bionic_tls.h revision 44b53ad6818de344e0b499ad8fdbb21fcb0ff2b6 
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#ifndef _SYS_TLS_H
29#define _SYS_TLS_H
30
31#include <sys/cdefs.h>
32
33__BEGIN_DECLS
34
35/** WARNING WARNING WARNING
36 **
37 ** This header file is *NOT* part of the public Bionic ABI/API
38 ** and should not be used/included by user-serviceable parts of
39 ** the system (e.g. applications).
40 **
41 ** It is only provided here for the benefit of the system dynamic
42 ** linker and the OpenGL sub-system (which needs to access the
43 ** pre-allocated slot directly for performance reason).
44 **/
45
46/* Maximum number of elements in the TLS array. */
47#define BIONIC_TLS_SLOTS            64
48
49/* Well-known TLS slots. What data goes in which slot is arbitrary unless otherwise noted. */
50enum {
51  TLS_SLOT_SELF = 0, /* The kernel requires this specific slot for x86. */
52  TLS_SLOT_THREAD_ID,
53  TLS_SLOT_ERRNO,
54  TLS_SLOT_OPENGL_API = 3,
55  TLS_SLOT_OPENGL = 4,
56  TLS_SLOT_STACK_GUARD = 5, /* GCC requires this specific slot for x86. */
57  TLS_SLOT_DLERROR,
58
59  TLS_SLOT_FIRST_USER_SLOT /* Must come last! */
60};
61
62/* This slot is only used to pass information from the dynamic linker to
63 * libc.so when the C library is loaded in to memory. The C runtime init
64 * function will then clear it. Since its use is extremely temporary,
65 * we reuse an existing location that isn't needed during libc startup.
66 */
67#define  TLS_SLOT_BIONIC_PREINIT    TLS_SLOT_OPENGL_API
68
69/* set the Thread Local Storage, must contain at least BIONIC_TLS_SLOTS pointers */
70extern void __init_tls(void**  tls, void*  thread_info);
71
72/* syscall only, do not call directly */
73extern int __set_tls(void *ptr);
74
75/* get the TLS */
76#ifdef __arm__
77/* The standard way to get the TLS is to call a kernel helper
78 * function (i.e. a function provided at a fixed address in a
79 * "magic page" mapped in all user-space address spaces ), which
80 * contains the most appropriate code path for the target device.
81 *
82 * However, for performance reasons, we're going to use our own
83 * machine code for the system's C shared library.
84 *
85 * We cannot use this optimization in the static version of the
86 * C library, because we don't know where the corresponding code
87 * is going to run.
88 */
89#  ifdef LIBC_STATIC
90
91/* Use the kernel helper in static C library. */
92  typedef volatile void* (__kernel_get_tls_t)(void);
93#    define __get_tls() (*(__kernel_get_tls_t *)0xffff0fe0)()
94
95#  else /* !LIBC_STATIC */
96/* Use optimized code path.
97 * Note that HAVE_ARM_TLS_REGISTER is build-specific
98 * (it must match your kernel configuration)
99 */
100#    ifdef HAVE_ARM_TLS_REGISTER
101 /* We can read the address directly from a coprocessor
102  * register, which avoids touching the data cache
103  * completely.
104  */
105#      define __get_tls() \
106    ({ register unsigned int __val asm("r0"); \
107       asm ("mrc p15, 0, r0, c13, c0, 3" : "=r"(__val) ); \
108       (volatile void*)__val; })
109#    else /* !HAVE_ARM_TLS_REGISTER */
110 /* The kernel provides the address of the TLS at a fixed
111  * address of the magic page too.
112  */
113#      define __get_tls() ( *((volatile void **) 0xffff0ff0) )
114#    endif
115#  endif /* !LIBC_STATIC */
116#elif defined(__mips__)
117#    define __get_tls() \
118    ({ register unsigned int __val asm("v1");   \
119        asm (                                   \
120            "   .set    push\n"                 \
121            "   .set    mips32r2\n"             \
122            "   rdhwr   %0,$29\n"               \
123            "   .set    pop\n"                  \
124            : "=r"(__val)                       \
125            );                                  \
126        (volatile void*)__val; })
127#else
128extern void*  __get_tls( void );
129#endif
130
131/* return the stack base and size, used by our malloc debugger */
132extern void*  __get_stack_base(int  *p_stack_size);
133
134__END_DECLS
135
136#if defined(__cplusplus)
137struct KernelArgumentBlock;
138extern void __libc_init_tls(KernelArgumentBlock& args);
139#endif
140
141#endif /* _SYS_TLS_H */
142