bionic/libc/private/bionic_tls.h

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/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef __BIONIC_PRIVATE_BIONIC_TLS_H_
#define __BIONIC_PRIVATE_BIONIC_TLS_H_
#include <sys/cdefs.h>
#include "__get_tls.h"
__BEGIN_DECLS
/** WARNING WARNING WARNING
**
** This header file is *NOT* part of the public Bionic ABI/API
** and should not be used/included by user-serviceable parts of
** the system (e.g. applications).
**
** It is only provided here for the benefit of the system dynamic
** linker and the OpenGL sub-system (which needs to access the
** pre-allocated slot directly for performance reason).
**/
/* Well-known TLS slots. What data goes in which slot is arbitrary unless otherwise noted. */
enum {
TLS_SLOT_SELF = 0, /* The kernel requires this specific slot for x86. */
TLS_SLOT_THREAD_ID,
TLS_SLOT_ERRNO,
/* This slot is used when starting a new thread, before any code that needs errno runs. */
TLS_SLOT_START_MUTEX = TLS_SLOT_ERRNO,
/* These two aren't used by bionic itself, but allow the graphics code to
* access TLS directly rather than using the pthread API. */
TLS_SLOT_OPENGL_API = 3,
TLS_SLOT_OPENGL = 4,
/* This slot is only used to pass information from the dynamic linker to
* libc.so when the C library is loaded in to memory. The C runtime init
* function will then clear it. Since its use is extremely temporary,
* we reuse an existing location that isn't needed during libc startup. */
TLS_SLOT_BIONIC_PREINIT = TLS_SLOT_OPENGL_API,
TLS_SLOT_STACK_GUARD = 5, /* GCC requires this specific slot for x86. */
TLS_SLOT_DLERROR,
TLS_SLOT_FIRST_USER_SLOT /* Must come last! */
};
/*
* Maximum number of elements in the TLS array.
* POSIX says this must be at least 128, but Android has traditionally had only 64, minus those
* ones used internally by bionic itself.
* There are two kinds of slot used internally by bionic --- there are the well-known slots
* enumerated above, and then there are those that are allocated during startup by calls to
* pthread_key_create; grep for GLOBAL_INIT_THREAD_LOCAL_BUFFER to find those. We need to manually
* maintain that second number, but pthread_test will fail if we forget.
*/
#define GLOBAL_INIT_THREAD_LOCAL_BUFFER_COUNT 4
/*
* This is PTHREAD_KEYS_MAX + TLS_SLOT_FIRST_USER_SLOT + GLOBAL_INIT_THREAD_LOCAL_BUFFER_COUNT
* rounded up to maintain stack alignment.
*/
#define BIONIC_ALIGN(x, a) (((x) + (a - 1)) & ~(a - 1))
#define BIONIC_TLS_SLOTS BIONIC_ALIGN(128 + TLS_SLOT_FIRST_USER_SLOT + GLOBAL_INIT_THREAD_LOCAL_BUFFER_COUNT, 4)
__END_DECLS
#if defined(__cplusplus)
class KernelArgumentBlock;
extern __LIBC_HIDDEN__ void __libc_init_tls(KernelArgumentBlock& args);
#endif
#endif /* __BIONIC_PRIVATE_BIONIC_TLS_H_ */