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/* Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Richard Henderson (rth@tamu.edu)

   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.  */

/* clone() is even more special than fork() as it mucks with stacks
   and invokes a function in the right context after its all over.  */

#include <sysdep.h>
#define _ERRNO_H        1
#include <bits/errno.h>
#include <asm/unistd.h>
#include <bp-sym.h>
#include <bp-asm.h>

/* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg); */

#define PARMS   LINKAGE         /* no space for saved regs */
#define FUNC    PARMS
#define STACK   FUNC+4
#define FLAGS   STACK+PTR_SIZE
#define ARG     FLAGS+4

        .text
ENTRY (BP_SYM (__clone))
        /* Sanity check arguments.  */
        movl    $-EINVAL,%eax
        movl    FUNC(%esp),%ecx         /* no NULL function pointers */
#ifdef PIC
        jecxz   SYSCALL_ERROR_LABEL
#else
        testl   %ecx,%ecx
        jz      SYSCALL_ERROR_LABEL
#endif
        movl    STACK(%esp),%ecx        /* no NULL stack pointers */
#ifdef PIC
        jecxz   SYSCALL_ERROR_LABEL
#else
        testl   %ecx,%ecx
        jz      SYSCALL_ERROR_LABEL
#endif

        /* Insert the argument onto the new stack.  */
        subl    $8,%ecx
        movl    ARG(%esp),%eax          /* no negative argument counts */
        movl    %eax,4(%ecx)

        /* Save the function pointer as the zeroth argument.
           It will be popped off in the child in the ebx frobbing below.  */
        movl    FUNC(%esp),%eax
        movl    %eax,0(%ecx)

        /* Do the system call */
        pushl   %ebx
        movl    FLAGS+4(%esp),%ebx
        movl    $SYS_ify(clone),%eax
        int     $0x80
        popl    %ebx

        test    %eax,%eax
        jl      SYSCALL_ERROR_LABEL
        jz      thread_start

L(pseudo_end):
        ret

thread_start:
        subl    %ebp,%ebp       /* terminate the stack frame */
        call    *%ebx
#ifdef PIC
        call    L(here)
L(here):
        popl    %ebx
        addl    $_GLOBAL_OFFSET_TABLE_+[.-L(here)], %ebx
#endif
        pushl   %eax
        call    JUMPTARGET (_exit)

PSEUDO_END (BP_SYM (__clone))

weak_alias (BP_SYM (__clone), BP_SYM (clone))