1 /* 2 * Copyright (c) 2014 Apple Inc. All rights reserved. 3 * 4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ 5 * 6 * This file contains Original Code and/or Modifications of Original Code 7 * as defined in and that are subject to the Apple Public Source License 8 * Version 2.0 (the 'License'). You may not use this file except in 9 * compliance with the License. The rights granted to you under the License 10 * may not be used to create, or enable the creation or redistribution of, 11 * unlawful or unlicensed copies of an Apple operating system, or to 12 * circumvent, violate, or enable the circumvention or violation of, any 13 * terms of an Apple operating system software license agreement. 14 * 15 * Please obtain a copy of the License at 16 * http://www.opensource.apple.com/apsl/ and read it before using this file. 17 * 18 * The Original Code and all software distributed under the License are 19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 23 * Please see the License for the specific language governing rights and 24 * limitations under the License. 25 * 26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ 27 */ 28 29 #include <mach/vm_param.h> 30 31 /* 32 * This file is compiled and linked to be the last .o of the __const section 33 * of the __DATA segment (see MakeInc.kernel, lastkernelconstructor is placed 34 * in the __LAST segment.) 35 * 36 * This blank page allows us to safely map the const section RO while the rest 37 * of __DATA is RW. This is needed since ld has no way of specifying section size 38 * alignment and no straight forward way to specify section ordering. 39 */ 40 41 #if defined(__arm64__) 42 /* PAGE_SIZE on ARM64 is an expression derived from a non-const global variable */ 43 #define PAD_SIZE PAGE_MAX_SIZE 44 #else 45 #define PAD_SIZE PAGE_SIZE 46 #endif 47 48 static const uint8_t __attribute__((section("__DATA,__const"))) data_const_padding[PAD_SIZE] = {[0 ... PAD_SIZE - 1] = 0xFF}; 49 const vm_offset_t __attribute__((section("__DATA,__data"))) _lastkerneldataconst = (vm_offset_t)&data_const_padding[0]; 50 const vm_size_t __attribute__((section("__DATA,__data"))) _lastkerneldataconst_padsize = sizeof(data_const_padding); 51