1 /* 2 * Copyright (C) 2019 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #pragma once 30 31 #include <sys/cdefs.h> 32 33 /** 34 * @file sys/ifunc.h 35 * @brief Declarations used for ifunc resolvers. Currently only meaningful for arm64. 36 */ 37 38 __BEGIN_DECLS 39 40 #if defined(__aarch64__) 41 42 /** 43 * Provides information about hardware capabilities to ifunc resolvers. 44 * 45 * Starting with API level 30, ifunc resolvers on arm64 are passed two arguments. The first is a 46 * uint64_t whose value is equal to getauxval(AT_HWCAP) | _IFUNC_ARG_HWCAP. The second is a pointer 47 * to a data structure of this type. Prior to API level 30, no arguments are passed to ifunc 48 * resolvers. Code that wishes to be compatible with prior API levels should not accept any 49 * arguments in the resolver. 50 */ 51 typedef struct __ifunc_arg_t { 52 /** Set to sizeof(__ifunc_arg_t). */ 53 unsigned long _size; 54 55 /** Set to getauxval(AT_HWCAP). */ 56 unsigned long _hwcap; 57 58 /** Set to getauxval(AT_HWCAP2). */ 59 unsigned long _hwcap2; 60 } __ifunc_arg_t; 61 62 /** 63 * If this bit is set in the first argument to an ifunc resolver, indicates that the second argument 64 * is a pointer to a data structure of type __ifunc_arg_t. This bit is always set on Android 65 * starting with API level 30. 66 */ 67 #define _IFUNC_ARG_HWCAP (1ULL << 62) 68 69 #endif 70 71 __END_DECLS 72