78 lines
2.3 KiB
ArmAsm
78 lines
2.3 KiB
ArmAsm
/* Copyright (C) 1996 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by David Mosberger <davidm@azstarnet.com>, 1996.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <sysdep.h>
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/*
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* This is for COMPATIBILITY with Linux/x86 only. Linux/Alpha system
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* calls return an error indication in a3. This allows to return
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* arbitrary 64bit values in v0 (because negative values are not
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* mistaken as error numbers). However, C allows to return only one
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* value so the interface below folds the error indication passed in
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* a3 back into v0: it sets v0 to -errno if an error occurs. Thus,
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* no negative 64bit numbers can be returned. To avoid this problem,
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* use assembly stubs wherever possible/convenient.
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*
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* Usage:
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*
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* long syscall(syscall_number, arg1, arg2, arg3, arg4, arg5)
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*
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* syscall_number = the index of the system call we're invoking
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* arg1-arg5 = up to 5 integer arguments to the system call
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*
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* We need to do some arg shifting: the kernel expects the
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* syscall number in v0 and the first five args in a0-a4.
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*
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*/
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LEAF(__syscall, 0)
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#ifdef PROF
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ldgp gp, 0(pv)
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.set noat
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lda AT, _mcount
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jsr AT, (AT), _mcount
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.set at
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.prologue 1
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#else
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.prologue 0
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#endif
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mov a0, v0 /* Syscall number -> v0 */
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mov a1, a0 /* arg1-arg5 -> a0-a4 */
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mov a2, a1
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mov a3, a2
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mov a4, a3
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mov a5, a4
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call_pal PAL_callsys /* Invoke system call */
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bne a3, error
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ret
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error:
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#ifndef PROF
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br gp, 2f
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2: ldgp gp, 0(gp)
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#endif
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jmp zero, __syscall_error
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END(__syscall)
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weak_alias(__syscall, syscall)
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