FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ktr.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2000 John Baldwin <jhb@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 /*
30 * This module holds the global variables used by KTR and the ktr_tracepoint()
31 * function that does the actual tracing.
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD: releng/12.0/sys/kern/kern_ktr.c 326271 2017-11-27 15:20:12Z pfg $");
36
37 #include "opt_ddb.h"
38 #include "opt_ktr.h"
39 #include "opt_alq.h"
40
41 #include <sys/param.h>
42 #include <sys/queue.h>
43 #include <sys/alq.h>
44 #include <sys/cons.h>
45 #include <sys/cpuset.h>
46 #include <sys/kdb.h>
47 #include <sys/kernel.h>
48 #include <sys/ktr.h>
49 #include <sys/libkern.h>
50 #include <sys/lock.h>
51 #include <sys/malloc.h>
52 #include <sys/mutex.h>
53 #include <sys/proc.h>
54 #include <sys/smp.h>
55 #include <sys/sysctl.h>
56 #include <sys/systm.h>
57 #include <sys/time.h>
58
59 #include <machine/cpu.h>
60
61 #ifdef DDB
62 #include <ddb/ddb.h>
63 #include <ddb/db_output.h>
64 #endif
65
66 #ifndef KTR_BOOT_ENTRIES
67 #define KTR_BOOT_ENTRIES 1024
68 #endif
69
70 #ifndef KTR_ENTRIES
71 #define KTR_ENTRIES 1024
72 #endif
73
74 /* Limit the allocations to something manageable. */
75 #define KTR_ENTRIES_MAX (8 * 1024 * 1024)
76
77 #ifndef KTR_MASK
78 #define KTR_MASK (0)
79 #endif
80
81 #ifndef KTR_CPUMASK
82 #define KTR_CPUMASK CPUSET_FSET
83 #endif
84
85 #ifndef KTR_TIME
86 #define KTR_TIME get_cyclecount()
87 #endif
88
89 #ifndef KTR_CPU
90 #define KTR_CPU PCPU_GET(cpuid)
91 #endif
92
93 static MALLOC_DEFINE(M_KTR, "KTR", "KTR");
94
95 FEATURE(ktr, "Kernel support for KTR kernel tracing facility");
96
97 volatile int ktr_idx = 0;
98 uint64_t ktr_mask = KTR_MASK;
99 uint64_t ktr_compile = KTR_COMPILE;
100 int ktr_entries = KTR_BOOT_ENTRIES;
101 int ktr_version = KTR_VERSION;
102 struct ktr_entry ktr_buf_init[KTR_BOOT_ENTRIES];
103 struct ktr_entry *ktr_buf = ktr_buf_init;
104 cpuset_t ktr_cpumask = CPUSET_T_INITIALIZER(KTR_CPUMASK);
105
106 static SYSCTL_NODE(_debug, OID_AUTO, ktr, CTLFLAG_RD, 0, "KTR options");
107
108 SYSCTL_INT(_debug_ktr, OID_AUTO, version, CTLFLAG_RD,
109 &ktr_version, 0, "Version of the KTR interface");
110
111 SYSCTL_UQUAD(_debug_ktr, OID_AUTO, compile, CTLFLAG_RD,
112 &ktr_compile, 0, "Bitmask of KTR event classes compiled into the kernel");
113
114 static int
115 sysctl_debug_ktr_cpumask(SYSCTL_HANDLER_ARGS)
116 {
117 char lktr_cpumask_str[CPUSETBUFSIZ];
118 cpuset_t imask;
119 int error;
120
121 cpusetobj_strprint(lktr_cpumask_str, &ktr_cpumask);
122 error = sysctl_handle_string(oidp, lktr_cpumask_str,
123 sizeof(lktr_cpumask_str), req);
124 if (error != 0 || req->newptr == NULL)
125 return (error);
126 if (cpusetobj_strscan(&imask, lktr_cpumask_str) == -1)
127 return (EINVAL);
128 CPU_COPY(&imask, &ktr_cpumask);
129
130 return (error);
131 }
132 SYSCTL_PROC(_debug_ktr, OID_AUTO, cpumask,
133 CTLFLAG_RWTUN | CTLFLAG_MPSAFE | CTLTYPE_STRING, NULL, 0,
134 sysctl_debug_ktr_cpumask, "S",
135 "Bitmask of CPUs on which KTR logging is enabled");
136
137 static int
138 sysctl_debug_ktr_clear(SYSCTL_HANDLER_ARGS)
139 {
140 int clear, error;
141
142 clear = 0;
143 error = sysctl_handle_int(oidp, &clear, 0, req);
144 if (error || !req->newptr)
145 return (error);
146
147 if (clear) {
148 bzero(ktr_buf, sizeof(*ktr_buf) * ktr_entries);
149 ktr_idx = 0;
150 }
151
152 return (error);
153 }
154 SYSCTL_PROC(_debug_ktr, OID_AUTO, clear, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
155 sysctl_debug_ktr_clear, "I", "Clear KTR Buffer");
156
157 /*
158 * This is a sysctl proc so that it is serialized as !MPSAFE along with
159 * the other ktr sysctl procs.
160 */
161 static int
162 sysctl_debug_ktr_mask(SYSCTL_HANDLER_ARGS)
163 {
164 uint64_t mask;
165 int error;
166
167 mask = ktr_mask;
168 error = sysctl_handle_64(oidp, &mask, 0, req);
169 if (error || !req->newptr)
170 return (error);
171 ktr_mask = mask;
172 return (error);
173 }
174
175 SYSCTL_PROC(_debug_ktr, OID_AUTO, mask, CTLTYPE_U64 | CTLFLAG_RWTUN, 0, 0,
176 sysctl_debug_ktr_mask, "QU",
177 "Bitmask of KTR event classes for which logging is enabled");
178
179 #if KTR_ENTRIES > KTR_BOOT_ENTRIES
180 /*
181 * A simplified version of sysctl_debug_ktr_entries.
182 * No need to care about SMP, scheduling, etc.
183 */
184 static void
185 ktr_entries_initializer(void *dummy __unused)
186 {
187 uint64_t mask;
188
189 /* Temporarily disable ktr in case malloc() is being traced. */
190 mask = ktr_mask;
191 ktr_mask = 0;
192 ktr_buf = malloc(sizeof(*ktr_buf) * KTR_ENTRIES, M_KTR,
193 M_WAITOK | M_ZERO);
194 memcpy(ktr_buf, ktr_buf_init + ktr_idx,
195 (KTR_BOOT_ENTRIES - ktr_idx) * sizeof(*ktr_buf));
196 if (ktr_idx != 0) {
197 memcpy(ktr_buf + KTR_BOOT_ENTRIES - ktr_idx, ktr_buf_init,
198 ktr_idx * sizeof(*ktr_buf));
199 ktr_idx = KTR_BOOT_ENTRIES;
200 }
201 ktr_entries = KTR_ENTRIES;
202 ktr_mask = mask;
203 }
204 SYSINIT(ktr_entries_initializer, SI_SUB_KMEM, SI_ORDER_ANY,
205 ktr_entries_initializer, NULL);
206 #endif
207
208 static int
209 sysctl_debug_ktr_entries(SYSCTL_HANDLER_ARGS)
210 {
211 uint64_t mask;
212 int entries, error;
213 struct ktr_entry *buf, *oldbuf;
214
215 entries = ktr_entries;
216 error = sysctl_handle_int(oidp, &entries, 0, req);
217 if (error || !req->newptr)
218 return (error);
219 if (entries > KTR_ENTRIES_MAX)
220 return (ERANGE);
221 /* Disable ktr temporarily. */
222 mask = ktr_mask;
223 ktr_mask = 0;
224 /* Wait for threads to go idle. */
225 if ((error = quiesce_all_cpus("ktrent", PCATCH)) != 0) {
226 ktr_mask = mask;
227 return (error);
228 }
229 if (ktr_buf != ktr_buf_init)
230 oldbuf = ktr_buf;
231 else
232 oldbuf = NULL;
233 /* Allocate a new buffer. */
234 buf = malloc(sizeof(*buf) * entries, M_KTR, M_WAITOK | M_ZERO);
235 /* Install the new buffer and restart ktr. */
236 ktr_buf = buf;
237 ktr_entries = entries;
238 ktr_idx = 0;
239 ktr_mask = mask;
240 if (oldbuf != NULL)
241 free(oldbuf, M_KTR);
242
243 return (error);
244 }
245
246 SYSCTL_PROC(_debug_ktr, OID_AUTO, entries, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
247 sysctl_debug_ktr_entries, "I", "Number of entries in the KTR buffer");
248
249 #ifdef KTR_VERBOSE
250 int ktr_verbose = KTR_VERBOSE;
251 TUNABLE_INT("debug.ktr.verbose", &ktr_verbose);
252 SYSCTL_INT(_debug_ktr, OID_AUTO, verbose, CTLFLAG_RW, &ktr_verbose, 0, "");
253 #endif
254
255 #ifdef KTR_ALQ
256 struct alq *ktr_alq;
257 char ktr_alq_file[MAXPATHLEN] = "/tmp/ktr.out";
258 int ktr_alq_cnt = 0;
259 int ktr_alq_depth = KTR_ENTRIES;
260 int ktr_alq_enabled = 0;
261 int ktr_alq_failed = 0;
262 int ktr_alq_max = 0;
263
264 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_max, CTLFLAG_RW, &ktr_alq_max, 0,
265 "Maximum number of entries to write");
266 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_cnt, CTLFLAG_RD, &ktr_alq_cnt, 0,
267 "Current number of written entries");
268 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_failed, CTLFLAG_RD, &ktr_alq_failed, 0,
269 "Number of times we overran the buffer");
270 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_depth, CTLFLAG_RW, &ktr_alq_depth, 0,
271 "Number of items in the write buffer");
272 SYSCTL_STRING(_debug_ktr, OID_AUTO, alq_file, CTLFLAG_RW, ktr_alq_file,
273 sizeof(ktr_alq_file), "KTR logging file");
274
275 static int
276 sysctl_debug_ktr_alq_enable(SYSCTL_HANDLER_ARGS)
277 {
278 int error;
279 int enable;
280
281 enable = ktr_alq_enabled;
282
283 error = sysctl_handle_int(oidp, &enable, 0, req);
284 if (error || !req->newptr)
285 return (error);
286
287 if (enable) {
288 if (ktr_alq_enabled)
289 return (0);
290 error = alq_open(&ktr_alq, (const char *)ktr_alq_file,
291 req->td->td_ucred, ALQ_DEFAULT_CMODE,
292 sizeof(struct ktr_entry), ktr_alq_depth);
293 if (error == 0) {
294 ktr_alq_cnt = 0;
295 ktr_alq_failed = 0;
296 ktr_alq_enabled = 1;
297 }
298 } else {
299 if (ktr_alq_enabled == 0)
300 return (0);
301 ktr_alq_enabled = 0;
302 alq_close(ktr_alq);
303 ktr_alq = NULL;
304 }
305
306 return (error);
307 }
308 SYSCTL_PROC(_debug_ktr, OID_AUTO, alq_enable,
309 CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_debug_ktr_alq_enable,
310 "I", "Enable KTR logging");
311 #endif
312
313 void
314 ktr_tracepoint(uint64_t mask, const char *file, int line, const char *format,
315 u_long arg1, u_long arg2, u_long arg3, u_long arg4, u_long arg5,
316 u_long arg6)
317 {
318 struct ktr_entry *entry;
319 #ifdef KTR_ALQ
320 struct ale *ale = NULL;
321 #endif
322 int newindex, saveindex;
323 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
324 struct thread *td;
325 #endif
326 int cpu;
327
328 if (panicstr || kdb_active)
329 return;
330 if ((ktr_mask & mask) == 0 || ktr_buf == NULL)
331 return;
332 cpu = KTR_CPU;
333 if (!CPU_ISSET(cpu, &ktr_cpumask))
334 return;
335 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
336 td = curthread;
337 if (td->td_pflags & TDP_INKTR)
338 return;
339 td->td_pflags |= TDP_INKTR;
340 #endif
341 #ifdef KTR_ALQ
342 if (ktr_alq_enabled) {
343 if (td->td_critnest == 0 &&
344 (td->td_flags & TDF_IDLETD) == 0 &&
345 td != ald_thread) {
346 if (ktr_alq_max && ktr_alq_cnt > ktr_alq_max)
347 goto done;
348 if ((ale = alq_get(ktr_alq, ALQ_NOWAIT)) == NULL) {
349 ktr_alq_failed++;
350 goto done;
351 }
352 ktr_alq_cnt++;
353 entry = (struct ktr_entry *)ale->ae_data;
354 } else {
355 goto done;
356 }
357 } else
358 #endif
359 {
360 do {
361 saveindex = ktr_idx;
362 newindex = (saveindex + 1) % ktr_entries;
363 } while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex) == 0);
364 entry = &ktr_buf[saveindex];
365 }
366 entry->ktr_timestamp = KTR_TIME;
367 entry->ktr_cpu = cpu;
368 entry->ktr_thread = curthread;
369 if (file != NULL)
370 while (strncmp(file, "../", 3) == 0)
371 file += 3;
372 entry->ktr_file = file;
373 entry->ktr_line = line;
374 #ifdef KTR_VERBOSE
375 if (ktr_verbose) {
376 #ifdef SMP
377 printf("cpu%d ", cpu);
378 #endif
379 if (ktr_verbose > 1) {
380 printf("%s.%d\t", entry->ktr_file,
381 entry->ktr_line);
382 }
383 printf(format, arg1, arg2, arg3, arg4, arg5, arg6);
384 printf("\n");
385 }
386 #endif
387 entry->ktr_desc = format;
388 entry->ktr_parms[0] = arg1;
389 entry->ktr_parms[1] = arg2;
390 entry->ktr_parms[2] = arg3;
391 entry->ktr_parms[3] = arg4;
392 entry->ktr_parms[4] = arg5;
393 entry->ktr_parms[5] = arg6;
394 #ifdef KTR_ALQ
395 if (ktr_alq_enabled && ale)
396 alq_post(ktr_alq, ale);
397 done:
398 #endif
399 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
400 td->td_pflags &= ~TDP_INKTR;
401 #endif
402 }
403
404 #ifdef DDB
405
406 struct tstate {
407 int cur;
408 int first;
409 };
410 static struct tstate tstate;
411 static int db_ktr_verbose;
412 static int db_mach_vtrace(void);
413
414 DB_SHOW_COMMAND(ktr, db_ktr_all)
415 {
416
417 tstate.cur = (ktr_idx - 1) % ktr_entries;
418 tstate.first = -1;
419 db_ktr_verbose = 0;
420 db_ktr_verbose |= (strchr(modif, 'v') != NULL) ? 2 : 0;
421 db_ktr_verbose |= (strchr(modif, 'V') != NULL) ? 1 : 0; /* just timestamp please */
422 if (strchr(modif, 'a') != NULL) {
423 db_disable_pager();
424 while (cncheckc() == -1)
425 if (db_mach_vtrace() == 0)
426 break;
427 } else {
428 while (!db_pager_quit)
429 if (db_mach_vtrace() == 0)
430 break;
431 }
432 }
433
434 static int
435 db_mach_vtrace(void)
436 {
437 struct ktr_entry *kp;
438
439 if (tstate.cur == tstate.first || ktr_buf == NULL) {
440 db_printf("--- End of trace buffer ---\n");
441 return (0);
442 }
443 kp = &ktr_buf[tstate.cur];
444
445 /* Skip over unused entries. */
446 if (kp->ktr_desc == NULL) {
447 db_printf("--- End of trace buffer ---\n");
448 return (0);
449 }
450 db_printf("%d (%p", tstate.cur, kp->ktr_thread);
451 #ifdef SMP
452 db_printf(":cpu%d", kp->ktr_cpu);
453 #endif
454 db_printf(")");
455 if (db_ktr_verbose >= 1) {
456 db_printf(" %10.10lld", (long long)kp->ktr_timestamp);
457 }
458 if (db_ktr_verbose >= 2) {
459 db_printf(" %s.%d", kp->ktr_file, kp->ktr_line);
460 }
461 db_printf(": ");
462 db_printf(kp->ktr_desc, kp->ktr_parms[0], kp->ktr_parms[1],
463 kp->ktr_parms[2], kp->ktr_parms[3], kp->ktr_parms[4],
464 kp->ktr_parms[5]);
465 db_printf("\n");
466
467 if (tstate.first == -1)
468 tstate.first = tstate.cur;
469
470 if (--tstate.cur < 0)
471 tstate.cur = ktr_entries - 1;
472
473 return (1);
474 }
475
476 #endif /* DDB */
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