sys/platform/pc32/include/thread.h

   1 /*
   2  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      Machine independant code should not directly include this file.
  35  *
  36  * $DragonFly: src/sys/platform/pc32/include/thread.h,v 1.17 2007/01/08 03:33:42 dillon Exp $
  37  */
  38
  39 #ifndef _MACHINE_THREAD_H_
  40 #define _MACHINE_THREAD_H_
  41
  42 #ifndef _MACHINE_SEGMENTS_H_
  43 #include <machine/segments.h>
  44 #endif
  45
  46 union savefpu;
  47
  48 struct md_thread {
  49     unsigned int        mtd_unused;     /* used to be mtd_cpl */
  50     union savefpu       *mtd_savefpu;
  51     struct savetls      mtd_savetls;
  52 };
  53
  54 #ifdef _KERNEL
  55
  56 #define td_savefpu      td_mach.mtd_savefpu
  57 #define td_tls          td_mach.mtd_savetls
  58
  59 /*
  60  * mycpu() retrieves the base of the current cpu's globaldata structure.
  61  * Note that it is *NOT* volatile, meaning that the value may be cached by
  62  * GCC.  We have to force a dummy memory reference so gcc does not cache
  63  * the gd pointer across a procedure call (which might block and cause us
  64  * to wakeup on a different cpu).
  65  *
  66  * Also note that in DragonFly a thread can be preempted, but only by an
  67  * interrupt thread and the original thread will resume after the
  68  * interrupt thread finishes or blocks.  A thread cannot move to another
  69  * cpu preemptively or at all, in fact, while you are in the kernel, even
  70  * if you block.
  71  */
  72
  73 struct globaldata;
  74
  75 extern int __mycpu__dummy;
  76
  77 static __inline
  78 struct globaldata *
  79 _get_mycpu(void)
  80 {
  81     struct globaldata *gd;
  82
  83     __asm ("movl %%fs:globaldata,%0" : "=r" (gd) : "m"(__mycpu__dummy));
  84     return(gd);
  85 }
  86
  87 #define mycpu   _get_mycpu()
  88
  89 #ifdef SMP
  90 #define mycpuid (_get_mycpu()->gd_cpuid)
  91 #else
  92 #define mycpuid 0
  93 #endif
  94
  95 /*
  96  * note: curthread is never NULL, but curproc can be.  Also note that
  97  * that only processes really use the PCB.  Threads fill in some fields
  98  * but mostly store contextual data on the stack and do not use (much of)
  99  * the PCB.
 100  */
 101 #define curthread       mycpu->gd_curthread
 102 #define curproc         curthread->td_proc
 103
 104 #endif  /* _KERNEL */
 105
 106 #endif  /* !_MACHINE_THREAD_H_ */