1 /* Copyright (C) 1996-2015 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
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>
26 #define CLONE_VM_BIT 8
27 #define CLONE_VM (1 << CLONE_VM_BIT)
29 #define CLONE_THREAD_BIT 16
30 #define CLONE_THREAD (1 << CLONE_THREAD_BIT)
32 /* int clone(int (*fn)(void *arg), x0
37 struct user_desc *tls, x5
42 /* Save args for the child. */
47 /* Sanity check args. */
49 cbz x10, .Lsyscall_error
50 cbz x1, .Lsyscall_error
52 /* Do the system call. */
53 /* X0:flags, x1:newsp, x2:parenttidptr, x3:newtls, x4:childtid. */
54 mov x0, x2 /* flags */
55 /* New sp is already in x1. */
59 mov x8, #SYS_ify(clone)
69 .type thread_start, %function
75 tbnz x11, #CLONE_THREAD_BIT, 3f
77 tbnz x11, #CLONE_VM_BIT, 2f
78 mov x8, #SYS_ify(getpid)
82 sub x1, x1, #PTHREAD_SIZEOF
83 str w0, [x1, #PTHREAD_PID_OFFSET]
84 str w0, [x1, #PTHREAD_TID_OFFSET]
87 /* Pick the function arg and execute. */
91 /* We are done, pass the return value through x0. */
92 b HIDDEN_JUMPTARGET(_exit)
94 .size thread_start, .-thread_start
96 weak_alias (__clone, clone)