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 (c) 2010, Oracle and/or its affiliates. All rights reserved. 24 * Copyright (c) 2012 by Delphix. All rights reserved. 25 */ 26 27 #include <mdb/mdb_modapi.h> 28 #include <mdb/mdb_ctf.h> 29 30 #include <sys/types.h> 31 #include <sys/regset.h> 32 #include <sys/stack.h> 33 #include <sys/thread.h> 34 #include <sys/modctl.h> 35 36 #include "findstack.h" 37 #include "thread.h" 38 #include "sobj.h" 39 40 #define TOO_BIG_FOR_A_STACK (1024 * 1024) 41 42 #define KTOU(p) ((p) - kbase + ubase) 43 #define UTOK(p) ((p) - ubase + kbase) 44 45 #define CRAWL_FOUNDALL (-1) 46 47 #if defined(__i386) || defined(__amd64) 48 struct rwindow { 49 uintptr_t rw_fp; 50 uintptr_t rw_rtn; 51 }; 52 #endif 53 54 #ifndef STACK_BIAS 55 #define STACK_BIAS 0 56 #endif 57 58 /* 59 * Given a stack pointer, try to crawl down it to the bottom. 60 * "frame" is a VA in MDB's address space. 61 * 62 * Returns the number of frames successfully crawled down, or 63 * CRAWL_FOUNDALL if it got to the bottom of the stack. 64 */ 65 static int 66 crawl(uintptr_t frame, uintptr_t kbase, uintptr_t ktop, uintptr_t ubase, 67 int kill_fp, findstack_info_t *fsip) 68 { 69 int levels = 0; 70 71 fsip->fsi_depth = 0; 72 fsip->fsi_overflow = 0; 73 74 fs_dprintf(("<0> frame = %p, kbase = %p, ktop = %p, ubase = %p\n", 75 frame, kbase, ktop, ubase)); 76 for (;;) { 77 uintptr_t fp; 78 long *fpp = (long *)&((struct rwindow *)frame)->rw_fp; 79 80 fs_dprintf(("<1> fpp = %p, frame = %p\n", fpp, frame)); 81 82 if ((frame & (STACK_ALIGN - 1)) != 0) 83 break; 84 85 fp = ((struct rwindow *)frame)->rw_fp + STACK_BIAS; 86 if (fsip->fsi_depth < fsip->fsi_max_depth) 87 fsip->fsi_stack[fsip->fsi_depth++] = 88 ((struct rwindow *)frame)->rw_rtn; 89 else 90 fsip->fsi_overflow = 1; 91 92 fs_dprintf(("<2> fp = %p\n", fp)); 93 94 if (fp == ktop) 95 return (CRAWL_FOUNDALL); 96 fs_dprintf(("<3> not at base\n")); 97 98 #if defined(__i386) || defined(__amd64) 99 if (ktop - fp == sizeof (struct rwindow)) { 100 fs_dprintf(("<4> found base\n")); 101 return (CRAWL_FOUNDALL); 102 } 103 #endif 104 105 fs_dprintf(("<5> fp = %p, kbase = %p, ktop - size = %p\n", 106 fp, kbase, ktop - sizeof (struct rwindow))); 107 108 if (fp < kbase || fp >= (ktop - sizeof (struct rwindow))) 109 break; 110 111 frame = KTOU(fp); 112 fs_dprintf(("<6> frame = %p\n", frame)); 113 114 /* 115 * NULL out the old %fp so we don't go down this stack 116 * more than once. 117 */ 118 if (kill_fp) { 119 fs_dprintf(("<7> fpp = %p\n", fpp)); 120 *fpp = 0; 121 } 122 123 fs_dprintf(("<8> levels = %d\n", levels)); 124 levels++; 125 } 126 127 return (levels); 128 } 129 130 typedef struct mdb_findstack_kthread { 131 struct _sobj_ops *t_sobj_ops; 132 uint_t t_state; 133 ushort_t t_flag; 134 ushort_t t_schedflag; 135 caddr_t t_stk; 136 caddr_t t_stkbase; 137 label_t t_pcb; 138 } mdb_findstack_kthread_t; 139 140 /*ARGSUSED*/ 141 int 142 stacks_findstack(uintptr_t addr, findstack_info_t *fsip, uint_t print_warnings) 143 { 144 mdb_findstack_kthread_t thr; 145 size_t stksz; 146 uintptr_t ubase, utop; 147 uintptr_t kbase, ktop; 148 uintptr_t win, sp; 149 150 fsip->fsi_failed = 0; 151 fsip->fsi_pc = 0; 152 fsip->fsi_sp = 0; 153 fsip->fsi_depth = 0; 154 fsip->fsi_overflow = 0; 155 156 if (mdb_ctf_vread(&thr, "kthread_t", "mdb_findstack_kthread_t", 157 addr, print_warnings ? 0 : MDB_CTF_VREAD_QUIET) == -1) { 158 fsip->fsi_failed = FSI_FAIL_BADTHREAD; 159 return (DCMD_ERR); 160 } 161 162 fsip->fsi_sobj_ops = (uintptr_t)thr.t_sobj_ops; 163 fsip->fsi_tstate = thr.t_state; 164 fsip->fsi_panic = !!(thr.t_flag & T_PANIC); 165 166 if ((thr.t_schedflag & TS_LOAD) == 0) { 167 if (print_warnings) 168 mdb_warn("thread %p isn't in memory\n", addr); 169 fsip->fsi_failed = FSI_FAIL_NOTINMEMORY; 170 return (DCMD_ERR); 171 } 172 173 if (thr.t_stk < thr.t_stkbase) { 174 if (print_warnings) 175 mdb_warn( 176 "stack base or stack top corrupt for thread %p\n", 177 addr); 178 fsip->fsi_failed = FSI_FAIL_THREADCORRUPT; 179 return (DCMD_ERR); 180 } 181 182 kbase = (uintptr_t)thr.t_stkbase; 183 ktop = (uintptr_t)thr.t_stk; 184 stksz = ktop - kbase; 185 186 #ifdef __amd64 187 /* 188 * The stack on amd64 is intentionally misaligned, so ignore the top 189 * half-frame. See thread_stk_init(). When handling traps, the frame 190 * is automatically aligned by the hardware, so we only alter ktop if 191 * needed. 192 */ 193 if ((ktop & (STACK_ALIGN - 1)) != 0) 194 ktop -= STACK_ENTRY_ALIGN; 195 #endif 196 197 /* 198 * If the stack size is larger than a meg, assume that it's bogus. 199 */ 200 if (stksz > TOO_BIG_FOR_A_STACK) { 201 if (print_warnings) 202 mdb_warn("stack size for thread %p is too big to be " 203 "reasonable\n", addr); 204 fsip->fsi_failed = FSI_FAIL_THREADCORRUPT; 205 return (DCMD_ERR); 206 } 207 208 /* 209 * This could be (and was) a UM_GC allocation. Unfortunately, 210 * stksz tends to be very large. As currently implemented, dcmds 211 * invoked as part of pipelines don't have their UM_GC-allocated 212 * memory freed until the pipeline completes. With stksz in the 213 * neighborhood of 20k, the popular ::walk thread |::findstack 214 * pipeline can easily run memory-constrained debuggers (kmdb) out 215 * of memory. This can be changed back to a gc-able allocation when 216 * the debugger is changed to free UM_GC memory more promptly. 217 */ 218 ubase = (uintptr_t)mdb_alloc(stksz, UM_SLEEP); 219 utop = ubase + stksz; 220 if (mdb_vread((caddr_t)ubase, stksz, kbase) != stksz) { 221 mdb_free((void *)ubase, stksz); 222 if (print_warnings) 223 mdb_warn("couldn't read entire stack for thread %p\n", 224 addr); 225 fsip->fsi_failed = FSI_FAIL_THREADCORRUPT; 226 return (DCMD_ERR); 227 } 228 229 /* 230 * Try the saved %sp first, if it looks reasonable. 231 */ 232 sp = KTOU((uintptr_t)thr.t_sp + STACK_BIAS); 233 if (sp >= ubase && sp <= utop) { 234 if (crawl(sp, kbase, ktop, ubase, 0, fsip) == CRAWL_FOUNDALL) { 235 fsip->fsi_sp = (uintptr_t)thr.t_sp; 236 #if !defined(__i386) 237 fsip->fsi_pc = (uintptr_t)thr.t_pc; 238 #endif 239 goto found; 240 } 241 } 242 243 /* 244 * Now walk through the whole stack, starting at the base, 245 * trying every possible "window". 246 */ 247 for (win = ubase; 248 win + sizeof (struct rwindow) <= utop; 249 win += sizeof (struct rwindow *)) { 250 if (crawl(win, kbase, ktop, ubase, 1, fsip) == CRAWL_FOUNDALL) { 251 fsip->fsi_sp = UTOK(win) - STACK_BIAS; 252 goto found; 253 } 254 } 255 256 /* 257 * We didn't conclusively find the stack. So we'll take another lap, 258 * and print out anything that looks possible. 259 */ 260 if (print_warnings) 261 mdb_printf("Possible stack pointers for thread %p:\n", addr); 262 (void) mdb_vread((caddr_t)ubase, stksz, kbase); 263 264 for (win = ubase; 265 win + sizeof (struct rwindow) <= utop; 266 win += sizeof (struct rwindow *)) { 267 uintptr_t fp = ((struct rwindow *)win)->rw_fp; 268 int levels; 269 270 if ((levels = crawl(win, kbase, ktop, ubase, 1, fsip)) > 1) { 271 if (print_warnings) 272 mdb_printf(" %p (%d)\n", fp, levels); 273 } else if (levels == CRAWL_FOUNDALL) { 274 /* 275 * If this is a live system, the stack could change 276 * between the two mdb_vread(ubase, utop, kbase)'s, 277 * and we could have a fully valid stack here. 278 */ 279 fsip->fsi_sp = UTOK(win) - STACK_BIAS; 280 goto found; 281 } 282 } 283 284 fsip->fsi_depth = 0; 285 fsip->fsi_overflow = 0; 286 fsip->fsi_failed = FSI_FAIL_STACKNOTFOUND; 287 288 mdb_free((void *)ubase, stksz); 289 return (DCMD_ERR); 290 found: 291 mdb_free((void *)ubase, stksz); 292 return (DCMD_OK); 293 } 294 295 void 296 stacks_findstack_cleanup() 297 {} 298 299 /*ARGSUSED*/ 300 int 301 stacks_module_cb(uintptr_t addr, const modctl_t *mp, stacks_module_t *smp) 302 { 303 char mod_modname[MODMAXNAMELEN + 1]; 304 305 if (!mp->mod_modname) 306 return (WALK_NEXT); 307 308 if (mdb_readstr(mod_modname, sizeof (mod_modname), 309 (uintptr_t)mp->mod_modname) == -1) { 310 mdb_warn("failed to read mod_modname in \"modctl\" walk"); 311 return (WALK_ERR); 312 } 313 314 if (strcmp(smp->sm_name, mod_modname)) 315 return (WALK_NEXT); 316 317 smp->sm_text = (uintptr_t)mp->mod_text; 318 smp->sm_size = mp->mod_text_size; 319 320 return (WALK_DONE); 321 } 322 323 int 324 stacks_module(stacks_module_t *smp) 325 { 326 if (mdb_walk("modctl", (mdb_walk_cb_t)stacks_module_cb, smp) != 0) { 327 mdb_warn("cannot walk \"modctl\""); 328 return (-1); 329 } 330 331 return (0); 332 } 333 334 /*ARGSUSED*/ 335 static void 336 print_sobj_help(int type, const char *name, const char *ops_name, void *ign) 337 { 338 mdb_printf(" %s", name); 339 } 340 341 /*ARGSUSED*/ 342 static void 343 print_tstate_help(uint_t state, const char *name, void *ignored) 344 { 345 mdb_printf(" %s", name); 346 } 347 348 void 349 stacks_help(void) 350 { 351 mdb_printf( 352 "::stacks processes all of the thread stacks on the system, grouping\n" 353 "together threads which have the same:\n" 354 "\n" 355 " * Thread state,\n" 356 " * Sync object type, and\n" 357 " * PCs in their stack trace.\n" 358 "\n" 359 "The default output (no address or options) is just a dump of the thread\n" 360 "groups in the system. For a view of active threads, use \"::stacks -i\",\n" 361 "which filters out FREE threads (interrupt threads which are currently\n" 362 "inactive) and threads sleeping on a CV. (Note that those threads may still\n" 363 "be noteworthy; this is just for a first glance.) More general filtering\n" 364 "options are described below, in the \"FILTERS\" section.\n" 365 "\n" 366 "::stacks can be used in a pipeline. The input to ::stacks is one or more\n" 367 "thread pointers. For example, to get a summary of threads in a process,\n" 368 "you can do:\n" 369 "\n" 370 " %<b>procp%</b>::walk thread | ::stacks\n" 371 "\n" 372 "When output into a pipe, ::stacks prints all of the threads input,\n" 373 "filtered by the given filtering options. This means that multiple\n" 374 "::stacks invocations can be piped together to achieve more complicated\n" 375 "filters. For example, to get threads which have both 'fop_read' and\n" 376 "'cv_wait_sig_swap' in their stack trace, you could do:\n" 377 "\n" 378 " ::stacks -c fop_read | ::stacks -c cv_wait_sig_swap_core\n" 379 "\n" 380 "To get the full list of threads in each group, use the '-a' flag:\n" 381 "\n" 382 " ::stacks -a\n" 383 "\n"); 384 mdb_dec_indent(2); 385 mdb_printf("%<b>OPTIONS%</b>\n"); 386 mdb_inc_indent(2); 387 mdb_printf("%s", 388 " -a Print all of the grouped threads, instead of just a count.\n" 389 " -f Force a re-run of the thread stack gathering.\n" 390 " -v Be verbose about thread stack gathering.\n" 391 "\n"); 392 mdb_dec_indent(2); 393 mdb_printf("%<b>FILTERS%</b>\n"); 394 mdb_inc_indent(2); 395 mdb_printf("%s", 396 " -i Show active threads; equivalent to '-S CV -T FREE'.\n" 397 " -c func[+offset]\n" 398 " Only print threads whose stacks contain func/func+offset.\n" 399 " -C func[+offset]\n" 400 " Only print threads whose stacks do not contain func/func+offset.\n" 401 " -m module\n" 402 " Only print threads whose stacks contain functions from module.\n" 403 " -M module\n" 404 " Only print threads whose stacks do not contain functions from\n" 405 " module.\n" 406 " -s {type | ALL}\n" 407 " Only print threads which are on a 'type' synchronization object\n" 408 " (SOBJ).\n" 409 " -S {type | ALL}\n" 410 " Only print threads which are not on a 'type' SOBJ.\n" 411 " -t tstate\n" 412 " Only print threads which are in thread state 'tstate'.\n" 413 " -T tstate\n" 414 " Only print threads which are not in thread state 'tstate'.\n" 415 "\n"); 416 mdb_printf(" SOBJ types:"); 417 sobj_type_walk(print_sobj_help, NULL); 418 mdb_printf("\n"); 419 mdb_printf("Thread states:"); 420 thread_walk_states(print_tstate_help, NULL); 421 mdb_printf(" panic\n"); 422 } 423