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 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26
27 #include <sys/types.h>
28 #include <sys/param.h>
29 #include <sys/stat.h>
30 #include <sys/open.h>
31 #include <sys/file.h>
32 #include <sys/conf.h>
33 #include <sys/modctl.h>
34 #include <sys/cmn_err.h>
35 #include <sys/bitmap.h>
36 #include <sys/debug.h>
37 #include <sys/kmem.h>
38 #include <sys/errno.h>
39 #include <sys/sysmacros.h>
40 #include <sys/lockstat.h>
41 #include <sys/atomic.h>
42 #include <sys/dtrace.h>
43
44 #include <sys/ddi.h>
45 #include <sys/sunddi.h>
46
47 typedef struct lockstat_probe {
48 const char *lsp_func;
49 const char *lsp_name;
50 int lsp_probe;
51 dtrace_id_t lsp_id;
52 } lockstat_probe_t;
53
54 lockstat_probe_t lockstat_probes[] =
55 {
56 { LS_MUTEX_ENTER, LSA_ACQUIRE, LS_MUTEX_ENTER_ACQUIRE },
57 { LS_MUTEX_ENTER, LSA_BLOCK, LS_MUTEX_ENTER_BLOCK },
58 { LS_MUTEX_ENTER, LSA_SPIN, LS_MUTEX_ENTER_SPIN },
59 { LS_MUTEX_EXIT, LSA_RELEASE, LS_MUTEX_EXIT_RELEASE },
60 { LS_MUTEX_DESTROY, LSA_RELEASE, LS_MUTEX_DESTROY_RELEASE },
61 { LS_MUTEX_TRYENTER, LSA_ACQUIRE, LS_MUTEX_TRYENTER_ACQUIRE },
62 { LS_LOCK_SET, LSS_ACQUIRE, LS_LOCK_SET_ACQUIRE },
63 { LS_LOCK_SET, LSS_SPIN, LS_LOCK_SET_SPIN },
64 { LS_LOCK_SET_SPL, LSS_ACQUIRE, LS_LOCK_SET_SPL_ACQUIRE },
65 { LS_LOCK_SET_SPL, LSS_SPIN, LS_LOCK_SET_SPL_SPIN },
66 { LS_LOCK_TRY, LSS_ACQUIRE, LS_LOCK_TRY_ACQUIRE },
67 { LS_LOCK_CLEAR, LSS_RELEASE, LS_LOCK_CLEAR_RELEASE },
68 { LS_LOCK_CLEAR_SPLX, LSS_RELEASE, LS_LOCK_CLEAR_SPLX_RELEASE },
69 { LS_CLOCK_UNLOCK, LSS_RELEASE, LS_CLOCK_UNLOCK_RELEASE },
70 { LS_RW_ENTER, LSR_ACQUIRE, LS_RW_ENTER_ACQUIRE },
71 { LS_RW_ENTER, LSR_BLOCK, LS_RW_ENTER_BLOCK },
72 { LS_RW_EXIT, LSR_RELEASE, LS_RW_EXIT_RELEASE },
73 { LS_RW_TRYENTER, LSR_ACQUIRE, LS_RW_TRYENTER_ACQUIRE },
74 { LS_RW_TRYUPGRADE, LSR_UPGRADE, LS_RW_TRYUPGRADE_UPGRADE },
75 { LS_RW_DOWNGRADE, LSR_DOWNGRADE, LS_RW_DOWNGRADE_DOWNGRADE },
76 { LS_THREAD_LOCK, LST_SPIN, LS_THREAD_LOCK_SPIN },
77 { LS_THREAD_LOCK_HIGH, LST_SPIN, LS_THREAD_LOCK_HIGH_SPIN },
78 { NULL }
79 };
80
81 static dev_info_t *lockstat_devi; /* saved in xxattach() for xxinfo() */
82 static kmutex_t lockstat_test; /* for testing purposes only */
83 static dtrace_provider_id_t lockstat_id;
84
85 /*ARGSUSED*/
86 static int
87 lockstat_enable(void *arg, dtrace_id_t id, void *parg)
88 {
89 lockstat_probe_t *probe = parg;
90
91 ASSERT(!lockstat_probemap[probe->lsp_probe]);
92
93 lockstat_probemap[probe->lsp_probe] = id;
94 membar_producer();
95
96 lockstat_hot_patch();
97 membar_producer();
98
99 /*
100 * Immediately generate a record for the lockstat_test mutex
101 * to verify that the mutex hot-patch code worked as expected.
102 */
103 mutex_enter(&lockstat_test);
104 mutex_exit(&lockstat_test);
105 return (0);
106 }
107
108 /*ARGSUSED*/
109 static void
110 lockstat_disable(void *arg, dtrace_id_t id, void *parg)
111 {
112 lockstat_probe_t *probe = parg;
113 int i;
114
115 ASSERT(lockstat_probemap[probe->lsp_probe]);
116
117 lockstat_probemap[probe->lsp_probe] = 0;
118 lockstat_hot_patch();
119 membar_producer();
120
121 /*
122 * See if we have any probes left enabled.
123 */
124 for (i = 0; i < LS_NPROBES; i++) {
125 if (lockstat_probemap[i]) {
126 /*
127 * This probe is still enabled. We don't need to deal
128 * with waiting for all threads to be out of the
129 * lockstat critical sections; just return.
130 */
131 return;
132 }
133 }
134
135 /*
136 * The delay() here isn't as cheesy as you might think. We don't
137 * want to busy-loop in the kernel, so we have to give up the
138 * CPU between calls to lockstat_active_threads(); that much is
139 * obvious. But the reason it's a do..while loop rather than a
140 * while loop is subtle. The memory barrier above guarantees that
141 * no threads will enter the lockstat code from this point forward.
142 * However, another thread could already be executing lockstat code
143 * without our knowledge if the update to its t_lockstat field hasn't
144 * cleared its CPU's store buffer. Delaying for one clock tick
145 * guarantees that either (1) the thread will have *ample* time to
146 * complete its work, or (2) the thread will be preempted, in which
147 * case it will have to grab and release a dispatcher lock, which
148 * will flush that CPU's store buffer. Either way we're covered.
149 */
150 do {
151 delay(1);
152 } while (lockstat_active_threads());
153 }
154
155 /*ARGSUSED*/
156 static int
157 lockstat_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
158 {
159 return (0);
160 }
161
162 /* ARGSUSED */
163 static int
164 lockstat_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
165 {
166 int error;
167
168 switch (infocmd) {
169 case DDI_INFO_DEVT2DEVINFO:
170 *result = (void *) lockstat_devi;
171 error = DDI_SUCCESS;
172 break;
173 case DDI_INFO_DEVT2INSTANCE:
174 *result = (void *)0;
175 error = DDI_SUCCESS;
176 break;
177 default:
178 error = DDI_FAILURE;
179 }
180 return (error);
181 }
182
183 /*ARGSUSED*/
184 static void
185 lockstat_provide(void *arg, const dtrace_probedesc_t *desc)
186 {
187 int i = 0;
188
189 for (i = 0; lockstat_probes[i].lsp_func != NULL; i++) {
190 lockstat_probe_t *probe = &lockstat_probes[i];
191
192 if (dtrace_probe_lookup(lockstat_id, "genunix",
193 probe->lsp_func, probe->lsp_name) != 0)
194 continue;
195
196 ASSERT(!probe->lsp_id);
197 probe->lsp_id = dtrace_probe_create(lockstat_id,
198 "genunix", probe->lsp_func, probe->lsp_name,
199 1, probe);
200 }
201 }
202
203 /*ARGSUSED*/
204 static void
205 lockstat_destroy(void *arg, dtrace_id_t id, void *parg)
206 {
207 lockstat_probe_t *probe = parg;
208
209 ASSERT(!lockstat_probemap[probe->lsp_probe]);
210 probe->lsp_id = 0;
211 }
212
213 static dtrace_pattr_t lockstat_attr = {
214 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
215 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
216 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
217 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
218 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
219 };
220
221 static dtrace_pops_t lockstat_pops = {
222 lockstat_provide,
223 NULL,
224 lockstat_enable,
225 lockstat_disable,
226 NULL,
227 NULL,
228 NULL,
229 NULL,
230 NULL,
231 lockstat_destroy
232 };
233
234 static int
235 lockstat_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
236 {
237 switch (cmd) {
238 case DDI_ATTACH:
239 break;
240 case DDI_RESUME:
241 return (DDI_SUCCESS);
242 default:
243 return (DDI_FAILURE);
244 }
245
246 if (ddi_create_minor_node(devi, "lockstat", S_IFCHR, 0,
247 DDI_PSEUDO, 0) == DDI_FAILURE ||
248 dtrace_register("lockstat", &lockstat_attr, DTRACE_PRIV_KERNEL,
249 NULL, &lockstat_pops, NULL, &lockstat_id) != 0) {
250 ddi_remove_minor_node(devi, NULL);
251 return (DDI_FAILURE);
252 }
253
254 lockstat_probe = dtrace_probe;
255 membar_producer();
256
257 ddi_report_dev(devi);
258 lockstat_devi = devi;
259 return (DDI_SUCCESS);
260 }
261
262 static int
263 lockstat_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
264 {
265 switch (cmd) {
266 case DDI_DETACH:
267 break;
268 case DDI_SUSPEND:
269 return (DDI_SUCCESS);
270 default:
271 return (DDI_FAILURE);
272 }
273
274 if (dtrace_unregister(lockstat_id) != 0)
275 return (DDI_FAILURE);
276
277 ddi_remove_minor_node(devi, NULL);
278 return (DDI_SUCCESS);
279 }
280
281 /*
282 * Configuration data structures
283 */
284 static struct cb_ops lockstat_cb_ops = {
285 lockstat_open, /* open */
286 nodev, /* close */
287 nulldev, /* strategy */
288 nulldev, /* print */
289 nodev, /* dump */
290 nodev, /* read */
291 nodev, /* write */
292 nodev, /* ioctl */
293 nodev, /* devmap */
294 nodev, /* mmap */
295 nodev, /* segmap */
296 nochpoll, /* poll */
297 ddi_prop_op, /* cb_prop_op */
298 0, /* streamtab */
299 D_MP | D_NEW /* Driver compatibility flag */
300 };
301
302 static struct dev_ops lockstat_ops = {
303 DEVO_REV, /* devo_rev, */
304 0, /* refcnt */
305 lockstat_info, /* getinfo */
306 nulldev, /* identify */
307 nulldev, /* probe */
308 lockstat_attach, /* attach */
309 lockstat_detach, /* detach */
310 nulldev, /* reset */
311 &lockstat_cb_ops, /* cb_ops */
312 NULL, /* bus_ops */
313 NULL, /* power */
314 ddi_quiesce_not_needed, /* quiesce */
315 };
316
317 static struct modldrv modldrv = {
318 &mod_driverops, /* Type of module. This one is a driver */
319 "Lock Statistics", /* name of module */
320 &lockstat_ops, /* driver ops */
321 };
322
323 static struct modlinkage modlinkage = {
324 MODREV_1, (void *)&modldrv, NULL
325 };
326
327 int
328 _init(void)
329 {
330 return (mod_install(&modlinkage));
331 }
332
333 int
334 _fini(void)
335 {
336 return (mod_remove(&modlinkage));
337 }
338
339 int
340 _info(struct modinfo *modinfop)
341 {
342 return (mod_info(&modlinkage, modinfop));
343 }