xref: /freebsd/lib/libsys/amd64/rfork_thread.S (revision cdecda8da32b67f2be34a4d2ea37f90986a45a00)
1/*-
2 * Copyright (c) 2000 Peter Wemm <peter@FreeBSD.org>
3 * Copyright (c) 2003 Alan L. Cox <alc@cs.rice.edu>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <machine/asm.h>
29/*
30 * With thanks to John Dyson for the original version of this.
31 */
32
33#include <SYS.h>
34
35/*
36 *              %edi   %rsi        %rdx       %rcx
37 * rfork_thread(flags, stack_addr, start_fnc, start_arg);
38 *
39 * flags:		Flags to rfork system call.  See rfork(2).
40 * stack_addr:		Top of stack for thread.
41 * start_fnc:		Address of thread function to call in child.
42 * start_arg:		Argument to pass to the thread function in child.
43 */
44
45ENTRY(rfork_thread)
46	pushq	%rbx
47	pushq	%r12
48	movq	%rdx, %rbx
49	movq	%rcx, %r12
50
51	/*
52	 * Prepare and execute the thread creation syscall
53	 */
54	_SYSCALL(rfork)
55	jb 	2f
56
57	/*
58	 * Check to see if we are in the parent or child
59	 */
60	cmpl	$0, %edx
61	jnz	1f
62	popq	%r12
63	popq	%rbx
64	ret
65
66	/*
67	 * If we are in the child (new thread), then
68	 * set-up the call to the internal subroutine.  If it
69	 * returns, then call __exit.
70	 */
711:
72	movq	%rsi, %rsp
73	movq	%r12, %rdi
74	call	*%rbx
75	movl	%eax, %edi
76
77	/*
78	 * Exit system call
79	 */
80	_SYSCALL(exit)
81
82	/*
83	 * Branch here if the thread creation fails:
84	 */
852:
86	popq	%r12
87	popq	%rbx
88	jmp	HIDENAME(cerror)
89END(rfork_thread)
90
91	.section .note.GNU-stack,"",%progbits
92