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probes declared in a kernel module when that module is unloaded. In particular, * Unloading a module with active SDT probes will cause a panic. [1] * A module's (FBT/SDT) probes aren't destroyed when the module is unloaded; trying to use them after the fact will generally cause a panic. This change fixes both problems by porting the DTrace module load/unload handlers from illumos and registering them with the corresponding EVENTHANDLER(9) handlers. This allows the DTrace framework to destroy all probes defined in a module when that module is unloaded, and to prevent a module unload from proceeding if some of its probes are active. The latter problem has already been fixed for FBT probes by checking lf->nenabled in kern_kldunload(), but moving the check into the DTrace framework generalizes it to all kernel providers and also fixes a race in the current implementation (since a probe may be activated between the check and the call to linker_file_unload()). Additionally, the SDT implementation has been reworked to define SDT providers/probes/argtypes in linker sets rather than using SYSINIT/SYSUNINIT to create and destroy SDT probes when a module is loaded or unloaded. This simplifies things quite a bit since it means that pretty much all of the SDT code can live in sdt.ko, and since it becomes easier to integrate SDT with the DTrace framework. Furthermore, this allows FreeBSD to be quite flexible in that SDT providers spanning multiple modules can be created on the fly when a module is loaded; at the moment it looks like illumos' SDT implementation requires all SDT probes to be statically defined in a single kernel table. PR: 166927, 166926, 166928 Reported by: davide [1] Reviewed by: avg, trociny (earlier version) MFC after: 1 month
52 lines
1.9 KiB
C
52 lines
1.9 KiB
C
/*-
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* Copyright 2006-2008 John Birrell <jb@FreeBSD.org>
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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 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 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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* $FreeBSD$
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*/
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#include "opt_kdtrace.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/sdt.h>
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/*
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* Hook for the DTrace probe function. The SDT provider will set this to
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* dtrace_probe() when it loads.
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*/
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sdt_probe_func_t sdt_probe_func = sdt_probe_stub;
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/*
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* This is a stub for probe calls in case kernel DTrace support isn't
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* enabled. It should never get called because there is no DTrace support
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* to enable it.
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*/
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void
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sdt_probe_stub(uint32_t id, uintptr_t arg0, uintptr_t arg1,
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uintptr_t arg2, uintptr_t arg3, uintptr_t arg4)
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{
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printf("sdt_probe_stub: Why did this get called?\n");
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}
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