1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
/* Copyright (C) 1996-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by David Huggins-Daines <dhd@debian.org>, 2000.
Based on the Alpha version by Richard Henderson <rth@tamu.edu>, 1996.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
/* clone() is even more special than fork() as it mucks with stacks
and invokes a function in the right context after its all over. */
#include <asm/unistd.h>
#include <sysdep.h>
#define _ERRNO_H 1
#include <bits/errno.h>
#include <tcb-offsets.h>
/* Non-thread code calls __clone with the following parameters:
int clone(int (*fn)(void *arg),
void *child_stack,
int flags,
void *arg)
NPTL Code will call __clone with the following parameters:
int clone(int (*fn)(void *arg),
void *child_stack,
int flags,
void *arg,
int *parent_tidptr,
struct user_desc *newtls,
int *child_pidptr)
The code should not mangle the extra input registers.
Syscall expects: Input to __clone:
4(r25) - function pointer (r26, arg0)
0(r25) - argument (r23, arg3)
r26 - clone flags. (r24, arg2)
r25+64 - user stack pointer. (r25, arg1)
r24 - parent tid pointer. (stack - 52)
r23 - struct user_desc newtls pointer. (stack - 56)
r22 - child tid pointer. (stack - 60)
r20 - clone syscall number (constant)
Return:
On success the thread ID of the child process is returend in
the callers context.
On error return -1, and set errno to the value returned by
the syscall.
*/
.text
ENTRY(__clone)
/* Prologue */
stwm %r4, 64(%sp)
stw %sp, -4(%sp)
#ifdef PIC
stw %r19, -32(%sp)
#endif
/* Sanity check arguments. */
comib,=,n 0, %arg0, .LerrorSanity /* no NULL function pointers */
comib,=,n 0, %arg1, .LerrorSanity /* no NULL stack pointers */
/* Save the function pointer, arg, and flags on the new stack. */
stwm %r26, 64(%r25)
stw %r23, -60(%r25)
stw %r24, -56(%r25)
/* Clone arguments are (int flags, void * child_stack) */
copy %r24, %r26 /* flags are first */
/* User stack pointer is in the correct register already */
/* Load args from stack... */
ldw -116(%sp), %r24 /* Load parent_tidptr */
ldw -120(%sp), %r23 /* Load newtls */
ldw -124(%sp), %r22 /* Load child_tidptr */
/* Save the PIC register. */
#ifdef PIC
copy %r19, %r4 /* parent */
#endif
/* Do the system call */
ble 0x100(%sr2, %r0)
ldi __NR_clone, %r20
ldi -4096, %r1
comclr,>>= %r1, %ret0, %r0 /* Note: unsigned compare. */
b,n .LerrorRest
/* Restore the PIC register. */
#ifdef PIC
copy %r4, %r19 /* parent */
#endif
comib,=,n 0, %ret0, .LthreadStart
/* Successful return from the parent
No need to restore the PIC register,
since we return immediately. */
ldw -84(%sp), %rp
bv %r0(%rp)
ldwm -64(%sp), %r4
.LerrorRest:
/* Something bad happened -- no child created */
bl __syscall_error, %rp
sub %r0, %ret0, %arg0
ldw -84(%sp), %rp
/* Return after setting errno, ret0 is set to -1 by __syscall_error. */
bv %r0(%rp)
ldwm -64(%sp), %r4
.LerrorSanity:
/* Sanity checks failed, return -1, and set errno to EINVAL. */
bl __syscall_error, %rp
ldi EINVAL, %arg0
ldw -84(%sp), %rp
bv %r0(%rp)
ldwm -64(%sp), %r4
.LthreadStart:
/* Load up the arguments. */
ldw -60(%sp), %arg0
ldw -64(%sp), %r22
/* $$dyncall fixes child's PIC register */
/* Call the user's function */
#ifdef PIC
copy %r19, %r4
#endif
bl $$dyncall, %r31
copy %r31, %rp
#ifdef PIC
copy %r4, %r19
#endif
/* The call to _exit needs saved r19. */
ble 0x100(%sr2, %r0)
ldi __NR_exit, %r20
/* We should not return from exit.
We do not restore r4, or the stack state. */
iitlbp %r0, (%sr0, %r0)
PSEUDO_END(__clone)
libc_hidden_def (__clone)
weak_alias (__clone, clone)
|
