1 /* Out-of-line LSE atomics for AArch64 architecture, Init.
2 Copyright (C) 2019-2021 Free Software Foundation, Inc.
3 Contributed by Linaro Ltd.
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
11
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
20
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
25
26 #include "auto-target.h"
27
28 /* Define the symbol gating the LSE implementations. */
29 _Bool __aarch64_have_lse_atomics
30 __attribute__((visibility("hidden"), nocommon));
31
32 /* Gate availability of __getauxval on glibc. All AArch64-supporting glibc
33 versions support it. */
34 #ifdef __gnu_linux__
35
36 # define AT_HWCAP 16
37 # define HWCAP_ATOMICS (1 << 8)
38
39 unsigned long int __getauxval (unsigned long int);
40
41 static void __attribute__((constructor))
init_have_lse_atomics(void)42 init_have_lse_atomics (void)
43 {
44 unsigned long hwcap = __getauxval (AT_HWCAP);
45 __aarch64_have_lse_atomics = (hwcap & HWCAP_ATOMICS) != 0;
46 }
47
48 #endif /* __gnu_linux__ */
49