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sdt.c
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Editing: sdt.c
/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END * * Portions Copyright 2006-2008 John Birrell jb@freebsd.org * * $FreeBSD$ * */ /* * This file contains a reimplementation of the statically-defined tracing (SDT) * framework for DTrace. Probes and SDT providers are defined using the macros * in sys/sdt.h, which append all the needed structures to linker sets. When * this module is loaded, it iterates over all of the loaded modules and * registers probes and providers with the DTrace framework based on the * contents of these linker sets. * * A list of SDT providers is maintained here since a provider may span multiple * modules. When a kernel module is unloaded, a provider defined in that module * is unregistered only if no other modules refer to it. The DTrace framework is * responsible for destroying individual probes when a kernel module is * unloaded; in particular, probes may not span multiple kernel modules. */ #include <sys/cdefs.h> #include <sys/param.h> #include <sys/systm.h> #include <sys/conf.h> #include <sys/endian.h> #include <sys/eventhandler.h> #include <sys/kernel.h> #include <sys/limits.h> #include <sys/linker.h> #include <sys/linker_set.h> #include <sys/lock.h> #include <sys/lockstat.h> #include <sys/malloc.h> #include <sys/module.h> #include <sys/mutex.h> #include <sys/queue.h> #include <sys/sdt.h> #include <sys/dtrace.h> #include <sys/dtrace_bsd.h> /* DTrace methods. */ static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *); static void sdt_provide_probes(void *, dtrace_probedesc_t *); static void sdt_destroy(void *, dtrace_id_t, void *); static void sdt_enable(void *, dtrace_id_t, void *); static void sdt_disable(void *, dtrace_id_t, void *); static void sdt_load(void); static int sdt_unload(void); static void sdt_create_provider(struct sdt_provider *); static void sdt_create_probe(struct sdt_probe *); static void sdt_kld_load(void *, struct linker_file *); static void sdt_kld_unload_try(void *, struct linker_file *, int *); static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers"); static int sdt_probes_enabled_count; static int lockstat_enabled_count; static dtrace_pattr_t sdt_attr = { { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN }, { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, }; static dtrace_pops_t sdt_pops = { .dtps_provide = sdt_provide_probes, .dtps_provide_module = NULL, .dtps_enable = sdt_enable, .dtps_disable = sdt_disable, .dtps_suspend = NULL, .dtps_resume = NULL, .dtps_getargdesc = sdt_getargdesc, .dtps_getargval = NULL, .dtps_usermode = NULL, .dtps_destroy = sdt_destroy, }; static TAILQ_HEAD(, sdt_provider) sdt_prov_list; static eventhandler_tag sdt_kld_load_tag; static eventhandler_tag sdt_kld_unload_try_tag; static void sdt_create_provider(struct sdt_provider *prov) { struct sdt_provider *curr, *newprov; TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry) if (strcmp(prov->name, curr->name) == 0) { /* The provider has already been defined. */ curr->sdt_refs++; return; } /* * Make a copy of prov so that we don't lose fields if its module is * unloaded but the provider isn't destroyed. This could happen with * a provider that spans multiple modules. */ newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO); newprov->name = strdup(prov->name, M_SDT); prov->sdt_refs = newprov->sdt_refs = 1; TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry); (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL, &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id); prov->id = newprov->id; } static void sdt_create_probe(struct sdt_probe *probe) { struct sdt_provider *prov; char mod[DTRACE_MODNAMELEN]; char func[DTRACE_FUNCNAMELEN]; char name[DTRACE_NAMELEN]; const char *from; char *to; size_t len; if (probe->version != (int)sizeof(*probe)) { printf("ignoring probe %p, version %u expected %u\n", probe, probe->version, (int)sizeof(*probe)); return; } TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry) if (strcmp(prov->name, probe->prov->name) == 0) break; KASSERT(prov != NULL, ("probe defined without a provider")); /* If no module name was specified, use the module filename. */ if (*probe->mod == 0) { len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod)); if (len > 3 && strcmp(mod + len - 3, ".ko") == 0) mod[len - 3] = '\0'; } else strlcpy(mod, probe->mod, sizeof(mod)); /* * Unfortunately this is necessary because the Solaris DTrace * code mixes consts and non-consts with casts to override * the incompatibilies. On FreeBSD, we use strict warnings * in the C compiler, so we have to respect const vs non-const. */ strlcpy(func, probe->func, sizeof(func)); if (func[0] == '\0') strcpy(func, "none"); from = probe->name; to = name; for (len = 0; len < (sizeof(name) - 1) && *from != '\0'; len++, from++, to++) { if (from[0] == '_' && from[1] == '_') { *to = '-'; from++; } else *to = *from; } *to = '\0'; if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) return; (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); } /* * Probes are created through the SDT module load/unload hook, so this function * has nothing to do. It only exists because the DTrace provider framework * requires one of provide_probes and provide_module to be defined. */ static void sdt_provide_probes(void *arg, dtrace_probedesc_t *desc) { } static void sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) { struct sdt_probe *probe = parg; probe->id = id; probe->sdtp_lf->nenabled++; if (strcmp(probe->prov->name, "lockstat") == 0) { lockstat_enabled_count++; if (lockstat_enabled_count == 1) lockstat_enabled = true; } sdt_probes_enabled_count++; if (sdt_probes_enabled_count == 1) sdt_probes_enabled = true; } static void sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) { struct sdt_probe *probe = parg; KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); sdt_probes_enabled_count--; if (sdt_probes_enabled_count == 0) sdt_probes_enabled = false; if (strcmp(probe->prov->name, "lockstat") == 0) { lockstat_enabled_count--; if (lockstat_enabled_count == 0) lockstat_enabled = false; } probe->id = 0; probe->sdtp_lf->nenabled--; } static void sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) { struct sdt_argtype *argtype; struct sdt_probe *probe = parg; if (desc->dtargd_ndx >= probe->n_args) { desc->dtargd_ndx = DTRACE_ARGNONE; return; } TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { if (desc->dtargd_ndx == argtype->ndx) { desc->dtargd_mapping = desc->dtargd_ndx; if (argtype->type == NULL) { desc->dtargd_native[0] = '\0'; desc->dtargd_xlate[0] = '\0'; continue; } strlcpy(desc->dtargd_native, argtype->type, sizeof(desc->dtargd_native)); if (argtype->xtype != NULL) strlcpy(desc->dtargd_xlate, argtype->xtype, sizeof(desc->dtargd_xlate)); } } } static void sdt_destroy(void *arg, dtrace_id_t id, void *parg) { } static void sdt_kld_load_providers(struct linker_file *lf) { struct sdt_provider **prov, **begin, **end; if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, NULL) == 0) { for (prov = begin; prov < end; prov++) sdt_create_provider(*prov); } } static void sdt_kld_load_probes(struct linker_file *lf) { struct sdt_probe **probe, **p_begin, **p_end; struct sdt_argtype **argtype, **a_begin, **a_end; if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, NULL) == 0) { for (probe = p_begin; probe < p_end; probe++) { (*probe)->sdtp_lf = lf; sdt_create_probe(*probe); TAILQ_INIT(&(*probe)->argtype_list); } } if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, NULL) == 0) { for (argtype = a_begin; argtype < a_end; argtype++) { (*argtype)->probe->n_args++; TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, *argtype, argtype_entry); } } } /* * Called from the kernel linker when a module is loaded, before * dtrace_module_loaded() is called. This is done so that it's possible to * register new providers when modules are loaded. The DTrace framework * explicitly disallows calling into the framework from the provide_module * provider method, so we cannot do this there. */ static void sdt_kld_load(void *arg __unused, struct linker_file *lf) { sdt_kld_load_providers(lf); sdt_kld_load_probes(lf); } static void sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) { struct sdt_provider *prov, **curr, **begin, **end, *tmp; if (*error != 0) /* We already have an error, so don't do anything. */ return; else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, NULL)) /* No DTrace providers are declared in this file. */ return; /* * Go through all the providers declared in this linker file and * unregister any that aren't declared in another loaded file. */ for (curr = begin; curr < end; curr++) { TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { if (strcmp(prov->name, (*curr)->name) != 0) continue; if (prov->sdt_refs == 1) { if (dtrace_unregister(prov->id) != 0) { *error = 1; return; } TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); free(prov->name, M_SDT); free(prov, M_SDT); } else prov->sdt_refs--; break; } } } static int sdt_load_providers_cb(linker_file_t lf, void *arg __unused) { sdt_kld_load_providers(lf); return (0); } static int sdt_load_probes_cb(linker_file_t lf, void *arg __unused) { sdt_kld_load_probes(lf); return (0); } static void sdt_load(void) { TAILQ_INIT(&sdt_prov_list); sdt_probe_func = dtrace_probe; sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL, EVENTHANDLER_PRI_ANY); sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try, sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY); /* * Pick up probes from the kernel and already-loaded linker files. * Define providers in a separate pass since a linker file may be using * providers defined in a file that appears later in the list. */ linker_file_foreach(sdt_load_providers_cb, NULL); linker_file_foreach(sdt_load_probes_cb, NULL); } static int sdt_unload(void) { struct sdt_provider *prov, *tmp; int ret; EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag); EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag); sdt_probe_func = sdt_probe_stub; TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { ret = dtrace_unregister(prov->id); if (ret != 0) return (ret); TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); free(prov->name, M_SDT); free(prov, M_SDT); } return (0); } static int sdt_modevent(module_t mod __unused, int type, void *data __unused) { switch (type) { case MOD_LOAD: case MOD_UNLOAD: case MOD_SHUTDOWN: return (0); default: return (EOPNOTSUPP); } } SYSINIT(sdt_load, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_load, NULL); SYSUNINIT(sdt_unload, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_unload, NULL); DEV_MODULE(sdt, sdt_modevent, NULL); MODULE_VERSION(sdt, 1); MODULE_DEPEND(sdt, dtrace, 1, 1, 1);
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