sys/platform/vkernel/i386/fork_tramp.s

   1 /*-
   2  * Copyright (c) 1990 The Regents of the University of California.
   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  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * $FreeBSD: src/sys/i386/i386/exception.s,v 1.65.2.3 2001/08/15 01:23:49 peter Exp $
  34  * $DragonFly: src/sys/platform/vkernel/i386/fork_tramp.s,v 1.3 2007/01/22 20:37:04 corecode Exp $
  35  */
  36
  37 #include "use_npx.h"
  38
  39 #include <machine/asmacros.h>
  40 #include <machine/segments.h>
  41 #include <machine/lock.h>
  42 #include <machine/psl.h>
  43 #include <machine/trap.h>
  44
  45 #include "assym.s"
  46
  47         .text
  48
  49 /*
  50  * This function is what cpu_heavy_restore jumps to after a new process
  51  * is created.  The LWKT subsystem switches while holding a critical
  52  * section and we maintain that abstraction here (e.g. because
  53  * cpu_heavy_restore needs it due to PCB_*() manipulation), then get out of
  54  * it before calling the initial function (typically fork_return()) and/or
  55  * returning to user mode.
  56  *
  57  * The MP lock is held on entry, but for processes fork_return(esi)
  58  * releases it.  'doreti' always runs without the MP lock.
  59  */
  60 ENTRY(fork_trampoline)
  61         movl    PCPU(curthread),%eax
  62         subl    $TDPRI_CRIT,TD_PRI(%eax)
  63
  64         /*
  65          * cpu_set_fork_handler intercepts this function call to
  66          * have this call a non-return function to stay in kernel mode.
  67          *
  68          * initproc has its own fork handler, start_init(), which DOES
  69          * return.
  70          *
  71          * The function (set in pcb_esi) gets passed two arguments,
  72          * the primary parameter set in pcb_ebx and a pointer to the
  73          * trapframe.
  74          *   void (func)(int arg, struct trapframe *frame);
  75          */
  76         pushl   %esp                    /* pass frame by reference */
  77         pushl   %ebx                    /* arg1 */
  78         call    *%esi                   /* function */
  79         addl    $8,%esp
  80         /* cut from syscall */
  81
  82         call    splz
  83
  84 #if defined(INVARIANTS) && defined(SMP)
  85         movl    PCPU(curthread),%eax
  86         cmpl    $0,TD_MPCOUNT(%eax)
  87         je      1f
  88         pushl   %esi
  89         pushl   TD_MPCOUNT(%eax)
  90         pushl   $pmsg4
  91         call    panic
  92 pmsg4:  .asciz  "fork_trampoline mpcount %d after calling %p"
  93         .p2align 2
  94 1:
  95 #endif
  96         /*
  97          * Return via doreti to handle ASTs.
  98          */
  99         MEXITCOUNT
 100         pushl   $0              /* if_ppl */
 101         pushl   $0              /* if_vec */
 102         pushl   %esp            /* pass by reference */
 103         call    go_user
 104         /* NOT REACHED */
 105
 106