1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <private/bionic_asm.h>
30
31// pid_t __bionic_clone(int flags, void* child_stack, pid_t* parent_tid, void* tls, pid_t* child_tid, int (*fn)(void*), void* arg);
32ENTRY_PRIVATE(__bionic_clone)
33        # Copy 'fn' and 'arg' onto the child stack.
34        movq    %r9, -16(%rsi)  # fn
35        movq    8(%rsp), %rax   # Read 'arg'.
36        movq    %rax, -8(%rsi)  # Write 'arg'.
37
38        subq    $16, %rsi
39
40        # Translate to the kernel calling convention and swap the 'tls' and 'child_tid' arguments.
41        # They're flipped for x86-64 compared to all our other architectures and __bionic_clone.
42        movq    %r8, %r10
43        movq    %rcx, %r8
44
45        # Make the system call.
46        movl    $__NR_clone, %eax
47        syscall
48
49        # Check result.
50        testq   %rax, %rax
51        jz      .L_bc_child
52        jg      .L_bc_parent
53
54        # An error occurred, set errno and return -1.
55        negl    %eax
56        movl    %eax, %edi
57        call    __set_errno_internal
58        ret
59
60.L_bc_child:
61        # We don't want anyone to unwind past this point.
62        .cfi_undefined %rip
63        .cfi_undefined %rbp
64
65        # We're in the child now, so call __start_thread
66        # with the arguments from the child stack moved into
67        # the appropriate registers.
68        popq    %rdi  # fn
69        popq    %rsi  # arg
70        call    __start_thread
71        hlt
72
73.L_bc_parent:
74        # We're the parent; nothing to do.
75        ret
76END(__bionic_clone)
77