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 = NULL; 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_stk < thr.t_stkbase) { 167 if (print_warnings) 168 mdb_warn( 169 "stack base or stack top corrupt for thread %p\n", 170 addr); 171 fsip->fsi_failed = FSI_FAIL_THREADCORRUPT; 172 return (DCMD_ERR); 173 } 174 175 kbase = (uintptr_t)thr.t_stkbase; 176 ktop = (uintptr_t)thr.t_stk; 177 stksz = ktop - kbase; 178 179 #ifdef __amd64 180 /* 181 * The stack on amd64 is intentionally misaligned, so ignore the top 182 * half-frame. See thread_stk_init(). When handling traps, the frame 183 * is automatically aligned by the hardware, so we only alter ktop if 184 * needed. 185 */ 186 if ((ktop & (STACK_ALIGN - 1)) != 0) 187 ktop -= STACK_ENTRY_ALIGN; 188 #endif 189 190 /* 191 * If the stack size is larger than a meg, assume that it's bogus. 192 */ 193 if (stksz > TOO_BIG_FOR_A_STACK) { 194 if (print_warnings) 195 mdb_warn("stack size for thread %p is too big to be " 196 "reasonable\n", addr); 197 fsip->fsi_failed = FSI_FAIL_THREADCORRUPT; 198 return (DCMD_ERR); 199 } 200 201 /* 202 * This could be (and was) a UM_GC allocation. Unfortunately, 203 * stksz tends to be very large. As currently implemented, dcmds 204 * invoked as part of pipelines don't have their UM_GC-allocated 205 * memory freed until the pipeline completes. With stksz in the 206 * neighborhood of 20k, the popular ::walk thread |::findstack 207 * pipeline can easily run memory-constrained debuggers (kmdb) out 208 * of memory. This can be changed back to a gc-able allocation when 209 * the debugger is changed to free UM_GC memory more promptly. 210 */ 211 ubase = (uintptr_t)mdb_alloc(stksz, UM_SLEEP); 212 utop = ubase + stksz; 213 if (mdb_vread((caddr_t)ubase, stksz, kbase) != stksz) { 214 mdb_free((void *)ubase, stksz); 215 if (print_warnings) 216 mdb_warn("couldn't read entire stack for thread %p\n", 217 addr); 218 fsip->fsi_failed = FSI_FAIL_THREADCORRUPT; 219 return (DCMD_ERR); 220 } 221 222 /* 223 * Try the saved %sp first, if it looks reasonable. 224 */ 225 sp = KTOU((uintptr_t)thr.t_sp + STACK_BIAS); 226 if (sp >= ubase && sp <= utop) { 227 if (crawl(sp, kbase, ktop, ubase, 0, fsip) == CRAWL_FOUNDALL) { 228 fsip->fsi_sp = (uintptr_t)thr.t_sp; 229 #if !defined(__i386) 230 fsip->fsi_pc = (uintptr_t)thr.t_pc; 231 #endif 232 goto found; 233 } 234 } 235 236 /* 237 * Now walk through the whole stack, starting at the base, 238 * trying every possible "window". 239 */ 240 for (win = ubase; 241 win + sizeof (struct rwindow) <= utop; 242 win += sizeof (struct rwindow *)) { 243 if (crawl(win, kbase, ktop, ubase, 1, fsip) == CRAWL_FOUNDALL) { 244 fsip->fsi_sp = UTOK(win) - STACK_BIAS; 245 goto found; 246 } 247 } 248 249 /* 250 * We didn't conclusively find the stack. So we'll take another lap, 251 * and print out anything that looks possible. 252 */ 253 if (print_warnings) 254 mdb_printf("Possible stack pointers for thread %p:\n", addr); 255 (void) mdb_vread((caddr_t)ubase, stksz, kbase); 256 257 for (win = ubase; 258 win + sizeof (struct rwindow) <= utop; 259 win += sizeof (struct rwindow *)) { 260 uintptr_t fp = ((struct rwindow *)win)->rw_fp; 261 int levels; 262 263 if ((levels = crawl(win, kbase, ktop, ubase, 1, fsip)) > 1) { 264 if (print_warnings) 265 mdb_printf(" %p (%d)\n", fp, levels); 266 } else if (levels == CRAWL_FOUNDALL) { 267 /* 268 * If this is a live system, the stack could change 269 * between the two mdb_vread(ubase, utop, kbase)'s, 270 * and we could have a fully valid stack here. 271 */ 272 fsip->fsi_sp = UTOK(win) - STACK_BIAS; 273 goto found; 274 } 275 } 276 277 fsip->fsi_depth = 0; 278 fsip->fsi_overflow = 0; 279 fsip->fsi_failed = FSI_FAIL_STACKNOTFOUND; 280 281 mdb_free((void *)ubase, stksz); 282 return (DCMD_ERR); 283 found: 284 mdb_free((void *)ubase, stksz); 285 return (DCMD_OK); 286 } 287 288 void 289 stacks_findstack_cleanup() 290 {} 291 292 /*ARGSUSED*/ 293 int 294 stacks_module_cb(uintptr_t addr, const modctl_t *mp, stacks_module_t *smp) 295 { 296 char mod_modname[MODMAXNAMELEN + 1]; 297 298 if (!mp->mod_modname) 299 return (WALK_NEXT); 300 301 if (mdb_readstr(mod_modname, sizeof (mod_modname), 302 (uintptr_t)mp->mod_modname) == -1) { 303 mdb_warn("failed to read mod_modname in \"modctl\" walk"); 304 return (WALK_ERR); 305 } 306 307 if (strcmp(smp->sm_name, mod_modname)) 308 return (WALK_NEXT); 309 310 smp->sm_text = (uintptr_t)mp->mod_text; 311 smp->sm_size = mp->mod_text_size; 312 313 return (WALK_DONE); 314 } 315 316 int 317 stacks_module(stacks_module_t *smp) 318 { 319 if (mdb_walk("modctl", (mdb_walk_cb_t)stacks_module_cb, smp) != 0) { 320 mdb_warn("cannot walk \"modctl\""); 321 return (-1); 322 } 323 324 return (0); 325 } 326 327 /*ARGSUSED*/ 328 static void 329 print_sobj_help(int type, const char *name, const char *ops_name, void *ign) 330 { 331 mdb_printf(" %s", name); 332 } 333 334 /*ARGSUSED*/ 335 static void 336 print_tstate_help(uint_t state, const char *name, void *ignored) 337 { 338 mdb_printf(" %s", name); 339 } 340 341 void 342 stacks_help(void) 343 { 344 mdb_printf( 345 "::stacks processes all of the thread stacks on the system, grouping\n" 346 "together threads which have the same:\n" 347 "\n" 348 " * Thread state,\n" 349 " * Sync object type, and\n" 350 " * PCs in their stack trace.\n" 351 "\n" 352 "The default output (no address or options) is just a dump of the thread\n" 353 "groups in the system. For a view of active threads, use \"::stacks -i\",\n" 354 "which filters out FREE threads (interrupt threads which are currently\n" 355 "inactive) and threads sleeping on a CV. (Note that those threads may still\n" 356 "be noteworthy; this is just for a first glance.) More general filtering\n" 357 "options are described below, in the \"FILTERS\" section.\n" 358 "\n" 359 "::stacks can be used in a pipeline. The input to ::stacks is one or more\n" 360 "thread pointers. For example, to get a summary of threads in a process,\n" 361 "you can do:\n" 362 "\n" 363 " %<b>procp%</b>::walk thread | ::stacks\n" 364 "\n" 365 "When output into a pipe, ::stacks prints all of the threads input,\n" 366 "filtered by the given filtering options. This means that multiple\n" 367 "::stacks invocations can be piped together to achieve more complicated\n" 368 "filters. For example, to get threads which have both 'fop_read' and\n" 369 "'cv_wait_sig_swap' in their stack trace, you could do:\n" 370 "\n" 371 " ::stacks -c fop_read | ::stacks -c cv_wait_sig_swap_core\n" 372 "\n" 373 "To get the full list of threads in each group, use the '-a' flag:\n" 374 "\n" 375 " ::stacks -a\n" 376 "\n"); 377 mdb_dec_indent(2); 378 mdb_printf("%<b>OPTIONS%</b>\n"); 379 mdb_inc_indent(2); 380 mdb_printf("%s", 381 " -a Print all of the grouped threads, instead of just a count.\n" 382 " -f Force a re-run of the thread stack gathering.\n" 383 " -v Be verbose about thread stack gathering.\n" 384 "\n"); 385 mdb_dec_indent(2); 386 mdb_printf("%<b>FILTERS%</b>\n"); 387 mdb_inc_indent(2); 388 mdb_printf("%s", 389 " -i Show active threads; equivalent to '-S CV -T FREE'.\n" 390 " -c func[+offset]\n" 391 " Only print threads whose stacks contain func/func+offset.\n" 392 " -C func[+offset]\n" 393 " Only print threads whose stacks do not contain func/func+offset.\n" 394 " -m module\n" 395 " Only print threads whose stacks contain functions from module.\n" 396 " -M module\n" 397 " Only print threads whose stacks do not contain functions from\n" 398 " module.\n" 399 " -s {type | ALL}\n" 400 " Only print threads which are on a 'type' synchronization object\n" 401 " (SOBJ).\n" 402 " -S {type | ALL}\n" 403 " Only print threads which are not on a 'type' SOBJ.\n" 404 " -t tstate\n" 405 " Only print threads which are in thread state 'tstate'.\n" 406 " -T tstate\n" 407 " Only print threads which are not in thread state 'tstate'.\n" 408 "\n"); 409 mdb_printf(" SOBJ types:"); 410 sobj_type_walk(print_sobj_help, NULL); 411 mdb_printf("\n"); 412 mdb_printf("Thread states:"); 413 thread_walk_states(print_tstate_help, NULL); 414 mdb_printf(" panic\n"); 415 }