1 /*
2  * Copyright (C) 2008 The Android Open Source Project
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *  * Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  *  * Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in
12  *    the documentation and/or other materials provided with the
13  *    distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #ifndef __BIONIC_PRIVATE_BIONIC_TLS_H_
30 #define __BIONIC_PRIVATE_BIONIC_TLS_H_
31 
32 #include <sys/cdefs.h>
33 
34 #include "bionic_macros.h"
35 #include "__get_tls.h"
36 
37 __BEGIN_DECLS
38 
39 /** WARNING WARNING WARNING
40  **
41  ** This header file is *NOT* part of the public Bionic ABI/API
42  ** and should not be used/included by user-serviceable parts of
43  ** the system (e.g. applications).
44  **
45  ** It is only provided here for the benefit of the system dynamic
46  ** linker and the OpenGL sub-system (which needs to access the
47  ** pre-allocated slot directly for performance reason).
48  **/
49 
50 // Well-known TLS slots. What data goes in which slot is arbitrary unless otherwise noted.
51 enum {
52   TLS_SLOT_SELF = 0, // The kernel requires this specific slot for x86.
53   TLS_SLOT_THREAD_ID,
54   TLS_SLOT_ERRNO,
55 
56   // These two aren't used by bionic itself, but allow the graphics code to
57   // access TLS directly rather than using the pthread API.
58   TLS_SLOT_OPENGL_API = 3,
59   TLS_SLOT_OPENGL = 4,
60 
61   // This slot is only used to pass information from the dynamic linker to
62   // libc.so when the C library is loaded in to memory. The C runtime init
63   // function will then clear it. Since its use is extremely temporary,
64   // we reuse an existing location that isn't needed during libc startup.
65   TLS_SLOT_BIONIC_PREINIT = TLS_SLOT_OPENGL_API,
66 
67   TLS_SLOT_STACK_GUARD = 5, // GCC requires this specific slot for x86.
68   TLS_SLOT_DLERROR,
69 
70   // Fast storage for Thread::Current() in ART.
71   TLS_SLOT_ART_THREAD_SELF,
72 
73   // Lets TSAN avoid using pthread_getspecific for finding the current thread
74   // state.
75   TLS_SLOT_TSAN,
76 
77   BIONIC_TLS_SLOTS // Must come last!
78 };
79 
80 /*
81  * Bionic uses some pthread keys internally. All pthread keys used internally
82  * should be created in constructors, except for keys that may be used in or
83  * before constructors.
84  *
85  * We need to manually maintain the count of pthread keys used internally, but
86  * pthread_test should fail if we forget.
87  *
88  * These are the pthread keys currently used internally by libc:
89  *
90  *  basename               libc (ThreadLocalBuffer)
91  *  dirname                libc (ThreadLocalBuffer)
92  *  uselocale              libc (can be used in constructors)
93  *  getmntent_mntent       libc (ThreadLocalBuffer)
94  *  getmntent_strings      libc (ThreadLocalBuffer)
95  *  ptsname                libc (ThreadLocalBuffer)
96  *  ttyname                libc (ThreadLocalBuffer)
97  *  strerror               libc (ThreadLocalBuffer)
98  *  strsignal              libc (ThreadLocalBuffer)
99  *  passwd                 libc (ThreadLocalBuffer)
100  *  group                  libc (ThreadLocalBuffer)
101  *  _res_key               libc (constructor in BSD code)
102  */
103 
104 #define LIBC_PTHREAD_KEY_RESERVED_COUNT 12
105 
106 /* Internally, jemalloc uses a single key for per thread data. */
107 #define JEMALLOC_PTHREAD_KEY_RESERVED_COUNT 1
108 #define BIONIC_PTHREAD_KEY_RESERVED_COUNT (LIBC_PTHREAD_KEY_RESERVED_COUNT + JEMALLOC_PTHREAD_KEY_RESERVED_COUNT)
109 
110 /*
111  * Maximum number of pthread keys allocated.
112  * This includes pthread keys used internally and externally.
113  */
114 #define BIONIC_PTHREAD_KEY_COUNT (BIONIC_PTHREAD_KEY_RESERVED_COUNT + PTHREAD_KEYS_MAX)
115 
116 __END_DECLS
117 
118 #if defined(__cplusplus)
119 class KernelArgumentBlock;
120 extern void __libc_init_main_thread(KernelArgumentBlock&);
121 #endif
122 
123 #endif /* __BIONIC_PRIVATE_BIONIC_TLS_H_ */
124