rtld to support __thread tls
davidxu at t2t2.com
Fri Mar 4 23:39:22 PST 2005
Oh, forgot to attach file rtld_tls.h which is needed
by libthread_xu, please copy it into src/libexec/rtld-elf
David Xu wrote:
Matthew Dillon wrote:
Well, lets not let this slip through the cracks. We want __thread
support and we have the GDT infrastructure to do it now. Maybe you
should push your current patch set to David Xu with a quick
summary and you and he can discuss architectural issues over the
<dillon at xxxxxxxxxxxxx>
Because Joerg is working on rtld, I just picked up an relative easier
task --- hack all necessary code to support __thread for static libary,
I have spent two hours to work out all patches, please see attached
file, they works on my machine (a SMP box).
I don't know what was committed into rtld by Joerg yet, since I have to
fix some broken code due to FreeBSD's swappable kernel stack issue,
not have enough time. =(
Note, this only works for static library! the patches do not affect
shared objects, however applying the patch should be safe.
you should use gcc3 to compile sample code tls_test.c. the gcc 2.95 does
not support __thread.
I use csh, so:
# setenv CCVER gcc34
# cc -o tls_test tls_test.c -static -lthread_xu
* Copyright (c) 2004 Doug Rabson
* All rights reserved.
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* 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: src/libexec/rtld-elf/rtld_tls.h,v 1.1 2004/08/03 08:50:58 dfr Exp $
* Semi-public interface from thread libraries to rtld for managing
* 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
* 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.
extern void *_rtld_allocate_tls(void* oldtls, size_t tcbsize, size_t tcbalign);
* 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.
extern void _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign);
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