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 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 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 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 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 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 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 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 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 329 _init(void) 330 { 331 return (mod_install(&modlinkage)); 332 } 333 334 int 335 _fini(void) 336 { 337 return (mod_remove(&modlinkage)); 338 } 339 340 int 341 _info(struct modinfo *modinfop) 342 { 343 return (mod_info(&modlinkage, modinfop)); 344 } 345