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
|
/* Copyright (C) 1996-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Richard Henderson (rth@tamu.edu)
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 <sysdep.h>
#define _ERRNO_H 1
#include <bits/errno.h>
#include <asm-syntax.h>
/* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
pid_t *ptid, struct user_desc *tls, pid_t *ctid); */
#define PARMS 4 /* no space for saved regs */
#define FUNC PARMS
#define STACK FUNC+4
#define FLAGS STACK+4
#define ARG FLAGS+4
#define PTID ARG+4
#define TLS PTID+4
#define CTID TLS+4
#define __NR_clone 120
#define SYS_clone 120
#define CLONE_VM 0x00000100
#define CLONE_THREAD 0x00010000
.text
ENTRY (__clone)
/* Sanity check arguments. */
movl $-EINVAL,%eax
movl FUNC(%esp),%ecx /* no NULL function pointers */
#ifdef PIC
jecxz SYSCALL_ERROR_LABEL
#else
testl %ecx,%ecx
jz SYSCALL_ERROR_LABEL
#endif
movl STACK(%esp),%ecx /* no NULL stack pointers */
#ifdef PIC
jecxz SYSCALL_ERROR_LABEL
#else
testl %ecx,%ecx
jz SYSCALL_ERROR_LABEL
#endif
/* Insert the argument onto the new stack. Make sure the new
thread is started with an alignment of (mod 16). */
andl $0xfffffff0, %ecx
subl $28,%ecx
movl ARG(%esp),%eax /* no negative argument counts */
movl %eax,12(%ecx)
/* Save the function pointer as the zeroth argument.
It will be popped off in the child in the ebx frobbing below. */
movl FUNC(%esp),%eax
movl %eax,8(%ecx)
/* Don't leak any information. */
movl $0,4(%ecx)
/* Do the system call */
pushl %ebx
cfi_adjust_cfa_offset (4)
pushl %esi
cfi_adjust_cfa_offset (4)
pushl %edi
cfi_adjust_cfa_offset (4)
movl TLS+12(%esp),%esi
cfi_rel_offset (esi, 4)
movl PTID+12(%esp),%edx
movl FLAGS+12(%esp),%ebx
cfi_rel_offset (ebx, 8)
movl CTID+12(%esp),%edi
cfi_rel_offset (edi, 0)
movl $SYS_ify(clone),%eax
/* Remember the flag value. */
movl %ebx, (%ecx)
/* End FDE now, because in the child the unwind info will be
wrong. */
cfi_endproc
int $0x80
popl %edi
popl %esi
popl %ebx
test %eax,%eax
jl SYSCALL_ERROR_LABEL
jz L(thread_start)
ret
L(thread_start):
cfi_startproc;
/* Clearing frame pointer is insufficient, use CFI. */
cfi_undefined (eip);
/* Note: %esi is zero. */
movl %esi,%ebp /* terminate the stack frame */
testl $CLONE_THREAD, %edi
je L(newpid)
L(haspid):
call *%ebx
#ifdef PIC
call L(here)
L(here):
popl %ebx
addl $_GLOBAL_OFFSET_TABLE_+[.-L(here)], %ebx
#endif
movl %eax, %ebx
movl $SYS_ify(exit), %eax
ENTER_KERNEL
.subsection 2
L(newpid):
testl $CLONE_VM, %edi
movl $-1, %eax
jne L(nomoregetpid)
movl $SYS_ify(getpid), %eax
ENTER_KERNEL
L(nomoregetpid):
movl %eax, %gs:PID
movl %eax, %gs:TID
jmp L(haspid)
.previous
cfi_endproc;
cfi_startproc
PSEUDO_END (__clone)
weak_alias (__clone, clone)
|
