103 lines
3.6 KiB
C
103 lines
3.6 KiB
C
/* $NetBSD: module_hook.h,v 1.6 2019/12/12 22:55:20 pgoyette Exp $ */
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/*-
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* Copyright (c) 2018 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Paul Goyette
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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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _SYS_MODULE_HOOK_H
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#define _SYS_MODULE_HOOK_H
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#include <sys/param.h> /* for COHERENCY_UNIT, for __cacheline_aligned */
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#include <sys/localcount.h>
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#include <sys/stdbool.h>
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void module_hook_init(void);
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void module_hook_set(bool *, struct localcount *);
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void module_hook_unset(bool *, struct localcount *);
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bool module_hook_tryenter(bool *, struct localcount *);
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void module_hook_exit(struct localcount *);
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/*
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* Macros for creating MP-safe vectored function calls, where
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* the function implementations are in modules which could be
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* unloaded.
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*/
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#define MODULE_HOOK(hook, type, args) \
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extern struct hook ## _t { \
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struct localcount lc; \
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type (*f)args; \
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bool hooked; \
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} hook __cacheline_aligned;
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/*
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* We use pserialize_perform() to issue a memory barrier on the current
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* CPU and on all other CPUs so that all prior memory operations on the
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* current CPU globally happen before all subsequent memory operations
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* on the current CPU, as perceived by any other CPU.
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*
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* pserialize_perform() might be rather heavy-weight here, but it only
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* happens during module loading, and it allows MODULE_HOOK_CALL() to
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* work without any other memory barriers.
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*/
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#define MODULE_HOOK_SET(hook, func) \
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do { \
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(hook).f = func; \
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module_hook_set(&(hook).hooked, &(hook).lc); \
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} while /* CONSTCOND */ (0)
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#define MODULE_HOOK_UNSET(hook) \
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do { \
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KASSERT((hook).f); \
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module_hook_unset(&(hook).hooked, &(hook).lc); \
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(hook).f = NULL; /* paranoia */ \
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} while /* CONSTCOND */ (0)
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#define MODULE_HOOK_CALL(hook, args, default, retval) \
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do { \
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if (module_hook_tryenter(&(hook).hooked, &(hook).lc)) { \
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(retval) = (*(hook).f)args; \
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module_hook_exit(&(hook).lc); \
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} else { \
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(retval) = (default); \
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} \
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} while /* CONSTCOND */ (0)
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#define MODULE_HOOK_CALL_VOID(hook, args, default) \
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do { \
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if (module_hook_tryenter(&(hook).hooked, &(hook).lc)) { \
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(*(hook).f)args; \
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module_hook_exit(&(hook).lc); \
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} else { \
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default; \
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} \
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} while /* CONSTCOND */ (0)
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#endif /* _SYS_MODULE_HOOK_H */
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