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/* Wrapper around clone system call.
   Copyright (C) 1997, 1998, 1999, 2000 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include "ppc_asm.h"
#define _ERRNO_H        1
#include <bits/errno.h>
#include <sys/syscall.h>

/* This is the only really unusual system call in PPC linux, but not
   because of any weirdness in the system call itself; because of
   all the freaky stuff we have to do to make the call useful.  */

/* int [r3] clone(int (*fn)(void *arg) [r3], void *child_stack [r4],
                  int flags [r5], void *arg [r6]); */

#ifdef __NR_clone
.globl      __clone;
.type      __clone, @function;
.align  2;


__clone:
        /* Check for child_stack == NULL || fn == NULL.  */
        cmpwi   cr0,r4,0
        cmpwi   cr1,r3,0
        cror    cr0*4+eq,cr1*4+eq,cr0*4+eq
        beq-    cr0,.Lbadargs

        /* Set up stack frame for parent.  */
        stwu    r1,-32(r1)
        stmw    r29,16(r1)
        
        /* Set up stack frame for child.  */
        clrrwi  r4,r4,4
        li      r0,0
        stwu    r0,-16(r4)

        /* Save fn, args, stack across syscall.  */
        mr      r29,r3                  /* Function in r29.  */
        mr      r30,r4                  /* Stack pointer in r30.  */
        mr      r31,r6                  /* Argument in r31.  */

        /* 'flags' argument is first parameter to clone syscall. (The other
           argument is the stack pointer, already in r4.)  */
        mr      r3,r5

        /* Do the call.  */
        li 0, __NR_clone
        sc

        /* Check for child process.  */
        cmpwi   cr1,r3,0
        crandc  cr1*4+eq,cr1*4+eq,cr0*4+so
        bne-    cr1,.Lparent            /* The '-' is to minimise the race.  */

        /* On at least mklinux DR3a5, clone() doesn't actually change
           the stack pointer.  I'm pretty sure this is a bug, because
           it adds a race condition if a signal is sent to a thread
           just after it is created (in the previous three instructions).  */
        mr      r1,r30
        /* Call procedure.  */
        mtctr   r29
        mr      r3,r31
        bctrl
        /* Call _exit with result from procedure.  */
#ifdef __PIC__
        b       _exit@plt
#else
        b       _exit
#endif

.Lparent:
        /* Parent.  Restore registers & return.  */
        lmw     r29,16(r1)
        addi    r1,r1,32
        bnslr+
#ifdef __PIC__
        b       __syscall_error@plt
#else
        b       __syscall_error
#endif

.Lbadargs:
        li      r3,EINVAL
#ifdef __PIC__
        b       __syscall_error@plt
#else
        b       __syscall_error
#endif

.size __clone,.-__clone
.weak clone;
clone=__clone
#endif