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
crawl(uintptr_t frame,uintptr_t kbase,uintptr_t ktop,uintptr_t ubase,int kill_fp,findstack_info_t * fsip)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
stacks_findstack(uintptr_t addr,findstack_info_t * fsip,uint_t print_warnings)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
stacks_findstack_cleanup()296 stacks_findstack_cleanup()
297 {}
298
299 /*ARGSUSED*/
300 int
stacks_module_cb(uintptr_t addr,const modctl_t * mp,stacks_module_t * smp)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
stacks_module(stacks_module_t * smp)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
print_sobj_help(int type,const char * name,const char * ops_name,void * ign)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
print_tstate_help(uint_t state,const char * name,void * ignored)343 print_tstate_help(uint_t state, const char *name, void *ignored)
344 {
345 mdb_printf(" %s", name);
346 }
347
348 void
stacks_help(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