libexec/rtld-elf/rtld_tls.h

   1 /*-
   2  * Copyright (c) 2004 Doug Rabson
   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  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  *      $FreeBSD$
  27  */
  28
  29 /*
  30  * Semi-public interface from thread libraries to rtld for managing
  31  * TLS.
  32  */
  33
  34 #ifndef _RTLD_TLS_H_
  35 #define _RTLD_TLS_H_
  36
  37 /*
  38  * Allocate a TLS block for a new thread. The memory allocated will
  39  * include 'tcbsize' bytes aligned to a 'tcbalign' boundary (in bytes)
  40  * for the thread library's private purposes. The location of the TCB
  41  * block is returned by this function. For architectures using
  42  * 'Variant I' TLS, the thread local storage follows the TCB, and for
  43  * 'Variant II', the thread local storage precedes it. For
  44  * architectures using the 'Variant II' model (e.g. i386, amd64,
  45  * sparc64), the TCB must begin with two pointer fields which are used
  46  * by rtld for its TLS implementation. For the 'Variant I' model, the
  47  * TCB must begin with a single pointer field for rtld's
  48  * implementation.
  49  *
  50  * If the value of 'oldtls' is non-NULL, the new TLS block will be
  51  * initialised using the values contained in 'oldtls' and 'oldtls'
  52  * will be freed. This is typically used when initialising a thread
  53  * library to migrate from using the initial bootstrap TLS block
  54  * created by rtld to one which contains suitable thread library
  55  * private data.
  56  *
  57  * The value returned from this function is suitable for installing
  58  * directly into the thread pointer register.
  59  */
  60 extern void *_rtld_allocate_tls(void* oldtls, size_t tcbsize, size_t tcbalign);
  61
  62 /*
  63  * Free a TLS block allocated using _rtld_allocate_tls(). The tcbsize
  64  * and tcbalign parameters must be the same as those used to allocate
  65  * the block.
  66  */
  67 extern void _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign);
  68
  69 #endif