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
lockstat_enable(void * arg,dtrace_id_t id,void * parg)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
lockstat_disable(void * arg,dtrace_id_t id,void * parg)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
lockstat_open(dev_t * devp,int flag,int otyp,cred_t * cred_p)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
lockstat_info(dev_info_t * dip,ddi_info_cmd_t infocmd,void * arg,void ** result)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
lockstat_provide(void * arg,const dtrace_probedesc_t * desc)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
lockstat_destroy(void * arg,dtrace_id_t id,void * parg)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
lockstat_attach(dev_info_t * devi,ddi_attach_cmd_t cmd)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
lockstat_detach(dev_info_t * devi,ddi_detach_cmd_t cmd)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
_init(void)328 _init(void)
329 {
330 	return (mod_install(&modlinkage));
331 }
332 
333 int
_fini(void)334 _fini(void)
335 {
336 	return (mod_remove(&modlinkage));
337 }
338 
339 int
_info(struct modinfo * modinfop)340 _info(struct modinfo *modinfop)
341 {
342 	return (mod_info(&modlinkage, modinfop));
343 }
344