xref: /xnu-8796.101.5/libsa/lastkerneldataconst.c (revision aca3beaa3dfbd42498b42c5e5ce20a938e6554e5)
1*aca3beaaSApple OSS Distributions /*
2*aca3beaaSApple OSS Distributions  * Copyright (c) 2014 Apple Inc. All rights reserved.
3*aca3beaaSApple OSS Distributions  *
4*aca3beaaSApple OSS Distributions  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5*aca3beaaSApple OSS Distributions  *
6*aca3beaaSApple OSS Distributions  * This file contains Original Code and/or Modifications of Original Code
7*aca3beaaSApple OSS Distributions  * as defined in and that are subject to the Apple Public Source License
8*aca3beaaSApple OSS Distributions  * Version 2.0 (the 'License'). You may not use this file except in
9*aca3beaaSApple OSS Distributions  * compliance with the License. The rights granted to you under the License
10*aca3beaaSApple OSS Distributions  * may not be used to create, or enable the creation or redistribution of,
11*aca3beaaSApple OSS Distributions  * unlawful or unlicensed copies of an Apple operating system, or to
12*aca3beaaSApple OSS Distributions  * circumvent, violate, or enable the circumvention or violation of, any
13*aca3beaaSApple OSS Distributions  * terms of an Apple operating system software license agreement.
14*aca3beaaSApple OSS Distributions  *
15*aca3beaaSApple OSS Distributions  * Please obtain a copy of the License at
16*aca3beaaSApple OSS Distributions  * http://www.opensource.apple.com/apsl/ and read it before using this file.
17*aca3beaaSApple OSS Distributions  *
18*aca3beaaSApple OSS Distributions  * The Original Code and all software distributed under the License are
19*aca3beaaSApple OSS Distributions  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20*aca3beaaSApple OSS Distributions  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21*aca3beaaSApple OSS Distributions  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22*aca3beaaSApple OSS Distributions  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23*aca3beaaSApple OSS Distributions  * Please see the License for the specific language governing rights and
24*aca3beaaSApple OSS Distributions  * limitations under the License.
25*aca3beaaSApple OSS Distributions  *
26*aca3beaaSApple OSS Distributions  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27*aca3beaaSApple OSS Distributions  */
28*aca3beaaSApple OSS Distributions 
29*aca3beaaSApple OSS Distributions #include <mach/vm_param.h>
30*aca3beaaSApple OSS Distributions 
31*aca3beaaSApple OSS Distributions /*
32*aca3beaaSApple OSS Distributions  * This file is compiled and linked to be the last .o of the __const section
33*aca3beaaSApple OSS Distributions  * of the __DATA segment (see MakeInc.kernel, lastkernelconstructor is placed
34*aca3beaaSApple OSS Distributions  * in the __LAST segment.)
35*aca3beaaSApple OSS Distributions  *
36*aca3beaaSApple OSS Distributions  * This blank page allows us to safely map the const section RO while the rest
37*aca3beaaSApple OSS Distributions  * of __DATA is RW. This is needed since ld has no way of specifying section size
38*aca3beaaSApple OSS Distributions  * alignment and no straight forward way to specify section ordering.
39*aca3beaaSApple OSS Distributions  */
40*aca3beaaSApple OSS Distributions 
41*aca3beaaSApple OSS Distributions #if defined(__arm64__)
42*aca3beaaSApple OSS Distributions /* PAGE_SIZE on ARM64 is an expression derived from a non-const global variable */
43*aca3beaaSApple OSS Distributions #define PAD_SIZE        PAGE_MAX_SIZE
44*aca3beaaSApple OSS Distributions #else
45*aca3beaaSApple OSS Distributions #define PAD_SIZE        PAGE_SIZE
46*aca3beaaSApple OSS Distributions #endif
47*aca3beaaSApple OSS Distributions 
48*aca3beaaSApple OSS Distributions static const uint8_t __attribute__((section("__DATA,__const"))) data_const_padding[PAD_SIZE] = {[0 ... PAD_SIZE - 1] = 0xFF};
49*aca3beaaSApple OSS Distributions const vm_offset_t    __attribute__((section("__DATA,__data")))  _lastkerneldataconst         = (vm_offset_t)&data_const_padding[0];
50*aca3beaaSApple OSS Distributions const vm_size_t      __attribute__((section("__DATA,__data")))  _lastkerneldataconst_padsize = sizeof(data_const_padding);
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