glibc/sysdeps/unix/sysv/linux/arm/libc-do-syscall.S

52 lines
1.7 KiB
ArmAsm

/* Copyright (C) 2010-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<https://www.gnu.org/licenses/>. */
/* When this file is built for inclusion in nscd, _FORTIFY_SOURCE is
defined but -O is not used, resulting in a warning from features.h. */
#undef _FORTIFY_SOURCE
#include <sysdep.h>
/* Out-of-line syscall stub. We expect the system call number in ip
and return the raw result in r0. No registers are clobbered.
We could avoid using the stack for this, but the goal is accurate
unwind information - and while there is a reserved prefix in the
ARM unwind tables for register to register moves, the actual opcodes
are not defined. */
#if defined(__thumb__)
.thumb
.syntax unified
.hidden __libc_do_syscall
#undef CALL_MCOUNT
#define CALL_MCOUNT
ENTRY (__libc_do_syscall)
.fnstart
push {r7, lr}
.save {r7, lr}
cfi_adjust_cfa_offset (8)
cfi_rel_offset (r7, 0)
cfi_rel_offset (lr, 4)
mov r7, ip
swi 0x0
pop {r7, pc}
.fnend
END (__libc_do_syscall)
#endif /* __thumb__ */