usr.bin/ktrdump/ktrdump.c

   1 /*-
   2  * Copyright (c) 2002 Jake Burkholder
   3  * Copyright (c) 2004 Robert Watson
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  *
  27  * $FreeBSD: src/usr.bin/ktrdump/ktrdump.c,v 1.10 2005/05/21 09:55:06 ru Exp $
  28  * $DragonFly: src/usr.bin/ktrdump/ktrdump.c,v 1.9 2007/06/08 18:46:32 swildner Exp $
  29  */
  30
  31 #include <sys/cdefs.h>
  32
  33 #include <sys/types.h>
  34 #include <sys/ktr.h>
  35 #include <sys/mman.h>
  36 #include <sys/stat.h>
  37 #include <sys/queue.h>
  38
  39 #include <err.h>
  40 #include <fcntl.h>
  41 #include <kvm.h>
  42 #include <limits.h>
  43 #include <nlist.h>
  44 #include <stdint.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49
  50 #define SBUFLEN 128
  51
  52 extern char *optarg;
  53 extern int optind;
  54
  55 struct ktr_buffer {
  56         struct ktr_entry *ents;
  57         int modified;
  58         int reset;
  59         int beg_idx;            /* Beginning index */
  60         int end_idx;            /* Ending index */
  61 };
  62
  63 static struct nlist nl[] = {
  64         { "_ktr_version" },
  65         { "_ktr_entries" },
  66         { "_ktr_idx" },
  67         { "_ktr_buf" },
  68         { "_ncpus" },
  69         { "_tsc_frequency" },
  70         { NULL }
  71 };
  72
  73 static int cflag;
  74 static int fflag;
  75 static int iflag;
  76 static int lflag;
  77 static int nflag;
  78 static int qflag;
  79 static int rflag;
  80 static int sflag;
  81 static int tflag;
  82 static int xflag;
  83 static int pflag;
  84 static int Mflag;
  85 static int Nflag;
  86 static double tsc_frequency;
  87 static double correction_factor = 0.0;
  88
  89 static char corefile[PATH_MAX];
  90 static char execfile[PATH_MAX];
  91
  92 static char errbuf[_POSIX2_LINE_MAX];
  93 static int ncpus;
  94 static kvm_t *kd;
  95 static int entries_per_buf;
  96 static int fifo_mask;
  97
  98 static void usage(void);
  99 static int earliest_ts(struct ktr_buffer *buf);
 100 static void print_header(FILE *fo, int row);
 101 static void print_entry(FILE *fo, kvm_t *kd, int n, int i, struct ktr_entry *entry, u_int64_t *last_timestamp);
 102 static struct ktr_info *kvm_ktrinfo(kvm_t *kd, void *kptr);
 103 static const char *kvm_string(kvm_t *kd, const char *kptr);
 104 static const char *trunc_path(const char *str, int maxlen);
 105 static void read_symbols(const char *execfile);
 106 static const char *address_to_symbol(void *kptr);
 107 static struct ktr_buffer *ktr_bufs_init(int);
 108 static void load_bufs(struct ktr_buffer *, struct ktr_entry **);
 109 static void print_buf(FILE *, struct ktr_buffer *, int, u_int64_t *);
 110 static void print_bufs_timesorted(FILE *, struct ktr_buffer *, u_int64_t *);
 111
 112
 113 /*
 114  * Reads the ktr trace buffer from kernel memory and prints the trace entries.
 115  */
 116 int
 117 main(int ac, char **av)
 118 {
 119         struct ktr_buffer *ktr_bufs;
 120         struct ktr_entry **ktr_kbuf;
 121         FILE *fo;
 122         int64_t tts;
 123         int *ktr_start_index;
 124         int version;
 125         int c;
 126         int n;
 127
 128         /*
 129          * Parse commandline arguments.
 130          */
 131         fo = stdout;
 132         while ((c = getopt(ac, av, "acfinqrtxpslA:N:M:o:")) != -1) {
 133                 switch (c) {
 134                 case 'a':
 135                         cflag = 1;
 136                         iflag = 1;
 137                         rflag = 1;
 138                         xflag = 1;
 139                         pflag = 1;
 140                         rflag = 1;
 141                         sflag = 1;
 142                         break;
 143                 case 'c':
 144                         cflag = 1;
 145                         break;
 146                 case 'N':
 147                         if (strlcpy(execfile, optarg, sizeof(execfile))
 148                             >= sizeof(execfile))
 149                                 errx(1, "%s: File name too long", optarg);
 150                         Nflag = 1;
 151                         break;
 152                 case 'f':
 153                         fflag = 1;
 154                         break;
 155                 case 'l':
 156                         lflag = 1;
 157                         break;
 158                 case 'i':
 159                         iflag = 1;
 160                         break;
 161                 case 'A':
 162                         correction_factor = strtod(optarg, NULL);
 163                         break;
 164                 case 'M':
 165                         if (strlcpy(corefile, optarg, sizeof(corefile))
 166                             >= sizeof(corefile))
 167                                 errx(1, "%s: File name too long", optarg);
 168                         Mflag = 1;
 169                         break;
 170                 case 'n':
 171                         nflag = 1;
 172                         break;
 173                 case 'o':
 174                         if ((fo = fopen(optarg, "w")) == NULL)
 175                                 err(1, "%s", optarg);
 176                         break;
 177                 case 'p':
 178                         pflag++;
 179                         break;
 180                 case 'q':
 181                         qflag++;
 182                         break;
 183                 case 'r':
 184                         rflag = 1;
 185                         break;
 186                 case 's':
 187                         sflag = 1;      /* sort across the cpus */
 188                         break;
 189                 case 't':
 190                         tflag = 1;
 191                         break;
 192                 case 'x':
 193                         xflag = 1;
 194                         break;
 195                 case '?':
 196                 default:
 197                         usage();
 198                 }
 199         }
 200         if (cflag + iflag + tflag + xflag + fflag + pflag == 0) {
 201                 cflag = 1;
 202                 iflag = 1;
 203                 tflag = 1;
 204                 pflag = 1;
 205         }
 206         if (correction_factor != 0.0 && (rflag == 0 || nflag)) {
 207                 fprintf(stderr, "Correction factor can only be applied with -r and without -n\n");
 208                 exit(1);
 209         }
 210         ac -= optind;
 211         av += optind;
 212         if (ac != 0)
 213                 usage();
 214
 215         /*
 216          * Open our execfile and corefile, resolve needed symbols and read in
 217          * the trace buffer.
 218          */
 219         if ((kd = kvm_openfiles(Nflag ? execfile : NULL,
 220             Mflag ? corefile : NULL, NULL, O_RDONLY, errbuf)) == NULL)
 221                 errx(1, "%s", errbuf);
 222         if (kvm_nlist(kd, nl) != 0)
 223                 errx(1, "%s", kvm_geterr(kd));
 224         if (kvm_read(kd, nl[0].n_value, &version, sizeof(version)) == -1)
 225                 errx(1, "%s", kvm_geterr(kd));
 226         if (kvm_read(kd, nl[4].n_value, &ncpus, sizeof(ncpus)) == -1)
 227                 errx(1, "%s", kvm_geterr(kd));
 228         ktr_start_index = malloc(sizeof(*ktr_start_index) * ncpus);
 229         if (version >= 3) {
 230                 if (kvm_read(kd, nl[5].n_value, &tts, sizeof(tts)) == -1)
 231                         errx(1, "%s", kvm_geterr(kd));
 232                 tsc_frequency = (double)tts;
 233         }
 234         if (version > KTR_VERSION)
 235                 errx(1, "ktr version too high for us to handle");
 236         if (kvm_read(kd, nl[1].n_value, &entries_per_buf,
 237                                 sizeof(entries_per_buf)) == -1)
 238                 errx(1, "%s", kvm_geterr(kd));
 239         fifo_mask = entries_per_buf - 1;
 240
 241         printf("TSC frequency is %6.3f MHz\n", tsc_frequency / 1000000.0);
 242
 243         ktr_kbuf = malloc(sizeof(*ktr_kbuf) * ncpus);
 244
 245         if (nflag == 0)
 246                 read_symbols(Nflag ? execfile : NULL);
 247
 248         if (kvm_read(kd, nl[3].n_value, ktr_kbuf, sizeof(*ktr_kbuf) * ncpus) == -1)
 249                 errx(1, "%s", kvm_geterr(kd));
 250
 251         ktr_bufs = ktr_bufs_init(ncpus);
 252
 253         if (sflag) {
 254                 u_int64_t last_timestamp = 0;
 255                 do {
 256                         load_bufs(ktr_bufs, ktr_kbuf);
 257                         print_bufs_timesorted(fo, ktr_bufs, &last_timestamp);
 258                         if (lflag)
 259                                 usleep(1000000 / 10);
 260                 } while (lflag);
 261         } else {
 262                 u_int64_t *last_timestamp = calloc(sizeof(u_int64_t), ncpus);
 263                 do {
 264                         load_bufs(ktr_bufs, ktr_kbuf);
 265                         for (n = 0; n < ncpus; ++n)
 266                                 print_buf(fo, ktr_bufs, n, &last_timestamp[n]);
 267                         if (lflag)
 268                                 usleep(1000000 / 10);
 269                 } while (lflag);
 270         }
 271         return (0);
 272 }
 273
 274 static void
 275 print_header(FILE *fo, int row)
 276 {
 277         if (qflag == 0 && (u_int32_t)row % 20 == 0) {
 278                 fprintf(fo, "%-6s ", "index");
 279                 if (cflag)
 280                         fprintf(fo, "%-3s ", "cpu");
 281                 if (tflag || rflag)
 282                         fprintf(fo, "%-16s ", "timestamp");
 283                 if (xflag) {
 284                         if (nflag)
 285                             fprintf(fo, "%-10s %-10s", "caller2", "caller1");
 286                         else
 287                             fprintf(fo, "%-20s %-20s", "caller2", "caller1");
 288                 }
 289                 if (iflag)
 290                         fprintf(fo, "%-20s ", "ID");
 291                 if (fflag)
 292                         fprintf(fo, "%10s%-30s ", "", "file and line");
 293                 if (pflag)
 294                         fprintf(fo, "%s", "trace");
 295                 fprintf(fo, "\n");
 296         }
 297 }
 298
 299 static void
 300 print_entry(FILE *fo, kvm_t *kd, int n, int row, struct ktr_entry *entry,
 301             u_int64_t *last_timestamp)
 302 {
 303         struct ktr_info *info = NULL;
 304
 305         fprintf(fo, " %06x ", row & 0x00FFFFFF);
 306         if (cflag)
 307                 fprintf(fo, "%-3d ", n);
 308         if (tflag || rflag) {
 309                 if (rflag && !nflag && tsc_frequency != 0.0) {
 310                         fprintf(fo, "%13.3f uS ",
 311                                 (double)(entry->ktr_timestamp - *last_timestamp) * 1000000.0 / tsc_frequency - correction_factor);
 312                 } else if (rflag) {
 313                         fprintf(fo, "%-16lld ", entry->ktr_timestamp -
 314                                                 *last_timestamp);
 315                 } else {
 316                         fprintf(fo, "%-16lld ", entry->ktr_timestamp);
 317                 }
 318         }
 319         if (xflag) {
 320                 if (nflag) {
 321                     fprintf(fo, "%p %p ",
 322                             entry->ktr_caller2, entry->ktr_caller1);
 323                 } else {
 324                     fprintf(fo, "%-20s ",
 325                             address_to_symbol(entry->ktr_caller2));
 326                     fprintf(fo, "%-20s ",
 327                             address_to_symbol(entry->ktr_caller1));
 328                 }
 329         }
 330         if (iflag) {
 331                 info = kvm_ktrinfo(kd, entry->ktr_info);
 332                 if (info)
 333                         fprintf(fo, "%-20s ", kvm_string(kd, info->kf_name));
 334                 else
 335                         fprintf(fo, "%-20s ", "<empty>");
 336         }
 337         if (fflag)
 338                 fprintf(fo, "%34s:%-4d ", trunc_path(kvm_string(kd, entry->ktr_file), 34), entry->ktr_line);
 339         if (pflag) {
 340                 if (info == NULL)
 341                         info = kvm_ktrinfo(kd, entry->ktr_info);
 342                 if (info) {
 343                         fprintf(fo, kvm_string(kd, info->kf_format),
 344                                 entry->ktr_data[0], entry->ktr_data[1],
 345                                 entry->ktr_data[2], entry->ktr_data[3],
 346                                 entry->ktr_data[4], entry->ktr_data[5],
 347                                 entry->ktr_data[6], entry->ktr_data[7],
 348                                 entry->ktr_data[8], entry->ktr_data[9]);
 349                 } else {
 350                         fprintf(fo, "");
 351                 }
 352         }
 353         fprintf(fo, "\n");
 354         *last_timestamp = entry->ktr_timestamp;
 355 }
 356
 357 static
 358 struct ktr_info *
 359 kvm_ktrinfo(kvm_t *kd, void *kptr)
 360 {
 361         static struct ktr_info save_info;
 362         static void *save_kptr;
 363
 364         if (kptr == NULL)
 365                 return(NULL);
 366         if (save_kptr != kptr) {
 367                 if (kvm_read(kd, (uintptr_t)kptr, &save_info, sizeof(save_info)) == -1) {
 368                         bzero(&save_info, sizeof(save_info));
 369                 } else {
 370                         save_kptr = kptr;
 371                 }
 372         }
 373         return(&save_info);
 374 }
 375
 376 static
 377 const char *
 378 kvm_string(kvm_t *kd, const char *kptr)
 379 {
 380         static char save_str[128];
 381         static const char *save_kptr;
 382         int l;
 383         int n;
 384
 385         if (kptr == NULL)
 386                 return("?");
 387         if (save_kptr != kptr) {
 388                 save_kptr = kptr;
 389                 l = 0;
 390                 while (l < sizeof(save_str) - 1) {
 391                         n = 256 - ((intptr_t)(kptr + l) & 255);
 392                         if (n > sizeof(save_str) - l - 1)
 393                                 n = sizeof(save_str) - l - 1;
 394                         if (kvm_read(kd, (uintptr_t)(kptr + l), save_str + l, n) < 0)
 395                                 break;
 396                         while (l < sizeof(save_str) && n) {
 397                             if (save_str[l] == 0)
 398                                     break;
 399                             --n;
 400                             ++l;
 401                         }
 402                         if (n)
 403                             break;
 404                 }
 405                 save_str[l] = 0;
 406         }
 407         return(save_str);
 408 }
 409
 410 static
 411 const char *
 412 trunc_path(const char *str, int maxlen)
 413 {
 414         int len = strlen(str);
 415
 416         if (len > maxlen)
 417                 return(str + len - maxlen);
 418         else
 419                 return(str);
 420 }
 421
 422 struct symdata {
 423         TAILQ_ENTRY(symdata) link;
 424         const char *symname;
 425         char *symaddr;
 426         char symtype;
 427 };
 428
 429 static TAILQ_HEAD(symlist, symdata) symlist;
 430 static struct symdata *symcache;
 431 static char *symbegin;
 432 static char *symend;
 433
 434 static
 435 void
 436 read_symbols(const char *execfile)
 437 {
 438         char buf[256];
 439         char cmd[256];
 440         int buflen = sizeof(buf);
 441         FILE *fp;
 442         struct symdata *sym;
 443         char *s1;
 444         char *s2;
 445         char *s3;
 446
 447         TAILQ_INIT(&symlist);
 448
 449         if (execfile == NULL) {
 450                 if (sysctlbyname("kern.bootfile", buf, &buflen, NULL, 0) < 0)
 451                         execfile = "/kernel";
 452                 else
 453                         execfile = buf;
 454         }
 455         snprintf(cmd, sizeof(cmd), "nm -n %s", execfile);
 456         if ((fp = popen(cmd, "r")) != NULL) {
 457                 while (fgets(buf, sizeof(buf), fp) != NULL) {
 458                     s1 = strtok(buf, " \t\n");
 459                     s2 = strtok(NULL, " \t\n");
 460                     s3 = strtok(NULL, " \t\n");
 461                     if (s1 && s2 && s3) {
 462                         sym = malloc(sizeof(struct symdata));
 463                         sym->symaddr = (char *)strtoul(s1, NULL, 16);
 464                         sym->symtype = s2[0];
 465                         sym->symname = strdup(s3);
 466                         if (strcmp(s3, "kernbase") == 0)
 467                                 symbegin = sym->symaddr;
 468                         if (strcmp(s3, "end") == 0)
 469                                 symend = sym->symaddr;
 470                         TAILQ_INSERT_TAIL(&symlist, sym, link);
 471                     }
 472                 }
 473                 pclose(fp);
 474         }
 475         symcache = TAILQ_FIRST(&symlist);
 476 }
 477
 478 static
 479 const char *
 480 address_to_symbol(void *kptr)
 481 {
 482         static char buf[64];
 483
 484         if (symcache == NULL ||
 485            (char *)kptr < symbegin || (char *)kptr >= symend
 486         ) {
 487                 snprintf(buf, sizeof(buf), "%p", kptr);
 488                 return(buf);
 489         }
 490         while ((char *)symcache->symaddr < (char *)kptr) {
 491                 if (TAILQ_NEXT(symcache, link) == NULL)
 492                         break;
 493                 symcache = TAILQ_NEXT(symcache, link);
 494         }
 495         while ((char *)symcache->symaddr > (char *)kptr) {
 496                 if (symcache != TAILQ_FIRST(&symlist))
 497                         symcache = TAILQ_PREV(symcache, symlist, link);
 498         }
 499         snprintf(buf, sizeof(buf), "%s+%d", symcache->symname,
 500                 (int)((char *)kptr - symcache->symaddr));
 501         return(buf);
 502 }
 503
 504 static
 505 struct ktr_buffer *
 506 ktr_bufs_init(int ncpus)
 507 {
 508         struct ktr_buffer *ktr_bufs, *it;
 509         int i;
 510
 511         ktr_bufs = malloc(sizeof(*ktr_bufs) * ncpus);
 512         if (!ktr_bufs)
 513                 err(1, "can't allocate data structures\n");
 514         for (i = 0; i < ncpus; ++i) {
 515                 it = ktr_bufs + i;
 516                 it->ents = malloc(sizeof(struct ktr_entry) * entries_per_buf);
 517                 if (it->ents == NULL)
 518                         err(1, "can't allocate data structures\n");
 519                 it->reset = 1;
 520                 it->beg_idx = -1;
 521                 it->end_idx = -1;
 522         }
 523         return ktr_bufs;
 524 }
 525
 526 static
 527 void
 528 get_indices(kvm_t *kd, int *idx)
 529 {
 530         if (kvm_read(kd, nl[2].n_value, idx, sizeof(*idx) * ncpus) == -1)
 531                 errx(1, "%s", kvm_geterr(kd));
 532 }
 533
 534 /*
 535  * Get the trace buffer data from the kernel
 536  */
 537 static
 538 void
 539 load_bufs(struct ktr_buffer *ktr_bufs, struct ktr_entry **kbufs)
 540 {
 541         static int *kern_idx;
 542         struct ktr_buffer *kbuf;
 543         int i;
 544
 545         if (!kern_idx) {
 546                 kern_idx = malloc(sizeof(*kern_idx) * ncpus);
 547                 if (!kern_idx) {
 548                         err(1, "can't allocate data structures\n");
 549                 }
 550         }
 551
 552         get_indices(kd, kern_idx);
 553         for (i = 0; i < ncpus; ++i) {
 554                 kbuf = &ktr_bufs[i];
 555                 if (kern_idx[i] == kbuf->end_idx)
 556                         continue;
 557                 kbuf->end_idx = kern_idx[i];
 558
 559                 /*
 560                  * If we do not have a notion of the beginning index, assume
 561                  * it is entries_per_buf before the ending index.  Don't
 562                  * worry about underflows/negative numbers, the indices will
 563                  * be masked.
 564                  */
 565                 if (kbuf->reset) {
 566                         kbuf->beg_idx = kbuf->end_idx - entries_per_buf + 1;
 567                         kbuf->reset = 0;
 568                 }
 569                 if (kvm_read(kd, (uintptr_t)kbufs[i], ktr_bufs[i].ents,
 570                                 sizeof(struct ktr_entry) * entries_per_buf)
 571                                                                         == -1)
 572                         errx(1, "%s", kvm_geterr(kd));
 573                 kbuf->modified = 1;
 574                 kbuf->beg_idx = earliest_ts(kbuf);
 575         }
 576
 577 }
 578
 579 /*
 580  * Locate the earliest timestamp iterating backwards from end_idx, but
 581  * not going further back then beg_idx.  We have to do this because
 582  * the kernel uses a circulating buffer.
 583  */
 584 static
 585 int
 586 earliest_ts(struct ktr_buffer *buf)
 587 {
 588         struct ktr_entry *save;
 589         int count, scan, i, earliest;
 590
 591         count = 0;
 592         earliest = buf->end_idx - 1;
 593         save = &buf->ents[earliest & fifo_mask];
 594         for (scan = buf->end_idx - 1; scan != buf->beg_idx -1; --scan) {
 595                 i = scan & fifo_mask;
 596                 if (buf->ents[i].ktr_timestamp < save->ktr_timestamp)
 597                         earliest = scan;
 598                 /*
 599                  * We may have gotten so far behind that beg_idx wrapped
 600                  * more then once around the buffer.  Just stop
 601                  */
 602                 if (++count == entries_per_buf)
 603                         break;
 604         }
 605         return earliest;
 606 }
 607
 608 static
 609 void
 610 print_buf(FILE *fo, struct ktr_buffer *ktr_bufs, int cpu,
 611           u_int64_t *last_timestamp)
 612 {
 613         int first, last;
 614         struct ktr_buffer *buf = ktr_bufs + cpu;
 615
 616         if (buf->modified == 0)
 617                 return;
 618         if (*last_timestamp == 0) {
 619                 *last_timestamp =
 620                         buf->ents[buf->beg_idx & fifo_mask].ktr_timestamp;
 621         }
 622         while (buf->beg_idx != buf->end_idx) {
 623                 print_header(fo, buf->beg_idx);
 624                 print_entry(fo, kd, cpu, buf->beg_idx,
 625                             &buf->ents[buf->beg_idx & fifo_mask],
 626                             last_timestamp);
 627                 ++buf->beg_idx;
 628         }
 629         buf->modified = 0;
 630 }
 631
 632 static
 633 void
 634 print_bufs_timesorted(FILE *fo, struct ktr_buffer *ktr_bufs,
 635                       u_int64_t *last_timestamp)
 636 {
 637         struct ktr_entry *ent;
 638         struct ktr_buffer *buf;
 639         int n, bestn;
 640         u_int64_t ts;
 641         static int row = 0;
 642
 643         for (;;) {
 644                 ts = 0;
 645                 bestn = -1;
 646                 for (n = 0; n < ncpus; ++n) {
 647                         buf = ktr_bufs + n;
 648                         if (buf->beg_idx == buf->end_idx)
 649                                 continue;
 650                         ent = &buf->ents[buf->beg_idx & fifo_mask];
 651                         if (ts == 0 || (ts >= ent->ktr_timestamp)) {
 652                                 ts = ent->ktr_timestamp;
 653                                 bestn = n;
 654                         }
 655                 }
 656                 if ((bestn < 0) || (ts < *last_timestamp))
 657                         break;
 658                 buf = ktr_bufs + bestn;
 659                 print_header(fo, row);
 660                 print_entry(fo, kd, bestn, row,
 661                             &buf->ents[buf->beg_idx & fifo_mask],
 662                             last_timestamp);
 663                 ++buf->beg_idx;
 664                 *last_timestamp = ts;
 665                 ++row;
 666         }
 667 }
 668
 669 static void
 670 usage(void)
 671 {
 672         fprintf(stderr, "usage: ktrdump [-acfilnpqrtx] [-N execfile] "
 673                         "[-M corefile] [-o outfile]\n");
 674         exit(1);
 675 }