187 lines
4.0 KiB
ArmAsm
187 lines
4.0 KiB
ArmAsm
/*
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* Mach Operating System
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* Copyright (c) 1992, 1991 Carnegie Mellon University
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
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* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie Mellon
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* the rights to redistribute these changes.
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*
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* from: Mach, Revision 2.2 92/04/04 11:35:26 rpd
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* $Id: boot2.S,v 1.4 1994/06/22 05:52:25 jkh Exp $
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*/
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#include "asm.h"
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/* Conventional GDT indexes. */
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#define BOOT_CS_INDEX 3
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#define BOOT_CS16_INDEX 5
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#define BOOT_DS_INDEX 4
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#ifdef BDE_DEBUGGER
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#define DB_CS_INDEX 14
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#define DB_CS16_INDEX 15
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#define DB_DS_INDEX 16
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#define GDT_INDEX 17
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#endif
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/* Vector numbers. */
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#define BREAKPOINT_VECTOR 3
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#define DEBUG_VECTOR 1
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/*
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* boot2() -- second stage boot
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*/
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.globl EXT(ouraddr)
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ENTRY(boot2)
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data32
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subl %eax, %eax
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mov %cs, %ax
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mov %ax, %ds
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mov %ax, %es
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data32
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shll $4, %eax
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addr32
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data32
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movl %eax, EXT(ouraddr)
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/* fix up GDT entries for bootstrap */
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#define FIXUP(gdt_index) \
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addr32; \
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movl %eax, EXT(Gdt)+(8*gdt_index)+2; /* actually movw %ax */ \
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addr32; \
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movb %bl, EXT(Gdt)+(8*gdt_index)+4
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data32
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shld $16, %eax, %ebx
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FIXUP(BOOT_CS_INDEX)
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FIXUP(BOOT_CS16_INDEX)
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FIXUP(BOOT_DS_INDEX)
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/* fix up GDT pointer */
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data32
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movl %eax, %ecx
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data32
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addl $ EXT(Gdt), %eax
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addr32
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data32
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movl %eax, EXT(Gdtr)+2
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#ifdef BDE_DEBUGGER
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/* fix up GDT entry for GDT */
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data32
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shld $16, %eax, %ebx
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FIXUP(GDT_INDEX)
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/* fix up IDT pointer */
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data32
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addl $ EXT(Idt), %ecx
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addr32
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data32
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movl %ecx, EXT(Idtr_prot)+2
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/* %es = vector table segment for a while */
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push %es
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data32
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subl %eax, %eax
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mov %ax, %es
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/* fix up GDT entries for bdb */
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data32
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movl $4*DEBUG_VECTOR, %esi
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addr32
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movl %es: 2(%esi), %eax /* actually movw to %ax */
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data32
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shll $4, %eax
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data32
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shld $16, %eax, %ebx
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FIXUP(DB_CS_INDEX)
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FIXUP(DB_CS16_INDEX)
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FIXUP(DB_DS_INDEX)
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/* Fetch entry points of bdb's protected mode trap handlers. These
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* are stored at 2 before the corresponding entry points for real mode.
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*/
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data32
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subl %ebx, %ebx
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addr32
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movl %es: (%esi), %ebx /* actually movw to %bx */
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data32
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subl %ecx, %ecx
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addr32
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movl %es: 4*(BREAKPOINT_VECTOR-DEBUG_VECTOR)(%esi), %ecx
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/* actually movw to %cx */
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/* %es = bdb segment for a while */
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data32
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shrl $4, %eax
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mov %ax, %es
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/* fix up IDT entries for bdb */
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data32
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subl $2, %ebx /* calculate EA to check it */
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jb 1f /* give up if it would trap */
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addr32
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movl %es: (%ebx), %eax /* actually movw to %ax */
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addr32
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movl %eax, EXT(Idt)+8*DEBUG_VECTOR /* actually movw %ax */
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1:
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data32
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subl $2, %ecx
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jb 1f
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addr32
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movl %es: (%ecx), %eax /* actually movw to %ax */
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addr32
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movl %eax, EXT(Idt)+8*BREAKPOINT_VECTOR /* actually movw %ax */
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1:
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/* finished with groping in real mode segments */
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pop %es
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#endif /* BDE_DEBUGGER */
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/* change to protected mode */
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data32
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call EXT(real_to_prot)
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/* clear the bss */
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movl $ EXT(edata), %edi /* no EXT(_edata) - krufty ld */
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movl $ EXT(end), %ecx /* or EXT(_end) */
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subl %edi, %ecx
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subb %al, %al
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rep
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stosb
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movzbl %dl, %edx /* discard head (%dh) and random high bits */
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pushl %edx
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call EXT(boot)
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oops:
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hlt
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jmp oops
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.data
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.align 2
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#if 0 /* XXX this would give losing "_ouraddr :". Better declared in C */
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EXT(ouraddr):
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#else
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_ouraddr:
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#endif
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.long 0
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