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
|
/* Copyright (C) 1996-2020 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
<https://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
.text
ENTRY (__clone)
/* Sanity check arguments. */
movl $-EINVAL,%eax
movl FUNC(%esp),%ecx /* no NULL function pointers */
testl %ecx,%ecx
jz SYSCALL_ERROR_LABEL
movl STACK(%esp),%ecx /* no NULL stack pointers */
testl %ecx,%ecx
jz SYSCALL_ERROR_LABEL
/* 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 */
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
PSEUDO_END (__clone)
libc_hidden_def (__clone)
weak_alias (__clone, clone)
|
