620 lines
12 KiB
ArmAsm
620 lines
12 KiB
ArmAsm
/* $NetBSD: start_dos.S,v 1.10 2010/12/20 01:12:44 jakllsch Exp $ */
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/*
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* startup for DOS .COM programs
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* with input from:
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* netbsd:sys/arch/i386/boot/start.S
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* Tor Egge's patches for NetBSD boot (pr port-i386/1002)
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* freebsd:sys/i386/boot/netboot/start2.S
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* XMS support by Martin Husemann
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*/
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/*
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* Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
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*
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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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/*
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Copyright 1988, 1989, 1990, 1991, 1992
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by Intel Corporation, Santa Clara, California.
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All Rights Reserved
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Permission to use, copy, modify, and distribute this software and
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its documentation for any purpose and without fee is hereby
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granted, provided that the above copyright notice appears in all
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copies and that both the copyright notice and this permission notice
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appear in supporting documentation, and that the name of Intel
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not be used in advertising or publicity pertaining to distribution
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of the software without specific, written prior permission.
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INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
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INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
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IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
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CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
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NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
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WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <machine/asm.h>
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CR0_PE = 0x1
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.data
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.globl _C_LABEL(ourseg)
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_C_LABEL(ourseg):
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.long 0
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/**************************************************************************
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GLOBAL DESCRIPTOR TABLE
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**************************************************************************/
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#ifdef __ELF__
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.align 16
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#else
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.align 4
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#endif
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gdt:
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.word 0, 0
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.byte 0, 0x00, 0x00, 0
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#ifdef SUPPORT_LINUX /* additional dummy */
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.word 0, 0
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.byte 0, 0x00, 0x00, 0
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#endif
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/* kernel code segment */
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.globl flatcodeseg
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flatcodeseg = . - gdt
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.word 0xffff, 0
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.byte 0, 0x9f, 0xcf, 0
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/* kernel data segment */
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.globl flatdataseg
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flatdataseg = . - gdt
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.word 0xffff, 0
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.byte 0, 0x93, 0xcf, 0
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/* boot code segment, base will be patched */
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bootcodeseg = . - gdt
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.word 0xffff, 0
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.byte 0, 0x9e, 0x40, 0
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/* boot data segment, base will be patched */
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bootdataseg = . - gdt
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#ifdef HEAP_BELOW_64K
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.word 0xffff, 0
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.byte 0, 0x92, 0x00, 0
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#else
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.word 0xffff, 0
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.byte 0, 0x92, 0x4f, 0
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#endif
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/* 16 bit real mode, base will be patched */
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bootrealseg = . - gdt
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.word 0xffff, 0
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.byte 0, 0x9e, 0x00, 0
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/* limits (etc) for data segment in real mode */
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bootrealdata = . - gdt
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.word 0xffff, 0
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.byte 0, 0x92, 0x00, 0
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gdtlen = . - gdt
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#ifdef __ELF__
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.align 16
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#else
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.align 4
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#endif
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gdtarg:
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.word gdtlen-1 /* limit */
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.long 0 /* addr, will be inserted */
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.text
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ENTRY(start)
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.code16
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# Check we are in real mode
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movl %cr0, %eax
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testl $CR0_PE, %eax
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jz 2f
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mov $1f, %si
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call message
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ret
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1: .asciz "must be in real mode\r\n"
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2:
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xorl %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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movl %eax, _C_LABEL(ourseg)
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#ifdef STACK_START
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add $STACK_START / 16, %ax
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mov %ax, %ss
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mov $0xfffc, %sp
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#endif
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/* fix up GDT entries for bootstrap */
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#define FIXUP(gdt_index) \
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movw %ax, gdt+gdt_index+2; \
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movb %bl, gdt+gdt_index+4
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mov %cs, %ax
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shll $4, %eax
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shldl $16, %eax, %ebx
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FIXUP(bootcodeseg)
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FIXUP(bootrealseg)
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FIXUP(bootdataseg)
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/* fix up GDT pointer */
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addl $gdt, %eax
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movl %eax, gdtarg+2
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/* change to protected mode */
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calll _C_LABEL(real_to_prot)
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.code32
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/* clear the bss */
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movl $_C_LABEL(edata), %edi
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movl $_C_LABEL(end), %ecx
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subl %edi, %ecx
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xorb %al, %al
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rep
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stosb
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call _C_LABEL(doscommain)
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ENTRY(_rtt)
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call _C_LABEL(prot_to_real)
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.code16
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ENTRY(exit16)
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sti
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movb $0x4c, %ah /* return */
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int $0x21
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/*
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* real_to_prot()
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* transfer from real mode to protected mode.
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*/
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ENTRY(real_to_prot)
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.code16
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pushl %eax
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# guarantee that interrupt is disabled when in prot mode
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cli
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# load the gdtr
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lgdtl %cs:gdtarg
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# set the PE bit of CR0
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movl %cr0, %eax
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orl $CR0_PE, %eax
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movl %eax, %cr0
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# make intrasegment jump to flush the processor pipeline and
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# reload CS register
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ljmp $bootcodeseg, $xprot
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xprot:
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.code32
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# we are in USE32 mode now
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# set up the protected mode segment registers : DS, SS, ES
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movl $bootdataseg, %eax
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mov %ax, %ds
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mov %ax, %es
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mov %ax, %ss
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#ifdef STACK_START
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addl $STACK_START, %esp
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#endif
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popl %eax
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ret
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/*
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* prot_to_real()
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* transfer from protected mode to real mode
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*/
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ENTRY(prot_to_real)
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.code32
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pushl %eax
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# set up a dummy stack frame for the second seg change.
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# Adjust the intersegment jump instruction following
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# the clearing of protected mode bit.
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# This is self-modifying code, but we need a writable
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# code segment, and an intersegment return does not give us that.
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movl _C_LABEL(ourseg), %eax
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movw %ax, xreal-2
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/*
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* Load the segment registers while still in protected mode.
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* Otherwise the control bits don't get changed.
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* The correct values are loaded later.
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*/
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movw $bootrealdata, %ax
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movw %ax, %ds
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movw %ax, %es
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movw %ax, %ss
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# Change to use16 mode.
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ljmp $bootrealseg, $x16
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x16:
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.code16
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# clear the PE bit of CR0
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movl %cr0, %eax
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andl $~CR0_PE, %eax
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movl %eax, %cr0
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# Here we have an 16 bits intersegment jump.
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ljmp $0, $xreal /* segment patched above */
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xreal:
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# we are in real mode now
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# set up the real mode segment registers : DS, SS, ES
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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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#ifdef STACK_START
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add $STACK_START / 16, %ax
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mov %ax, %ss
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subl $STACK_START, %esp
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#else
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mov %ax, %ss
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#endif
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push %bp
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movw %sp, %bp
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/* check we are returning to an address below 64k */
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movw 2/*bp*/ + 4/*eax*/ + 2(%bp), %ax /* high bits ret addr */
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test %ax, %ax
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jne 1f
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pop %bp
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sti
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popl %eax
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retl
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1: movw $2f, %si
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call message
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movl 2/*bp*/ + 4/*eax*/(%bp), %eax /* return address */
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call dump_eax
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jmp exit16
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2: .asciz "prot_to_real can't return to "
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/**************************************************************************
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___MAIN - Dummy to keep GCC happy
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**************************************************************************/
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ENTRY(__main)
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ret
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/*
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* pbzero(dst, cnt)
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* where dst is a physical address and cnt is the length
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*/
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ENTRY(pbzero)
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.code32
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pushl %ebp
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movl %esp, %ebp
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pushl %es
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pushl %edi
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cld
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# set %es to point at the flat segment
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movl $flatdataseg, %eax
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mov %ax, %es
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movl 8(%ebp), %edi # destination
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movl 12(%ebp), %ecx # count
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xorl %eax, %eax # value
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rep
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stosb
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popl %edi
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popl %es
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popl %ebp
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ret
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/*
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* vpbcopy(src, dst, cnt)
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* where src is a virtual address and dst is a physical address
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*/
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ENTRY(vpbcopy)
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.code32
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pushl %ebp
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movl %esp, %ebp
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pushl %es
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pushl %esi
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pushl %edi
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cld
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# set %es to point at the flat segment
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movl $flatdataseg, %eax
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mov %ax, %es
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movl 8(%ebp), %esi # source
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movl 12(%ebp), %edi # destination
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movl 16(%ebp), %ecx # count
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rep
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movsb
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popl %edi
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popl %esi
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popl %es
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popl %ebp
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ret
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/*
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* pvbcopy(src, dst, cnt)
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* where src is a physical address and dst is a virtual address
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*/
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ENTRY(pvbcopy)
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.code32
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pushl %ebp
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movl %esp, %ebp
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pushl %ds
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pushl %esi
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pushl %edi
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cld
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# set %ds to point at the flat segment
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movl $flatdataseg, %eax
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mov %ax, %ds
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movl 8(%ebp), %esi # source
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movl 12(%ebp), %edi # destination
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movl 16(%ebp), %ecx # count
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rep
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movsb
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popl %edi
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popl %esi
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popl %ds
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popl %ebp
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ret
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ENTRY(vtophys)
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.code32
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movl _C_LABEL(ourseg), %eax
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shll $4, %eax
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addl 4(%esp), %eax
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ret
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message:
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.code16
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pushal
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message_1:
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cld
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1: lodsb
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testb %al, %al
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jz 2f
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movb $0xe, %ah
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movw $1, %bx
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int $0x10
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jmp 1b
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2: movb $0x86, %ah
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mov $16, %cx
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int $0x15 /* delay about a second */
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popal
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ret
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/* These are useful for debugging
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*/
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.data
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eax_buf:
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.long 0, 0, 0, 0
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.text
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ENTRY(dump_eax)
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.code16
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pushal
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movw $eax_buf, %si
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mov %si, %di
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movw $8, %cx
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1: roll $4, %eax
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mov %ax, %bx
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andb $0x0f, %al
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addb $0x30, %al /* 30..3f - clear AF */
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#if 1 /* 5 bytes to generate real hex... */
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daa /* 30..39, 40..45 */
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addb $0xc0, %al /* f0..f9, 00..05 */
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adcb $0x40, %al /* 30..39, 41..45 */
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#endif
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movb %al, (%di) /* %es != %ds, so can't ... */
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inc %di /* ... use stosb */
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mov %bx, %ax
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loop 1b
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movw $0x20, %ax /* space + null */
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movw %ax, (%di)
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jmp message_1
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.globl _C_LABEL(trace_word)
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_C_LABEL(trace_word):
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.code32
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movl 4(%esp), %edx
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call _C_LABEL(prot_to_real)
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.code16
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movl %edx, %eax
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call dump_eax
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calll _C_LABEL(real_to_prot)
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.code32
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ret
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.globl _C_LABEL(trace_str)
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_C_LABEL(trace_str):
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.code32
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pushl %esi
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call _C_LABEL(prot_to_real)
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.code16
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mov %sp, %si
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mov 8(%si), %si
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call message
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calll _C_LABEL(real_to_prot)
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.code32
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popl %esi
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ret
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#ifdef XMS
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/* pointer to XMS driver, 0 if no XMS used */
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.data
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_C_LABEL(xmsdrv):
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.long 0
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.text
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ENTRY(checkxms)
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.code32
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pushl %ebp
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movl %esp, %ebp
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pushl %ebx
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pushl %edx
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pushl %es
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pushl %esi
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pushl %edi
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call _C_LABEL(prot_to_real) # enter real mode
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.code16
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movw $0x4300, %ax
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int $0x2f /* check if XMS installed */
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cmpb $0x80, %al
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jnz noxms
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movw $0x4310, %ax
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int $0x2f /* get driver address */
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movw %bx, _C_LABEL(xmsdrv) /* save es:bx to _xmsdrv */
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movw %es, _C_LABEL(xmsdrv) + 2
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movb $0x08, %ah /* XMS: query free extended memory */
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#if 0
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movb $0x00, %bl
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#endif
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lcall *_C_LABEL(xmsdrv)
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jmp xdone
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noxms: /* no XMS manager found */
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mov $0, %dx
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xdone:
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calll _C_LABEL(real_to_prot) # back to protected mode
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.code32
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xorl %eax, %eax
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movw %dx, %ax
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popl %edi
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popl %esi
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popl %es
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popl %edx
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popl %ebx
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popl %ebp
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ret
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/*
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Allocate a block of XMS memory with the requested size
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void *xmsalloc(long int kBytes);
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Depends on _xmsdrv being set by getextmem() before first call
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to this function.
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Return value: a physical address.
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*/
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ENTRY(xmsalloc)
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.code32
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pushl %ebp
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movl %esp, %ebp
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pushl %ebx
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pushl %edx
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pushl %esi
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pushl %edi
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movl 0x8(%ebp), %edx # Kbytes needed
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call _C_LABEL(prot_to_real) # enter real mode
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.code16
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movb $0x09, %ah # XMS allocate block
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lcall *_C_LABEL(xmsdrv) # result: handle in %dx
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movb $0x0c, %ah # XMS lock block
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lcall *_C_LABEL(xmsdrv) # result: 32 bit physical addr in DX:BX
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calll _C_LABEL(real_to_prot) # back to protected mode
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.code32
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movl %edx, %eax
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shl $16, %eax
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movw %bx, %ax # result in %eax
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popl %edi
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popl %esi
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popl %edx
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popl %ebx
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popl %ebp
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ret
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/*
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* ppbcopy(src, dst, cnt)
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* where src and dst are physical addresses
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*/
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ENTRY(ppbcopy)
|
|
.code32
|
|
pushl %ebp
|
|
movl %esp, %ebp
|
|
pushl %es
|
|
pushl %esi
|
|
pushl %edi
|
|
|
|
cld
|
|
|
|
# set %es to point at the flat segment
|
|
movl $flatdataseg, %eax
|
|
mov %ax, %es
|
|
|
|
movl 8(%ebp), %esi # source
|
|
movl 12(%ebp), %edi # destination
|
|
movl 16(%ebp), %ecx # count
|
|
|
|
es
|
|
rep
|
|
movsb
|
|
|
|
popl %edi
|
|
popl %esi
|
|
popl %es
|
|
popl %ebp
|
|
ret
|
|
|
|
#endif
|