about summary refs log tree commit diff
path: root/sysdeps/unix/sysv/linux/i386/clone.S
blob: 0603218acdc07aff265e6a20af4c863a01f4bbd7 (plain) (blame)
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
162
/* Copyright (C) 1996-2000,02,03,04,2005 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>
#include <bp-sym.h>
#include <bp-asm.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	LINKAGE		/* no space for saved regs */
#define FUNC	PARMS
#define STACK	FUNC+4
#define FLAGS	STACK+PTR_SIZE
#define ARG	FLAGS+4
#define PTID	ARG+PTR_SIZE
#define TLS	PTID+PTR_SIZE
#define CTID	TLS+PTR_SIZE

#define __NR_clone 120
#define SYS_clone 120

#define CLONE_VM	0x00000100
#define CLONE_THREAD	0x00010000

        .text
ENTRY (BP_SYM (__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)
#ifndef RESET_PID
	movl	$0,(%ecx)
#endif

	/* 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

#ifdef RESET_PID
	/* Remember the flag value.  */
	movl	%ebx, (%ecx)
#endif

	/* 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)

L(pseudo_end):
	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 */
#ifdef RESET_PID
	testl	$CLONE_THREAD, %edi
	je	L(newpid)
L(haspid):
#endif
	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

#ifdef RESET_PID
	.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
#endif
	cfi_endproc;

	cfi_startproc
PSEUDO_END (BP_SYM (__clone))

weak_alias (BP_SYM (__clone), BP_SYM (clone))