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
|
/* Definitions for lowlevel handling in ld.so, FreeBSD variant
Copyright (C) 2006-2007 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#ifndef _RTLD_LOWLEVEL_H
#define _RTLD_LOWLEVEL_H 1
#include <atomic.h>
#include <lowlevellock.h>
/* Special multi-reader lock used in ld.so. */
#define __RTLD_MRLOCK_WRITER 1
#define __RTLD_MRLOCK_RWAIT 2
#define __RTLD_MRLOCK_WWAIT 4
#define __RTLD_MRLOCK_RBITS \
~(__RTLD_MRLOCK_WRITER | __RTLD_MRLOCK_RWAIT | __RTLD_MRLOCK_WWAIT)
#define __RTLD_MRLOCK_INC 8
#define __RTLD_MRLOCK_TRIES 5
#define __rtld_mrlock_define(CLASS,NAME) \
CLASS __rtld_mrlock_t NAME;
#define _RTLD_MRLOCK_INITIALIZER 0
#define __rtld_mrlock_initialize(NAME) \
(void) ((NAME).lv = 0)
#define __rtld_mrlock_lock(lock) \
do { \
__label__ out; \
while (1) \
{ \
int oldval; \
for (int tries = 0; tries < __RTLD_MRLOCK_TRIES; ++tries) \
{ \
oldval = (lock).iv; \
while (__builtin_expect ((oldval \
& (__RTLD_MRLOCK_WRITER \
| __RTLD_MRLOCK_WWAIT)) \
== 0, 1)) \
{ \
int newval = ((oldval & __RTLD_MRLOCK_RBITS) \
+ __RTLD_MRLOCK_INC); \
int ret = atomic_compare_and_exchange_val_acq (&(lock.iv), \
newval, \
oldval); \
if (__builtin_expect (ret == oldval, 1)) \
goto out; \
oldval = ret; \
} \
atomic_delay (); \
} \
if ((oldval & __RTLD_MRLOCK_RWAIT) == 0) \
{ \
atomic_or (&(lock.iv), __RTLD_MRLOCK_RWAIT); \
oldval |= __RTLD_MRLOCK_RWAIT; \
} \
lll_futex_wait (&(lock), oldval); \
} \
out:; \
} while (0)
#define __rtld_mrlock_unlock(lock) \
do { \
int oldval = atomic_exchange_and_add (&(lock.iv), -__RTLD_MRLOCK_INC); \
if (__builtin_expect ((oldval \
& (__RTLD_MRLOCK_RBITS | __RTLD_MRLOCK_WWAIT)) \
== (__RTLD_MRLOCK_INC | __RTLD_MRLOCK_WWAIT), 0)) \
/* We have to wake all threads since there might be some queued \
readers already. */ \
lll_futex_wake (&(lock), 0x7fffffff); \
} while (0)
/* There can only ever be one thread trying to get the exclusive lock. */
#define __rtld_mrlock_change(lock) \
do { \
__label__ out; \
while (1) \
{ \
int oldval; \
for (int tries = 0; tries < __RTLD_MRLOCK_TRIES; ++tries) \
{ \
oldval = lock.iv; \
while (__builtin_expect ((oldval & __RTLD_MRLOCK_RBITS) == 0, 1)) \
{ \
int newval = ((oldval & __RTLD_MRLOCK_RWAIT) \
+ __RTLD_MRLOCK_WRITER); \
int ret = atomic_compare_and_exchange_val_acq (&(lock.iv), \
newval, \
oldval); \
if (__builtin_expect (ret == oldval, 1)) \
goto out; \
oldval = ret; \
} \
atomic_delay (); \
} \
atomic_or (&(lock.iv), __RTLD_MRLOCK_WWAIT); \
oldval |= __RTLD_MRLOCK_WWAIT; \
lll_futex_wait (&(lock), oldval); \
} \
out:; \
} while (0)
#define __rtld_mrlock_done(lock) \
do { \
int oldval = atomic_exchange_and_add (&(lock.iv), -__RTLD_MRLOCK_WRITER); \
if (__builtin_expect ((oldval & __RTLD_MRLOCK_RWAIT) != 0, 0)) \
lll_futex_wake (&(lock), 0x7fffffff); \
} while (0)
#endif
|
