usr/src/lib/libc/sparcv9/gen/smt_pause.s

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
  23  */
  24
  25         .file   "smt_pause.s"
  26
  27 #include <sys/asm_linkage.h>
  28 #include <../assym.h>
  29
  30 /*
  31  * void smt_pause(void)
  32  *
  33  * Do nothing efficiently.
  34  */
  35
  36 #define BANKS   (4 * 64)
  37         ENTRY(smt_pause)
  38         save %sp, -SA(MINFRAME+BANKS), %sp
  39         ld      [%g7 + UL_LWPID], %i3   ! curthread->ul_lwpid
  40         add     %fp, STACK_BIAS-BANKS, %i0
  41         and     %i3, 0x3, %i2           ! save last 2 bits
  42         sllx    %i2, 0x6, %i1           ! pick a slot
  43         add     %i1, %i0, %o0
  44         casx    [%o0], %g0, %g0
  45         casx    [%o0], %g0, %g0
  46         ret
  47         restore
  48         SET_SIZE(smt_pause)