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 * $FreeBSD$ 22 */ 23 24 /* 25 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 26 * Use is subject to license terms. 27 */ 28 29 /* 30 * Copyright 2016 Joyent, Inc. 31 * Copyright (c) 2012 by Delphix. All rights reserved. 32 */ 33 34 #ifndef _SYS_DTRACE_IMPL_H 35 #define _SYS_DTRACE_IMPL_H 36 37 #ifdef __cplusplus 38 extern "C" { 39 #endif 40 41 /* 42 * DTrace Dynamic Tracing Software: Kernel Implementation Interfaces 43 * 44 * Note: The contents of this file are private to the implementation of the 45 * Solaris system and DTrace subsystem and are subject to change at any time 46 * without notice. Applications and drivers using these interfaces will fail 47 * to run on future releases. These interfaces should not be used for any 48 * purpose except those expressly outlined in dtrace(7D) and libdtrace(3LIB). 49 * Please refer to the "Solaris Dynamic Tracing Guide" for more information. 50 */ 51 52 #include <sys/dtrace.h> 53 54 #ifndef illumos 55 #ifdef __sparcv9 56 typedef uint32_t pc_t; 57 #else 58 typedef uintptr_t pc_t; 59 #endif 60 typedef u_long greg_t; 61 #endif 62 63 /* 64 * DTrace Implementation Constants and Typedefs 65 */ 66 #define DTRACE_MAXPROPLEN 128 67 #define DTRACE_DYNVAR_CHUNKSIZE 256 68 69 #ifdef __FreeBSD__ 70 #define NCPU MAXCPU 71 #endif /* __FreeBSD__ */ 72 73 struct dtrace_probe; 74 struct dtrace_ecb; 75 struct dtrace_predicate; 76 struct dtrace_action; 77 struct dtrace_provider; 78 struct dtrace_state; 79 80 typedef struct dtrace_probe dtrace_probe_t; 81 typedef struct dtrace_ecb dtrace_ecb_t; 82 typedef struct dtrace_predicate dtrace_predicate_t; 83 typedef struct dtrace_action dtrace_action_t; 84 typedef struct dtrace_provider dtrace_provider_t; 85 typedef struct dtrace_meta dtrace_meta_t; 86 typedef struct dtrace_state dtrace_state_t; 87 typedef uint32_t dtrace_optid_t; 88 typedef uint32_t dtrace_specid_t; 89 typedef uint64_t dtrace_genid_t; 90 91 /* 92 * DTrace Probes 93 * 94 * The probe is the fundamental unit of the DTrace architecture. Probes are 95 * created by DTrace providers, and managed by the DTrace framework. A probe 96 * is identified by a unique <provider, module, function, name> tuple, and has 97 * a unique probe identifier assigned to it. (Some probes are not associated 98 * with a specific point in text; these are called _unanchored probes_ and have 99 * no module or function associated with them.) Probes are represented as a 100 * dtrace_probe structure. To allow quick lookups based on each element of the 101 * probe tuple, probes are hashed by each of provider, module, function and 102 * name. (If a lookup is performed based on a regular expression, a 103 * dtrace_probekey is prepared, and a linear search is performed.) Each probe 104 * is additionally pointed to by a linear array indexed by its identifier. The 105 * identifier is the provider's mechanism for indicating to the DTrace 106 * framework that a probe has fired: the identifier is passed as the first 107 * argument to dtrace_probe(), where it is then mapped into the corresponding 108 * dtrace_probe structure. From the dtrace_probe structure, dtrace_probe() can 109 * iterate over the probe's list of enabling control blocks; see "DTrace 110 * Enabling Control Blocks", below.) 111 */ 112 struct dtrace_probe { 113 dtrace_id_t dtpr_id; /* probe identifier */ 114 dtrace_ecb_t *dtpr_ecb; /* ECB list; see below */ 115 dtrace_ecb_t *dtpr_ecb_last; /* last ECB in list */ 116 void *dtpr_arg; /* provider argument */ 117 dtrace_cacheid_t dtpr_predcache; /* predicate cache ID */ 118 int dtpr_aframes; /* artificial frames */ 119 dtrace_provider_t *dtpr_provider; /* pointer to provider */ 120 char *dtpr_mod; /* probe's module name */ 121 char *dtpr_func; /* probe's function name */ 122 char *dtpr_name; /* probe's name */ 123 dtrace_probe_t *dtpr_nextmod; /* next in module hash */ 124 dtrace_probe_t *dtpr_prevmod; /* previous in module hash */ 125 dtrace_probe_t *dtpr_nextfunc; /* next in function hash */ 126 dtrace_probe_t *dtpr_prevfunc; /* previous in function hash */ 127 dtrace_probe_t *dtpr_nextname; /* next in name hash */ 128 dtrace_probe_t *dtpr_prevname; /* previous in name hash */ 129 dtrace_genid_t dtpr_gen; /* probe generation ID */ 130 }; 131 132 typedef int dtrace_probekey_f(const char *, const char *, int); 133 134 typedef struct dtrace_probekey { 135 char *dtpk_prov; /* provider name to match */ 136 dtrace_probekey_f *dtpk_pmatch; /* provider matching function */ 137 char *dtpk_mod; /* module name to match */ 138 dtrace_probekey_f *dtpk_mmatch; /* module matching function */ 139 char *dtpk_func; /* func name to match */ 140 dtrace_probekey_f *dtpk_fmatch; /* func matching function */ 141 char *dtpk_name; /* name to match */ 142 dtrace_probekey_f *dtpk_nmatch; /* name matching function */ 143 dtrace_id_t dtpk_id; /* identifier to match */ 144 } dtrace_probekey_t; 145 146 typedef struct dtrace_hashbucket { 147 struct dtrace_hashbucket *dthb_next; /* next on hash chain */ 148 dtrace_probe_t *dthb_chain; /* chain of probes */ 149 int dthb_len; /* number of probes here */ 150 } dtrace_hashbucket_t; 151 152 typedef struct dtrace_hash { 153 dtrace_hashbucket_t **dth_tab; /* hash table */ 154 int dth_size; /* size of hash table */ 155 int dth_mask; /* mask to index into table */ 156 int dth_nbuckets; /* total number of buckets */ 157 uintptr_t dth_nextoffs; /* offset of next in probe */ 158 uintptr_t dth_prevoffs; /* offset of prev in probe */ 159 uintptr_t dth_stroffs; /* offset of str in probe */ 160 } dtrace_hash_t; 161 162 /* 163 * DTrace Enabling Control Blocks 164 * 165 * When a provider wishes to fire a probe, it calls into dtrace_probe(), 166 * passing the probe identifier as the first argument. As described above, 167 * dtrace_probe() maps the identifier into a pointer to a dtrace_probe_t 168 * structure. This structure contains information about the probe, and a 169 * pointer to the list of Enabling Control Blocks (ECBs). Each ECB points to 170 * DTrace consumer state, and contains an optional predicate, and a list of 171 * actions. (Shown schematically below.) The ECB abstraction allows a single 172 * probe to be multiplexed across disjoint consumers, or across disjoint 173 * enablings of a single probe within one consumer. 174 * 175 * Enabling Control Block 176 * dtrace_ecb_t 177 * +------------------------+ 178 * | dtrace_epid_t ---------+--------------> Enabled Probe ID (EPID) 179 * | dtrace_state_t * ------+--------------> State associated with this ECB 180 * | dtrace_predicate_t * --+---------+ 181 * | dtrace_action_t * -----+----+ | 182 * | dtrace_ecb_t * ---+ | | | Predicate (if any) 183 * +-------------------+----+ | | dtrace_predicate_t 184 * | | +---> +--------------------+ 185 * | | | dtrace_difo_t * ---+----> DIFO 186 * | | +--------------------+ 187 * | | 188 * Next ECB | | Action 189 * (if any) | | dtrace_action_t 190 * : +--> +-------------------+ 191 * : | dtrace_actkind_t -+------> kind 192 * v | dtrace_difo_t * --+------> DIFO (if any) 193 * | dtrace_recdesc_t -+------> record descr. 194 * | dtrace_action_t * +------+ 195 * +-------------------+ | 196 * | Next action 197 * +-------------------------------+ (if any) 198 * | 199 * | Action 200 * | dtrace_action_t 201 * +--> +-------------------+ 202 * | dtrace_actkind_t -+------> kind 203 * | dtrace_difo_t * --+------> DIFO (if any) 204 * | dtrace_action_t * +------+ 205 * +-------------------+ | 206 * | Next action 207 * +-------------------------------+ (if any) 208 * | 209 * : 210 * v 211 * 212 * 213 * dtrace_probe() iterates over the ECB list. If the ECB needs less space 214 * than is available in the principal buffer, the ECB is processed: if the 215 * predicate is non-NULL, the DIF object is executed. If the result is 216 * non-zero, the action list is processed, with each action being executed 217 * accordingly. When the action list has been completely executed, processing 218 * advances to the next ECB. The ECB abstraction allows disjoint consumers 219 * to multiplex on single probes. 220 * 221 * Execution of the ECB results in consuming dte_size bytes in the buffer 222 * to record data. During execution, dte_needed bytes must be available in 223 * the buffer. This space is used for both recorded data and tuple data. 224 */ 225 struct dtrace_ecb { 226 dtrace_epid_t dte_epid; /* enabled probe ID */ 227 uint32_t dte_alignment; /* required alignment */ 228 size_t dte_needed; /* space needed for execution */ 229 size_t dte_size; /* size of recorded payload */ 230 dtrace_predicate_t *dte_predicate; /* predicate, if any */ 231 dtrace_action_t *dte_action; /* actions, if any */ 232 dtrace_ecb_t *dte_next; /* next ECB on probe */ 233 dtrace_state_t *dte_state; /* pointer to state */ 234 uint32_t dte_cond; /* security condition */ 235 dtrace_probe_t *dte_probe; /* pointer to probe */ 236 dtrace_action_t *dte_action_last; /* last action on ECB */ 237 uint64_t dte_uarg; /* library argument */ 238 }; 239 240 struct dtrace_predicate { 241 dtrace_difo_t *dtp_difo; /* DIF object */ 242 dtrace_cacheid_t dtp_cacheid; /* cache identifier */ 243 int dtp_refcnt; /* reference count */ 244 }; 245 246 struct dtrace_action { 247 dtrace_actkind_t dta_kind; /* kind of action */ 248 uint16_t dta_intuple; /* boolean: in aggregation */ 249 uint32_t dta_refcnt; /* reference count */ 250 dtrace_difo_t *dta_difo; /* pointer to DIFO */ 251 dtrace_recdesc_t dta_rec; /* record description */ 252 dtrace_action_t *dta_prev; /* previous action */ 253 dtrace_action_t *dta_next; /* next action */ 254 }; 255 256 typedef struct dtrace_aggregation { 257 dtrace_action_t dtag_action; /* action; must be first */ 258 dtrace_aggid_t dtag_id; /* identifier */ 259 dtrace_ecb_t *dtag_ecb; /* corresponding ECB */ 260 dtrace_action_t *dtag_first; /* first action in tuple */ 261 uint32_t dtag_base; /* base of aggregation */ 262 uint8_t dtag_hasarg; /* boolean: has argument */ 263 uint64_t dtag_initial; /* initial value */ 264 void (*dtag_aggregate)(uint64_t *, uint64_t, uint64_t); 265 } dtrace_aggregation_t; 266 267 /* 268 * DTrace Buffers 269 * 270 * Principal buffers, aggregation buffers, and speculative buffers are all 271 * managed with the dtrace_buffer structure. By default, this structure 272 * includes twin data buffers -- dtb_tomax and dtb_xamot -- that serve as the 273 * active and passive buffers, respectively. For speculative buffers, 274 * dtb_xamot will be NULL; for "ring" and "fill" buffers, dtb_xamot will point 275 * to a scratch buffer. For all buffer types, the dtrace_buffer structure is 276 * always allocated on a per-CPU basis; a single dtrace_buffer structure is 277 * never shared among CPUs. (That is, there is never true sharing of the 278 * dtrace_buffer structure; to prevent false sharing of the structure, it must 279 * always be aligned to the coherence granularity -- generally 64 bytes.) 280 * 281 * One of the critical design decisions of DTrace is that a given ECB always 282 * stores the same quantity and type of data. This is done to assure that the 283 * only metadata required for an ECB's traced data is the EPID. That is, from 284 * the EPID, the consumer can determine the data layout. (The data buffer 285 * layout is shown schematically below.) By assuring that one can determine 286 * data layout from the EPID, the metadata stream can be separated from the 287 * data stream -- simplifying the data stream enormously. The ECB always 288 * proceeds the recorded data as part of the dtrace_rechdr_t structure that 289 * includes the EPID and a high-resolution timestamp used for output ordering 290 * consistency. 291 * 292 * base of data buffer ---> +--------+--------------------+--------+ 293 * | rechdr | data | rechdr | 294 * +--------+------+--------+----+--------+ 295 * | data | rechdr | data | 296 * +---------------+--------+-------------+ 297 * | data, cont. | 298 * +--------+--------------------+--------+ 299 * | rechdr | data | | 300 * +--------+--------------------+ | 301 * | || | 302 * | || | 303 * | \/ | 304 * : : 305 * . . 306 * . . 307 * . . 308 * : : 309 * | | 310 * limit of data buffer ---> +--------------------------------------+ 311 * 312 * When evaluating an ECB, dtrace_probe() determines if the ECB's needs of the 313 * principal buffer (both scratch and payload) exceed the available space. If 314 * the ECB's needs exceed available space (and if the principal buffer policy 315 * is the default "switch" policy), the ECB is dropped, the buffer's drop count 316 * is incremented, and processing advances to the next ECB. If the ECB's needs 317 * can be met with the available space, the ECB is processed, but the offset in 318 * the principal buffer is only advanced if the ECB completes processing 319 * without error. 320 * 321 * When a buffer is to be switched (either because the buffer is the principal 322 * buffer with a "switch" policy or because it is an aggregation buffer), a 323 * cross call is issued to the CPU associated with the buffer. In the cross 324 * call context, interrupts are disabled, and the active and the inactive 325 * buffers are atomically switched. This involves switching the data pointers, 326 * copying the various state fields (offset, drops, errors, etc.) into their 327 * inactive equivalents, and clearing the state fields. Because interrupts are 328 * disabled during this procedure, the switch is guaranteed to appear atomic to 329 * dtrace_probe(). 330 * 331 * DTrace Ring Buffering 332 * 333 * To process a ring buffer correctly, one must know the oldest valid record. 334 * Processing starts at the oldest record in the buffer and continues until 335 * the end of the buffer is reached. Processing then resumes starting with 336 * the record stored at offset 0 in the buffer, and continues until the 337 * youngest record is processed. If trace records are of a fixed-length, 338 * determining the oldest record is trivial: 339 * 340 * - If the ring buffer has not wrapped, the oldest record is the record 341 * stored at offset 0. 342 * 343 * - If the ring buffer has wrapped, the oldest record is the record stored 344 * at the current offset. 345 * 346 * With variable length records, however, just knowing the current offset 347 * doesn't suffice for determining the oldest valid record: assuming that one 348 * allows for arbitrary data, one has no way of searching forward from the 349 * current offset to find the oldest valid record. (That is, one has no way 350 * of separating data from metadata.) It would be possible to simply refuse to 351 * process any data in the ring buffer between the current offset and the 352 * limit, but this leaves (potentially) an enormous amount of otherwise valid 353 * data unprocessed. 354 * 355 * To effect ring buffering, we track two offsets in the buffer: the current 356 * offset and the _wrapped_ offset. If a request is made to reserve some 357 * amount of data, and the buffer has wrapped, the wrapped offset is 358 * incremented until the wrapped offset minus the current offset is greater 359 * than or equal to the reserve request. This is done by repeatedly looking 360 * up the ECB corresponding to the EPID at the current wrapped offset, and 361 * incrementing the wrapped offset by the size of the data payload 362 * corresponding to that ECB. If this offset is greater than or equal to the 363 * limit of the data buffer, the wrapped offset is set to 0. Thus, the 364 * current offset effectively "chases" the wrapped offset around the buffer. 365 * Schematically: 366 * 367 * base of data buffer ---> +------+--------------------+------+ 368 * | EPID | data | EPID | 369 * +------+--------+------+----+------+ 370 * | data | EPID | data | 371 * +---------------+------+-----------+ 372 * | data, cont. | 373 * +------+---------------------------+ 374 * | EPID | data | 375 * current offset ---> +------+---------------------------+ 376 * | invalid data | 377 * wrapped offset ---> +------+--------------------+------+ 378 * | EPID | data | EPID | 379 * +------+--------+------+----+------+ 380 * | data | EPID | data | 381 * +---------------+------+-----------+ 382 * : : 383 * . . 384 * . ... valid data ... . 385 * . . 386 * : : 387 * +------+-------------+------+------+ 388 * | EPID | data | EPID | data | 389 * +------+------------++------+------+ 390 * | data, cont. | leftover | 391 * limit of data buffer ---> +-------------------+--------------+ 392 * 393 * If the amount of requested buffer space exceeds the amount of space 394 * available between the current offset and the end of the buffer: 395 * 396 * (1) all words in the data buffer between the current offset and the limit 397 * of the data buffer (marked "leftover", above) are set to 398 * DTRACE_EPIDNONE 399 * 400 * (2) the wrapped offset is set to zero 401 * 402 * (3) the iteration process described above occurs until the wrapped offset 403 * is greater than the amount of desired space. 404 * 405 * The wrapped offset is implemented by (re-)using the inactive offset. 406 * In a "switch" buffer policy, the inactive offset stores the offset in 407 * the inactive buffer; in a "ring" buffer policy, it stores the wrapped 408 * offset. 409 * 410 * DTrace Scratch Buffering 411 * 412 * Some ECBs may wish to allocate dynamically-sized temporary scratch memory. 413 * To accommodate such requests easily, scratch memory may be allocated in 414 * the buffer beyond the current offset plus the needed memory of the current 415 * ECB. If there isn't sufficient room in the buffer for the requested amount 416 * of scratch space, the allocation fails and an error is generated. Scratch 417 * memory is tracked in the dtrace_mstate_t and is automatically freed when 418 * the ECB ceases processing. Note that ring buffers cannot allocate their 419 * scratch from the principal buffer -- lest they needlessly overwrite older, 420 * valid data. Ring buffers therefore have their own dedicated scratch buffer 421 * from which scratch is allocated. 422 */ 423 #define DTRACEBUF_RING 0x0001 /* bufpolicy set to "ring" */ 424 #define DTRACEBUF_FILL 0x0002 /* bufpolicy set to "fill" */ 425 #define DTRACEBUF_NOSWITCH 0x0004 /* do not switch buffer */ 426 #define DTRACEBUF_WRAPPED 0x0008 /* ring buffer has wrapped */ 427 #define DTRACEBUF_DROPPED 0x0010 /* drops occurred */ 428 #define DTRACEBUF_ERROR 0x0020 /* errors occurred */ 429 #define DTRACEBUF_FULL 0x0040 /* "fill" buffer is full */ 430 #define DTRACEBUF_CONSUMED 0x0080 /* buffer has been consumed */ 431 #define DTRACEBUF_INACTIVE 0x0100 /* buffer is not yet active */ 432 433 typedef struct dtrace_buffer { 434 uint64_t dtb_offset; /* current offset in buffer */ 435 uint64_t dtb_size; /* size of buffer */ 436 uint32_t dtb_flags; /* flags */ 437 uint32_t dtb_drops; /* number of drops */ 438 caddr_t dtb_tomax; /* active buffer */ 439 caddr_t dtb_xamot; /* inactive buffer */ 440 uint32_t dtb_xamot_flags; /* inactive flags */ 441 uint32_t dtb_xamot_drops; /* drops in inactive buffer */ 442 uint64_t dtb_xamot_offset; /* offset in inactive buffer */ 443 uint32_t dtb_errors; /* number of errors */ 444 uint32_t dtb_xamot_errors; /* errors in inactive buffer */ 445 #ifndef _LP64 446 uint64_t dtb_pad1; /* pad out to 64 bytes */ 447 #endif 448 uint64_t dtb_switched; /* time of last switch */ 449 uint64_t dtb_interval; /* observed switch interval */ 450 uint64_t dtb_pad2[6]; /* pad to avoid false sharing */ 451 } dtrace_buffer_t; 452 453 /* 454 * DTrace Aggregation Buffers 455 * 456 * Aggregation buffers use much of the same mechanism as described above 457 * ("DTrace Buffers"). However, because an aggregation is fundamentally a 458 * hash, there exists dynamic metadata associated with an aggregation buffer 459 * that is not associated with other kinds of buffers. This aggregation 460 * metadata is _only_ relevant for the in-kernel implementation of 461 * aggregations; it is not actually relevant to user-level consumers. To do 462 * this, we allocate dynamic aggregation data (hash keys and hash buckets) 463 * starting below the _limit_ of the buffer, and we allocate data from the 464 * _base_ of the buffer. When the aggregation buffer is copied out, _only_ the 465 * data is copied out; the metadata is simply discarded. Schematically, 466 * aggregation buffers look like: 467 * 468 * base of data buffer ---> +-------+------+-----------+-------+ 469 * | aggid | key | value | aggid | 470 * +-------+------+-----------+-------+ 471 * | key | 472 * +-------+-------+-----+------------+ 473 * | value | aggid | key | value | 474 * +-------+------++-----+------+-----+ 475 * | aggid | key | value | | 476 * +-------+------+-------------+ | 477 * | || | 478 * | || | 479 * | \/ | 480 * : : 481 * . . 482 * . . 483 * . . 484 * : : 485 * | /\ | 486 * | || +------------+ 487 * | || | | 488 * +---------------------+ | 489 * | hash keys | 490 * | (dtrace_aggkey structures) | 491 * | | 492 * +----------------------------------+ 493 * | hash buckets | 494 * | (dtrace_aggbuffer structure) | 495 * | | 496 * limit of data buffer ---> +----------------------------------+ 497 * 498 * 499 * As implied above, just as we assure that ECBs always store a constant 500 * amount of data, we assure that a given aggregation -- identified by its 501 * aggregation ID -- always stores data of a constant quantity and type. 502 * As with EPIDs, this allows the aggregation ID to serve as the metadata for a 503 * given record. 504 * 505 * Note that the size of the dtrace_aggkey structure must be sizeof (uintptr_t) 506 * aligned. (If this the structure changes such that this becomes false, an 507 * assertion will fail in dtrace_aggregate().) 508 */ 509 typedef struct dtrace_aggkey { 510 uint32_t dtak_hashval; /* hash value */ 511 uint32_t dtak_action:4; /* action -- 4 bits */ 512 uint32_t dtak_size:28; /* size -- 28 bits */ 513 caddr_t dtak_data; /* data pointer */ 514 struct dtrace_aggkey *dtak_next; /* next in hash chain */ 515 } dtrace_aggkey_t; 516 517 typedef struct dtrace_aggbuffer { 518 uintptr_t dtagb_hashsize; /* number of buckets */ 519 uintptr_t dtagb_free; /* free list of keys */ 520 dtrace_aggkey_t **dtagb_hash; /* hash table */ 521 } dtrace_aggbuffer_t; 522 523 /* 524 * DTrace Speculations 525 * 526 * Speculations have a per-CPU buffer and a global state. Once a speculation 527 * buffer has been comitted or discarded, it cannot be reused until all CPUs 528 * have taken the same action (commit or discard) on their respective 529 * speculative buffer. However, because DTrace probes may execute in arbitrary 530 * context, other CPUs cannot simply be cross-called at probe firing time to 531 * perform the necessary commit or discard. The speculation states thus 532 * optimize for the case that a speculative buffer is only active on one CPU at 533 * the time of a commit() or discard() -- for if this is the case, other CPUs 534 * need not take action, and the speculation is immediately available for 535 * reuse. If the speculation is active on multiple CPUs, it must be 536 * asynchronously cleaned -- potentially leading to a higher rate of dirty 537 * speculative drops. The speculation states are as follows: 538 * 539 * DTRACESPEC_INACTIVE <= Initial state; inactive speculation 540 * DTRACESPEC_ACTIVE <= Allocated, but not yet speculatively traced to 541 * DTRACESPEC_ACTIVEONE <= Speculatively traced to on one CPU 542 * DTRACESPEC_ACTIVEMANY <= Speculatively traced to on more than one CPU 543 * DTRACESPEC_COMMITTING <= Currently being commited on one CPU 544 * DTRACESPEC_COMMITTINGMANY <= Currently being commited on many CPUs 545 * DTRACESPEC_DISCARDING <= Currently being discarded on many CPUs 546 * 547 * The state transition diagram is as follows: 548 * 549 * +----------------------------------------------------------+ 550 * | | 551 * | +------------+ | 552 * | +-------------------| COMMITTING |<-----------------+ | 553 * | | +------------+ | | 554 * | | copied spec. ^ commit() on | | discard() on 555 * | | into principal | active CPU | | active CPU 556 * | | | commit() | | 557 * V V | | | 558 * +----------+ +--------+ +-----------+ 559 * | INACTIVE |---------------->| ACTIVE |--------------->| ACTIVEONE | 560 * +----------+ speculation() +--------+ speculate() +-----------+ 561 * ^ ^ | | | 562 * | | | discard() | | 563 * | | asynchronously | discard() on | | speculate() 564 * | | cleaned V inactive CPU | | on inactive 565 * | | +------------+ | | CPU 566 * | +-------------------| DISCARDING |<-----------------+ | 567 * | +------------+ | 568 * | asynchronously ^ | 569 * | copied spec. | discard() | 570 * | into principal +------------------------+ | 571 * | | V 572 * +----------------+ commit() +------------+ 573 * | COMMITTINGMANY |<----------------------------------| ACTIVEMANY | 574 * +----------------+ +------------+ 575 */ 576 typedef enum dtrace_speculation_state { 577 DTRACESPEC_INACTIVE = 0, 578 DTRACESPEC_ACTIVE, 579 DTRACESPEC_ACTIVEONE, 580 DTRACESPEC_ACTIVEMANY, 581 DTRACESPEC_COMMITTING, 582 DTRACESPEC_COMMITTINGMANY, 583 DTRACESPEC_DISCARDING 584 } dtrace_speculation_state_t; 585 586 typedef struct dtrace_speculation { 587 dtrace_speculation_state_t dtsp_state; /* current speculation state */ 588 int dtsp_cleaning; /* non-zero if being cleaned */ 589 dtrace_buffer_t *dtsp_buffer; /* speculative buffer */ 590 } dtrace_speculation_t; 591 592 /* 593 * DTrace Dynamic Variables 594 * 595 * The dynamic variable problem is obviously decomposed into two subproblems: 596 * allocating new dynamic storage, and freeing old dynamic storage. The 597 * presence of the second problem makes the first much more complicated -- or 598 * rather, the absence of the second renders the first trivial. This is the 599 * case with aggregations, for which there is effectively no deallocation of 600 * dynamic storage. (Or more accurately, all dynamic storage is deallocated 601 * when a snapshot is taken of the aggregation.) As DTrace dynamic variables 602 * allow for both dynamic allocation and dynamic deallocation, the 603 * implementation of dynamic variables is quite a bit more complicated than 604 * that of their aggregation kin. 605 * 606 * We observe that allocating new dynamic storage is tricky only because the 607 * size can vary -- the allocation problem is much easier if allocation sizes 608 * are uniform. We further observe that in D, the size of dynamic variables is 609 * actually _not_ dynamic -- dynamic variable sizes may be determined by static 610 * analysis of DIF text. (This is true even of putatively dynamically-sized 611 * objects like strings and stacks, the sizes of which are dictated by the 612 * "stringsize" and "stackframes" variables, respectively.) We exploit this by 613 * performing this analysis on all DIF before enabling any probes. For each 614 * dynamic load or store, we calculate the dynamically-allocated size plus the 615 * size of the dtrace_dynvar structure plus the storage required to key the 616 * data. For all DIF, we take the largest value and dub it the _chunksize_. 617 * We then divide dynamic memory into two parts: a hash table that is wide 618 * enough to have every chunk in its own bucket, and a larger region of equal 619 * chunksize units. Whenever we wish to dynamically allocate a variable, we 620 * always allocate a single chunk of memory. Depending on the uniformity of 621 * allocation, this will waste some amount of memory -- but it eliminates the 622 * non-determinism inherent in traditional heap fragmentation. 623 * 624 * Dynamic objects are allocated by storing a non-zero value to them; they are 625 * deallocated by storing a zero value to them. Dynamic variables are 626 * complicated enormously by being shared between CPUs. In particular, 627 * consider the following scenario: 628 * 629 * CPU A CPU B 630 * +---------------------------------+ +---------------------------------+ 631 * | | | | 632 * | allocates dynamic object a[123] | | | 633 * | by storing the value 345 to it | | | 634 * | ---------> | 635 * | | | wishing to load from object | 636 * | | | a[123], performs lookup in | 637 * | | | dynamic variable space | 638 * | <--------- | 639 * | deallocates object a[123] by | | | 640 * | storing 0 to it | | | 641 * | | | | 642 * | allocates dynamic object b[567] | | performs load from a[123] | 643 * | by storing the value 789 to it | | | 644 * : : : : 645 * . . . . 646 * 647 * This is obviously a race in the D program, but there are nonetheless only 648 * two valid values for CPU B's load from a[123]: 345 or 0. Most importantly, 649 * CPU B may _not_ see the value 789 for a[123]. 650 * 651 * There are essentially two ways to deal with this: 652 * 653 * (1) Explicitly spin-lock variables. That is, if CPU B wishes to load 654 * from a[123], it needs to lock a[123] and hold the lock for the 655 * duration that it wishes to manipulate it. 656 * 657 * (2) Avoid reusing freed chunks until it is known that no CPU is referring 658 * to them. 659 * 660 * The implementation of (1) is rife with complexity, because it requires the 661 * user of a dynamic variable to explicitly decree when they are done using it. 662 * Were all variables by value, this perhaps wouldn't be debilitating -- but 663 * dynamic variables of non-scalar types are tracked by reference. That is, if 664 * a dynamic variable is, say, a string, and that variable is to be traced to, 665 * say, the principal buffer, the DIF emulation code returns to the main 666 * dtrace_probe() loop a pointer to the underlying storage, not the contents of 667 * the storage. Further, code calling on DIF emulation would have to be aware 668 * that the DIF emulation has returned a reference to a dynamic variable that 669 * has been potentially locked. The variable would have to be unlocked after 670 * the main dtrace_probe() loop is finished with the variable, and the main 671 * dtrace_probe() loop would have to be careful to not call any further DIF 672 * emulation while the variable is locked to avoid deadlock. More generally, 673 * if one were to implement (1), DIF emulation code dealing with dynamic 674 * variables could only deal with one dynamic variable at a time (lest deadlock 675 * result). To sum, (1) exports too much subtlety to the users of dynamic 676 * variables -- increasing maintenance burden and imposing serious constraints 677 * on future DTrace development. 678 * 679 * The implementation of (2) is also complex, but the complexity is more 680 * manageable. We need to be sure that when a variable is deallocated, it is 681 * not placed on a traditional free list, but rather on a _dirty_ list. Once a 682 * variable is on a dirty list, it cannot be found by CPUs performing a 683 * subsequent lookup of the variable -- but it may still be in use by other 684 * CPUs. To assure that all CPUs that may be seeing the old variable have 685 * cleared out of probe context, a dtrace_sync() can be issued. Once the 686 * dtrace_sync() has completed, it can be known that all CPUs are done 687 * manipulating the dynamic variable -- the dirty list can be atomically 688 * appended to the free list. Unfortunately, there's a slight hiccup in this 689 * mechanism: dtrace_sync() may not be issued from probe context. The 690 * dtrace_sync() must be therefore issued asynchronously from non-probe 691 * context. For this we rely on the DTrace cleaner, a cyclic that runs at the 692 * "cleanrate" frequency. To ease this implementation, we define several chunk 693 * lists: 694 * 695 * - Dirty. Deallocated chunks, not yet cleaned. Not available. 696 * 697 * - Rinsing. Formerly dirty chunks that are currently being asynchronously 698 * cleaned. Not available, but will be shortly. Dynamic variable 699 * allocation may not spin or block for availability, however. 700 * 701 * - Clean. Clean chunks, ready for allocation -- but not on the free list. 702 * 703 * - Free. Available for allocation. 704 * 705 * Moreover, to avoid absurd contention, _each_ of these lists is implemented 706 * on a per-CPU basis. This is only for performance, not correctness; chunks 707 * may be allocated from another CPU's free list. The algorithm for allocation 708 * then is this: 709 * 710 * (1) Attempt to atomically allocate from current CPU's free list. If list 711 * is non-empty and allocation is successful, allocation is complete. 712 * 713 * (2) If the clean list is non-empty, atomically move it to the free list, 714 * and reattempt (1). 715 * 716 * (3) If the dynamic variable space is in the CLEAN state, look for free 717 * and clean lists on other CPUs by setting the current CPU to the next 718 * CPU, and reattempting (1). If the next CPU is the current CPU (that 719 * is, if all CPUs have been checked), atomically switch the state of 720 * the dynamic variable space based on the following: 721 * 722 * - If no free chunks were found and no dirty chunks were found, 723 * atomically set the state to EMPTY. 724 * 725 * - If dirty chunks were found, atomically set the state to DIRTY. 726 * 727 * - If rinsing chunks were found, atomically set the state to RINSING. 728 * 729 * (4) Based on state of dynamic variable space state, increment appropriate 730 * counter to indicate dynamic drops (if in EMPTY state) vs. dynamic 731 * dirty drops (if in DIRTY state) vs. dynamic rinsing drops (if in 732 * RINSING state). Fail the allocation. 733 * 734 * The cleaning cyclic operates with the following algorithm: for all CPUs 735 * with a non-empty dirty list, atomically move the dirty list to the rinsing 736 * list. Perform a dtrace_sync(). For all CPUs with a non-empty rinsing list, 737 * atomically move the rinsing list to the clean list. Perform another 738 * dtrace_sync(). By this point, all CPUs have seen the new clean list; the 739 * state of the dynamic variable space can be restored to CLEAN. 740 * 741 * There exist two final races that merit explanation. The first is a simple 742 * allocation race: 743 * 744 * CPU A CPU B 745 * +---------------------------------+ +---------------------------------+ 746 * | | | | 747 * | allocates dynamic object a[123] | | allocates dynamic object a[123] | 748 * | by storing the value 345 to it | | by storing the value 567 to it | 749 * | | | | 750 * : : : : 751 * . . . . 752 * 753 * Again, this is a race in the D program. It can be resolved by having a[123] 754 * hold the value 345 or a[123] hold the value 567 -- but it must be true that 755 * a[123] have only _one_ of these values. (That is, the racing CPUs may not 756 * put the same element twice on the same hash chain.) This is resolved 757 * simply: before the allocation is undertaken, the start of the new chunk's 758 * hash chain is noted. Later, after the allocation is complete, the hash 759 * chain is atomically switched to point to the new element. If this fails 760 * (because of either concurrent allocations or an allocation concurrent with a 761 * deletion), the newly allocated chunk is deallocated to the dirty list, and 762 * the whole process of looking up (and potentially allocating) the dynamic 763 * variable is reattempted. 764 * 765 * The final race is a simple deallocation race: 766 * 767 * CPU A CPU B 768 * +---------------------------------+ +---------------------------------+ 769 * | | | | 770 * | deallocates dynamic object | | deallocates dynamic object | 771 * | a[123] by storing the value 0 | | a[123] by storing the value 0 | 772 * | to it | | to it | 773 * | | | | 774 * : : : : 775 * . . . . 776 * 777 * Once again, this is a race in the D program, but it is one that we must 778 * handle without corrupting the underlying data structures. Because 779 * deallocations require the deletion of a chunk from the middle of a hash 780 * chain, we cannot use a single-word atomic operation to remove it. For this, 781 * we add a spin lock to the hash buckets that is _only_ used for deallocations 782 * (allocation races are handled as above). Further, this spin lock is _only_ 783 * held for the duration of the delete; before control is returned to the DIF 784 * emulation code, the hash bucket is unlocked. 785 */ 786 typedef struct dtrace_key { 787 uint64_t dttk_value; /* data value or data pointer */ 788 uint64_t dttk_size; /* 0 if by-val, >0 if by-ref */ 789 } dtrace_key_t; 790 791 typedef struct dtrace_tuple { 792 uint32_t dtt_nkeys; /* number of keys in tuple */ 793 uint32_t dtt_pad; /* padding */ 794 dtrace_key_t dtt_key[1]; /* array of tuple keys */ 795 } dtrace_tuple_t; 796 797 typedef struct dtrace_dynvar { 798 uint64_t dtdv_hashval; /* hash value -- 0 if free */ 799 struct dtrace_dynvar *dtdv_next; /* next on list or hash chain */ 800 void *dtdv_data; /* pointer to data */ 801 dtrace_tuple_t dtdv_tuple; /* tuple key */ 802 } dtrace_dynvar_t; 803 804 typedef enum dtrace_dynvar_op { 805 DTRACE_DYNVAR_ALLOC, 806 DTRACE_DYNVAR_NOALLOC, 807 DTRACE_DYNVAR_DEALLOC 808 } dtrace_dynvar_op_t; 809 810 typedef struct dtrace_dynhash { 811 dtrace_dynvar_t *dtdh_chain; /* hash chain for this bucket */ 812 uintptr_t dtdh_lock; /* deallocation lock */ 813 #ifdef _LP64 814 uintptr_t dtdh_pad[6]; /* pad to avoid false sharing */ 815 #else 816 uintptr_t dtdh_pad[14]; /* pad to avoid false sharing */ 817 #endif 818 } dtrace_dynhash_t; 819 820 typedef struct dtrace_dstate_percpu { 821 dtrace_dynvar_t *dtdsc_free; /* free list for this CPU */ 822 dtrace_dynvar_t *dtdsc_dirty; /* dirty list for this CPU */ 823 dtrace_dynvar_t *dtdsc_rinsing; /* rinsing list for this CPU */ 824 dtrace_dynvar_t *dtdsc_clean; /* clean list for this CPU */ 825 uint64_t dtdsc_drops; /* number of capacity drops */ 826 uint64_t dtdsc_dirty_drops; /* number of dirty drops */ 827 uint64_t dtdsc_rinsing_drops; /* number of rinsing drops */ 828 #ifdef _LP64 829 uint64_t dtdsc_pad; /* pad to avoid false sharing */ 830 #else 831 uint64_t dtdsc_pad[2]; /* pad to avoid false sharing */ 832 #endif 833 } dtrace_dstate_percpu_t; 834 835 typedef enum dtrace_dstate_state { 836 DTRACE_DSTATE_CLEAN = 0, 837 DTRACE_DSTATE_EMPTY, 838 DTRACE_DSTATE_DIRTY, 839 DTRACE_DSTATE_RINSING 840 } dtrace_dstate_state_t; 841 842 typedef struct dtrace_dstate { 843 void *dtds_base; /* base of dynamic var. space */ 844 size_t dtds_size; /* size of dynamic var. space */ 845 size_t dtds_hashsize; /* number of buckets in hash */ 846 size_t dtds_chunksize; /* size of each chunk */ 847 dtrace_dynhash_t *dtds_hash; /* pointer to hash table */ 848 dtrace_dstate_state_t dtds_state; /* current dynamic var. state */ 849 dtrace_dstate_percpu_t *dtds_percpu; /* per-CPU dyn. var. state */ 850 } dtrace_dstate_t; 851 852 /* 853 * DTrace Variable State 854 * 855 * The DTrace variable state tracks user-defined variables in its dtrace_vstate 856 * structure. Each DTrace consumer has exactly one dtrace_vstate structure, 857 * but some dtrace_vstate structures may exist without a corresponding DTrace 858 * consumer (see "DTrace Helpers", below). As described in <sys/dtrace.h>, 859 * user-defined variables can have one of three scopes: 860 * 861 * DIFV_SCOPE_GLOBAL => global scope 862 * DIFV_SCOPE_THREAD => thread-local scope (i.e. "self->" variables) 863 * DIFV_SCOPE_LOCAL => clause-local scope (i.e. "this->" variables) 864 * 865 * The variable state tracks variables by both their scope and their allocation 866 * type: 867 * 868 * - The dtvs_globals and dtvs_locals members each point to an array of 869 * dtrace_statvar structures. These structures contain both the variable 870 * metadata (dtrace_difv structures) and the underlying storage for all 871 * statically allocated variables, including statically allocated 872 * DIFV_SCOPE_GLOBAL variables and all DIFV_SCOPE_LOCAL variables. 873 * 874 * - The dtvs_tlocals member points to an array of dtrace_difv structures for 875 * DIFV_SCOPE_THREAD variables. As such, this array tracks _only_ the 876 * variable metadata for DIFV_SCOPE_THREAD variables; the underlying storage 877 * is allocated out of the dynamic variable space. 878 * 879 * - The dtvs_dynvars member is the dynamic variable state associated with the 880 * variable state. The dynamic variable state (described in "DTrace Dynamic 881 * Variables", above) tracks all DIFV_SCOPE_THREAD variables and all 882 * dynamically-allocated DIFV_SCOPE_GLOBAL variables. 883 */ 884 typedef struct dtrace_statvar { 885 uint64_t dtsv_data; /* data or pointer to it */ 886 size_t dtsv_size; /* size of pointed-to data */ 887 int dtsv_refcnt; /* reference count */ 888 dtrace_difv_t dtsv_var; /* variable metadata */ 889 } dtrace_statvar_t; 890 891 typedef struct dtrace_vstate { 892 dtrace_state_t *dtvs_state; /* back pointer to state */ 893 dtrace_statvar_t **dtvs_globals; /* statically-allocated glbls */ 894 int dtvs_nglobals; /* number of globals */ 895 dtrace_difv_t *dtvs_tlocals; /* thread-local metadata */ 896 int dtvs_ntlocals; /* number of thread-locals */ 897 dtrace_statvar_t **dtvs_locals; /* clause-local data */ 898 int dtvs_nlocals; /* number of clause-locals */ 899 dtrace_dstate_t dtvs_dynvars; /* dynamic variable state */ 900 } dtrace_vstate_t; 901 902 /* 903 * DTrace Machine State 904 * 905 * In the process of processing a fired probe, DTrace needs to track and/or 906 * cache some per-CPU state associated with that particular firing. This is 907 * state that is always discarded after the probe firing has completed, and 908 * much of it is not specific to any DTrace consumer, remaining valid across 909 * all ECBs. This state is tracked in the dtrace_mstate structure. 910 */ 911 #define DTRACE_MSTATE_ARGS 0x00000001 912 #define DTRACE_MSTATE_PROBE 0x00000002 913 #define DTRACE_MSTATE_EPID 0x00000004 914 #define DTRACE_MSTATE_TIMESTAMP 0x00000008 915 #define DTRACE_MSTATE_STACKDEPTH 0x00000010 916 #define DTRACE_MSTATE_CALLER 0x00000020 917 #define DTRACE_MSTATE_IPL 0x00000040 918 #define DTRACE_MSTATE_FLTOFFS 0x00000080 919 #define DTRACE_MSTATE_WALLTIMESTAMP 0x00000100 920 #define DTRACE_MSTATE_USTACKDEPTH 0x00000200 921 #define DTRACE_MSTATE_UCALLER 0x00000400 922 923 typedef struct dtrace_mstate { 924 uintptr_t dtms_scratch_base; /* base of scratch space */ 925 uintptr_t dtms_scratch_ptr; /* current scratch pointer */ 926 size_t dtms_scratch_size; /* scratch size */ 927 uint32_t dtms_present; /* variables that are present */ 928 uint64_t dtms_arg[5]; /* cached arguments */ 929 dtrace_epid_t dtms_epid; /* current EPID */ 930 uint64_t dtms_timestamp; /* cached timestamp */ 931 hrtime_t dtms_walltimestamp; /* cached wall timestamp */ 932 int dtms_stackdepth; /* cached stackdepth */ 933 int dtms_ustackdepth; /* cached ustackdepth */ 934 struct dtrace_probe *dtms_probe; /* current probe */ 935 uintptr_t dtms_caller; /* cached caller */ 936 uint64_t dtms_ucaller; /* cached user-level caller */ 937 int dtms_ipl; /* cached interrupt pri lev */ 938 int dtms_fltoffs; /* faulting DIFO offset */ 939 uintptr_t dtms_strtok; /* saved strtok() pointer */ 940 uintptr_t dtms_strtok_limit; /* upper bound of strtok ptr */ 941 uint32_t dtms_access; /* memory access rights */ 942 dtrace_difo_t *dtms_difo; /* current dif object */ 943 file_t *dtms_getf; /* cached rval of getf() */ 944 } dtrace_mstate_t; 945 946 #define DTRACE_COND_OWNER 0x1 947 #define DTRACE_COND_USERMODE 0x2 948 #define DTRACE_COND_ZONEOWNER 0x4 949 950 #define DTRACE_PROBEKEY_MAXDEPTH 8 /* max glob recursion depth */ 951 952 /* 953 * Access flag used by dtrace_mstate.dtms_access. 954 */ 955 #define DTRACE_ACCESS_KERNEL 0x1 /* the priv to read kmem */ 956 957 958 /* 959 * DTrace Activity 960 * 961 * Each DTrace consumer is in one of several states, which (for purposes of 962 * avoiding yet-another overloading of the noun "state") we call the current 963 * _activity_. The activity transitions on dtrace_go() (from DTRACIOCGO), on 964 * dtrace_stop() (from DTRACIOCSTOP) and on the exit() action. Activities may 965 * only transition in one direction; the activity transition diagram is a 966 * directed acyclic graph. The activity transition diagram is as follows: 967 * 968 * 969 * +----------+ +--------+ +--------+ 970 * | INACTIVE |------------------>| WARMUP |------------------>| ACTIVE | 971 * +----------+ dtrace_go(), +--------+ dtrace_go(), +--------+ 972 * before BEGIN | after BEGIN | | | 973 * | | | | 974 * exit() action | | | | 975 * from BEGIN ECB | | | | 976 * | | | | 977 * v | | | 978 * +----------+ exit() action | | | 979 * +-----------------------------| DRAINING |<-------------------+ | | 980 * | +----------+ | | 981 * | | | | 982 * | dtrace_stop(), | | | 983 * | before END | | | 984 * | | | | 985 * | v | | 986 * | +---------+ +----------+ | | 987 * | | STOPPED |<----------------| COOLDOWN |<----------------------+ | 988 * | +---------+ dtrace_stop(), +----------+ dtrace_stop(), | 989 * | after END before END | 990 * | | 991 * | +--------+ | 992 * +----------------------------->| KILLED |<--------------------------+ 993 * deadman timeout or +--------+ deadman timeout or 994 * killed consumer killed consumer 995 * 996 * Note that once a DTrace consumer has stopped tracing, there is no way to 997 * restart it; if a DTrace consumer wishes to restart tracing, it must reopen 998 * the DTrace pseudodevice. 999 */ 1000 typedef enum dtrace_activity { 1001 DTRACE_ACTIVITY_INACTIVE = 0, /* not yet running */ 1002 DTRACE_ACTIVITY_WARMUP, /* while starting */ 1003 DTRACE_ACTIVITY_ACTIVE, /* running */ 1004 DTRACE_ACTIVITY_DRAINING, /* before stopping */ 1005 DTRACE_ACTIVITY_COOLDOWN, /* while stopping */ 1006 DTRACE_ACTIVITY_STOPPED, /* after stopping */ 1007 DTRACE_ACTIVITY_KILLED /* killed */ 1008 } dtrace_activity_t; 1009 1010 /* 1011 * DTrace Helper Implementation 1012 * 1013 * A description of the helper architecture may be found in <sys/dtrace.h>. 1014 * Each process contains a pointer to its helpers in its p_dtrace_helpers 1015 * member. This is a pointer to a dtrace_helpers structure, which contains an 1016 * array of pointers to dtrace_helper structures, helper variable state (shared 1017 * among a process's helpers) and a generation count. (The generation count is 1018 * used to provide an identifier when a helper is added so that it may be 1019 * subsequently removed.) The dtrace_helper structure is self-explanatory, 1020 * containing pointers to the objects needed to execute the helper. Note that 1021 * helpers are _duplicated_ across fork(2), and destroyed on exec(2). No more 1022 * than dtrace_helpers_max are allowed per-process. 1023 */ 1024 #define DTRACE_HELPER_ACTION_USTACK 0 1025 #define DTRACE_NHELPER_ACTIONS 1 1026 1027 typedef struct dtrace_helper_action { 1028 int dtha_generation; /* helper action generation */ 1029 int dtha_nactions; /* number of actions */ 1030 dtrace_difo_t *dtha_predicate; /* helper action predicate */ 1031 dtrace_difo_t **dtha_actions; /* array of actions */ 1032 struct dtrace_helper_action *dtha_next; /* next helper action */ 1033 } dtrace_helper_action_t; 1034 1035 typedef struct dtrace_helper_provider { 1036 int dthp_generation; /* helper provider generation */ 1037 uint32_t dthp_ref; /* reference count */ 1038 dof_helper_t dthp_prov; /* DOF w/ provider and probes */ 1039 } dtrace_helper_provider_t; 1040 1041 typedef struct dtrace_helpers { 1042 dtrace_helper_action_t **dthps_actions; /* array of helper actions */ 1043 dtrace_vstate_t dthps_vstate; /* helper action var. state */ 1044 dtrace_helper_provider_t **dthps_provs; /* array of providers */ 1045 uint_t dthps_nprovs; /* count of providers */ 1046 uint_t dthps_maxprovs; /* provider array size */ 1047 int dthps_generation; /* current generation */ 1048 pid_t dthps_pid; /* pid of associated proc */ 1049 int dthps_deferred; /* helper in deferred list */ 1050 struct dtrace_helpers *dthps_next; /* next pointer */ 1051 struct dtrace_helpers *dthps_prev; /* prev pointer */ 1052 } dtrace_helpers_t; 1053 1054 /* 1055 * DTrace Helper Action Tracing 1056 * 1057 * Debugging helper actions can be arduous. To ease the development and 1058 * debugging of helpers, DTrace contains a tracing-framework-within-a-tracing- 1059 * framework: helper tracing. If dtrace_helptrace_enabled is non-zero (which 1060 * it is by default on DEBUG kernels), all helper activity will be traced to a 1061 * global, in-kernel ring buffer. Each entry includes a pointer to the specific 1062 * helper, the location within the helper, and a trace of all local variables. 1063 * The ring buffer may be displayed in a human-readable format with the 1064 * ::dtrace_helptrace mdb(1) dcmd. 1065 */ 1066 #define DTRACE_HELPTRACE_NEXT (-1) 1067 #define DTRACE_HELPTRACE_DONE (-2) 1068 #define DTRACE_HELPTRACE_ERR (-3) 1069 1070 typedef struct dtrace_helptrace { 1071 dtrace_helper_action_t *dtht_helper; /* helper action */ 1072 int dtht_where; /* where in helper action */ 1073 int dtht_nlocals; /* number of locals */ 1074 int dtht_fault; /* type of fault (if any) */ 1075 int dtht_fltoffs; /* DIF offset */ 1076 uint64_t dtht_illval; /* faulting value */ 1077 uint64_t dtht_locals[1]; /* local variables */ 1078 } dtrace_helptrace_t; 1079 1080 /* 1081 * DTrace Credentials 1082 * 1083 * In probe context, we have limited flexibility to examine the credentials 1084 * of the DTrace consumer that created a particular enabling. We use 1085 * the Least Privilege interfaces to cache the consumer's cred pointer and 1086 * some facts about that credential in a dtrace_cred_t structure. These 1087 * can limit the consumer's breadth of visibility and what actions the 1088 * consumer may take. 1089 */ 1090 #define DTRACE_CRV_ALLPROC 0x01 1091 #define DTRACE_CRV_KERNEL 0x02 1092 #define DTRACE_CRV_ALLZONE 0x04 1093 1094 #define DTRACE_CRV_ALL (DTRACE_CRV_ALLPROC | DTRACE_CRV_KERNEL | \ 1095 DTRACE_CRV_ALLZONE) 1096 1097 #define DTRACE_CRA_PROC 0x0001 1098 #define DTRACE_CRA_PROC_CONTROL 0x0002 1099 #define DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER 0x0004 1100 #define DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE 0x0008 1101 #define DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG 0x0010 1102 #define DTRACE_CRA_KERNEL 0x0020 1103 #define DTRACE_CRA_KERNEL_DESTRUCTIVE 0x0040 1104 1105 #define DTRACE_CRA_ALL (DTRACE_CRA_PROC | \ 1106 DTRACE_CRA_PROC_CONTROL | \ 1107 DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER | \ 1108 DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE | \ 1109 DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG | \ 1110 DTRACE_CRA_KERNEL | \ 1111 DTRACE_CRA_KERNEL_DESTRUCTIVE) 1112 1113 typedef struct dtrace_cred { 1114 cred_t *dcr_cred; 1115 uint8_t dcr_destructive; 1116 uint8_t dcr_visible; 1117 uint16_t dcr_action; 1118 } dtrace_cred_t; 1119 1120 /* 1121 * DTrace Consumer State 1122 * 1123 * Each DTrace consumer has an associated dtrace_state structure that contains 1124 * its in-kernel DTrace state -- including options, credentials, statistics and 1125 * pointers to ECBs, buffers, speculations and formats. A dtrace_state 1126 * structure is also allocated for anonymous enablings. When anonymous state 1127 * is grabbed, the grabbing consumers dts_anon pointer is set to the grabbed 1128 * dtrace_state structure. 1129 */ 1130 struct dtrace_state { 1131 #ifdef illumos 1132 dev_t dts_dev; /* device */ 1133 #else 1134 struct cdev *dts_dev; /* device */ 1135 #endif 1136 int dts_necbs; /* total number of ECBs */ 1137 dtrace_ecb_t **dts_ecbs; /* array of ECBs */ 1138 dtrace_epid_t dts_epid; /* next EPID to allocate */ 1139 size_t dts_needed; /* greatest needed space */ 1140 struct dtrace_state *dts_anon; /* anon. state, if grabbed */ 1141 dtrace_activity_t dts_activity; /* current activity */ 1142 dtrace_vstate_t dts_vstate; /* variable state */ 1143 dtrace_buffer_t *dts_buffer; /* principal buffer */ 1144 dtrace_buffer_t *dts_aggbuffer; /* aggregation buffer */ 1145 dtrace_speculation_t *dts_speculations; /* speculation array */ 1146 int dts_nspeculations; /* number of speculations */ 1147 int dts_naggregations; /* number of aggregations */ 1148 dtrace_aggregation_t **dts_aggregations; /* aggregation array */ 1149 #ifdef illumos 1150 vmem_t *dts_aggid_arena; /* arena for aggregation IDs */ 1151 #else 1152 struct unrhdr *dts_aggid_arena; /* arena for aggregation IDs */ 1153 #endif 1154 uint64_t dts_errors; /* total number of errors */ 1155 uint32_t dts_speculations_busy; /* number of spec. busy */ 1156 uint32_t dts_speculations_unavail; /* number of spec unavail */ 1157 uint32_t dts_stkstroverflows; /* stack string tab overflows */ 1158 uint32_t dts_dblerrors; /* errors in ERROR probes */ 1159 uint32_t dts_reserve; /* space reserved for END */ 1160 hrtime_t dts_laststatus; /* time of last status */ 1161 #ifdef illumos 1162 cyclic_id_t dts_cleaner; /* cleaning cyclic */ 1163 cyclic_id_t dts_deadman; /* deadman cyclic */ 1164 #else 1165 struct callout dts_cleaner; /* Cleaning callout. */ 1166 struct callout dts_deadman; /* Deadman callout. */ 1167 #endif 1168 hrtime_t dts_alive; /* time last alive */ 1169 char dts_speculates; /* boolean: has speculations */ 1170 char dts_destructive; /* boolean: has dest. actions */ 1171 int dts_nformats; /* number of formats */ 1172 char **dts_formats; /* format string array */ 1173 dtrace_optval_t dts_options[DTRACEOPT_MAX]; /* options */ 1174 dtrace_cred_t dts_cred; /* credentials */ 1175 size_t dts_nretained; /* number of retained enabs */ 1176 int dts_getf; /* number of getf() calls */ 1177 uint64_t dts_rstate[NCPU][2]; /* per-CPU random state */ 1178 }; 1179 1180 struct dtrace_provider { 1181 dtrace_pattr_t dtpv_attr; /* provider attributes */ 1182 dtrace_ppriv_t dtpv_priv; /* provider privileges */ 1183 dtrace_pops_t dtpv_pops; /* provider operations */ 1184 char *dtpv_name; /* provider name */ 1185 void *dtpv_arg; /* provider argument */ 1186 hrtime_t dtpv_defunct; /* when made defunct */ 1187 struct dtrace_provider *dtpv_next; /* next provider */ 1188 }; 1189 1190 struct dtrace_meta { 1191 dtrace_mops_t dtm_mops; /* meta provider operations */ 1192 char *dtm_name; /* meta provider name */ 1193 void *dtm_arg; /* meta provider user arg */ 1194 uint64_t dtm_count; /* no. of associated provs. */ 1195 }; 1196 1197 /* 1198 * DTrace Enablings 1199 * 1200 * A dtrace_enabling structure is used to track a collection of ECB 1201 * descriptions -- before they have been turned into actual ECBs. This is 1202 * created as a result of DOF processing, and is generally used to generate 1203 * ECBs immediately thereafter. However, enablings are also generally 1204 * retained should the probes they describe be created at a later time; as 1205 * each new module or provider registers with the framework, the retained 1206 * enablings are reevaluated, with any new match resulting in new ECBs. To 1207 * prevent probes from being matched more than once, the enabling tracks the 1208 * last probe generation matched, and only matches probes from subsequent 1209 * generations. 1210 */ 1211 typedef struct dtrace_enabling { 1212 dtrace_ecbdesc_t **dten_desc; /* all ECB descriptions */ 1213 int dten_ndesc; /* number of ECB descriptions */ 1214 int dten_maxdesc; /* size of ECB array */ 1215 dtrace_vstate_t *dten_vstate; /* associated variable state */ 1216 dtrace_genid_t dten_probegen; /* matched probe generation */ 1217 dtrace_ecbdesc_t *dten_current; /* current ECB description */ 1218 int dten_error; /* current error value */ 1219 int dten_primed; /* boolean: set if primed */ 1220 struct dtrace_enabling *dten_prev; /* previous enabling */ 1221 struct dtrace_enabling *dten_next; /* next enabling */ 1222 } dtrace_enabling_t; 1223 1224 /* 1225 * DTrace Anonymous Enablings 1226 * 1227 * Anonymous enablings are DTrace enablings that are not associated with a 1228 * controlling process, but rather derive their enabling from DOF stored as 1229 * properties in the dtrace.conf file. If there is an anonymous enabling, a 1230 * DTrace consumer state and enabling are created on attach. The state may be 1231 * subsequently grabbed by the first consumer specifying the "grabanon" 1232 * option. As long as an anonymous DTrace enabling exists, dtrace(7D) will 1233 * refuse to unload. 1234 */ 1235 typedef struct dtrace_anon { 1236 dtrace_state_t *dta_state; /* DTrace consumer state */ 1237 dtrace_enabling_t *dta_enabling; /* pointer to enabling */ 1238 processorid_t dta_beganon; /* which CPU BEGIN ran on */ 1239 } dtrace_anon_t; 1240 1241 /* 1242 * DTrace Error Debugging 1243 */ 1244 #ifdef DEBUG 1245 #define DTRACE_ERRDEBUG 1246 #endif 1247 1248 #ifdef DTRACE_ERRDEBUG 1249 1250 typedef struct dtrace_errhash { 1251 const char *dter_msg; /* error message */ 1252 int dter_count; /* number of times seen */ 1253 } dtrace_errhash_t; 1254 1255 #define DTRACE_ERRHASHSZ 256 /* must be > number of err msgs */ 1256 1257 #endif /* DTRACE_ERRDEBUG */ 1258 1259 /* 1260 * DTrace Toxic Ranges 1261 * 1262 * DTrace supports safe loads from probe context; if the address turns out to 1263 * be invalid, a bit will be set by the kernel indicating that DTrace 1264 * encountered a memory error, and DTrace will propagate the error to the user 1265 * accordingly. However, there may exist some regions of memory in which an 1266 * arbitrary load can change system state, and from which it is impossible to 1267 * recover from such a load after it has been attempted. Examples of this may 1268 * include memory in which programmable I/O registers are mapped (for which a 1269 * read may have some implications for the device) or (in the specific case of 1270 * UltraSPARC-I and -II) the virtual address hole. The platform is required 1271 * to make DTrace aware of these toxic ranges; DTrace will then check that 1272 * target addresses are not in a toxic range before attempting to issue a 1273 * safe load. 1274 */ 1275 typedef struct dtrace_toxrange { 1276 uintptr_t dtt_base; /* base of toxic range */ 1277 uintptr_t dtt_limit; /* limit of toxic range */ 1278 } dtrace_toxrange_t; 1279 1280 #ifdef illumos 1281 extern uint64_t dtrace_getarg(int, int); 1282 #else 1283 extern uint64_t __noinline dtrace_getarg(int, int); 1284 #endif 1285 extern greg_t dtrace_getfp(void); 1286 extern int dtrace_getipl(void); 1287 extern uintptr_t dtrace_caller(int); 1288 extern uint32_t dtrace_cas32(uint32_t *, uint32_t, uint32_t); 1289 extern void *dtrace_casptr(volatile void *, volatile void *, volatile void *); 1290 extern void dtrace_copyin(uintptr_t, uintptr_t, size_t, volatile uint16_t *); 1291 extern void dtrace_copyinstr(uintptr_t, uintptr_t, size_t, volatile uint16_t *); 1292 extern void dtrace_copyout(uintptr_t, uintptr_t, size_t, volatile uint16_t *); 1293 extern void dtrace_copyoutstr(uintptr_t, uintptr_t, size_t, 1294 volatile uint16_t *); 1295 extern void dtrace_getpcstack(pc_t *, int, int, uint32_t *); 1296 extern ulong_t dtrace_getreg(struct trapframe *, uint_t); 1297 extern int dtrace_getstackdepth(int); 1298 extern void dtrace_getupcstack(uint64_t *, int); 1299 extern void dtrace_getufpstack(uint64_t *, uint64_t *, int); 1300 extern int dtrace_getustackdepth(void); 1301 extern uintptr_t dtrace_fulword(void *); 1302 extern uint8_t dtrace_fuword8(void *); 1303 extern uint16_t dtrace_fuword16(void *); 1304 extern uint32_t dtrace_fuword32(void *); 1305 extern uint64_t dtrace_fuword64(void *); 1306 extern void dtrace_probe_error(dtrace_state_t *, dtrace_epid_t, int, int, 1307 int, uintptr_t); 1308 extern int dtrace_assfail(const char *, const char *, int); 1309 extern int dtrace_attached(void); 1310 #ifdef illumos 1311 extern hrtime_t dtrace_gethrestime(void); 1312 #endif 1313 1314 #ifdef __sparc 1315 extern void dtrace_flush_windows(void); 1316 extern void dtrace_flush_user_windows(void); 1317 extern uint_t dtrace_getotherwin(void); 1318 extern uint_t dtrace_getfprs(void); 1319 #else 1320 extern void dtrace_copy(uintptr_t, uintptr_t, size_t); 1321 extern void dtrace_copystr(uintptr_t, uintptr_t, size_t, volatile uint16_t *); 1322 #endif 1323 1324 /* 1325 * DTrace Assertions 1326 * 1327 * DTrace calls ASSERT and VERIFY from probe context. To assure that a failed 1328 * ASSERT or VERIFY does not induce a markedly more catastrophic failure (e.g., 1329 * one from which a dump cannot be gleaned), DTrace must define its own ASSERT 1330 * and VERIFY macros to be ones that may safely be called from probe context. 1331 * This header file must thus be included by any DTrace component that calls 1332 * ASSERT and/or VERIFY from probe context, and _only_ by those components. 1333 * (The only exception to this is kernel debugging infrastructure at user-level 1334 * that doesn't depend on calling ASSERT.) 1335 */ 1336 #undef ASSERT 1337 #undef VERIFY 1338 #define VERIFY(EX) ((void)((EX) || \ 1339 dtrace_assfail(#EX, __FILE__, __LINE__))) 1340 #ifdef DEBUG 1341 #define ASSERT(EX) ((void)((EX) || \ 1342 dtrace_assfail(#EX, __FILE__, __LINE__))) 1343 #else 1344 #define ASSERT(X) ((void)0) 1345 #endif 1346 1347 #ifdef __cplusplus 1348 } 1349 #endif 1350 1351 #endif /* _SYS_DTRACE_IMPL_H */ 1352