xref: /freebsd-14.2/lib/libc/amd64/gen/rfork_thread.S (revision 1d386b48)
1/*-
2 * Copyright (c) 2000 Peter Wemm <[email protected]>
3 * Copyright (c) 2003 Alan L. Cox <[email protected]>
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	movq	$SYS_rfork, %rax
55	KERNCALL
56	jb 	2f
57
58	/*
59	 * Check to see if we are in the parent or child
60	 */
61	cmpl	$0, %edx
62	jnz	1f
63	popq	%r12
64	popq	%rbx
65	ret
66
67	/*
68	 * If we are in the child (new thread), then
69	 * set-up the call to the internal subroutine.  If it
70	 * returns, then call __exit.
71	 */
721:
73	movq	%rsi, %rsp
74	movq	%r12, %rdi
75	call	*%rbx
76	movl	%eax, %edi
77
78	/*
79	 * Exit system call
80	 */
81	movq	$SYS_exit, %rax
82	KERNCALL
83
84	/*
85	 * Branch here if the thread creation fails:
86	 */
872:
88	popq	%r12
89	popq	%rbx
90	jmp	HIDENAME(cerror)
91END(rfork_thread)
92
93	.section .note.GNU-stack,"",%progbits
94