1 /* Startup code for ARM & ELF
2 Copyright (C) 1995, 1996, 1997, 1998, 2001, 2002, 2005, 2008
3 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 In addition to the permissions in the GNU Lesser General Public
12 License, the Free Software Foundation gives you unlimited
13 permission to link the compiled version of this file with other
14 programs, and to distribute those programs without any restriction
15 coming from the use of this file. (The GNU Lesser General Public
16 License restrictions do apply in other respects; for example, they
17 cover modification of the file, and distribution when not linked
18 into another program.)
20 Note that people who make modified versions of this file are not
21 obligated to grant this special exception for their modified
22 versions; it is their choice whether to do so. The GNU Lesser
23 General Public License gives permission to release a modified
24 version without this exception; this exception also makes it
25 possible to release a modified version which carries forward this
28 The GNU C Library is distributed in the hope that it will be useful,
29 but WITHOUT ANY WARRANTY; without even the implied warranty of
30 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
31 Lesser General Public License for more details.
33 You should have received a copy of the GNU Lesser General Public
34 License along with the GNU C Library; if not, write to the Free
35 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
38 /* This is the canonical entry point, usually the first thing in the text
41 Note that the code in the .init section has already been run.
42 This includes _init and _libc_init
45 At this entry point, most registers' values are unspecified, except:
47 a1 Contains a function pointer to be registered with `atexit'.
48 This is how the dynamic linker arranges to have DT_FINI
49 functions called for shared libraries that have been loaded
50 before this code runs.
52 sp The stack contains the arguments and environment:
57 (4*(argc+1))(sp) envp[0]
62 #if defined(__ARM_EABI__)
63 /* Tag_ABI_align8_preserved: This code preserves 8-byte
64 alignment in any callee. */
66 /* Tag_ABI_align8_needed: This code may require 8-byte alignment from
71 #if defined(__thumb2__)
78 .type _start,#function
80 #if !defined(__USING_SJLJ_EXCEPTIONS__)
81 /* Protect against unhandled exceptions. */
84 /* Clear the frame pointer and link register since this is the outermost frame. */
88 /* Pop argc off the stack and save a pointer to argv */
92 /* Push stack limit */
103 ldr ip, .L_GOT+4 /* __libc_csu_fini */
106 str ip, [sp, #-4]! /* Push __libc_csu_fini */
108 ldr a4, .L_GOT+8 /* __libc_csu_init */
111 ldr a1, .L_GOT+12 /* main */
114 /* __libc_start_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
115 /* Let the libc call main and exit with its return code. */
116 bl __libc_start_main(PLT)
118 /* Fetch address of __libc_csu_fini */
119 ldr ip, =__libc_csu_fini
121 /* Push __libc_csu_fini */
124 /* Set up the other arguments in registers */
126 ldr a4, =__libc_csu_init
128 /* __libc_start_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
129 /* Let the libc call main and exit with its return code. */
133 /* should never get here....*/
139 .word _GLOBAL_OFFSET_TABLE_ - .L_GOT
140 .word __libc_csu_fini(GOT)
141 .word __libc_csu_init(GOT)
146 #if !defined(__USING_SJLJ_EXCEPTIONS__)
151 /* Define a symbol for the first piece of initialized data. */
157 data_start = __data_start