1/* Copyright (C) 1996-2018 Free Software Foundation, Inc.
2   Contributed by David Huggins-Daines <dhd@debian.org>, 2000.
3   Based on the Alpha version by Richard Henderson <rth@tamu.edu>, 1996.
4
5   The GNU C Library is free software; you can redistribute it and/or
6   modify it under the terms of the GNU Lesser General Public
7   License as published by the Free Software Foundation; either
8   version 2.1 of the License, or (at your option) any later version.
9
10   The GNU C Library is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   Lesser General Public License for more details.
14
15   You should have received a copy of the GNU Lesser General Public
16   License along with the GNU C Library.  If not, see
17   <http://www.gnu.org/licenses/>.  */
18
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.  */
21
22#include <asm/unistd.h>
23#include <sysdep.h>
24#define _ERRNO_H	1
25#include <bits/errno.h>
26
27/* Non-thread code calls __clone with the following parameters:
28   int clone(int (*fn)(void *arg),
29	     void *child_stack,
30	     int flags,
31	     void *arg)
32
33   NPTL Code will call __clone with the following parameters:
34   int clone(int (*fn)(void *arg),
35	     void *child_stack,
36	     int flags,
37	     void *arg,
38	     int *parent_tidptr,
39	     struct user_desc *newtls,
40	     int *child_pidptr)
41
42   The code should not mangle the extra input registers.
43   Syscall expects:				Input to __clone:
44	4(r25) - function pointer 		(r26, arg0)
45	0(r25) - argument			(r23, arg3)
46	r26 - clone flags.			(r24, arg2)
47	r25+64 - user stack pointer.		(r25, arg1)
48	r24 - parent tid pointer.		(stack - 52)
49	r23 - struct user_desc newtls pointer.	(stack - 56)
50	r22 - child tid pointer.		(stack - 60)
51	r20 - clone syscall number		(constant)
52
53   Return:
54
55	On success the thread ID of the child process is returend in
56	the callers context.
57	On error return -1, and set errno to the value returned by
58	the syscall.
59 */
60
61        .text
62ENTRY(__clone)
63	/* Prologue */
64	stwm	%r4, 64(%sp)
65	.cfi_def_cfa_offset -64
66	.cfi_offset 4, 0
67	stw	%sp, -4(%sp)
68#ifdef __PIC__
69	stw	%r19, -32(%sp)
70	.cfi_offset 19, 32
71#endif
72
73	/* Sanity check arguments.  */
74	comib,=,n  0, %arg0, .LerrorSanity        /* no NULL function pointers */
75	comib,=,n  0, %arg1, .LerrorSanity        /* no NULL stack pointers */
76
77	/* Save the function pointer, arg, and flags on the new stack.  */
78	stwm    %r26, 64(%r25)
79	stw	%r23, -60(%r25)
80	stw     %r24, -56(%r25)
81	/* Clone arguments are (int flags, void * child_stack) */
82	copy	%r24, %r26		/* flags are first */
83	/* User stack pointer is in the correct register already */
84
85	/* Load args from stack... */
86	ldw	-116(%sp), %r24		/* Load parent_tidptr */
87	ldw	-120(%sp), %r23 	/* Load newtls */
88	ldw	-124(%sp), %r22		/* Load child_tidptr */
89
90	/* Save the PIC register. */
91#ifdef __PIC__
92	copy	%r19, %r4		/* parent */
93#endif
94
95	/* Do the system call */
96	ble     0x100(%sr2, %r0)
97	ldi	__NR_clone, %r20
98
99	ldi	-4096, %r1
100	comclr,>>= %r1, %ret0, %r0	/* Note: unsigned compare. */
101	b,n	.LerrorRest
102
103	/* Restore the PIC register.  */
104#ifdef __PIC__
105	copy	%r4, %r19		/* parent */
106#endif
107
108	comib,=,n 0, %ret0, .LthreadStart
109
110	/* Successful return from the parent
111	   No need to restore the PIC register,
112	   since we return immediately. */
113
114	ldw	-84(%sp), %rp
115	bv	%r0(%rp)
116	ldwm	-64(%sp), %r4
117
118.LerrorRest:
119	/* Something bad happened -- no child created */
120	bl	__syscall_error, %rp
121	sub     %r0, %ret0, %arg0
122	ldw	-84(%sp), %rp
123	/* Return after setting errno, ret0 is set to -1 by __syscall_error. */
124	bv	%r0(%rp)
125	ldwm	-64(%sp), %r4
126
127.LerrorSanity:
128	/* Sanity checks failed, return -1, and set errno to EINVAL. */
129	bl	__syscall_error, %rp
130	ldi     EINVAL, %arg0
131	ldw	-84(%sp), %rp
132	bv	%r0(%rp)
133	ldwm	-64(%sp), %r4
134
135.LthreadStart:
136	/* Load up the arguments.  */
137	ldw	-60(%sp), %arg0
138	ldw     -64(%sp), %r22
139
140	/* $$dyncall fixes child's PIC register */
141
142	/* Call the user's function */
143#ifdef __PIC__
144	copy	%r19, %r4
145#endif
146	bl	$$dyncall, %r31
147	copy	%r31, %rp
148#ifdef __PIC__
149	copy	%r4, %r19
150#endif
151	copy	%r28, %r26
152	ble     0x100(%sr2, %r0)
153	ldi	__NR_exit, %r20
154
155	/* We should not return from exit.
156           We do not restore r4, or the stack state.  */
157	iitlbp	%r0, (%sr0, %r0)
158
159PSEUDO_END(__clone)
160
161libc_hidden_def (__clone)
162weak_alias (__clone, clone)
163