1 /* Copyright (C) 2001 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, write to the Free
16 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19 /* clone() is even more special than fork() as it mucks with stacks
20 and invokes a function in the right context after its all over. */
24 #include <bits/errno.h>
25 #include <asm-syntax.h>
29 /* The userland implementation is:
30 int clone (int (*fn)(void *arg), void *child_stack, int flags, void *arg),
32 int clone (long flags, void *child_stack).
34 The parameters are passed in register from userland:
41 rax: system call number
47 ENTRY (BP_SYM (__clone))
48 /* Sanity check arguments. */
50 testq %rdi,%rdi /* no NULL function pointers */
51 jz SYSCALL_ERROR_LABEL
52 testq %rsi,%rsi /* no NULL stack pointers */
53 jz SYSCALL_ERROR_LABEL
55 /* Insert the argument onto the new stack. */
59 /* Save the function pointer. It will be popped off in the
60 child in the ebx frobbing below. */
63 /* Do the system call. */
65 movq $SYS_ify(clone),%rax
69 jl SYSCALL_ERROR_LABEL
76 /* Set up arguments for the function call. */
77 popq %rax /* Function to call. */
78 popq %rdi /* Argument. */
80 /* Call exit with return value from function call. */
82 call JUMPTARGET (_exit)
84 PSEUDO_END (BP_SYM (__clone))
86 weak_alias (BP_SYM (__clone), BP_SYM (clone))