/* Copyright (C) 2005-2018 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

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

#include <sysdep.h>

#define _ERRNO_H        1

#include <bits/errno.h>

#include <tcb-offsets.h>

/* Clone the calling process, but without copying the whole address space.

   The calling process is suspended until the new process exits or is

   replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,

   and the process ID of the new process to the old process.  */

.Lthread_start:						ASM_LINE_SEP

	/* r26, r25, r24, r23 are free since vfork has no arguments */

ENTRY(__vfork)

	/* We must not create a frame. When the child unwinds to call

	   exec it will clobber the same frame that the parent

	   needs to unwind.  */

	/* Save the PIC register. */

#ifdef PIC

	copy	%r19, %r25	/* parent */

#endif

	/* Syscall saves and restores all register states */

	ble	0x100(%sr2,%r0)

	ldi	__NR_vfork,%r20

	/* Check for error */

	ldi	-4096,%r1

	comclr,>>= %r1,%ret0,%r0        /* Note: unsigned compare. */

	b,n	.Lerror

	/* Return, and DO NOT restore rp. The child may have called

	   functions that updated the frame's rp. This works because

	   the kernel ensures rp is preserved across the vfork

	   syscall.  */

	bv,n	%r0(%rp)

.Lerror:

	/* Now we need a stack to call a function. We are assured

	   that there is no child now, so it's safe to create

	   a frame.  */

	stw	%rp, -20(%sp)

	.cfi_offset 2, -20

	stwm	%r3, 64(%sp)

	.cfi_def_cfa_offset -64

	.cfi_offset 3, 0

	stw	%sp, -4(%sp)

	sub	%r0,%ret0,%r3

	SYSCALL_ERROR_HANDLER

	/* Restore the PIC register (in delay slot) on error */

#ifdef PIC

	copy	%r25, %r19    /* parent */

#else

	nop

#endif

	/* Write syscall return into errno location */

	stw	%r3, 0(%ret0)

	ldw	-84(%sp), %rp

	bv	%r0(%rp)

	ldwm	-64(%sp), %r3

PSEUDO_END (__vfork)

libc_hidden_def (__vfork)

weak_alias (__vfork, vfork)