a38d172e95
While here predict false. Note the code is wrong (regardless of this change). Dereference of the pointer can race with module unload. A fix would set the probe to a nop stub instead of NULL.
130 lines
3.6 KiB
C
130 lines
3.6 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2007-2008 John Birrell <jb@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_kdb.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/eventhandler.h>
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#include <sys/kdb.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/proc.h>
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#include <sys/dtrace_bsd.h>
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#include <sys/sysctl.h>
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#include <sys/sysent.h>
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#define KDTRACE_PROC_SIZE 64
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#define KDTRACE_THREAD_SIZE 256
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FEATURE(kdtrace_hooks,
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"Kernel DTrace hooks which are required to load DTrace kernel modules");
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static MALLOC_DEFINE(M_KDTRACE, "kdtrace", "DTrace hooks");
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/* Hooks used in the machine-dependent trap handlers. */
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dtrace_trap_func_t dtrace_trap_func;
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dtrace_doubletrap_func_t dtrace_doubletrap_func;
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dtrace_pid_probe_ptr_t dtrace_pid_probe_ptr;
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dtrace_return_probe_ptr_t dtrace_return_probe_ptr;
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bool __read_frequently systrace_enabled;
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systrace_probe_func_t systrace_probe_func;
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/* Return the DTrace process data size compiled in the kernel hooks. */
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size_t
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kdtrace_proc_size()
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{
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return (KDTRACE_PROC_SIZE);
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}
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static void
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kdtrace_proc_ctor(void *arg __unused, struct proc *p)
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{
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p->p_dtrace = malloc(KDTRACE_PROC_SIZE, M_KDTRACE, M_WAITOK|M_ZERO);
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}
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static void
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kdtrace_proc_dtor(void *arg __unused, struct proc *p)
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{
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if (p->p_dtrace != NULL) {
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free(p->p_dtrace, M_KDTRACE);
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p->p_dtrace = NULL;
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}
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}
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/* Return the DTrace thread data size compiled in the kernel hooks. */
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size_t
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kdtrace_thread_size()
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{
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return (KDTRACE_THREAD_SIZE);
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}
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static void
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kdtrace_thread_ctor(void *arg __unused, struct thread *td)
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{
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td->td_dtrace = malloc(KDTRACE_THREAD_SIZE, M_KDTRACE, M_WAITOK|M_ZERO);
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}
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static void
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kdtrace_thread_dtor(void *arg __unused, struct thread *td)
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{
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if (td->td_dtrace != NULL) {
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free(td->td_dtrace, M_KDTRACE);
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td->td_dtrace = NULL;
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}
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}
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/*
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* Initialise the kernel DTrace hooks.
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*/
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static void
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init_dtrace(void *dummy __unused)
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{
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EVENTHANDLER_REGISTER(process_ctor, kdtrace_proc_ctor, NULL,
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EVENTHANDLER_PRI_ANY);
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EVENTHANDLER_REGISTER(process_dtor, kdtrace_proc_dtor, NULL,
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EVENTHANDLER_PRI_ANY);
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EVENTHANDLER_REGISTER(thread_ctor, kdtrace_thread_ctor, NULL,
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EVENTHANDLER_PRI_ANY);
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EVENTHANDLER_REGISTER(thread_dtor, kdtrace_thread_dtor, NULL,
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EVENTHANDLER_PRI_ANY);
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}
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SYSINIT(kdtrace, SI_SUB_KDTRACE, SI_ORDER_FIRST, init_dtrace, NULL);
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