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 from probe context. To assure that a failed ASSERT
1294 * does not induce a markedly more catastrophic failure (e.g., one from which
1295 * a dump cannot be gleaned), DTrace must define its own ASSERT to be one that
1296 * may safely be called from probe context. This header file must thus be
1297 * included by any DTrace component that calls ASSERT from probe context, and
1298 * _only_ by those components. (The only exception to this is kernel
1299 * debugging infrastructure at user-level that doesn't depend on calling
1300 * ASSERT.)
1301 */
1302 #undef ASSERT
1303 #ifdef DEBUG
1304 #define ASSERT(EX) ((void)((EX) || \
1305 dtrace_assfail(#EX, __FILE__, __LINE__)))
1306 #else
1307 #define ASSERT(X) ((void)0)
1308 #endif
1309
1310 #ifdef __cplusplus
1311 }
1312 #endif
1313
1314 #endif /* _SYS_DTRACE_IMPL_H */