1 /* $NetBSD: module_hook.h,v 1.7 2024/05/12 10:38:03 rillig Exp $ */ 2 3 /*- 4 * Copyright (c) 2018 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Paul Goyette 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #ifndef _SYS_MODULE_HOOK_H 33 #define _SYS_MODULE_HOOK_H 34 35 #include <sys/param.h> /* for COHERENCY_UNIT, for __cacheline_aligned */ 36 #include <sys/localcount.h> 37 #include <sys/stdbool.h> 38 39 void module_hook_init(void); 40 void module_hook_set(bool *, struct localcount *); 41 void module_hook_unset(bool *, struct localcount *); 42 bool module_hook_tryenter(bool *, struct localcount *); 43 void module_hook_exit(struct localcount *); 44 45 /* 46 * Macros for creating MP-safe vectored function calls, where 47 * the function implementations are in modules which could be 48 * unloaded. 49 */ 50 51 #define MODULE_HOOK(hook, type, args) \ 52 extern struct hook ## _t { \ 53 struct localcount lc; \ 54 type (*f)args; \ 55 bool hooked; \ 56 } hook __cacheline_aligned; 57 58 /* 59 * We use pserialize_perform() to issue a memory barrier on the current 60 * CPU and on all other CPUs so that all prior memory operations on the 61 * current CPU globally happen before all subsequent memory operations 62 * on the current CPU, as perceived by any other CPU. 63 * 64 * pserialize_perform() might be rather heavy-weight here, but it only 65 * happens during module loading, and it allows MODULE_HOOK_CALL() to 66 * work without any other memory barriers. 67 */ 68 69 #define MODULE_HOOK_SET(hook, func) \ 70 do { \ 71 (hook).f = func; \ 72 module_hook_set(&(hook).hooked, &(hook).lc); \ 73 } while (0) 74 75 #define MODULE_HOOK_UNSET(hook) \ 76 do { \ 77 KASSERT((hook).f); \ 78 module_hook_unset(&(hook).hooked, &(hook).lc); \ 79 (hook).f = NULL; /* paranoia */ \ 80 } while (0) 81 82 #define MODULE_HOOK_CALL(hook, args, default, retval) \ 83 do { \ 84 if (module_hook_tryenter(&(hook).hooked, &(hook).lc)) { \ 85 (retval) = (*(hook).f)args; \ 86 module_hook_exit(&(hook).lc); \ 87 } else { \ 88 (retval) = (default); \ 89 } \ 90 } while (0) 91 92 #define MODULE_HOOK_CALL_VOID(hook, args, default) \ 93 do { \ 94 if (module_hook_tryenter(&(hook).hooked, &(hook).lc)) { \ 95 (*(hook).f)args; \ 96 module_hook_exit(&(hook).lc); \ 97 } else { \ 98 default; \ 99 } \ 100 } while (0) 101 102 #endif /* _SYS_MODULE_HOOK_H */ 103