sys/platform/pc32/i386/vm86bios.s

   1 /*-
   2  * Copyright (c) 1998 Jonathan Lemon
   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  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/i386/i386/vm86bios.s,v 1.15.2.1 2000/05/16 06:58:07 dillon Exp $
  27  * $DragonFly: src/sys/platform/pc32/i386/vm86bios.s,v 1.14 2007/01/22 19:37:04 corecode Exp $
  28  */
  29
  30 #include <machine/asmacros.h>           /* miscellaneous asm macros */
  31 #include <machine/trap.h>
  32
  33 #include "assym.s"
  34
  35 #define SCR_NEWPTD      PCB_ESI         /* readability macros */
  36 #define SCR_VMFRAME     PCB_EBP         /* see vm86.c for explanation */
  37 #define SCR_STACK       PCB_ESP
  38 #define SCR_PGTABLE     PCB_EBX
  39 #define SCR_ARGFRAME    PCB_EIP
  40 #define SCR_TSS0        PCB_SPARE
  41 #define SCR_TSS1        (PCB_SPARE+4)
  42
  43         .data
  44         ALIGN_DATA
  45
  46         .globl  in_vm86call, vm86pcb
  47
  48 in_vm86call:            .long   0
  49 vm86pcb:                .long   0
  50
  51         .text
  52
  53 /*
  54  * vm86_bioscall(struct trapframe_vm86 *vm86)
  55  */
  56 ENTRY(vm86_bioscall)
  57         movl    vm86pcb,%edx            /* scratch data area */
  58         movl    4(%esp),%eax
  59         movl    %eax,SCR_ARGFRAME(%edx) /* save argument pointer */
  60         pushl   %ebx
  61         pushl   %ebp
  62         pushl   %esi
  63         pushl   %edi
  64         pushl   %gs
  65
  66 #if NNPX > 0
  67         movl    PCPU(curthread),%ecx
  68         cmpl    %ecx,PCPU(npxthread)    /* do we need to save fp? */
  69         jne     1f
  70         testl   %ecx,%ecx
  71         je      1f                      /* no curthread/npxthread */
  72         pushl   %edx
  73         pushl   TD_SAVEFPU(%ecx)
  74         call    npxsave
  75         popl    %ecx                    /* pop argument (now garabge) */
  76         popl    %edx                    /* recover our pcb */
  77 #endif
  78
  79         /* %ecx is garbage at this point */
  80 1:
  81         movl    SCR_VMFRAME(%edx),%ebx  /* target frame location */
  82         movl    %ebx,%edi               /* destination */
  83         movl    SCR_ARGFRAME(%edx),%esi /* source (set on entry) */
  84         movl    $VM86_FRAMESIZE/4,%ecx  /* sizeof(struct vm86frame)/4 */
  85         cld
  86         rep
  87         movsl                           /* copy frame to new stack */
  88
  89         /*
  90          * YYY I really dislike replacing td_pcb, even temporarily.  Find
  91          * another way.
  92          */
  93         movl    PCPU(curthread),%ebx
  94         movl    TD_PCB(%ebx),%eax       /* save curpcb */
  95         pushl   %eax                    /* save curpcb */
  96         pushl   TD_SAVEFPU(%ebx)        /* save fpu pointer */
  97         movl    %edx,TD_PCB(%ebx)       /* set curpcb to vm86pcb */
  98         leal    PCB_SAVEFPU(%edx),%eax  /* new savefpu pointer */
  99         movl    %eax,TD_SAVEFPU(%ebx)
 100
 101         movl    PCPU(tss_gdt),%ebx      /* entry in GDT */
 102         movl    0(%ebx),%eax
 103         movl    %eax,SCR_TSS0(%edx)     /* save first word */
 104         movl    4(%ebx),%eax
 105         andl    $~0x200, %eax           /* flip 386BSY -> 386TSS */
 106         movl    %eax,SCR_TSS1(%edx)     /* save second word */
 107
 108         movl    PCB_EXT(%edx),%edi      /* vm86 tssd entry */
 109         movl    0(%edi),%eax
 110         movl    %eax,0(%ebx)
 111         movl    4(%edi),%eax
 112         movl    %eax,4(%ebx)
 113         movl    $GPROC0_SEL*8,%esi      /* GSEL(entry, SEL_KPL) */
 114         ltr     %si
 115
 116         movl    %cr3,%eax
 117         pushl   %eax                    /* save address space */
 118         movl    IdlePTD,%ecx
 119         movl    %ecx,%ebx
 120         addl    $KERNBASE,%ebx          /* va of Idle PTD */
 121         movl    0(%ebx),%eax
 122         pushl   %eax                    /* old ptde != 0 when booting */
 123         pushl   %ebx                    /* keep for reuse */
 124
 125         movl    %esp,SCR_STACK(%edx)    /* save current stack location */
 126
 127         movl    SCR_NEWPTD(%edx),%eax   /* mapping for vm86 page table */
 128         movl    %eax,0(%ebx)            /* ... install as PTD entry 0 */
 129
 130         movl    %ecx,%cr3               /* new page tables */
 131         movl    SCR_VMFRAME(%edx),%esp  /* switch to new stack */
 132
 133         pushl   %esp                    /* pass frame by reference */
 134         call    vm86_prepcall           /* finish setup */
 135         addl    $4,%esp
 136
 137         movl    $1,in_vm86call          /* set flag for trap() */
 138
 139         /*
 140          * Return via _doreti, restore the same cpl as our current cpl
 141          */
 142         movl    PCPU(curthread),%eax
 143         pushl   $0                      /* DUMMY CPL FOR DORETI */
 144         MEXITCOUNT
 145         jmp     doreti
 146
 147
 148 /*
 149  * vm86_biosret(struct trapframe_vm86 *vm86)
 150  */
 151 ENTRY(vm86_biosret)
 152         movl    vm86pcb,%edx            /* data area */
 153
 154         movl    4(%esp),%esi            /* source */
 155         movl    SCR_ARGFRAME(%edx),%edi /* destination */
 156         movl    $VM86_FRAMESIZE/4,%ecx  /* size */
 157         cld
 158         rep
 159         movsl                           /* copy frame to original frame */
 160
 161         movl    SCR_STACK(%edx),%esp    /* back to old stack */
 162         popl    %ebx                    /* saved va of Idle PTD */
 163         popl    %eax
 164         movl    %eax,0(%ebx)            /* restore old pte */
 165         popl    %eax
 166         movl    %eax,%cr3               /* install old page table */
 167
 168         movl    $0,in_vm86call          /* reset trapflag */
 169
 170         movl    PCPU(tss_gdt),%ebx      /* entry in GDT */
 171         movl    SCR_TSS0(%edx),%eax
 172         movl    %eax,0(%ebx)            /* restore first word */
 173         movl    SCR_TSS1(%edx),%eax
 174         movl    %eax,4(%ebx)            /* restore second word */
 175         movl    $GPROC0_SEL*8,%esi      /* GSEL(entry, SEL_KPL) */
 176         ltr     %si
 177
 178         movl    PCPU(curthread),%eax
 179         popl    TD_SAVEFPU(%eax)        /* restore savefpu pointer */
 180         popl    TD_PCB(%eax)            /* restore curpcb */
 181         movl    SCR_ARGFRAME(%edx),%edx /* original stack frame */
 182         movl    TF_TRAPNO(%edx),%eax    /* return (trapno) */
 183
 184         popl    %gs
 185         popl    %edi
 186         popl    %esi
 187         popl    %ebp
 188         popl    %ebx
 189         ret                             /* back to our normal program */