/* Copyright (C) 1996-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by David Mosberger <davidm@azstarnet.com>, 1996.

   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

   <http://www.gnu.org/licenses/>.  */

#include <sysdep.h>

/*

 * This is for COMPATIBILITY with Linux/x86 only.  Linux/Alpha system

 * calls return an error indication in a3.  This allows arbitrary 64bit

 * values to be returned in v0 (because negative values are not

 * mistaken as error numbers).  However, C allows only one value to

 * be returned, so the interface below folds the error indication passed in

 * a3 back into v0: it sets v0 to -errno if an error occurs.  Thus,

 * no negative 64bit numbers can be returned.  To avoid this problem,

 * use assembly stubs wherever possible/convenient.

 *

 * Usage:

 *

 * long	syscall(syscall_number, arg1, arg2, arg3, arg4, arg5, arg6)

 *

 * syscall_number = the index of the system call we're invoking

 * arg1-arg6 = up to 6 integer arguments to the system call

 *

 * We need to do some arg shifting: the kernel expects the

 * syscall number in v0 and the first six args in a0-a5.

 *

 */

LEAF(__syscall, 0)

#ifdef PROF

	ldgp	gp, 0(pv)

	.set noat

	lda	AT, _mcount

	jsr	AT, (AT), _mcount

	.set at

	.prologue 1

#else

	.prologue 0

#endif

	mov	a0, v0		/* Syscall number -> v0 */

	mov	a1, a0		/* arg1-arg5 -> a0-a4 */

	mov	a2, a1

	mov	a3, a2

	mov	a4, a3

	mov	a5, a4

	ldq	a5,0(sp)	/* arg6 -> a5 */

	call_pal PAL_callsys	/* Invoke system call */

	bne	a3, SYSCALL_ERROR_LABEL

	ret

PSEUDO_END(__syscall)

weak_alias (__syscall, syscall)