glibc/sysdeps/unix/sysv/linux/mips/vfork.S

/* Copyright (C) 2005-2015 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/>.  */

/* vfork() is just a special case of clone().  */

#include <sys/asm.h>
#include <sysdep.h>
#include <asm/unistd.h>
#include <sgidefs.h>
#include <tls.h>


/* int vfork() */

	.text
	.set		nomips16
LOCALSZ= 1
FRAMESZ= (((NARGSAVE+LOCALSZ)*SZREG)+ALSZ)&ALMASK
GPOFF= FRAMESZ-(1*SZREG)
NESTED(__vfork,FRAMESZ,sp)
#ifdef __PIC__
	SETUP_GP
#endif
	PTR_SUBU sp, FRAMESZ
	cfi_adjust_cfa_offset (FRAMESZ)
	SETUP_GP64_REG (a5, __vfork)
#ifdef __PIC__
	SAVE_GP (GPOFF)
#endif
#ifdef PROF
# if (_MIPS_SIM != _ABIO32)
	PTR_S		a5, GPOFF(sp)
# endif
	.set		noat
	move		$1, ra
# if (_MIPS_SIM == _ABIO32)
	subu		sp,sp,8
# endif
	jal		_mcount
	.set		at
# if (_MIPS_SIM != _ABIO32)
	PTR_L		a5, GPOFF(sp)
# endif
#endif

	PTR_ADDU	sp, FRAMESZ
	cfi_adjust_cfa_offset (-FRAMESZ)

	/* Save the PID value.  */
	READ_THREAD_POINTER(v1)	   /* Get the thread pointer.  */
	lw	a2, PID_OFFSET(v1) /* Load the saved PID.  */
	subu	a2, $0, a2	   /* Negate it.  */
	bnez	a2, 1f		   /* If it was zero... */
	lui	a2, 0x8000	   /* use 0x80000000 instead.  */
1:	sw	a2, PID_OFFSET(v1) /* Store the temporary PID.  */

	li		a0, 0x4112	/* CLONE_VM | CLONE_VFORK | SIGCHLD */
	move		a1, sp

	/* Do the system call */
	li		v0,__NR_clone
	syscall

	/* Restore the old PID value in the parent.  */
	beqz	v0, 1f		/* If we are the parent... */
	READ_THREAD_POINTER(v1)	/* Get the thread pointer.  */
	lw	a2, PID_OFFSET(v1) /* Load the saved PID.  */
	subu	a2, $0, a2	   /* Re-negate it.  */
	lui	a0, 0x8000	   /* Load 0x80000000... */
	bne	a2, a0, 2f	   /* ... compare against it... */
	li	a2, 0		   /* ... use 0 instead.  */
2:	sw	a2, PID_OFFSET(v1) /* Restore the PID.  */
1:

	cfi_remember_state
	bnez		a3,L(error)

	/* Successful return from the parent or child.  */
	RESTORE_GP64_REG
	ret

	/* Something bad happened -- no child created.  */
L(error):
	cfi_restore_state
#ifdef __PIC__
	PTR_LA		t9, __syscall_error
	RESTORE_GP64_REG
	jr		t9
#else
	RESTORE_GP64_REG
	j		__syscall_error
#endif
	END(__vfork)

libc_hidden_def(__vfork)
weak_alias (__vfork, vfork)
strong_alias (__vfork, __libc_vfork)