sys/kern/kern_sdt.c

   1 /*-
   2  * Copyright 2006-2008 John Birrell <jb@FreeBSD.org>
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  16  * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
  17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  23  * SUCH DAMAGE.
  24  *
  25  * $FreeBSD$
  26  *
  27  * Backend for the Statically Defined Tracing (SDT) kernel support. This is
  28  * required to allow a module to load even though DTrace kernel support may
  29  * not be present. A module may be built with SDT probes in it which are
  30  * registered and deregistered via SYSINIT/SYSUNINIT.
  31  *
  32  */
  33
  34 #include "opt_kdtrace.h"
  35
  36 #include <sys/cdefs.h>
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/kernel.h>
  40 #include <sys/linker.h>
  41 #include <sys/lock.h>
  42 #include <sys/proc.h>
  43 #include <sys/sx.h>
  44 #include <sys/sdt.h>
  45
  46 /*
  47  * This is the list of statically defined tracing providers.
  48  */
  49 static TAILQ_HEAD(sdt_provider_list_head, sdt_provider) sdt_provider_list;
  50
  51 /*
  52  * Mutex to serialise access to the SDT provider list.
  53  */
  54 static struct sx sdt_sx;
  55
  56 /*
  57  * Hook for the DTrace probe function. The 'sdt' provider will set this
  58  * to dtrace_probe when it loads.
  59  */
  60 sdt_probe_func_t sdt_probe_func = sdt_probe_stub;
  61
  62 /*
  63  * This is a stub for probe calls in case kernel DTrace support isn't
  64  * compiled in. It should never get called because there is no DTrace
  65  * support to enable it.
  66  */
  67 void
  68 sdt_probe_stub(u_int32_t id, uintptr_t arg0, uintptr_t arg1,
  69     uintptr_t arg2, uintptr_t arg3, uintptr_t arg4)
  70 {
  71         printf("sdt_probe_stub: Why did this get called?\n");
  72 }
  73
  74 /*
  75  * Called from SYSINIT to register a provider.
  76  */
  77 void
  78 sdt_provider_register(void *arg)
  79 {
  80         struct sdt_provider *prov = arg;
  81
  82         sx_xlock(&sdt_sx);
  83
  84         TAILQ_INSERT_TAIL(&sdt_provider_list, prov, prov_entry);
  85
  86         TAILQ_INIT(&prov->probe_list);
  87
  88         sx_xunlock(&sdt_sx);
  89 }
  90
  91 /*
  92  * Called from SYSUNINIT to de-register a provider.
  93  */
  94 void
  95 sdt_provider_deregister(void *arg)
  96 {
  97         struct sdt_provider *prov = arg;
  98
  99         sx_xlock(&sdt_sx);
 100
 101         TAILQ_REMOVE(&sdt_provider_list, prov, prov_entry);
 102
 103         sx_xunlock(&sdt_sx);
 104 }
 105
 106 /*
 107  * Called from SYSINIT to register a statically defined trace probe.
 108  */
 109 void
 110 sdt_probe_register(void *arg)
 111 {
 112         struct sdt_probe *probe = arg;
 113
 114         /*
 115          * Check the reference structure version. Only version 1 is
 116          * supported at the moment.
 117          */
 118         if (probe->version != sizeof(struct sdt_probe)) {
 119                 printf("%s:%s:%s has version %d when %d required\n", probe->mod, probe->func, probe->name, probe->version, (int) sizeof(struct sdt_probe));
 120                 return;
 121         }
 122
 123         sx_xlock(&sdt_sx);
 124
 125         TAILQ_INSERT_TAIL(&probe->prov->probe_list, probe, probe_entry);
 126
 127         TAILQ_INIT(&probe->argtype_list);
 128
 129         probe->state = SDT_INIT;
 130
 131         sx_xunlock(&sdt_sx);
 132 }
 133
 134 /*
 135  * Called from SYSUNINIT to de-register a statically defined trace probe.
 136  */
 137 void
 138 sdt_probe_deregister(void *arg)
 139 {
 140         struct sdt_probe *probe = arg;
 141
 142         sx_xlock(&sdt_sx);
 143
 144         if (probe->state == SDT_INIT) {
 145                 TAILQ_REMOVE(&probe->prov->probe_list, probe, probe_entry);
 146                 probe->state = SDT_UNINIT;
 147         }
 148
 149         sx_xunlock(&sdt_sx);
 150 }
 151
 152 /*
 153  * Called from SYSINIT to register a statically defined trace probe argument.
 154  */
 155 void
 156 sdt_argtype_register(void *arg)
 157 {
 158         struct sdt_argtype *argtype = arg;
 159
 160         sx_xlock(&sdt_sx);
 161
 162         TAILQ_INSERT_TAIL(&argtype->probe->argtype_list, argtype, argtype_entry);
 163
 164         argtype->probe->n_args++;
 165
 166         sx_xunlock(&sdt_sx);
 167 }
 168
 169 /*
 170  * Called from SYSUNINIT to de-register a statically defined trace probe argument.
 171  */
 172 void
 173 sdt_argtype_deregister(void *arg)
 174 {
 175         struct sdt_argtype *argtype = arg;
 176
 177         sx_xlock(&sdt_sx);
 178
 179         TAILQ_REMOVE(&argtype->probe->argtype_list, argtype, argtype_entry);
 180
 181         sx_xunlock(&sdt_sx);
 182 }
 183
 184 static void
 185 sdt_init(void *arg)
 186 {
 187         sx_init_flags(&sdt_sx, "Statically Defined Tracing", SX_NOWITNESS);
 188
 189         TAILQ_INIT(&sdt_provider_list);
 190 }
 191
 192 SYSINIT(sdt, SI_SUB_KDTRACE, SI_ORDER_FIRST, sdt_init, NULL);
 193
 194 static void
 195 sdt_uninit(void *arg)
 196 {
 197         sx_destroy(&sdt_sx);
 198 }
 199
 200 SYSUNINIT(sdt, SI_SUB_KDTRACE, SI_ORDER_FIRST, sdt_uninit, NULL);
 201
 202 /*
 203  * List statically defined tracing providers.
 204  */
 205 int
 206 sdt_provider_listall(sdt_provider_listall_func_t callback_func,void *arg)
 207 {
 208         int error = 0;
 209         struct sdt_provider *prov;
 210
 211         sx_xlock(&sdt_sx);
 212
 213         TAILQ_FOREACH(prov, &sdt_provider_list, prov_entry) {
 214                 if ((error = callback_func(prov, arg)) != 0)
 215                         break;
 216         }
 217
 218         sx_xunlock(&sdt_sx);
 219
 220         return (error);
 221 }
 222
 223 /*
 224  * List statically defined tracing probes.
 225  */
 226 int
 227 sdt_probe_listall(struct sdt_provider *prov,
 228     sdt_probe_listall_func_t callback_func,void *arg)
 229 {
 230         int error = 0;
 231         int locked;
 232         struct sdt_probe *probe;
 233
 234         locked = sx_xlocked(&sdt_sx);
 235         if (!locked)
 236                 sx_xlock(&sdt_sx);
 237
 238         TAILQ_FOREACH(probe, &prov->probe_list, probe_entry) {
 239                 if ((error = callback_func(probe, arg)) != 0)
 240                         break;
 241         }
 242
 243         if (!locked)
 244                 sx_xunlock(&sdt_sx);
 245
 246         return (error);
 247 }
 248
 249 /*
 250  * List statically defined tracing probe arguments.
 251  */
 252 int
 253 sdt_argtype_listall(struct sdt_probe *probe,
 254     sdt_argtype_listall_func_t callback_func,void *arg)
 255 {
 256         int error = 0;
 257         int locked;
 258         struct sdt_argtype *argtype;
 259
 260         locked = sx_xlocked(&sdt_sx);
 261         if (!locked)
 262                 sx_xlock(&sdt_sx);
 263
 264         TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) {
 265                 if ((error = callback_func(argtype, arg)) != 0)
 266                         break;
 267         }
 268
 269         if (!locked)
 270                 sx_xunlock(&sdt_sx);
 271
 272         return (error);
 273 }