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