diff options
Diffstat (limited to 'i386/pc/rv86/rv86_trap_handler.S')
| -rw-r--r-- | i386/pc/rv86/rv86_trap_handler.S | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/i386/pc/rv86/rv86_trap_handler.S b/i386/pc/rv86/rv86_trap_handler.S new file mode 100644 index 0000000..793f6b6 --- /dev/null +++ b/i386/pc/rv86/rv86_trap_handler.S @@ -0,0 +1,167 @@ +/* + * Copyright (c) 1995-1994 The University of Utah and + * the Computer Systems Laboratory at the University of Utah (CSL). + * All rights reserved. + * + * Permission to use, copy, modify and distribute this software is hereby + * granted provided that (1) source code retains these copyright, permission, + * and disclaimer notices, and (2) redistributions including binaries + * reproduce the notices in supporting documentation, and (3) all advertising + * materials mentioning features or use of this software display the following + * acknowledgement: ``This product includes software developed by the + * Computer Systems Laboratory at the University of Utah.'' + * + * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS + * IS" CONDITION. THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF + * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. + * + * CSL requests users of this software to return to csl-dist@cs.utah.edu any + * improvements that they make and grant CSL redistribution rights. + * + * Author: Bryan Ford, University of Utah CSL + */ + +#include <mach/machine/asm.h> +#include <mach/machine/eflags.h> + +#include "i386_asm.h" +#include "trap.h" +#include "trap_asm.h" + + .text + +ENTRY(rv86_trap_handler) + cmpl $T_GENERAL_PROTECTION,TR_TRAPNO(%esp) + jz gpf_from_v86 + + UNEXPECTED_TRAP + +gpf_from_v86: + + /* Load the linear/physical-address data segment, + for easy access to real-mode memory. */ + movl $LINEAR_DS,%eax + movw %ax,%ds + + /* Find the physical address of the trapping instruction (ebx). */ + movzwl TR_CS(%esp),%ebx + shll $4,%ebx + addl TR_EIP(%esp),%ebx + + /* See if we're just trying to get out of v86 mode. */ + cmpl %ss:EXT(rv86_return_int_pa),%ebx + je EXT(rv86_return) + + /* Check the instruction (al). */ + movb (%ebx),%al + cmpb $0xcd,%al + je gpf_int_n + + UNEXPECTED_TRAP + + +gpf_int_n: + + /* Bump the ip past the int instruction. */ + addw $2,TR_EIP(%esp) + + /* Find the real mode interrupt vector number (esi). */ + movzbl 1(%ebx),%esi + + /* See if it's a copy-extended-memory interrupt request; + if so, just handle it here. */ + cmpl $0x15,%esi + jne 1f + cmpb $0x87,TR_EAX+1(%esp) + je copy_ext_mem +1: + + /* XXX The stuff down here is essentially the same as in moss. */ + +reflect_v86_intr: + + /* Find the address of the real mode interrupt vector (esi). */ + shll $2,%esi + + /* Make room for the real-mode interrupt stack frame. */ + subw $6,TR_ESP(%esp) + + /* Find the physical address of the v86 stack (ebx). */ + movzwl TR_SS(%esp),%ebx + shll $4,%ebx + addl TR_ESP(%esp),%ebx + + /* Store the return information into the v86 stack frame. */ + movl TR_EIP(%esp),%eax + movw %ax,(%ebx) + movl TR_CS(%esp),%eax + movw %ax,2(%ebx) + movl TR_EFLAGS(%esp),%eax + movw %ax,4(%ebx) + + /* Find the real-mode interrupt vector to invoke, + and set up the real_call_thread's kernel stack frame + to point to it. */ + movl (%esi),%eax + movw %ax,TR_EIP(%esp) + shrl $16,%eax + movw %ax,TR_CS(%esp) + andl $-1-EFL_IF-EFL_TF,TR_EFLAGS(%esp) + + /* Restore saved state and return. */ + addl $4*4,%esp + popa + addl $4*2,%esp + iret + + + +/* We intercepted a copy-extended-memory software interrupt + (int 0x15 function 0x87). + This is used by HIMEM.SYS, for example, to manage extended memory. + The BIOS's routine isn't going to work in v86 mode, + so do it ourselves. */ +copy_ext_mem: + + /* Find the parameter block provided by the caller (ebx). */ + movzwl TR_V86_ES(%esp),%ebx + movzwl TR_ESI(%esp),%eax + shll $4,%ebx + addl %eax,%ebx + + /* Source address (esi). */ + movl 0x12(%ebx),%esi + andl $0x00ffffff,%esi + + /* Destination address (edi). */ + movl 0x1a(%ebx),%edi + andl $0x00ffffff,%edi + + /* Number of bytes (ecx). */ + movzwl TR_ECX(%esp),%ecx + addl %ecx,%ecx + + /* Use the standard i386 bcopy routine to copy the data. + This assumes it's "friendly" in its use of segment registers + (i.e. always uses ss for stack data and ds/es for the data to copy). + The bcopy is simple enough that this should always be true. */ + movw %ds,%ax + movw %ax,%es + cld + pushl %ecx + pushl %edi + pushl %esi + call EXT(bcopy) + addl $3*4,%esp + + /* Clear the carry flag to indicate that the copy was successful. + AH is also cleared, below. */ + andl $-1-EFL_CF,TR_EFLAGS(%esp) + + /* Restore saved state and return. */ + addl $4*4,%esp + popa + xorb %ah,%ah + addl $4*2,%esp + iret + |