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/* Copyright (C) 2001,02 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. */
/* 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-syntax.h>
#include <bp-sym.h>
#include <bp-asm.h>
/* The userland implementation is:
int clone (int (*fn)(void *arg), void *child_stack, int flags, void *arg),
the kernel entry is:
int clone (long flags, void *child_stack).
The parameters are passed in register from userland:
rdi: fn
rsi: child_stack
rdx: flags
rcx: arg
The kernel expects:
rax: system call number
rdi: flags
rsi: child_stack */
.text
ENTRY (BP_SYM (__clone))
/* Sanity check arguments. */
movq $-EINVAL,%rax
testq %rdi,%rdi /* no NULL function pointers */
jz SYSCALL_ERROR_LABEL
testq %rsi,%rsi /* no NULL stack pointers */
jz SYSCALL_ERROR_LABEL
/* Insert the argument onto the new stack. */
subq $16,%rsi
movq %rcx,8(%rsi)
/* Save the function pointer. It will be popped off in the
child in the ebx frobbing below. */
movq %rdi,0(%rsi)
/* Do the system call. */
movq %rdx, %rdi
movq $SYS_ify(clone),%rax
syscall
testq %rax,%rax
jl SYSCALL_ERROR_LABEL
jz thread_start
L(pseudo_end):
ret
thread_start:
/* Set up arguments for the function call. */
popq %rax /* Function to call. */
popq %rdi /* Argument. */
call *%rax
/* Call exit with return value from function call. */
movq %rax, %rdi
call HIDDEN_JUMPTARGET (_exit)
PSEUDO_END (BP_SYM (__clone))
weak_alias (BP_SYM (__clone), BP_SYM (clone))
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