1 /*
2 * Copyright (c) 2025 Apple Computer, 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 #include <mach/vm_param.h>
29 #include <stdint.h>
30
31 #define _STR(X) #X
32 #define STR(X) _STR(X)
33
34 void start() asm ("start");
35
36 /*
37 * A library-free routine to return the number of bytes in a pointer. This
38 * allows us to test the kernel loader policy without having an external
39 * dependency on dyld and/or the presence of a slice in a library dependency
40 * (which it often does not, even if the kernel supports the policy).
41 *
42 * No C code. The stack is not guaranteed to be aligned yet.
43 */
44 __attribute__((naked, noreturn))
45 void
start()46 start()
47 {
48 /* exit(__WORDSIZE/8) */
49 asm volatile (
50 "mov x0, " STR(__WORDSIZE/8) "\n"
51 "mov x16, #1\n"
52 "svc #(" STR(SWI_SYSCALL) ")\n");
53 }
54