[src/FreeBSD]: src/external/cddl/osnet/dev/sdt Import sdt.c from FreeBSD

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/0fcf5cf84bcd
branches:  FreeBSD
changeset: 319390:0fcf5cf84bcd
user:      christos <christos%NetBSD.org@localhost>
date:      Fri Oct 02 16:56:17 2015 +0000

description:
Import sdt.c from FreeBSD

diffstat:

 external/cddl/osnet/dev/sdt/sdt.c |  404 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 404 insertions(+), 0 deletions(-)

diffs (truncated from 408 to 300 lines):

diff -r c7b43a6afbd7 -r 0fcf5cf84bcd external/cddl/osnet/dev/sdt/sdt.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/external/cddl/osnet/dev/sdt/sdt.c Fri Oct 02 16:56:17 2015 +0000
@@ -0,0 +1,404 @@
+/*
+ * 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@localhost
+ *
+ * $FreeBSD: head/sys/cddl/dev/sdt/sdt.c 285703 2015-07-19 22:14:09Z markj $
+ *
+ */
+
+/*
+ * 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/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 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 = {
+       sdt_provide_probes,
+       NULL,
+       sdt_enable,
+       sdt_disable,
+       NULL,
+       NULL,
+       sdt_getargdesc,
+       NULL,
+       NULL,
+       sdt_destroy,
+};
+
+static TAILQ_HEAD(, sdt_provider) sdt_prov_list;
+
+eventhandler_tag       sdt_kld_load_tag;
+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;
+
+       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));
+
+       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++;
+}
+
+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"));
+
+       if (strcmp(probe->prov->name, "lockstat") == 0)
+               lockstat_enabled--;
+       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)
+{
+}
+
+/*
+ * 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)
+{
+       struct sdt_provider **prov, **begin, **end;
+       struct sdt_probe **probe, **p_begin, **p_end;
+       struct sdt_argtype **argtype, **a_begin, **a_end;
+
+       if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
+           NULL) == 0) {
+               for (prov = begin; prov < end; prov++)
+                       sdt_create_provider(*prov);
+       }
+
+       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);
+               }
+       }
+}
+
+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. */