freebsd-skq/libexec/rtld-elf/rtld_tls.h
kib 563a44c171 Change compiler setting to make default visibility of the symbols for
rtld on x86 to be hidden.  This is a micro-optimization, which allows
intrinsic references inside rtld to be handled without indirection
through PLT.  The visibility of rtld symbols for other objects in the
symbol namespace is controlled by a version script.

Reviewed by:	kan, jilles
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2015-03-29 18:53:21 +00:00

71 lines
2.9 KiB
C

/*-
* Copyright (c) 2004 Doug Rabson
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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 AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
/*
* Semi-public interface from thread libraries to rtld for managing
* TLS.
*/
#ifndef _RTLD_TLS_H_
#define _RTLD_TLS_H_
/*
* Allocate a TLS block for a new thread. The memory allocated will
* include 'tcbsize' bytes aligned to a 'tcbalign' boundary (in bytes)
* for the thread library's private purposes. The location of the TCB
* block is returned by this function. For architectures using
* 'Variant I' TLS, the thread local storage follows the TCB, and for
* 'Variant II', the thread local storage precedes it. For
* architectures using the 'Variant II' model (e.g. i386, amd64,
* sparc64), the TCB must begin with two pointer fields which are used
* by rtld for its TLS implementation. For the 'Variant I' model, the
* TCB must begin with a single pointer field for rtld's
* implementation.
*
* If the value of 'oldtls' is non-NULL, the new TLS block will be
* initialised using the values contained in 'oldtls' and 'oldtls'
* will be freed. This is typically used when initialising a thread
* library to migrate from using the initial bootstrap TLS block
* created by rtld to one which contains suitable thread library
* private data.
*
* The value returned from this function is suitable for installing
* directly into the thread pointer register.
*/
void *_rtld_allocate_tls(void* oldtls, size_t tcbsize, size_t tcbalign)
__exported;
/*
* Free a TLS block allocated using _rtld_allocate_tls(). The tcbsize
* and tcbalign parameters must be the same as those used to allocate
* the block.
*/
void _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign) __exported;
#endif