xref: /illumos-gate/usr/src/uts/common/dtrace/lockstat.c (revision ee6ee36a8ff1701c4e61e6f118446b145220478c)
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  * Copyright 2022 Oxide Computer Company
25  */
26 
27 
28 #include <sys/types.h>
29 #include <sys/param.h>
30 #include <sys/stat.h>
31 #include <sys/open.h>
32 #include <sys/file.h>
33 #include <sys/conf.h>
34 #include <sys/modctl.h>
35 #include <sys/cmn_err.h>
36 #include <sys/bitmap.h>
37 #include <sys/debug.h>
38 #include <sys/kmem.h>
39 #include <sys/errno.h>
40 #include <sys/sysmacros.h>
41 #include <sys/lockstat.h>
42 #include <sys/atomic.h>
43 #include <sys/dtrace.h>
44 
45 #include <sys/ddi.h>
46 #include <sys/sunddi.h>
47 
48 typedef struct lockstat_probe {
49 	const char	*lsp_func;
50 	const char	*lsp_name;
51 	int		lsp_probe;
52 	dtrace_id_t	lsp_id;
53 } lockstat_probe_t;
54 
55 lockstat_probe_t lockstat_probes[] =
56 {
57 	{ LS_MUTEX_ENTER,	LSA_ACQUIRE,	LS_MUTEX_ENTER_ACQUIRE },
58 	{ LS_MUTEX_ENTER,	LSA_BLOCK,	LS_MUTEX_ENTER_BLOCK },
59 	{ LS_MUTEX_ENTER,	LSA_SPIN,	LS_MUTEX_ENTER_SPIN },
60 	{ LS_MUTEX_EXIT,	LSA_RELEASE,	LS_MUTEX_EXIT_RELEASE },
61 	{ LS_MUTEX_DESTROY,	LSA_RELEASE,	LS_MUTEX_DESTROY_RELEASE },
62 	{ LS_MUTEX_TRYENTER,	LSA_ACQUIRE,	LS_MUTEX_TRYENTER_ACQUIRE },
63 	{ LS_LOCK_SET,		LSS_ACQUIRE,	LS_LOCK_SET_ACQUIRE },
64 	{ LS_LOCK_SET,		LSS_SPIN,	LS_LOCK_SET_SPIN },
65 	{ LS_LOCK_SET_SPL,	LSS_ACQUIRE,	LS_LOCK_SET_SPL_ACQUIRE },
66 	{ LS_LOCK_SET_SPL,	LSS_SPIN,	LS_LOCK_SET_SPL_SPIN },
67 	{ LS_LOCK_TRY,		LSS_ACQUIRE,	LS_LOCK_TRY_ACQUIRE },
68 	{ LS_LOCK_CLEAR,	LSS_RELEASE,	LS_LOCK_CLEAR_RELEASE },
69 	{ LS_LOCK_CLEAR_SPLX,	LSS_RELEASE,	LS_LOCK_CLEAR_SPLX_RELEASE },
70 	{ LS_CLOCK_UNLOCK,	LSS_RELEASE,	LS_CLOCK_UNLOCK_RELEASE },
71 	{ LS_RW_ENTER,		LSR_ACQUIRE,	LS_RW_ENTER_ACQUIRE },
72 	{ LS_RW_ENTER,		LSR_BLOCK,	LS_RW_ENTER_BLOCK },
73 	{ LS_RW_EXIT,		LSR_RELEASE,	LS_RW_EXIT_RELEASE },
74 	{ LS_RW_TRYENTER,	LSR_ACQUIRE,	LS_RW_TRYENTER_ACQUIRE },
75 	{ LS_RW_TRYUPGRADE,	LSR_UPGRADE,	LS_RW_TRYUPGRADE_UPGRADE },
76 	{ LS_RW_DOWNGRADE,	LSR_DOWNGRADE,	LS_RW_DOWNGRADE_DOWNGRADE },
77 	{ LS_THREAD_LOCK,	LST_SPIN,	LS_THREAD_LOCK_SPIN },
78 	{ LS_THREAD_LOCK_HIGH,	LST_SPIN,	LS_THREAD_LOCK_HIGH_SPIN },
79 	{ NULL }
80 };
81 
82 static dev_info_t	*lockstat_devi;	/* saved in xxattach() for xxinfo() */
83 static kmutex_t		lockstat_test;	/* for testing purposes only */
84 static dtrace_provider_id_t lockstat_id;
85 
86 /*ARGSUSED*/
87 static int
lockstat_enable(void * arg,dtrace_id_t id,void * parg)88 lockstat_enable(void *arg, dtrace_id_t id, void *parg)
89 {
90 	lockstat_probe_t *probe = parg;
91 
92 	ASSERT(!lockstat_probemap[probe->lsp_probe]);
93 
94 	lockstat_probemap[probe->lsp_probe] = id;
95 	membar_producer();
96 
97 	lockstat_hotpatch_probe(probe->lsp_probe);
98 	membar_producer();
99 
100 	/*
101 	 * Immediately generate a record for the lockstat_test mutex
102 	 * to verify that the mutex hot-patch code worked as expected.
103 	 */
104 	mutex_enter(&lockstat_test);
105 	mutex_exit(&lockstat_test);
106 	return (0);
107 }
108 
109 /*ARGSUSED*/
110 static void
lockstat_disable(void * arg,dtrace_id_t id,void * parg)111 lockstat_disable(void *arg, dtrace_id_t id, void *parg)
112 {
113 	lockstat_probe_t *probe = parg;
114 	int i;
115 
116 	ASSERT(lockstat_probemap[probe->lsp_probe]);
117 
118 	lockstat_probemap[probe->lsp_probe] = 0;
119 	lockstat_hotpatch_probe(probe->lsp_probe);
120 	membar_producer();
121 
122 	/*
123 	 * See if we have any probes left enabled.
124 	 */
125 	for (i = 0; i < LS_NPROBES; i++) {
126 		if (lockstat_probemap[i]) {
127 			/*
128 			 * This probe is still enabled.  We don't need to deal
129 			 * with waiting for all threads to be out of the
130 			 * lockstat critical sections; just return.
131 			 */
132 			return;
133 		}
134 	}
135 
136 	/*
137 	 * The delay() here isn't as cheesy as you might think.  We don't
138 	 * want to busy-loop in the kernel, so we have to give up the
139 	 * CPU between calls to lockstat_active_threads(); that much is
140 	 * obvious.  But the reason it's a do..while loop rather than a
141 	 * while loop is subtle.  The memory barrier above guarantees that
142 	 * no threads will enter the lockstat code from this point forward.
143 	 * However, another thread could already be executing lockstat code
144 	 * without our knowledge if the update to its t_lockstat field hasn't
145 	 * cleared its CPU's store buffer.  Delaying for one clock tick
146 	 * guarantees that either (1) the thread will have *ample* time to
147 	 * complete its work, or (2) the thread will be preempted, in which
148 	 * case it will have to grab and release a dispatcher lock, which
149 	 * will flush that CPU's store buffer.  Either way we're covered.
150 	 */
151 	do {
152 		delay(1);
153 	} while (lockstat_active_threads());
154 }
155 
156 /*ARGSUSED*/
157 static int
lockstat_open(dev_t * devp,int flag,int otyp,cred_t * cred_p)158 lockstat_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
159 {
160 	return (0);
161 }
162 
163 /* ARGSUSED */
164 static int
lockstat_info(dev_info_t * dip,ddi_info_cmd_t infocmd,void * arg,void ** result)165 lockstat_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
166 {
167 	int error;
168 
169 	switch (infocmd) {
170 	case DDI_INFO_DEVT2DEVINFO:
171 		*result = (void *) lockstat_devi;
172 		error = DDI_SUCCESS;
173 		break;
174 	case DDI_INFO_DEVT2INSTANCE:
175 		*result = (void *)0;
176 		error = DDI_SUCCESS;
177 		break;
178 	default:
179 		error = DDI_FAILURE;
180 	}
181 	return (error);
182 }
183 
184 /*ARGSUSED*/
185 static void
lockstat_provide(void * arg,const dtrace_probedesc_t * desc)186 lockstat_provide(void *arg, const dtrace_probedesc_t *desc)
187 {
188 	int i = 0;
189 
190 	for (i = 0; lockstat_probes[i].lsp_func != NULL; i++) {
191 		lockstat_probe_t *probe = &lockstat_probes[i];
192 
193 		if (dtrace_probe_lookup(lockstat_id, "genunix",
194 		    probe->lsp_func, probe->lsp_name) != 0)
195 			continue;
196 
197 		ASSERT(!probe->lsp_id);
198 		probe->lsp_id = dtrace_probe_create(lockstat_id,
199 		    "genunix", probe->lsp_func, probe->lsp_name,
200 		    1, probe);
201 	}
202 }
203 
204 /*ARGSUSED*/
205 static void
lockstat_destroy(void * arg,dtrace_id_t id,void * parg)206 lockstat_destroy(void *arg, dtrace_id_t id, void *parg)
207 {
208 	lockstat_probe_t *probe = parg;
209 
210 	ASSERT(!lockstat_probemap[probe->lsp_probe]);
211 	probe->lsp_id = 0;
212 }
213 
214 static dtrace_pattr_t lockstat_attr = {
215 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
216 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
217 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
218 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
219 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
220 };
221 
222 static dtrace_pops_t lockstat_pops = {
223 	lockstat_provide,
224 	NULL,
225 	lockstat_enable,
226 	lockstat_disable,
227 	NULL,
228 	NULL,
229 	NULL,
230 	NULL,
231 	NULL,
232 	lockstat_destroy
233 };
234 
235 static int
lockstat_attach(dev_info_t * devi,ddi_attach_cmd_t cmd)236 lockstat_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
237 {
238 	switch (cmd) {
239 	case DDI_ATTACH:
240 		break;
241 	case DDI_RESUME:
242 		return (DDI_SUCCESS);
243 	default:
244 		return (DDI_FAILURE);
245 	}
246 
247 	if (ddi_create_minor_node(devi, "lockstat", S_IFCHR, 0,
248 	    DDI_PSEUDO, 0) == DDI_FAILURE ||
249 	    dtrace_register("lockstat", &lockstat_attr, DTRACE_PRIV_KERNEL,
250 	    NULL, &lockstat_pops, NULL, &lockstat_id) != 0) {
251 		ddi_remove_minor_node(devi, NULL);
252 		return (DDI_FAILURE);
253 	}
254 
255 	lockstat_probe = dtrace_probe;
256 	membar_producer();
257 
258 	ddi_report_dev(devi);
259 	lockstat_devi = devi;
260 	return (DDI_SUCCESS);
261 }
262 
263 static int
lockstat_detach(dev_info_t * devi,ddi_detach_cmd_t cmd)264 lockstat_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
265 {
266 	switch (cmd) {
267 	case DDI_DETACH:
268 		break;
269 	case DDI_SUSPEND:
270 		return (DDI_SUCCESS);
271 	default:
272 		return (DDI_FAILURE);
273 	}
274 
275 	if (dtrace_unregister(lockstat_id) != 0)
276 		return (DDI_FAILURE);
277 
278 	ddi_remove_minor_node(devi, NULL);
279 	return (DDI_SUCCESS);
280 }
281 
282 /*
283  * Configuration data structures
284  */
285 static struct cb_ops lockstat_cb_ops = {
286 	lockstat_open,		/* open */
287 	nodev,			/* close */
288 	nulldev,		/* strategy */
289 	nulldev,		/* print */
290 	nodev,			/* dump */
291 	nodev,			/* read */
292 	nodev,			/* write */
293 	nodev,			/* ioctl */
294 	nodev,			/* devmap */
295 	nodev,			/* mmap */
296 	nodev,			/* segmap */
297 	nochpoll,		/* poll */
298 	ddi_prop_op,		/* cb_prop_op */
299 	0,			/* streamtab */
300 	D_MP | D_NEW		/* Driver compatibility flag */
301 };
302 
303 static struct dev_ops lockstat_ops = {
304 	DEVO_REV,		/* devo_rev, */
305 	0,			/* refcnt */
306 	lockstat_info,		/* getinfo */
307 	nulldev,		/* identify */
308 	nulldev,		/* probe */
309 	lockstat_attach,	/* attach */
310 	lockstat_detach,	/* detach */
311 	nulldev,		/* reset */
312 	&lockstat_cb_ops,	/* cb_ops */
313 	NULL,			/* bus_ops */
314 	NULL,			/* power */
315 	ddi_quiesce_not_needed,		/* quiesce */
316 };
317 
318 static struct modldrv modldrv = {
319 	&mod_driverops,		/* Type of module.  This one is a driver */
320 	"Lock Statistics",	/* name of module */
321 	&lockstat_ops,		/* driver ops */
322 };
323 
324 static struct modlinkage modlinkage = {
325 	MODREV_1, (void *)&modldrv, NULL
326 };
327 
328 int
_init(void)329 _init(void)
330 {
331 	return (mod_install(&modlinkage));
332 }
333 
334 int
_fini(void)335 _fini(void)
336 {
337 	return (mod_remove(&modlinkage));
338 }
339 
340 int
_info(struct modinfo * modinfop)341 _info(struct modinfo *modinfop)
342 {
343 	return (mod_info(&modlinkage, modinfop));
344 }
345