1 /* Copyright (C) 2001, 2002, 2003, 2004, 2005 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 #define CLONE_VM 0x00000100
30 #define CLONE_THREAD 0x00010000
32 /* The userland implementation is:
33 int clone (int (*fn)(void *arg), void *child_stack, int flags, void *arg),
35 int clone (long flags, void *child_stack).
37 The parameters are passed in register and on the stack from userland:
42 r8d: TID field in parent
44 %esp+8: TID field in child
47 rax: system call number
50 rdx: TID field in parent
51 r10: TID field in child
56 ENTRY (BP_SYM (__clone))
57 /* Sanity check arguments. */
59 testq %rdi,%rdi /* no NULL function pointers */
60 jz SYSCALL_ERROR_LABEL
61 testq %rsi,%rsi /* no NULL stack pointers */
62 jz SYSCALL_ERROR_LABEL
64 /* Insert the argument onto the new stack. */
68 /* Save the function pointer. It will be popped off in the
69 child in the ebx frobbing below. */
72 /* Do the system call. */
77 movl $SYS_ify(clone),%eax
79 /* End FDE now, because in the child the unwind info will be
85 jl SYSCALL_ERROR_LABEL
93 /* Clearing frame pointer is insufficient, use CFI. */
95 /* Clear the frame pointer. The ABI suggests this be done, to mark
96 the outermost frame obviously. */
100 testq $CLONE_THREAD, %rdi
102 testq $CLONE_VM, %rdi
105 movl $SYS_ify(getpid), %eax
107 2: movl %eax, %fs:PID
112 /* Set up arguments for the function call. */
113 popq %rax /* Function to call. */
114 popq %rdi /* Argument. */
116 /* Call exit with return value from function call. */
118 call HIDDEN_JUMPTARGET (_exit)
122 PSEUDO_END (BP_SYM (__clone))
124 weak_alias (BP_SYM (__clone), BP_SYM (clone))