sbin/ddb/ddb_capture.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2008 Robert N. M. Watson
   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 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include <sys/types.h>
  33 #include <sys/sysctl.h>
  34
  35 #include <err.h>
  36 #include <errno.h>
  37 #include <fcntl.h>
  38 #include <kvm.h>
  39 #include <limits.h>
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43 #include <sysexits.h>
  44 #include <unistd.h>
  45
  46 #include "ddb.h"
  47
  48 /*
  49  * Interface with the ddb(4) capture buffer of a live kernel using sysctl, or
  50  * for a crash dump using libkvm.
  51  */
  52 #define SYSCTL_DDB_CAPTURE_BUFOFF       "debug.ddb.capture.bufoff"
  53 #define SYSCTL_DDB_CAPTURE_BUFSIZE      "debug.ddb.capture.bufsize"
  54 #define SYSCTL_DDB_CAPTURE_MAXBUFSIZE   "debug.ddb.capture.maxbufsize"
  55 #define SYSCTL_DDB_CAPTURE_DATA         "debug.ddb.capture.data"
  56 #define SYSCTL_DDB_CAPTURE_INPROGRESS   "debug.ddb.capture.inprogress"
  57
  58 static struct nlist namelist[] = {
  59 #define X_DB_CAPTURE_BUF        0
  60         { .n_name = "_db_capture_buf" },
  61 #define X_DB_CAPTURE_BUFSIZE    1
  62         { .n_name = "_db_capture_bufsize" },
  63 #define X_DB_CAPTURE_MAXBUFSIZE 2
  64         { .n_name = "_db_capture_maxbufsize" },
  65 #define X_DB_CAPTURE_BUFOFF     3
  66         { .n_name = "_db_capture_bufoff" },
  67 #define X_DB_CAPTURE_INPROGRESS 4
  68         { .n_name = "_db_capture_inprogress" },
  69         { .n_name = "" },
  70 };
  71
  72 static int
  73 kread(kvm_t *kvm, void *kvm_pointer, void *address, size_t size,
  74     size_t offset)
  75 {
  76         ssize_t ret;
  77
  78         ret = kvm_read(kvm, (unsigned long)kvm_pointer + offset, address,
  79             size);
  80         if (ret < 0 || (size_t)ret != size)
  81                 return (-1);
  82         return (0);
  83 }
  84
  85 static int
  86 kread_symbol(kvm_t *kvm, int read_index, void *address, size_t size,
  87     size_t offset)
  88 {
  89         ssize_t ret;
  90
  91         ret = kvm_read(kvm, namelist[read_index].n_value + offset, address, size);
  92         if (ret < 0 || (size_t)ret != size)
  93                 return (-1);
  94         return (0);
  95 }
  96
  97 static void
  98 ddb_capture_print_kvm(kvm_t *kvm)
  99 {
 100         u_int db_capture_bufoff;
 101         char *buffer, *db_capture_buf;
 102
 103         if (kread_symbol(kvm, X_DB_CAPTURE_BUF, &db_capture_buf,
 104             sizeof(db_capture_buf), 0) < 0)
 105                 errx(-1, "kvm: unable to read db_capture_buf");
 106
 107         if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
 108             sizeof(db_capture_bufoff), 0) < 0)
 109                 errx(-1, "kvm: unable to read db_capture_bufoff");
 110
 111         buffer = malloc(db_capture_bufoff + 1);
 112         if (buffer == NULL)
 113                 err(-1, "malloc: db_capture_bufoff (%u)",
 114                     db_capture_bufoff);
 115         bzero(buffer, db_capture_bufoff + 1);
 116
 117         if (kread(kvm, db_capture_buf, buffer, db_capture_bufoff, 0) < 0)
 118                 errx(-1, "kvm: unable to read buffer");
 119
 120         printf("%s\n", buffer);
 121         free(buffer);
 122 }
 123
 124 static void
 125 ddb_capture_print_sysctl(void)
 126 {
 127         size_t buflen, len;
 128         char *buffer;
 129         int ret;
 130
 131 repeat:
 132         if (sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, NULL, &buflen, NULL, 0) < 0)
 133                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
 134         if (buflen == 0)
 135                 return;
 136         buffer = malloc(buflen);
 137         if (buffer == NULL)
 138                 err(EX_OSERR, "malloc");
 139         bzero(buffer, buflen);
 140         len = buflen;
 141         ret = sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, buffer, &len, NULL, 0);
 142         if (ret < 0 && errno != ENOMEM)
 143                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
 144         if (ret < 0) {
 145                 free(buffer);
 146                 goto repeat;
 147         }
 148
 149         printf("%s\n", buffer);
 150         free(buffer);
 151 }
 152
 153 static void
 154 ddb_capture_status_kvm(kvm_t *kvm)
 155 {
 156         u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
 157
 158         if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
 159             sizeof(db_capture_bufoff), 0) < 0)
 160                 errx(-1, "kvm: unable to read db_capture_bufoff");
 161         if (kread_symbol(kvm, X_DB_CAPTURE_BUFSIZE, &db_capture_bufsize,
 162             sizeof(db_capture_bufsize), 0) < 0)
 163                 errx(-1, "kvm: unable to read db_capture_bufsize");
 164         if (kread_symbol(kvm, X_DB_CAPTURE_INPROGRESS,
 165             &db_capture_inprogress, sizeof(db_capture_inprogress), 0) < 0)
 166                 err(-1, "kvm: unable to read db_capture_inprogress");
 167         printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
 168         if (db_capture_inprogress)
 169                 printf("capture is on\n");
 170         else
 171                 printf("capture is off\n");
 172
 173 }
 174
 175 static void
 176 ddb_capture_status_sysctl(void)
 177 {
 178         u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
 179         size_t len;
 180
 181         len = sizeof(db_capture_bufoff);
 182         if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFOFF, &db_capture_bufoff, &len,
 183             NULL, 0) < 0)
 184                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFOFF);
 185         len = sizeof(db_capture_bufoff);
 186         if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFSIZE, &db_capture_bufsize,
 187             &len, NULL, 0) < 0)
 188                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFSIZE);
 189         len = sizeof(db_capture_inprogress);
 190         if (sysctlbyname(SYSCTL_DDB_CAPTURE_INPROGRESS,
 191             &db_capture_inprogress, &len, NULL, 0) < 0)
 192                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_INPROGRESS);
 193         printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
 194         if (db_capture_inprogress)
 195                 printf("capture is on\n");
 196         else
 197                 printf("capture is off\n");
 198 }
 199
 200 void
 201 ddb_capture(int argc, char *argv[])
 202 {
 203         char *mflag, *nflag, errbuf[_POSIX2_LINE_MAX];
 204         kvm_t *kvm;
 205         int ch;
 206
 207         mflag = NULL;
 208         nflag = NULL;
 209         kvm = NULL;
 210         while ((ch = getopt(argc, argv, "M:N:")) != -1) {
 211                 switch (ch) {
 212                 case 'M':
 213                         mflag = optarg;
 214                         break;
 215
 216                 case 'N':
 217                         nflag = optarg;
 218                         break;
 219
 220                 default:
 221                         usage();
 222                 }
 223         }
 224         argc -= optind;
 225         argv += optind;
 226
 227         if (argc != 1)
 228                 usage();
 229
 230         if (mflag != NULL) {
 231                 kvm = kvm_openfiles(nflag, mflag, NULL, O_RDONLY, errbuf);
 232                 if (kvm == NULL)
 233                         errx(-1, "ddb_capture: kvm_openfiles: %s", errbuf);
 234                 if (kvm_nlist(kvm, namelist) != 0)
 235                         errx(-1, "ddb_capture: kvm_nlist");
 236         } else if (nflag != NULL)
 237                 usage();
 238         if (strcmp(argv[0], "print") == 0) {
 239                 if (kvm != NULL)
 240                         ddb_capture_print_kvm(kvm);
 241                 else
 242                         ddb_capture_print_sysctl();
 243         } else if (strcmp(argv[0], "status") == 0) {
 244                 if (kvm != NULL)
 245                         ddb_capture_status_kvm(kvm);
 246                 else
 247                         ddb_capture_status_sysctl();
 248         } else
 249                 usage();
 250 }