1/* Copyright (C) 1996-2022 Free Software Foundation, Inc.
2   This file is part of the GNU C Library.
3
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.
8
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.
13
14   You should have received a copy of the GNU Lesser General Public
15   License along with the GNU C Library.  If not, see
16   <https://www.gnu.org/licenses/>.  */
17
18/* clone() is even more special than fork() as it mucks with stacks
19   and invokes a function in the right context after its all over.  */
20
21#include <sysdep.h>
22#define _ERRNO_H	1
23#include <bits/errno.h>
24
25/* int clone(int (*fn)(void *arg), void *child_stack, int flags,
26	     void *arg, pid_t *ptid, void *tls, pid_t *ctid);
27
28   Note that everything past ARG is technically optional, based
29   on FLAGS, and that CTID is arg 7, and thus is on the stack.
30   However, since a load from top-of-stack better be legal always,
31   we don't bother checking FLAGS.  */
32
33        .text
34	.align	4
35	.globl	__clone
36	.ent	__clone
37	.usepv	__clone, USEPV_PROF
38
39	cfi_startproc
40__clone:
41#ifdef PROF
42	.set noat
43	ldgp	gp,0(pv)
44	lda	AT, _mcount
45	jsr	AT, (AT), _mcount
46	.set at
47#endif
48
49	/* Sanity check arguments.  */
50	ldiq	v0, EINVAL
51	beq	a0, SYSCALL_ERROR_LABEL	/* no NULL function pointers */
52	beq	a1, SYSCALL_ERROR_LABEL	/* no NULL stack pointers */
53
54	/* Save the fn ptr and arg on the new stack.  */
55	subq	a1, 32, a1
56	stq	a0, 0(a1)
57	stq	a3, 8(a1)
58	stq	a2, 16(a1)
59
60	/* The syscall is of the form clone(flags, usp, ptid, ctid, tls).
61	   Shift the flags, ptid, ctid, tls arguments into place; the
62	   child_stack argument is already correct.  */
63	mov	a2, a0
64	mov	a4, a2
65	ldq	a3, 0(sp)
66	mov	a5, a4
67
68	/* Do the system call.  */
69	ldiq	v0, __NR_clone
70	call_pal PAL_callsys
71
72	bne	a3, SYSCALL_ERROR_LABEL
73	beq	v0, thread_start
74
75	/* Successful return from the parent.  */
76	ret
77
78PSEUDO_END(__clone)
79	cfi_endproc
80
81/* Load up the arguments to the function.  Put this block of code in
82   its own function so that we can terminate the stack trace with our
83   debug info.  */
84
85	.align	4
86	.ent thread_start
87	cfi_startproc
88thread_start:
89	mov	0, fp
90	cfi_def_cfa_register(fp)
91	cfi_undefined(ra)
92
93	/* Load up the arguments.  */
94	ldq	pv, 0(sp)
95	ldq	a0, 8(sp)
96	addq	sp, 32, sp
97
98	/* Call the user's function.  */
99	jsr	ra, (pv)
100	ldgp	gp, 0(ra)
101
102	mov     v0, a0
103	ldiq	v0, __NR_exit
104	call_pal PAL_callsys
105
106	/* Die horribly.  */
107	.align	4
108	halt
109
110	.align	4
111	cfi_endproc
112	.end thread_start
113
114libc_hidden_def (__clone)
115weak_alias (__clone, clone)
116