb_t; 66 typedef struct dtrace_predicate dtrace_predicate_t; 67 typedef struct dtrace_action dtrace_action_t; 68 typedef struct dtrace_provider dtrace_provider_t; 69 typedef struct dtrace_meta dtrace_meta_t; 70 typedef struct dtrace_state dtrace_state_t; 71 typedef uint32_t dtrace_optid_t; 72 typedef uint32_t dtrace_specid_t; 73 typedef uint64_t dtrace_genid_t; 74 75 /* 76 * DTrace Probes 77 * 78 * The probe is the fundamental unit of the DTrace architecture. Probes are 79 * created by DTrace providers, and managed by the DTrace framework. A probe 80 * is identified by a unique <provider, module, function, name> tuple, and has 81 * a unique probe identifier assigned to it. (Some probes are not associated 82 * with a specific point in text; these are called _unanchored probes_ and have 83 * no module or function associated with them.) Probes are represented as a 84 * dtrace_probe structure. To allow quick lookups based on each element of the 85 * probe tuple, probes are hashed by each of provider, module, function and 86 * name. (If a lookup is performed based on a regular expression, a 87 * dtrace_probekey is prepared, and a linear search is performed.) Each probe 88 * is additionally pointed to by a linear array indexed by its identifier. The 89 * identifier is the provider's mechanism for indicating to the DTrace 90 * framework that a probe has fired: the identifier is passed as the first 91 * argument to dtrace_probe(), where it is then mapped into the corresponding 92 * dtrace_probe structure. From the dtrace_probe structure, dtrace_probe() can 93 * iterate over the probe's list of enabling control blocks; see "DTrace 94 * Enabling Control Blocks", below.) 95 */ 96 struct dtrace_probe { 97 dtrace_id_t dtpr_id; /* probe identifier */ 98 dtrace_ecb_t *dtpr_ecb; /* ECB list; see below */ 99 dtrace_ecb_t *dtpr_ecb_last; /* last ECB in list */ 100 void *dtpr_arg; /* provider argument */ 101 dtrace_cacheid_t dtpr_predcache; /* predicate cache ID */ 102 int dtpr_aframes; /* artificial frames */ 103 dtrace_provider_t *dtpr_provider; /* pointer to provider */ 104 char *dtpr_mod; /* probe's module name */ 105 char *dtpr_func; /* probe's function name */ 106 char *dtpr_name; /* probe's name */ 107 dtrace_probe_t *dtpr_nextmod; /* next in module hash */ 108 dtrace_probe_t *dtpr_prevmod; /* previous in module hash */ 109 dtrace_probe_t *dtpr_nextfunc; /* next in function hash */ 110 dtrace_probe_t *dtpr_prevfunc; /* previous in function hash */ 111 dtrace_probe_t *dtpr_nextname; /* next in name hash */ 112 dtrace_probe_t *dtpr_prevname; /* previous in name hash */ 113 dtrace_genid_t dtpr_gen; /* probe generation ID */ 114 }; 115 116 typedef int dtrace_probekey_f(const char *, const char *, int); 117 118 typedef struct dtrace_probekey { 119 const char *dtpk_prov; /* provider name to match */ 120 dtrace_probekey_f *dtpk_pmatch; /* provider matching function */ 121 const char *dtpk_mod; /* module name to match */ 122 dtrace_probekey_f *dtpk_mmatch; /* module matching function */ 123 const char *dtpk_func; /* func name to match */ 124 dtrace_probekey_f *dtpk_fmatch; /* func matching function */ 125 const char *dtpk_name; /* name to match */ 126 dtrace_probekey_f *dtpk_nmatch; /* name matching function */ 127 dtrace_id_t dtpk_id; /* identifier to match */ 128 } dtrace_probekey_t; 129 130 typedef struct dtrace_hashbucket { 131 struct dtrace_hashbucket *dthb_next; /* next on hash chain */ 132 dtrace_probe_t *dthb_chain; /* chain of probes */ 133 int dthb_len; /* number of probes here */ 134 } dtrace_hashbucket_t; 135 136 typedef struct dtrace_hash { 137 dtrace_hashbucket_t **dth_tab; /* hash table */ 138 int dth_size; /* size of hash table */ 139 int dth_mask; /* mask to index into table */ 140 int dth_nbuckets; /* total number of buckets */ 141 uintptr_t dth_nextoffs; /* offset of next in probe */ 142 uintptr_t dth_prevoffs; /* offset of prev in probe */ 143 uintptr_t dth_stroffs; /* offset of str in probe */ 144 } dtrace_hash_t; 145 146 /* 147 * DTrace Enabling Control Blocks 148 * 149 * When a provider wishes to fire a probe, it calls into dtrace_probe(), 150 * passing the probe identifier as the first argument. As described above, 151 * dtrace_probe() maps the identifier into a pointer to a dtrace_probe_t 152 * structure. This structure contains information about the probe, and a 153 * pointer to the list of Enabling Control Blocks (ECBs). Each ECB points to 154 * DTrace consumer state, and contains an optional predicate, and a list of 155 * actions. (Shown schematically below.) The ECB abstraction allows a single 156 * probe to be multiplexed across disjoint consumers, or across disjoint 157 * enablings of a single probe within one consumer. 158 * 159 * Enabling Control Block 160 * dtrace_ecb_t 161 * +------------------------+ 162 * | dtrace_epid_t ---------+--------------> Enabled Probe ID (EPID) 163 * | dtrace_state_t * ------+--------------> State associated with this ECB 164 * | dtrace_predicate_t * --+---------+ 165 * | dtrace_action_t * -----+----+ | 166 * | dtrace_ecb_t * ---+ | | | Predicate (if any) 167 * +-------------------+----+ | | dtrace_predicate_t 168 * | | +---> +--------------------+ 169 * | | | dtrace_difo_t * ---+----> DIFO 170 * | | +--------------------+ 171 * | | 172 * Next ECB | | Action 173 * (if any) | | dtrace_action_t 174 * : +--> +-------------------+ 175 * : | dtrace_actkind_t -+------> kind 176 * v | dtrace_difo_t * --+------> DIFO (if any) 177 * | dtrace_recdesc_t -+------> record descr. 178 * | dtrace_action_t * +------+ 179 * +-------------------+ | 180 * | Next action 181 * +-------------------------------+ (if any) 182 * | 183 * | Action 184 * | dtrace_action_t 185 * +--> +-------------------+ 186 * | dtrace_actkind_t -+------> kind 187 * | dtrace_difo_t * --+------> DIFO (if any) 188 * | dtrace_action_t * +------+ 189 * +-------------------+ | 190 * | Next action 191 * +-------------------------------+ (if any) 192 * | 193 * : 194 * v 195 * 196 * 197 * dtrace_probe() iterates over the ECB list. If the ECB needs less space 198 * than is available in the principal buffer, the ECB is processed: if the 199 * predicate is non-NULL, the DIF object is executed. If the result is 200 * non-zero, the action list is processed, with each action being executed 201 * accordingly. When the action list has been completely executed, processing 202 * advances to the next ECB. processing advances to the next ECB. If the 203 * result is non-zero; For each ECB, it first determines the The ECB 204 * abstraction allows disjoint consumers to multiplex on single probes. 205 */ 206 struct dtrace_ecb { 207 dtrace_epid_t dte_epid; /* enabled probe ID */ 208 uint32_t dte_alignment; /* required alignment */ 209 size_t dte_needed; /* bytes needed */ 210 size_t dte_size; /* total size of payload */ 211 dtrace_predicate_t *dte_predicate; /* predicate, if any */ 212 dtrace_action_t *dte_action; /* actions, if any */ 213 dtrace_ecb_t *dte_next; /* next ECB on probe */ 214 dtrace_state_t *dte_state; /* pointer to state */ 215 uint32_t dte_cond; /* security condition */ 216 dtrace_probe_t *dte_probe; /* pointer to probe */ 217 dtrace_action_t *dte_action_last; /* last action on ECB */ 218 uint64_t dte_uarg; /* library argument */ 219 }; 220 221 struct dtrace_predicate { 222 dtrace_difo_t *dtp_difo; /* DIF object */ 223 dtrace_cacheid_t dtp_cacheid; /* cache identifier */ 224 int dtp_refcnt; /* reference count */ 225 }; 226 227 struct dtrace_action { 228 dtrace_actkind_t dta_kind; /* kind of action */ 229 uint16_t dta_intuple; /* boolean: in aggregation */ 230 uint32_t dta_refcnt; /* reference count */ 231 dtrace_difo_t *dta_difo; /* pointer to DIFO */ 232 dtrace_recdesc_t dta_rec; /* record description */ 233 dtrace_action_t *dta_prev; /* previous action */ 234 dtrace_action_t *dta_next; /* next action */ 235 }; 236 237 typedef struct dtrace_aggregation { 238 dtrace_action_t dtag_action; /* action; must be first */ 239 dtrace_aggid_t dtag_id; /* identifier */ 240 dtrace_ecb_t *dtag_ecb; /* corresponding ECB */ 241 dtrace_action_t *dtag_first; /* first action in tuple */ 242 uint32_t dtag_base; /* base of aggregation */ 243 uint8_t dtag_hasarg; /* boolean: has argument */ 244 uint64_t dtag_initial; /* initial value */ 245 void (*dtag_aggregate)(uint64_t *, uint64_t, uint64_t); 246 } dtrace_aggregation_t; 247 248 /* 249 * DTrace Buffers 250 * 251 * Principal buffers, aggregation buffers, and speculative buffers are all 252 * managed with the dtrace_buffer structure. By default, this structure 253 * includes twin data buffers -- dtb_tomax and dtb_xamot -- that serve as the 254 * active and passive buffers, respectively. For speculative buffers, 255 * dtb_xamot will be NULL; for "ring" and "fill" buffers, dtb_xamot will point 256 * to a scratch buffer. For all buffer types, the dtrace_buffer structure is 257 * always allocated on a per-CPU basis; a single dtrace_buffer structure is 258 * never shared among CPUs. (That is, there is never true sharing of the 259 * dtrace_buffer structure; to prevent false sharing of the structure, it must 260 * always be aligned to the coherence granularity -- generally 64 bytes.) 261 * 262 * One of the critical design decisions of DTrace is that a given ECB always 263 * stores the same quantity and type of data. This is done to assure that the 264 * only metadata required for an ECB's traced data is the EPID. That is, from 265 * the EPID, the consumer can determine the data layout. (The data buffer 266 * layout is shown schematically below.) By assuring that one can determine 267 * data layout from the EPID, the metadata stream can be separated from the 268 * data stream -- simplifying the data stream enormously. 269 * 270 * base of data buffer ---> +------+--------------------+------+ 271 * | EPID | data | EPID | 272 * +------+--------+------+----+------+ 273 * | data | EPID | data | 274 * +---------------+------+-----------+ 275 * | data, cont. | 276 * +------+--------------------+------+ 277 * | EPID | data | | 278 * +------+--------------------+ | 279 * | || | 280 * | || | 281 * | \/ | 282 * : : 283 * . . 284 * . . 285 * . . 286 * : : 287 * | | 288 * limit of data buffer ---> +----------------------------------+ 289 * 290 * When evaluating an ECB, dtrace_probe() determines if the ECB's needs of the 291 * principal buffer (both scratch and payload) exceed the available space. If 292 * the ECB's needs exceed available space (and if the principal buffer policy 293 * is the default "switch" policy), the ECB is dropped, the buffer's drop count 294 * is incremented, and processing advances to the next ECB. If the ECB's needs 295 * can be met with the available space, the ECB is processed, but the offset in 296 * the principal buffer is only advanced if the ECB completes processing 297 * without error. 298 * 299 * When a buffer is to be switched (either because the buffer is the principal 300 * buffer with a "switch" policy or because it is an aggregation buffer), a 301 * cross call is issued to the CPU associated with the buffer. In the cross 302 * call context, interrupts are disabled, and the active and the inactive 303 * buffers are atomically switched. This involves switching the data pointers, 304 * copying the various state fields (offset, drops, errors, etc.) into their 305 * inactive equivalents, and clearing the state fields. Because interrupts are 306 * disabled during this procedure, the switch is guaranteed to appear atomic to 307 * dtrace_probe(). 308 * 309 * DTrace Ring Buffering 310 * 311 * To process a ring buffer correctly, one must know the oldest valid record. 312 * Processing starts at the oldest record in the buffer and continues until 313 * the end of the buffer is reached. Processing then resumes starting with 314 * the record stored at offset 0 in the buffer, and continues until the 315 * youngest record is processed. If trace records are of a fixed-length, 316 * determining the oldest record is trivial: 317 * 318 * - If the ring buffer has not wrapped, the oldest record is the record 319 * stored at offset 0. 320 * 321 * - If the ring buffer has wrapped, the oldest record is the record stored 322 * at the current offset. 323 * 324 * With variable length records, however, just knowing the current offset 325 * doesn't suffice for determining the oldest valid record: assuming that one 326 * allows for arbitrary data, one has no way of searching forward from the 327 * current offset to find the oldest valid record. (That is, one has no way 328 * of separating data from metadata.) It would be possible to simply refuse to 329 * process any data in the ring buffer between the current offset and the 330 * limit, but this leaves (potentially) an enormous amount of otherwise valid 331 * data unprocessed. 332 * 333 * To effect ring buffering, we track two offsets in the buffer: the current 334 * offset and the _wrapped_ offset. If a request is made to reserve some 335 * amount of data, and the buffer has wrapped, the wrapped offset is 336 * incremented until the wrapped offset minus the current offset is greater 337 * than or equal to the reserve request. This is done by repeatedly looking 338 * up the ECB corresponding to the EPID at the current wrapped offset, and 339 * incrementing the wrapped offset by the size of the data payload 340 * corresponding to that ECB. If this offset is greater than or equal to the 341 * limit of the data buffer, the wrapped offset is set to 0. Thus, the 342 * current offset effectively "chases" the wrapped offset around the buffer. 343 * Schematically: 344 * 345 * base of data buffer ---> +------+--------------------+------+ 346 * | EPID | data | EPID | 347 * +------+--------+------+----+------+ 348 * | data | EPID | data | 349 * +---------------+------+-----------+ 350 * | data, cont. | 351 * +------+---------------------------+ 352 * | EPID | data | 353 * current offset ---> +------+---------------------------+ 354 * | invalid data | 355 * wrapped offset ---> +------+--------------------+------+ 356 * | EPID | data | EPID | 357 * +------+--------+------+----+------+ 358 * | data | EPID | data | 359 * +---------------+------+-----------+ 360 * : : 361 * . . 362 * . ... valid data ... . 363 * . . 364 * : : 365 * +------+-------------+------+------+ 366 * | EPID | data | EPID | data | 367 * +------+------------++------+------+ 368 * | data, cont. | leftover | 369 * limit of data buffer ---> +-------------------+--------------+ 370 * 371 * If the amount of requested buffer space exceeds the amount of space 372 * available between the current offset and the end of the buffer: 373 * 374 * (1) all words in the data buffer between the current offset and the limit 375 * of the data buffer (marked "leftover", above) are set to 376 * DTRACE_EPIDNONE 377 * 378 * (2) the wrapped offset is set to zero 379 * 380 * (3) the iteration process described above occurs until the wrapped offset 381 * is greater than the amount of desired space. 382 * 383 * The wrapped offset is implemented by (re-)using the inactive offset. 384 * In a "switch" buffer policy, the inactive offset stores the offset in 385 * the inactive buffer; in a "ring" buffer policy, it stores the wrapped 386 * offset. 387 * 388 * DTrace Scratch Buffering 389 * 390 * Some ECBs may wish to allocate dynamically-sized temporary scratch memory. 391 * To accommodate such requests easily, scratch memory may be allocated in 392 * the buffer beyond the current offset plus the needed memory of the current 393 * ECB. If there isn't sufficient room in the buffer for the requested amount 394 * of scratch space, the allocation fails and an error is generated. Scratch 395 * memory is tracked in the dtrace_mstate_t and is automatically freed when 396 * the ECB ceases processing. Note that ring buffers cannot allocate their 397 * scratch from the principal buffer -- lest they needlessly overwrite older, 398 * valid data. Ring buffers therefore have their own dedicated scratch buffer 399 * from which scratch is allocated. 400 */ 401 #define DTRACEBUF_RING 0x0001 /* bufpolicy set to "ring" */ 402 #define DTRACEBUF_FILL 0x0002 /* bufpolicy set to "fill" */ 403 #define DTRACEBUF_NOSWITCH 0x0004 /* do not switch buffer */ 404 #define DTRACEBUF_WRAPPED 0x0008 /* ring buffer has wrapped */ 405 #define DTRACEBUF_DROPPED 0x0010 /* drops occurred */ 406 #define DTRACEBUF_ERROR 0x0020 /* errors occurred */ 407 #define DTRACEBUF_FULL 0x0040 /* "fill" buffer is full */ 408 #define DTRACEBUF_CONSUMED 0x0080 /* buffer has been consumed */ 409 #define DTRACEBUF_INACTIVE 0x0100 /* buffer is not yet active */ 410 411 typedef struct dtrace_buffer { 412 uint64_t dtb_offset; /* current offset in buffer */ 413 uint64_t dtb_size; /* size of buffer */ 414 uint32_t dtb_flags; /* flags */ 415 uint32_t dtb_drops; /* number of drops */ 416 caddr_t dtb_tomax; /* active buffer */ 417 caddr_t dtb_xamot; /* inactive buffer */ 418 uint32_t dtb_xamot_flags; /* inactive flags */ 419 uint32_t dtb_xamot_drops; /* drops in inactive buffer */ 420 uint64_t dtb_xamot_offset; /* offset in inactive buffer */ 421 uint32_t dtb_errors; /* number of errors */ 422 uint32_t dtb_xamot_errors; /* errors in inactive buffer */ 423 #ifndef _LP64 424 uint64_t dtb_pad1; /* pad out to 64 bytes */ 425 #endif 426 uint64_t dtb_switched; /* time of last switch */ 427 uint64_t dtb_interval; /* observed switch interval */ 428 uint64_t dtb_pad2[6]; /* pad to avoid false sharing */ 429 } dtrace_buffer_t; 430 431 /* 432 * DTrace Aggregation Buffers 433 * 434 * Aggregation buffers use much of the same mechanism as described above 435 * ("DTrace Buffers"). However, because an aggregation is fundamentally a 436 * hash, there exists dynamic metadata associated with an aggregation buffer 437 * that is not associated with other kinds of buffers. This aggregation 438 * metadata is _only_ relevant for the in-kernel implementation of 439 * aggregations; it is not actually relevant to user-level consumers. To do 440 * this, we allocate dynamic aggregation data (hash keys and hash buckets) 441 * starting below the _limit_ of the buffer, and we allocate data from the 442 * _base_ of the buffer. When the aggregation buffer is copied out, _only_ the 443 * data is copied out; the metadata is simply discarded. Schematically, 444 * aggregation buffers look like: 445 * 446 * base of data buffer ---> +-------+------+-----------+-------+ 447 * | aggid | key | value | aggid | 448 * +-------+------+-----------+-------+ 449 * | key | 450 * +-------+-------+-----+------------+ 451 * | value | aggid | key | value | 452 * +-------+------++-----+------+-----+ 453 * | aggid | key | value | | 454 * +-------+------+-------------+ | 455 * | || | 456 * | || | 457 * | \/ | 458 * : : 459 * . . 460 * . . 461 * . . 462 * : : 463 * | /\ | 464 * | || +------------+ 465 * | || | | 466 * +---------------------+ | 467 * | hash keys | 468 * | (dtrace_aggkey structures) | 469 * | | 470 * +----------------------------------+ 471 * | hash buckets | 472 * | (dtrace_aggbuffer structure) | 473 * | | 474 * limit of data buffer ---> +----------------------------------+ 475 * 476 * 477 * As implied above, just as we assure that ECBs always store a constant 478 * amount of data, we assure that a given aggregation -- identified by its 479 * aggregation ID -- always stores data of a constant quantity and type. 480 * As with EPIDs, this allows the aggregation ID to serve as the metadata for a 481 * given record. 482 * 483 * Note that the size of the dtrace_aggkey structure must be sizeof (uintptr_t) 484 * aligned. (If this the structure changes such that this becomes false, an 485 * assertion will fail in dtrace_aggregate().) 486 */ 487 typedef struct dtrace_aggkey { 488 uint32_t dtak_hashval; /* hash value */ 489 uint32_t dtak_action:4; /* action -- 4 bits */ 490 uint32_t dtak_size:28; /* size -- 28 bits */ 491 caddr_t dtak_data; /* data pointer */ 492 struct dtrace_aggkey *dtak_next; /* next in hash chain */ 493 } dtrace_aggkey_t; 494 495 typedef struct dtrace_aggbuffer { 496 uintptr_t dtagb_hashsize; /* number of buckets */ 497 uintptr_t dtagb_free; /* free list of keys */ 498 dtrace_aggkey_t **dtagb_hash; /* hash table */ 499 } dtrace_aggbuffer_t; 500 501 /* 502 * DTrace Speculations 503 * 504 * Speculations have a per-CPU buffer and a global state. Once a speculation 505 * buffer has been comitted or discarded, it cannot be reused until all CPUs 506 * have taken the same action (commit or discard) on their respective 507 * speculative buffer. However, because DTrace probes may execute in arbitrary 508 * context, other CPUs cannot simply be cross-called at probe firing time to 509 * perform the necessary commit or discard. The speculation states thus 510 * optimize for the case that a speculative buffer is only active on one CPU at 511 * the time of a commit() or discard() -- for if this is the case, other CPUs 512 * need not take action, and the speculation is immediately available for 513 * reuse. If the speculation is active on multiple CPUs, it must be 514 * asynchronously cleaned -- potentially leading to a higher rate of dirty 515 * speculative drops. The speculation states are as follows: 516 * 517 * DTRACESPEC_INACTIVE <= Initial state; inactive speculation 518 * DTRACESPEC_ACTIVE <= Allocated, but not yet speculatively traced to 519 * DTRACESPEC_ACTIVEONE <= Speculatively traced to on one CPU 520 * DTRACESPEC_ACTIVEMANY <= Speculatively traced to on more than one CPU 521 * DTRACESPEC_COMMITTING <= Currently being commited on one CPU 522 * DTRACESPEC_COMMITTINGMANY <= Currently being commited on many CPUs 523 * DTRACESPEC_DISCARDING <= Currently being discarded on many CPUs 524 * 525 * The state transition diagram is as follows: 526 * 527 * +----------------------------------------------------------+ 528 * | | 529 * | +------------+ | 530 * | +-------------------| COMMITTING |<-----------------+ | 531 * | | +------------+ | | 532 * | | copied spec. ^ commit() on | | discard() on 533 * | | into principal | active CPU | | active CPU 534 * | | | commit() | | 535 * V V | | | 536 * +----------+ +--------+ +-----------+ 537 * | INACTIVE |---------------->| ACTIVE |--------------->| ACTIVEONE | 538 * +----------+ speculation() +--------+ speculate() +-----------+ 539 * ^ ^ | | | 540 * | | | discard() | | 541 * | | asynchronously | discard() on | | speculate() 542 * | | cleaned V inactive CPU | | on inactive 543 * | | +------------+ | | CPU 544 * | +-------------------| DISCARDING |<-----------------+ | 545 * | +------------+ | 546 * | asynchronously ^ | 547 * | copied spec. | discard() | 548 * | into principal +------------------------+ | 549 * | | V 550 * +----------------+ commit() +------------+ 551 * | COMMITTINGMANY |<----------------------------------| ACTIVEMANY | 552 * +----------------+ +------------+ 553 */ 554 typedef enum dtrace_speculation_state { 555 DTRACESPEC_INACTIVE = 0, 556 DTRACESPEC_ACTIVE, 557 DTRACESPEC_ACTIVEONE, 558 DTRACESPEC_ACTIVEMANY, 559 DTRACESPEC_COMMITTING, 560 DTRACESPEC_COMMITTINGMANY, 561 DTRACESPEC_DISCARDING 562 } dtrace_speculation_state_t; 563 564 typedef struct dtrace_speculation { 565 dtrace_speculation_state_t dtsp_state; /* current speculation state */ 566 int dtsp_cleaning; /* non-zero if being cleaned */ 567 dtrace_buffer_t *dtsp_buffer; /* speculative buffer */ 568 } dtrace_speculation_t; 569 570 /* 571 * DTrace Dynamic Variables 572 * 573 * The dynamic variable problem is obviously decomposed into two subproblems: 574 * allocating new dynamic storage, and freeing old dynamic storage. The 575 * presence of the second problem makes the first much more complicated -- or 576 * rather, the absence of the second renders the first trivial. This is the 577 * case with aggregations, for which there is effectively no deallocation of 578 * dynamic storage. (Or more accurately, all dynamic storage is deallocated 579 * when a snapshot is taken of the aggregation.) As DTrace dynamic variables 580 * allow for both dynamic allocation and dynamic deallocation, the 581 * implementation of dynamic variables is quite a bit more complicated than 582 * that of their aggregation kin. 583 * 584 * We observe that allocating new dynamic storage is tricky only because the 585 * size can vary -- the allocation problem is much easier if allocation sizes 586 * are uniform. We further observe that in D, the size of dynamic variables is 587 * actually _not_ dynamic -- dynamic variable sizes may be determined by static 588 * analysis of DIF text. (This is true even of putatively dynamically-sized 589 * objects like strings and stacks, the sizes of which are dictated by the 590 * "stringsize" and "stackframes" variables, respectively.) We exploit this by 591 * performing this analysis on all DIF before enabling any probes. For each 592 * dynamic load or store, we calculate the dynamically-allocated size plus the 593 * size of the dtrace_dynvar structure plus the storage required to key the 594 * data. For all DIF, we take the largest value and dub it the _chunksize_. 595 * We then divide dynamic memory into two parts: a hash table that is wide 596 * enough to have every chunk in its own bucket, and a larger region of equal 597 * chunksize units. Whenever we wish to dynamically allocate a variable, we 598 * always allocate a single chunk of memory. Depending on the uniformity of 599 * allocation, this will waste some amount of memory -- but it eliminates the 600 * non-determinism inherent in traditional heap fragmentation. 601 * 602 * Dynamic objects are allocated by storing a non-zero value to them; they are 603 * deallocated by storing a zero value to them. Dynamic variables are 604 * complicated enormously by being shared between CPUs. In particular, 605 * consider the following scenario: 606 * 607 * CPU A CPU B 608 * +---------------------------------+ +---------------------------------+ 609 * | | | | 610 * | allocates dynamic object a[123] | | | 611 * | by storing the value 345 to it | | | 612 * | ---------> | 613 * | | | wishing to load from object | 614 * | | | a[123], performs lookup in | 615 * | | | dynamic variable space | 616 * | <--------- | 617 * | deallocates object a[123] by | | | 618 * | storing 0 to it | | | 619 * | | | | 620 * | allocates dynamic object b[567] | | performs load from a[123] | 621 * | by storing the value 789 to it | | | 622 * : : : : 623 * . . . . 624 * 625 * This is obviously a race in the D program, but there are nonetheless only 626 * two valid values for CPU B's load from a[123]: 345 or 0. Most importantly, 627 * CPU B may _not_ see the value 789 for a[123]. 628 * 629 * There are essentially two ways to deal with this: 630 * 631 * (1) Explicitly spin-lock variables. That is, if CPU B wishes to load 632 * from a[123], it needs to lock a[123] and hold the lock for the 633 * duration that it wishes to manipulate it. 634 * 635 * (2) Avoid reusing freed chunks until it is known that no CPU is referring 636 * to them. 637 * 638 * The implementation of (1) is rife with complexity, because it requires the 639 * user of a dynamic variable to explicitly decree when they are done using it. 640 * Were all variables by value, this perhaps wouldn't be debilitating -- but 641 * dynamic variables of non-scalar types are tracked by reference. That is, if 642 * a dynamic variable is, say, a string, and that variable is to be traced to, 643 * say, the principal buffer, the DIF emulation code returns to the main 644 * dtrace_probe() loop a pointer to the underlying storage, not the contents of 645 * the storage. Further, code calling on DIF emulation would have to be aware 646 * that the DIF emulation has returned a reference to a dynamic variable that 647 * has been potentially locked. The variable would have to be unlocked after 648 * the main dtrace_probe() loop is finished with the variable, and the main 649 * dtrace_probe() loop would have to be careful to not call any further DIF 650 * emulation while the variable is locked to avoid deadlock. More generally, 651 * if one were to implement (1), DIF emulation code dealing with dynamic 652 * variables could only deal with one dynamic variable at a time (lest deadlock 653 * result). To sum, (1) exports too much subtlety to the users of dynamic 654 * variables -- increasing maintenance burden and imposing serious constraints 655 * on future DTrace development. 656 * 657 * The implementation of (2) is also complex, but the complexity is more 658 * manageable. We need to be sure that when a variable is deallocated, it is 659 * not placed on a traditional free list, but rather on a _dirty_ list. Once a 660 * variable is on a dirty list, it cannot be found by CPUs performing a 661 * subsequent lookup of the variable -- but it may still be in use by other 662 * CPUs. To assure that all CPUs that may be seeing the old variable have 663 * cleared out of probe context, a dtrace_sync() can be issued. Once the 664 * dtrace_sync() has completed, it can be known that all CPUs are done 665 * manipulating the dynamic variable -- the dirty list can be atomically 666 * appended to the free list. Unfortunately, there's a slight hiccup in this 667 * mechanism: dtrace_sync() may not be issued from probe context. The 668 * dtrace_sync() must be therefore issued asynchronously from non-probe 669 * context. For this we rely on the DTrace cleaner, a cyclic that runs at the 670 * "cleanrate" frequency. To ease this implementation, we define several chunk 671 * lists: 672 * 673 * - Dirty. Deallocated chunks, not yet cleaned. Not available. 674 * 675 * - Rinsing. Formerly dirty chunks that are currently being asynchronously 676 * cleaned. Not available, but will be shortly. Dynamic variable 677 * allocation may not spin or block for availability, however. 678 * 679 * - Clean. Clean chunks, ready for allocation -- but not on the free list. 680 * 681 * - Free. Available for allocation. 682 * 683 * Moreover, to avoid absurd contention, _each_ of these lists is implemented 684 * on a per-CPU basis. This is only for performance, not correctness; chunks 685 * may be allocated from another CPU's free list. The algorithm for allocation 686 * then is this: 687 * 688 * (1) Attempt to atomically allocate from current CPU's free list. If list 689 * is non-empty and allocation is successful, allocation is complete. 690 * 691 * (2) If the clean list is non-empty, atomically move it to the free list, 692 * and reattempt (1). 693 * 694 * (3) If the dynamic variable space is in the CLEAN state, look for free 695 * and clean lists on other CPUs by setting the current CPU to the next 696 * CPU, and reattempting (1). If the next CPU is the current CPU (that 697 * is, if all CPUs have been checked), atomically switch the state of 698 * the dynamic variable space based on the following: 699 * 700 * - If no free chunks were found and no dirty chunks were found, 701 * atomically set the state to EMPTY. 702 * 703 * - If dirty chunks were found, atomically set the state to DIRTY. 704 * 705 * - If rinsing chunks were found, atomically set the state to RINSING. 706 * 707 * (4) Based on state of dynamic variable space state, increment appropriate 708 * counter to indicate dynamic drops (if in EMPTY state) vs. dynamic 709 * dirty drops (if in DIRTY state) vs. dynamic rinsing drops (if in 710 * RINSING state). Fail the allocation. 711 * 712 * The cleaning cyclic operates with the following algorithm: for all CPUs 713 * with a non-empty dirty list, atomically move the dirty list to the rinsing 714 * list. Perform a dtrace_sync(). For all CPUs with a non-empty rinsing list, 715 * atomically move the rinsing list to the clean list. Perform another 716 * dtrace_sync(). By this point, all CPUs have seen the new clean list; the 717 * state of the dynamic variable space can be restored to CLEAN. 718 * 719 * There exist two final races that merit explanation. The first is a simple 720 * allocation race: 721 * 722 * CPU A CPU B 723 * +---------------------------------+ +---------------------------------+ 724 * | | | | 725 * | allocates dynamic object a[123] | | allocates dynamic object a[123] | 726 * | by storing the value 345 to it | | by storing the value 567 to it | 727 * | | | | 728 * : : : : 729 * . . . . 730 * 731 * Again, this is a race in the D program. It can be resolved by having a[123] 732 * hold the value 345 or a[123] hold the value 567 -- but it must be true that 733 * a[123] have only _one_ of these values. (That is, the racing CPUs may not 734 * put the same element twice on the same hash chain.) This is resolved 735 * simply: before the allocation is undertaken, the start of the new chunk's 736 * hash chain is noted. Later, after the allocation is complete, the hash 737 * chain is atomically switched to point to the new element. If this fails 738 * (because of either concurrent allocations or an allocation concurrent with a 739 * deletion), the newly allocated chunk is deallocated to the dirty list, and 740 * the whole process of looking up (and potentially allocating) the dynamic 741 * variable is reattempted. 742 * 743 * The final race is a simple deallocation race: 744 * 745 * CPU A CPU B 746 * +---------------------------------+ +---------------------------------+ 747 * | | | | 748 * | deallocates dynamic object | | deallocates dynamic object | 749 * | a[123] by storing the value 0 | | a[123] by storing the value 0 | 750 * | to it | | to it | 751 * | | | | 752 * : : : : 753 * . . . . 754 * 755 * Once again, this is a race in the D program, but it is one that we must 756 * handle without corrupting the underlying data structures. Because 757 * deallocations require the deletion of a chunk from the middle of a hash 758 * chain, we cannot use a single-word atomic operation to remove it. For this, 759 * we add a spin lock to the hash buckets that is _only_ used for deallocations 760 * (allocation races are handled as above). Further, this spin lock is _only_ 761 * held for the duration of the delete; before control is returned to the DIF 762 * emulation code, the hash bucket is unlocked. 763 */ 764 typedef struct dtrace_key { 765 uint64_t dttk_value; /* data value or data pointer */ 766 uint64_t dttk_size; /* 0 if by-val, >0 if by-ref */ 767 } dtrace_key_t; 768 769 typedef struct dtrace_tuple { 770 uint32_t dtt_nkeys; /* number of keys in tuple */ 771 uint32_t dtt_pad; /* padding */ 772 dtrace_key_t dtt_key[1]; /* array of tuple keys */ 773 } dtrace_tuple_t; 774 775 typedef struct dtrace_dynvar { 776 uint64_t dtdv_hashval; /* hash value -- 0 if free */ 777 struct dtrace_dynvar *dtdv_next; /* next on list or hash chain */ 778 void *dtdv_data; /* pointer to data */ 779 dtrace_tuple_t dtdv_tuple; /* tuple key */ 780 } dtrace_dynvar_t; 781 782 typedef enum dtrace_dynvar_op { 783 DTRACE_DYNVAR_ALLOC, 784 DTRACE_DYNVAR_NOALLOC, 785 DTRACE_DYNVAR_DEALLOC 786 } dtrace_dynvar_op_t; 787 788 typedef struct dtrace_dynhash { 789 dtrace_dynvar_t *dtdh_chain; /* hash chain for this bucket */ 790 uintptr_t dtdh_lock; /* deallocation lock */ 791 #ifdef _LP64 792 uintptr_t dtdh_pad[6]; /* pad to avoid false sharing */ 793 #else 794 uintptr_t dtdh_pad[14]; /* pad to avoid false sharing */ 795 #endif 796 } dtrace_dynhash_t; 797 798 typedef struct dtrace_dstate_percpu { 799 dtrace_dynvar_t *dtdsc_free; /* free list for this CPU */ 800 dtrace_dynvar_t *dtdsc_dirty; /* dirty list for this CPU */ 801 dtrace_dynvar_t *dtdsc_rinsing; /* rinsing list for this CPU */ 802 dtrace_dynvar_t *dtdsc_clean; /* clean list for this CPU */ 803 uint64_t dtdsc_drops; /* number of capacity drops */ 804 uint64_t dtdsc_dirty_drops; /* number of dirty drops */ 805 uint64_t dtdsc_rinsing_drops; /* number of rinsing drops */ 806 #ifdef _LP64 807 uint64_t dtdsc_pad; /* pad to avoid false sharing */ 808 #else 809 uint64_t dtdsc_pad[2]; /* pad to avoid false sharing */ 810 #endif 811 } dtrace_dstate_percpu_t; 812 813 typedef enum dtrace_dstate_state { 814 DTRACE_DSTATE_CLEAN = 0, 815 DTRACE_DSTATE_EMPTY, 816 DTRACE_DSTATE_DIRTY, 817 DTRACE_DSTATE_RINSING 818 } dtrace_dstate_state_t; 819 820 typedef struct dtrace_dstate { 821 void *dtds_base; /* base of dynamic var. space */ 822 size_t dtds_size; /* size of dynamic var. space */ 823 size_t dtds_hashsize; /* number of buckets in hash */ 824 size_t dtds_chunksize; /* size of each chunk */ 825 dtrace_dynhash_t *dtds_hash; /* pointer to hash table */ 826 dtrace_dstate_state_t dtds_state; /* current dynamic var. state */ 827 dtrace_dstate_percpu_t *dtds_percpu; /* per-CPU dyn. var. state */ 828 } dtrace_dstate_t; 829 830 /* 831 * DTrace Variable State 832 * 833 * The DTrace variable state tracks user-defined variables in its dtrace_vstate 834 * structure. Each DTrace consumer has exactly one dtrace_vstate structure, 835 * but some dtrace_vstate structures may exist without a corresponding DTrace 836 * consumer (see "DTrace Helpers", below). As described in <sys/dtrace.h>, 837 * user-defined variables can have one of three scopes: 838 * 839 * DIFV_SCOPE_GLOBAL => global scope 840 * DIFV_SCOPE_THREAD => thread-local scope (i.e. "self->" variables) 841 * DIFV_SCOPE_LOCAL => clause-local scope (i.e. "this->" variables) 842 * 843 * The variable state tracks variables by both their scope and their allocation 844 * type: 845 * 846 * - The dtvs_globals and dtvs_locals members each point to an array of 847 * dtrace_statvar structures. These structures contain both the variable 848 * metadata (dtrace_difv structures) and the underlying storage for all 849 * statically allocated variables, including statically allocated 850 * DIFV_SCOPE_GLOBAL variables and all DIFV_SCOPE_LOCAL variables. 851 * 852 * - The dtvs_tlocals member points to an array of dtrace_difv structures for 853 * DIFV_SCOPE_THREAD variables. As such, this array tracks _only_ the 854 * variable metadata for DIFV_SCOPE_THREAD variables; the underlying storage 855 * is allocated out of the dynamic variable space. 856 * 857 * - The dtvs_dynvars member is the dynamic variable state associated with the 858 * variable state. The dynamic variable state (described in "DTrace Dynamic 859 * Variables", above) tracks all DIFV_SCOPE_THREAD variables and all 860 * dynamically-allocated DIFV_SCOPE_GLOBAL variables. 861 */ 862 typedef struct dtrace_statvar { 863 uint64_t dtsv_data; /* data or pointer to it */ 864 size_t dtsv_size; /* size of pointed-to data */ 865 int dtsv_refcnt; /* reference count */ 866 dtrace_difv_t dtsv_var; /* variable metadata */ 867 } dtrace_statvar_t; 868 869 typedef struct dtrace_vstate { 870 dtrace_state_t *dtvs_state; /* back pointer to state */ 871 dtrace_statvar_t **dtvs_globals; /* statically-allocated glbls */ 872 int dtvs_nglobals; /* number of globals */ 873 dtrace_difv_t *dtvs_tlocals; /* thread-local metadata */ 874 int dtvs_ntlocals; /* number of thread-locals */ 875 dtrace_statvar_t **dtvs_locals; /* clause-local data */ 876 int dtvs_nlocals; /* number of clause-locals */ 877 dtrace_dstate_t dtvs_dynvars; /* dynamic variable state */ 878 } dtrace_vstate_t; 879 880 /* 881 * DTrace Machine State 882 * 883 * In the process of processing a fired probe, DTrace needs to track and/or 884 * cache some per-CPU state associated with that particular firing. This is 885 * state that is always discarded after the probe firing has completed, and 886 * much of it is not specific to any DTrace consumer, remaining valid across 887 * all ECBs. This state is tracked in the dtrace_mstate structure. 888 */ 889 #define DTRACE_MSTATE_ARGS 0x00000001 890 #define DTRACE_MSTATE_PROBE 0x00000002 891 #define DTRACE_MSTATE_EPID 0x00000004 892 #define DTRACE_MSTATE_TIMESTAMP 0x00000008 893 #define DTRACE_MSTATE_STACKDEPTH 0x00000010 894 #define DTRACE_MSTATE_CALLER 0x00000020 895 #define DTRACE_MSTATE_IPL 0x00000040 896 #define DTRACE_MSTATE_FLTOFFS 0x00000080 897 #define DTRACE_MSTATE_WALLTIMESTAMP 0x00000100 898 #define DTRACE_MSTATE_USTACKDEPTH 0x00000200 899 #define DTRACE_MSTATE_UCALLER 0x00000400 900 901 typedef struct dtrace_mstate { 902 uintptr_t dtms_scratch_base; /* base of scratch space */ 903 uintptr_t dtms_scratch_ptr; /* current scratch pointer */ 904 size_t dtms_scratch_size; /* scratch size */ 905 uint32_t dtms_present; /* variables that are present */ 906 uint64_t dtms_arg[5]; /* cached arguments */ 907 dtrace_epid_t dtms_epid; /* current EPID */ 908 uint64_t dtms_timestamp; /* cached timestamp */ 909 hrtime_t dtms_walltimestamp; /* cached wall timestamp */ 910 int dtms_stackdepth; /* cached stackdepth */ 911 int dtms_ustackdepth; /* cached ustackdepth */ 912 struct dtrace_probe *dtms_probe; /* current probe */ 913 uintptr_t dtms_caller; /* cached caller */ 914 uint64_t dtms_ucaller; /* cached user-level caller */ 915 int dtms_ipl; /* cached interrupt pri lev */ 916 int dtms_fltoffs; /* faulting DIFO offset */ 917 uintptr_t dtms_strtok; /* saved strtok() pointer */ 918 uint32_t dtms_access; /* memory access rights */ 919 dtrace_difo_t *dtms_difo; /* current dif object */ 920 file_t *dtms_getf; /* cached rval of getf() */ 921 } dtrace_mstate_t; 922 923 #define DTRACE_COND_OWNER 0x1 924 #define DTRACE_COND_USERMODE 0x2 925 #define DTRACE_COND_ZONEOWNER 0x4 926 927 #define DTRACE_PROBEKEY_MAXDEPTH 8 /* max glob recursion depth */ 928 929 /* 930 * Access flag used by dtrace_mstate.dtms_access. 931 */ 932 #define DTRACE_ACCESS_KERNEL 0x1 /* the priv to read kmem */ 933 #define DTRACE_ACCESS_PROC 0x2 /* the priv for proc state */ 934 #define DTRACE_ACCESS_ARGS 0x4 /* the priv to examine args */ 935 936 /* 937 * DTrace Activity 938 * 939 * Each DTrace consumer is in one of several states, which (for purposes of 940 * avoiding yet-another overloading of the noun "state") we call the current 941 * _activity_. The activity transitions on dtrace_go() (from DTRACIOCGO), on 942 * dtrace_stop() (from DTRACIOCSTOP) and on the exit() action. Activities may 943 * only transition in one direction; the activity transition diagram is a 944 * directed acyclic graph. The activity transition diagram is as follows: 945 * 946 * 947 * +----------+ +--------+ +--------+ 948 * | INACTIVE |------------------>| WARMUP |------------------>| ACTIVE | 949 * +----------+ dtrace_go(), +--------+ dtrace_go(), +--------+ 950 * before BEGIN | after BEGIN | | | 951 * | | | | 952 * exit() action | | | | 953 * from BEGIN ECB | | | | 954 * | | | | 955 * v | | | 956 * +----------+ exit() action | | | 957 * +-----------------------------| DRAINING |<-------------------+ | | 958 * | +----------+ | | 959 * | | | | 960 * | dtrace_stop(), | | | 961 * | before END | | | 962 * | | | | 963 * | v | | 964 * | +---------+ +----------+ | | 965 * | | STOPPED |<----------------| COOLDOWN |<----------------------+ | 966 * | +---------+ dtrace_stop(), +----------+ dtrace_stop(), | 967 * | after END before END | 968 * | | 969 * | +--------+ | 970 * +----------------------------->| KILLED |<--------------------------+ 971 * deadman timeout or +--------+ deadman timeout or 972 * killed consumer killed consumer 973 * 974 * Note that once a DTrace consumer has stopped tracing, there is no way to 975 * restart it; if a DTrace consumer wishes to restart tracing, it must reopen 976 * the DTrace pseudodevice. 977 */ 978 typedef enum dtrace_activity { 979 DTRACE_ACTIVITY_INACTIVE = 0, /* not yet running */ 980 DTRACE_ACTIVITY_WARMUP, /* while starting */ 981 DTRACE_ACTIVITY_ACTIVE, /* running */ 982 DTRACE_ACTIVITY_DRAINING, /* before stopping */ 983 DTRACE_ACTIVITY_COOLDOWN, /* while stopping */ 984 DTRACE_ACTIVITY_STOPPED, /* after stopping */ 985 DTRACE_ACTIVITY_KILLED /* killed */ 986 } dtrace_activity_t; 987 988 /* 989 * DTrace Helper Implementation 990 * 991 * A description of the helper architecture may be found in <sys/dtrace.h>. 992 * Each process contains a pointer to its helpers in its p_dtrace_helpers 993 * member. This is a pointer to a dtrace_helpers structure, which contains an 994 * array of pointers to dtrace_helper structures, helper variable state (shared 995 * among a process's helpers) and a generation count. (The generation count is 996 * used to provide an identifier when a helper is added so that it may be 997 * subsequently removed.) The dtrace_helper structure is self-explanatory, 998 * containing pointers to the objects needed to execute the helper. Note that 999 * helpers are _duplicated_ across fork(2), and destroyed on exec(2). No more 1000 * than dtrace_helpers_max are allowed per-process. 1001 */ 1002 #define DTRACE_HELPER_ACTION_USTACK 0 1003 #define DTRACE_NHELPER_ACTIONS 1 1004 1005 typedef struct dtrace_helper_action { 1006 int dtha_generation; /* helper action generation */ 1007 int dtha_nactions; /* number of actions */ 1008 dtrace_difo_t *dtha_predicate; /* helper action predicate */ 1009 dtrace_difo_t **dtha_actions; /* array of actions */ 1010 struct dtrace_helper_action *dtha_next; /* next helper action */ 1011 } dtrace_helper_action_t; 1012 1013 typedef struct dtrace_helper_provider { 1014 int dthp_generation; /* helper provider generation */ 1015 uint32_t dthp_ref; /* reference count */ 1016 dof_helper_t dthp_prov; /* DOF w/ provider and probes */ 1017 } dtrace_helper_provider_t; 1018 1019 typedef struct dtrace_helpers { 1020 dtrace_helper_action_t **dthps_actions; /* array of helper actions */ 1021 dtrace_vstate_t dthps_vstate; /* helper action var. state */ 1022 dtrace_helper_provider_t **dthps_provs; /* array of providers */ 1023 uint_t dthps_nprovs; /* count of providers */ 1024 uint_t dthps_maxprovs; /* provider array size */ 1025 int dthps_generation; /* current generation */ 1026 pid_t dthps_pid; /* pid of associated proc */ 1027 int dthps_deferred; /* helper in deferred list */ 1028 struct dtrace_helpers *dthps_next; /* next pointer */ 1029 struct dtrace_helpers *dthps_prev; /* prev pointer */ 1030 } dtrace_helpers_t; 1031 1032 /* 1033 * DTrace Helper Action Tracing 1034 * 1035 * Debugging helper actions can be arduous. To ease the development and 1036 * debugging of helpers, DTrace contains a tracing-framework-within-a-tracing- 1037 * framework: helper tracing. If dtrace_helptrace_enabled is non-zero (which 1038 * it is by default on DEBUG kernels), all helper activity will be traced to a 1039 * global, in-kernel ring buffer. Each entry includes a pointer to the specific 1040 * helper, the location within the helper, and a trace of all local variables. 1041 * The ring buffer may be displayed in a human-readable format with the 1042 * ::dtrace_helptrace mdb(1) dcmd. 1043 */ 1044 #define DTRACE_HELPTRACE_NEXT (-1) 1045 #define DTRACE_HELPTRACE_DONE (-2) 1046 #define DTRACE_HELPTRACE_ERR (-3) 1047 1048 typedef struct dtrace_helptrace { 1049 dtrace_helper_action_t *dtht_helper; /* helper action */ 1050 int dtht_where; /* where in helper action */ 1051 int dtht_nlocals; /* number of locals */ 1052 int dtht_fault; /* type of fault (if any) */ 1053 int dtht_fltoffs; /* DIF offset */ 1054 uint64_t dtht_illval; /* faulting value */ 1055 uint64_t dtht_locals[1]; /* local variables */ 1056 } dtrace_helptrace_t; 1057 1058 /* 1059 * DTrace Credentials 1060 * 1061 * In probe context, we have limited flexibility to examine the credentials 1062 * of the DTrace consumer that created a particular enabling. We use 1063 * the Least Privilege interfaces to cache the consumer's cred pointer and 1064 * some facts about that credential in a dtrace_cred_t structure. These 1065 * can limit the consumer's breadth of visibility and what actions the 1066 * consumer may take. 1067 */ 1068 #define DTRACE_CRV_ALLPROC 0x01 1069 #define DTRACE_CRV_KERNEL 0x02 1070 #define DTRACE_CRV_ALLZONE 0x04 1071 1072 #define DTRACE_CRV_ALL (DTRACE_CRV_ALLPROC | DTRACE_CRV_KERNEL | \ 1073 DTRACE_CRV_ALLZONE) 1074 1075 #define DTRACE_CRA_PROC 0x0001 1076 #define DTRACE_CRA_PROC_CONTROL 0x0002 1077 #define DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER 0x0004 1078 #define DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE 0x0008 1079 #define DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG 0x0010 1080 #define DTRACE_CRA_KERNEL 0x0020 1081 #define DTRACE_CRA_KERNEL_DESTRUCTIVE 0x0040 1082 1083 #define DTRACE_CRA_ALL (DTRACE_CRA_PROC | \ 1084 DTRACE_CRA_PROC_CONTROL | \ 1085 DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER | \ 1086 DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE | \ 1087 DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG | \ 1088 DTRACE_CRA_KERNEL | \ 1089 DTRACE_CRA_KERNEL_DESTRUCTIVE) 1090 1091 typedef struct dtrace_cred { 1092 cred_t *dcr_cred; 1093 uint8_t dcr_destructive; 1094 uint8_t dcr_visible; 1095 uint16_t dcr_action; 1096 } dtrace_cred_t; 1097 1098 /* 1099 * DTrace Consumer State 1100 * 1101 * Each DTrace consumer has an associated dtrace_state structure that contains 1102 * its in-kernel DTrace state -- including options, credentials, statistics and 1103 * pointers to ECBs, buffers, speculations and formats. A dtrace_state 1104 * structure is also allocated for anonymous enablings. When anonymous state 1105 * is grabbed, the grabbing consumers dts_anon pointer is set to the grabbed 1106 * dtrace_state structure. 1107 */ 1108 struct dtrace_state { 1109 dev_t dts_dev; /* device */ 1110 int dts_necbs; /* total number of ECBs */ 1111 dtrace_ecb_t **dts_ecbs; /* array of ECBs */ 1112 dtrace_epid_t dts_epid; /* next EPID to allocate */ 1113 size_t dts_needed; /* greatest needed space */ 1114 struct dtrace_state *dts_anon; /* anon. state, if grabbed */ 1115 dtrace_activity_t dts_activity; /* current activity */ 1116 dtrace_vstate_t dts_vstate; /* variable state */ 1117 dtrace_buffer_t *dts_buffer; /* principal buffer */ 1118 dtrace_buffer_t *dts_aggbuffer; /* aggregation buffer */ 1119 dtrace_speculation_t *dts_speculations; /* speculation array */ 1120 int dts_nspeculations; /* number of speculations */ 1121 int dts_naggregations; /* number of aggregations */ 1122 dtrace_aggregation_t **dts_aggregations; /* aggregation array */ 1123 vmem_t *dts_aggid_arena; /* arena for aggregation IDs */ 1124 uint64_t dts_errors; /* total number of errors */ 1125 uint32_t dts_speculations_busy; /* number of spec. busy */ 1126 uint32_t dts_speculations_unavail; /* number of spec unavail */ 1127 uint32_t dts_stkstroverflows; /* stack string tab overflows */ 1128 uint32_t dts_dblerrors; /* errors in ERROR probes */ 1129 uint32_t dts_reserve; /* space reserved for END */ 1130 hrtime_t dts_laststatus; /* time of last status */ 1131 cyclic_id_t dts_cleaner; /* cleaning cyclic */ 1132 cyclic_id_t dts_deadman; /* deadman cyclic */ 1133 hrtime_t dts_alive; /* time last alive */ 1134 char dts_speculates; /* boolean: has speculations */ 1135 char dts_destructive; /* boolean: has dest. actions */ 1136 int dts_nformats; /* number of formats */ 1137 char **dts_formats; /* format string array */ 1138 dtrace_optval_t dts_options[DTRACEOPT_MAX]; /* options */ 1139 dtrace_cred_t dts_cred; /* credentials */ 1140 size_t dts_nretained; /* number of retained enabs */ 1141 int dts_getf; /* number of getf() calls */ 1142 }; 1143 1144 struct dtrace_provider { 1145 dtrace_pattr_t dtpv_attr; /* provider attributes */ 1146 dtrace_ppriv_t dtpv_priv; /* provider privileges */ 1147 dtrace_pops_t dtpv_pops; /* provider operations */ 1148 char *dtpv_name; /* provider name */ 1149 void *dtpv_arg; /* provider argument */ 1150 hrtime_t dtpv_defunct; /* when made defunct */ 1151 struct dtrace_provider *dtpv_next; /* next provider */ 1152 }; 1153 1154 struct dtrace_meta { 1155 dtrace_mops_t dtm_mops; /* meta provider operations */ 1156 char *dtm_name; /* meta provider name */ 1157 void *dtm_arg; /* meta provider user arg */ 1158 uint64_t dtm_count; /* no. of associated provs. */ 1159 }; 1160 1161 /* 1162 * DTrace Enablings 1163 * 1164 * A dtrace_enabling structure is used to track a collection of ECB 1165 * descriptions -- before they have been turned into actual ECBs. This is 1166 * created as a result of DOF processing, and is generally used to generate 1167 * ECBs immediately thereafter. However, enablings are also generally 1168 * retained should the probes they describe be created at a later time; as 1169 * each new module or provider registers with the framework, the retained 1170 * enablings are reevaluated, with any new match resulting in new ECBs. To 1171 * prevent probes from being matched more than once, the enabling tracks the 1172 * last probe generation matched, and only matches probes from subsequent 1173 * generations. 1174 */ 1175 typedef struct dtrace_enabling { 1176 dtrace_ecbdesc_t **dten_desc; /* all ECB descriptions */ 1177 int dten_ndesc; /* number of ECB descriptions */ 1178 int dten_maxdesc; /* size of ECB array */ 1179 dtrace_vstate_t *dten_vstate; /* associated variable state */ 1180 dtrace_genid_t dten_probegen; /* matched probe generation */ 1181 dtrace_ecbdesc_t *dten_current; /* current ECB description */ 1182 int dten_error; /* current error value */ 1183 int dten_primed; /* boolean: set if primed */ 1184 struct dtrace_enabling *dten_prev; /* previous enabling */ 1185 struct dtrace_enabling *dten_next; /* next enabling */ 1186 } dtrace_enabling_t; 1187 1188 /* 1189 * DTrace Anonymous Enablings 1190 * 1191 * Anonymous enablings are DTrace enablings that are not associated with a 1192 * controlling process, but rather derive their enabling from DOF stored as 1193 * properties in the dtrace.conf file. If there is an anonymous enabling, a 1194 * DTrace consumer state and enabling are created on attach. The state may be 1195 * subsequently grabbed by the first consumer specifying the "grabanon" 1196 * option. As long as an anonymous DTrace enabling exists, dtrace(7D) will 1197 * refuse to unload. 1198 */ 1199 typedef struct dtrace_anon { 1200 dtrace_state_t *dta_state; /* DTrace consumer state */ 1201 dtrace_enabling_t *dta_enabling; /* pointer to enabling */ 1202 processorid_t dta_beganon; /* which CPU BEGIN ran on */ 1203 } dtrace_anon_t; 1204 1205 /* 1206 * DTrace Error Debugging 1207 */ 1208 #ifdef DEBUG 1209 #define DTRACE_ERRDEBUG 1210 #endif 1211 1212 #ifdef DTRACE_ERRDEBUG 1213 1214 typedef struct dtrace_errhash { 1215 const char *dter_msg; /* error message */ 1216 int dter_count; /* number of times seen */ 1217 } dtrace_errhash_t; 1218 1219 #define DTRACE_ERRHASHSZ 256 /* must be > number of err msgs */ 1220 1221 #endif /* DTRACE_ERRDEBUG */ 1222 1223 /* 1224 * DTrace Toxic Ranges 1225 * 1226 * DTrace supports safe loads from probe context; if the address turns out to 1227 * be invalid, a bit will be set by the kernel indicating that DTrace 1228 * encountered a memory error, and DTrace will propagate the error to the user 1229 * accordingly. However, there may exist some regions of memory in which an 1230 * arbitrary load can change system state, and from which it is impossible to 1231 * recover from such a load after it has been attempted. Examples of this may 1232 * include memory in which programmable I/O registers are mapped (for which a 1233 * read may have some implications for the device) or (in the specific case of 1234 * UltraSPARC-I and -II) the virtual address hole. The platform is required 1235 * to make DTrace aware of these toxic ranges; DTrace will then check that 1236 * target addresses are not in a toxic range before attempting to issue a 1237 * safe load. 1238 */ 1239 typedef struct dtrace_toxrange { 1240 uintptr_t dtt_base; /* base of toxic range */ 1241 uintptr_t dtt_limit; /* limit of toxic range */ 1242 } dtrace_toxrange_t; 1243 1244 extern uint64_t dtrace_getarg(int, int); 1245 extern greg_t dtrace_getfp(void); 1246 extern int dtrace_getipl(void); 1247 extern uintptr_t dtrace_caller(int); 1248 extern uint32_t dtrace_cas32(uint32_t *, uint32_t, uint32_t); 1249 extern void *dtrace_casptr(void *, void *, void *); 1250 extern void dtrace_copyin(uintptr_t, uintptr_t, size_t, volatile uint16_t *); 1251 extern void dtrace_copyinstr(uintptr_t, uintptr_t, size_t, volatile uint16_t *); 1252 extern void dtrace_copyout(uintptr_t, uintptr_t, size_t, volatile uint16_t *); 1253 extern void dtrace_copyoutstr(uintptr_t, uintptr_t, size_t, 1254 volatile uint16_t *); 1255 extern void dtrace_getpcstack(pc_t *, int, int, uint32_t *); 1256 extern ulong_t dtrace_getreg(struct regs *, uint_t); 1257 extern uint64_t dtrace_getvmreg(uint_t, volatile uint16_t *); 1258 extern int dtrace_getstackdepth(int); 1259 extern void dtrace_getupcstack(uint64_t *, int); 1260 extern void dtrace_getufpstack(uint64_t *, uint64_t *, int); 1261 extern int dtrace_getustackdepth(void); 1262 extern uintptr_t dtrace_fulword(void *); 1263 extern uint8_t dtrace_fuword8(void *); 1264 extern uint16_t dtrace_fuword16(void *); 1265 extern uint32_t dtrace_fuword32(void *); 1266 extern uint64_t dtrace_fuword64(void *); 1267 extern void dtrace_probe_error(dtrace_state_t *, dtrace_epid_t, int, int, 1268 int, uintptr_t); 1269 extern int dtrace_assfail(const char *, const char *, int); 1270 extern int dtrace_attached(void); 1271 extern hrtime_t dtrace_gethrestime(); 1272 1273 #ifdef __sparc 1274 extern void dtrace_flush_windows(void); 1275 extern void dtrace_flush_user_windows(void); 1276 extern uint_t dtrace_getotherwin(void); 1277 extern uint_t dtrace_getfprs(void); 1278 #else 1279 extern void dtrace_copy(uintptr_t, uintptr_t, size_t); 1280 extern void dtrace_copystr(uintptr_t, uintptr_t, size_t, volatile uint16_t *); 1281 #endif 1282 1283 /* 1284 * DTrace Assertions 1285 * 1286 * DTrace calls ASSERT from probe context. To assure that a failed ASSERT 1287 * does not induce a markedly more catastrophic failure (e.g., one from which 1288 * a dump cannot be gleaned), DTrace must define its own ASSERT to be one that 1289 * may safely be called from probe context. This header file must thus be 1290 * included by any DTrace component that calls ASSERT from probe context, and 1291 * _only_ by those components. (The only exception to this is kernel 1292 * debugging infrastructure at user-level that doesn't depend on calling 1293 * ASSERT.) 1294 */ 1295 #undef ASSERT 1296 #ifdef DEBUG 1297 #define ASSERT(EX) ((void)((EX) || \ 1298 dtrace_assfail(#EX, __FILE__, __LINE__))) 1299 #else 1300 #define ASSERT(X) ((void)0) 1301 #endif 1302 1303 #ifdef __cplusplus 1304 } 1305 #endif 1306 1307 #endif /* _SYS_DTRACE_IMPL_H */