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 2009 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #include <sys/dtrace.h>
28 #include <sys/cmn_err.h>
29 #include <sys/tnf.h>
30 #include <sys/atomic.h>
31 #include <sys/prsystm.h>
32 #include <sys/modctl.h>
33 #include <sys/aio_impl.h>
34
35 #ifdef __sparc
36 #include <sys/privregs.h>
37 #endif
38
39 void (*dtrace_cpu_init)(processorid_t);
40 void (*dtrace_modload)(struct modctl *);
41 void (*dtrace_modunload)(struct modctl *);
42 void (*dtrace_helpers_cleanup)(void);
43 void (*dtrace_helpers_fork)(proc_t *, proc_t *);
44 void (*dtrace_cpustart_init)(void);
45 void (*dtrace_cpustart_fini)(void);
46 void (*dtrace_cpc_fire)(uint64_t);
47
48 void (*dtrace_debugger_init)(void);
49 void (*dtrace_debugger_fini)(void);
50
51 dtrace_vtime_state_t dtrace_vtime_active = 0;
52 dtrace_cacheid_t dtrace_predcache_id = DTRACE_CACHEIDNONE + 1;
53
54 /*
55 * dtrace_cpc_in_use usage statement: this global variable is used by the cpc
56 * hardware overflow interrupt handler and the kernel cpc framework to check
57 * whether or not the DTrace cpc provider is currently in use. The variable is
58 * set before counters are enabled with the first enabling and cleared when
59 * the last enabling is disabled. Its value at any given time indicates the
60 * number of active dcpc based enablings. The global 'kcpc_cpuctx_lock' rwlock
61 * is held during initial setting to protect races between kcpc_open() and the
62 * first enabling. The locking provided by the DTrace subsystem, the kernel
63 * cpc framework and the cpu management framework protect consumers from race
64 * conditions on enabling and disabling probes.
65 */
66 uint32_t dtrace_cpc_in_use = 0;
67
68 typedef struct dtrace_hrestime {
69 lock_t dthr_lock; /* lock for this element */
70 timestruc_t dthr_hrestime; /* hrestime value */
71 int64_t dthr_adj; /* hrestime_adj value */
72 hrtime_t dthr_hrtime; /* hrtime value */
73 } dtrace_hrestime_t;
74
75 static dtrace_hrestime_t dtrace_hrestime[2];
76
77 /*
78 * Making available adjustable high-resolution time in DTrace is regrettably
79 * more complicated than one might think it should be. The problem is that
80 * the variables related to adjusted high-resolution time (hrestime,
81 * hrestime_adj and friends) are adjusted under hres_lock -- and this lock may
82 * be held when we enter probe context. One might think that we could address
83 * this by having a single snapshot copy that is stored under a different lock
84 * from hres_tick(), using the snapshot iff hres_lock is locked in probe
85 * context. Unfortunately, this too won't work: because hres_lock is grabbed
86 * in more than just hres_tick() context, we could enter probe context
87 * concurrently on two different CPUs with both locks (hres_lock and the
88 * snapshot lock) held. As this implies, the fundamental problem is that we
89 * need to have access to a snapshot of these variables that we _know_ will
90 * not be locked in probe context. To effect this, we have two snapshots
91 * protected by two different locks, and we mandate that these snapshots are
92 * recorded in succession by a single thread calling dtrace_hres_tick(). (We
93 * assure this by calling it out of the same CY_HIGH_LEVEL cyclic that calls
94 * hres_tick().) A single thread can't be in two places at once: one of the
95 * snapshot locks is guaranteed to be unheld at all times. The
96 * dtrace_gethrestime() algorithm is thus to check first one snapshot and then
97 * the other to find the unlocked snapshot.
98 */
99 void
100 dtrace_hres_tick(void)
101 {
102 int i;
103 ushort_t spl;
104
105 for (i = 0; i < 2; i++) {
106 dtrace_hrestime_t tmp;
107
108 spl = hr_clock_lock();
109 tmp.dthr_hrestime = hrestime;
110 tmp.dthr_adj = hrestime_adj;
111 tmp.dthr_hrtime = dtrace_gethrtime();
112 hr_clock_unlock(spl);
113
114 lock_set(&dtrace_hrestime[i].dthr_lock);
115 dtrace_hrestime[i].dthr_hrestime = tmp.dthr_hrestime;
116 dtrace_hrestime[i].dthr_adj = tmp.dthr_adj;
117 dtrace_hrestime[i].dthr_hrtime = tmp.dthr_hrtime;
118 dtrace_membar_producer();
119
120 /*
121 * To allow for lock-free examination of this lock, we use
122 * the same trick that is used hres_lock; for more details,
123 * see the description of this technique in sun4u/sys/clock.h.
124 */
125 dtrace_hrestime[i].dthr_lock++;
126 }
127 }
128
129 hrtime_t
130 dtrace_gethrestime(void)
131 {
132 dtrace_hrestime_t snap;
133 hrtime_t now;
134 int i = 0, adj, nslt;
135
136 for (;;) {
137 snap.dthr_lock = dtrace_hrestime[i].dthr_lock;
138 dtrace_membar_consumer();
139 snap.dthr_hrestime = dtrace_hrestime[i].dthr_hrestime;
140 snap.dthr_hrtime = dtrace_hrestime[i].dthr_hrtime;
141 snap.dthr_adj = dtrace_hrestime[i].dthr_adj;
142 dtrace_membar_consumer();
143
144 if ((snap.dthr_lock & ~1) == dtrace_hrestime[i].dthr_lock)
145 break;
146
147 /*
148 * If we're here, the lock was either locked, or it
149 * transitioned while we were taking the snapshot. Either
150 * way, we're going to try the other dtrace_hrestime element;
151 * we know that it isn't possible for both to be locked
152 * simultaneously, so we will ultimately get a good snapshot.
153 */
154 i ^= 1;
155 }
156
157 /*
158 * We have a good snapshot. Now perform any necessary adjustments.
159 */
160 nslt = dtrace_gethrtime() - snap.dthr_hrtime;
161 ASSERT(nslt >= 0);
162
163 now = ((hrtime_t)snap.dthr_hrestime.tv_sec * (hrtime_t)NANOSEC) +
164 snap.dthr_hrestime.tv_nsec;
165
166 if (snap.dthr_adj != 0) {
167 if (snap.dthr_adj > 0) {
168 adj = (nslt >> adj_shift);
169 if (adj > snap.dthr_adj)
170 adj = (int)snap.dthr_adj;
171 } else {
172 adj = -(nslt >> adj_shift);
173 if (adj < snap.dthr_adj)
174 adj = (int)snap.dthr_adj;
175 }
176 now += adj;
177 }
178
179 return (now);
180 }
181
182 void
183 dtrace_vtime_enable(void)
184 {
185 dtrace_vtime_state_t state, nstate;
186
187 do {
188 state = dtrace_vtime_active;
189
190 switch (state) {
191 case DTRACE_VTIME_INACTIVE:
192 nstate = DTRACE_VTIME_ACTIVE;
193 break;
194
195 case DTRACE_VTIME_INACTIVE_TNF:
196 nstate = DTRACE_VTIME_ACTIVE_TNF;
197 break;
198
199 case DTRACE_VTIME_ACTIVE:
200 case DTRACE_VTIME_ACTIVE_TNF:
201 panic("DTrace virtual time already enabled");
202 /*NOTREACHED*/
203 }
204
205 } while (cas32((uint32_t *)&dtrace_vtime_active,
206 state, nstate) != state);
207 }
208
209 void
210 dtrace_vtime_disable(void)
211 {
212 dtrace_vtime_state_t state, nstate;
213
214 do {
215 state = dtrace_vtime_active;
216
217 switch (state) {
218 case DTRACE_VTIME_ACTIVE:
219 nstate = DTRACE_VTIME_INACTIVE;
220 break;
221
222 case DTRACE_VTIME_ACTIVE_TNF:
223 nstate = DTRACE_VTIME_INACTIVE_TNF;
224 break;
225
226 case DTRACE_VTIME_INACTIVE:
227 case DTRACE_VTIME_INACTIVE_TNF:
228 panic("DTrace virtual time already disabled");
229 /*NOTREACHED*/
230 }
231
232 } while (cas32((uint32_t *)&dtrace_vtime_active,
233 state, nstate) != state);
234 }
235
236 void
237 dtrace_vtime_enable_tnf(void)
238 {
239 dtrace_vtime_state_t state, nstate;
240
241 do {
242 state = dtrace_vtime_active;
243
244 switch (state) {
245 case DTRACE_VTIME_ACTIVE:
246 nstate = DTRACE_VTIME_ACTIVE_TNF;
247 break;
248
249 case DTRACE_VTIME_INACTIVE:
250 nstate = DTRACE_VTIME_INACTIVE_TNF;
251 break;
252
253 case DTRACE_VTIME_ACTIVE_TNF:
254 case DTRACE_VTIME_INACTIVE_TNF:
255 panic("TNF already active");
256 /*NOTREACHED*/
257 }
258
259 } while (cas32((uint32_t *)&dtrace_vtime_active,
260 state, nstate) != state);
261 }
262
263 void
264 dtrace_vtime_disable_tnf(void)
265 {
266 dtrace_vtime_state_t state, nstate;
267
268 do {
269 state = dtrace_vtime_active;
270
271 switch (state) {
272 case DTRACE_VTIME_ACTIVE_TNF:
273 nstate = DTRACE_VTIME_ACTIVE;
274 break;
275
276 case DTRACE_VTIME_INACTIVE_TNF:
277 nstate = DTRACE_VTIME_INACTIVE;
278 break;
279
280 case DTRACE_VTIME_ACTIVE:
281 case DTRACE_VTIME_INACTIVE:
282 panic("TNF already inactive");
283 /*NOTREACHED*/
284 }
285
286 } while (cas32((uint32_t *)&dtrace_vtime_active,
287 state, nstate) != state);
288 }
289
290 void
291 dtrace_vtime_switch(kthread_t *next)
292 {
293 dtrace_icookie_t cookie;
294 hrtime_t ts;
295
296 if (tnf_tracing_active) {
297 tnf_thread_switch(next);
298
299 if (dtrace_vtime_active == DTRACE_VTIME_INACTIVE_TNF)
300 return;
301 }
302
303 cookie = dtrace_interrupt_disable();
304 ts = dtrace_gethrtime();
305
306 if (curthread->t_dtrace_start != 0) {
307 curthread->t_dtrace_vtime += ts - curthread->t_dtrace_start;
308 curthread->t_dtrace_start = 0;
309 }
310
311 next->t_dtrace_start = ts;
312
313 dtrace_interrupt_enable(cookie);
314 }
315
316 void (*dtrace_fasttrap_fork_ptr)(proc_t *, proc_t *);
317 void (*dtrace_fasttrap_exec_ptr)(proc_t *);
318 void (*dtrace_fasttrap_exit_ptr)(proc_t *);
319
320 /*
321 * This function is called by cfork() in the event that it appears that
322 * there may be dtrace tracepoints active in the parent process's address
323 * space. This first confirms the existence of dtrace tracepoints in the
324 * parent process and calls into the fasttrap module to remove the
325 * corresponding tracepoints from the child. By knowing that there are
326 * existing tracepoints, and ensuring they can't be removed, we can rely
327 * on the fasttrap module remaining loaded.
328 */
329 void
330 dtrace_fasttrap_fork(proc_t *p, proc_t *cp)
331 {
332 ASSERT(p->p_proc_flag & P_PR_LOCK);
333 ASSERT(p->p_dtrace_count > 0);
334 ASSERT(dtrace_fasttrap_fork_ptr != NULL);
335
336 dtrace_fasttrap_fork_ptr(p, cp);
337 }