1/* Special .init and .fini section support for Alpha.
2 Copyright (C) 2001-2022 Free Software Foundation, Inc.
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
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 In addition to the permissions in the GNU Lesser General Public
11 License, the Free Software Foundation gives you unlimited
12 permission to link the compiled version of this file with other
13 programs, and to distribute those programs without any restriction
14 coming from the use of this file. (The GNU Lesser General Public
15 License restrictions do apply in other respects; for example, they
16 cover modification of the file, and distribution when not linked
17 into another program.)
18
19 Note that people who make modified versions of this file are not
20 obligated to grant this special exception for their modified
21 versions; it is their choice whether to do so. The GNU Lesser
22 General Public License gives permission to release a modified
23 version without this exception; this exception also makes it
24 possible to release a modified version which carries forward this
25 exception.
26
27 The GNU C Library is distributed in the hope that it will be useful,
28 but WITHOUT ANY WARRANTY; without even the implied warranty of
29 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
30 Lesser General Public License for more details.
31
32 You should have received a copy of the GNU Lesser General Public
33 License along with the GNU C Library. If not, see
34 <https://www.gnu.org/licenses/>. */
35
36/* crti.S puts a function prologue at the beginning of the .init and
37 .fini sections and defines global symbols for those addresses, so
38 they can be called as functions. The symbols _init and _fini are
39 magic and cause the linker to emit DT_INIT and DT_FINI.
40
41 This differs from what would be generated for ordinary code in that
42 we save and restore the GP within the function. In order for linker
43 relaxation to work, the value in the GP register on exit from a function
44 must be valid for the function entry point. Normally, a function is
45 contained within one object file and this is not an issue, provided
46 that the function reloads the gp after making any function calls.
47 However, _init and _fini are constructed from pieces of many object
48 files, all of which may have different GP values. So we must reload
49 the GP value from crti.o in crtn.o. */
50
51#include <libc-symbols.h>
52#include <sysdep.h>
53
54#ifndef PREINIT_FUNCTION
55# define PREINIT_FUNCTION __gmon_start__
56#endif
57
58#ifndef PREINIT_FUNCTION_WEAK
59# define PREINIT_FUNCTION_WEAK 1
60#endif
61
62#if PREINIT_FUNCTION_WEAK
63 weak_extern (PREINIT_FUNCTION)
64#else
65 .hidden PREINIT_FUNCTION
66#endif
67
68 .section .init, "ax", @progbits
69 .globl _init
70 .hidden _init
71 .type _init, @function
72 .usepv _init, std
73_init:
74 ldgp $29, 0($27)
75 subq $30, 16, $30
76#if PREINIT_FUNCTION_WEAK
77 lda $27, PREINIT_FUNCTION
78#endif
79 stq $26, 0($30)
80 stq $29, 8($30)
81#if PREINIT_FUNCTION_WEAK
82 beq $27, 1f
83 jsr $26, ($27), PREINIT_FUNCTION
84 ldq $29, 8($30)
851:
86#else
87 bsr $26, PREINIT_FUNCTION !samegp
88#endif
89 .p2align 3
90
91 .section .fini, "ax", @progbits
92 .globl _fini
93 .hidden _fini
94 .type _fini,@function
95 .usepv _fini,std
96_fini:
97 ldgp $29, 0($27)
98 subq $30, 16, $30
99 stq $26, 0($30)
100 stq $29, 8($30)
101 .p2align 3
102

source code of glibc/sysdeps/alpha/crti.S