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