xref: /titanic_41/usr/src/cmd/mdb/common/modules/genunix/findstack_subr.c (revision 28e4da25922bdfc5cba7ab29f47de911bbd78009)
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