1/* Copyright (C) 1995-2021 Free Software Foundation, Inc.
2
3   This file is part of the GNU C Library.
4
5   The GNU C Library is free software; you can redistribute it and/or
6   modify it under the terms of the GNU Lesser General Public License as
7   published by the Free Software Foundation; either version 2.1 of the
8   License, or (at your option) any later version.
9
10   The GNU C Library is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   Lesser General Public License for more details.
14
15   You should have received a copy of the GNU Lesser General Public
16   License along with the GNU C Library.  If not, see
17   <https://www.gnu.org/licenses/>.  */
18
19#include <sysdep.h>
20
21/* This is the canonical entry point, usually the first thing in the text
22   segment.
23
24   Note that the code in the .init section has already been run.
25   This includes _init and _libc_init
26
27
28   At this entry point, most registers' values are unspecified, except:
29
30   x0/w0	Contains a function pointer to be registered with `atexit'.
31		This is how the dynamic linker arranges to have DT_FINI
32		functions called for shared libraries that have been loaded
33		before this code runs.
34
35   sp		The stack contains the arguments and environment:
36		0(sp)			argc
37		8(sp)			argv[0]
38		...
39		(8*argc)(sp)		NULL
40		(8*(argc+1))(sp)	envp[0]
41		...
42					NULL
43 */
44
45	.text
46ENTRY(_start)
47	/* Create an initial frame with 0 LR and FP */
48	cfi_undefined (x30)
49	mov	x29, #0
50	mov	x30, #0
51
52	/* Setup rtld_fini in argument register */
53	mov	x5, x0
54
55	/* Load argc and a pointer to argv */
56	ldr	PTR_REG (1), [sp, #0]
57	add	x2, sp, #PTR_SIZE
58
59	/* Setup stack limit in argument register */
60	mov	x6, sp
61
62#ifdef PIC
63# ifdef SHARED
64        adrp    x0, :got:main
65	ldr     PTR_REG (0), [x0, #:got_lo12:main]
66# else
67	adrp	x0, __wrap_main
68	add	x0, x0, :lo12:__wrap_main
69# endif
70#else
71	/* Set up the other arguments in registers */
72	MOVL (0, main)
73#endif
74	mov	x3, #0		/* Used to be init.  */
75	mov	x4, #0		/* Used to be fini.  */
76
77	/* __libc_start_main (main, argc, argv, init, fini, rtld_fini,
78			      stack_end) */
79
80	/* Let the libc call main and exit with its return code.  */
81	bl	__libc_start_main
82
83	/* should never get here....*/
84	bl	abort
85
86#if defined PIC && !defined SHARED
87	/* When main is not defined in the executable but in a shared library
88	   then a wrapper is needed in crt1.o of the static-pie enabled libc,
89	   because crt1.o and rcrt1.o share code and the later must avoid the
90	   use of GOT relocations before __libc_start_main is called.  */
91__wrap_main:
92	BTI_C
93	b	main
94#endif
95END(_start)
96
97	/* Define a symbol for the first piece of initialized data.  */
98	.data
99	.globl __data_start
100__data_start:
101	.long 0
102	.weak data_start
103	data_start = __data_start
104