Date: Sat, 07 Dec 2002 15:52:01 +0100 From: Dag-Erling Smorgrav <des@ofug.org> To: sparc@freebsd.org Cc: peter@freebsd.org Subject: libc_r Message-ID: <xzpbs3xj2zy.fsf@flood.ping.uio.no>
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--=-=-=
I was quite surprised to discover that sparc64, which is supposedly a
tier 1 platform and our reference 64-bit platform, doesn't have a
working libc_r, so I decided to take a shot at it. I've arrived at
what I believe is a correct implementation for _atomic_lock() (see
attached source code). It seems to work as expected when called from
a simple test program which attempts to acquire the same lock twice:
l is now 0x0
_atomic_lock() returned 0x0
l after _atomic_lock(): 0xff00000000000000
l is now 0xff00000000000000
_atomic_lock() returned 0xff
l after _atomic_lock(): 0xff00000000000000
I've never written sparc assembler before, so caveat emptor, slippery
when wet, do not look into laser with remaining eye, etc.
I haven't started on pthread_private.h yet, and I'm not sure I can
handle it on my own, but I hope this will inspire someone to tackle
it.
DES
--
Dag-Erling Smorgrav - des@ofug.org
--=-=-=
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: attachment; filename=_atomic_lock.S
Content-Transfer-Encoding: quoted-printable
/*-
* Copyright (c) 2002 Dag-Erling Co=EFdan Sm=F8rgrav
* 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
* in this position and unchanged.
* 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
*/
#include <machine/asm.h>
__FBSDID("$FreeBSD$");
/*
* long _atomic_lock(long *)
*
* Atomically acquire a lock by storing a non-zero value in its
* location, provided it is not already locked. Note that we only use
* the first byte of the location provided.
*/
ENTRY(_atomic_lock)
ldstub [%o0], %o1
membar #LoadLoad
retl
mov %o1, %o0
END(_atomic_lock)
--=-=-=--
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