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#
# Copyright (C) 2001-2004 Jakub Jermar
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

#include <arch/boot/boot.h>
#include <arch/boot/memmap.h>
#include <arch/mm/page.h>
#include <arch/pm.h>

.section K_TEXT_START, "ax"

KTEXT=8
KDATA=16

.code32
.align 4
multiboot_header:
    .long MULTIBOOT_HEADER_MAGIC
    .long MULTIBOOT_HEADER_FLAGS
    .long -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)    # checksum
    .long multiboot_header + BOOT_OFFSET
    .long unmapped_ktext_start + BOOT_OFFSET
    .long 0
    .long 0
    .long multiboot_image_start + BOOT_OFFSET
    
multiboot_image_start:
    movl $BOOTSTRAP_OFFSET - 0x400, %esp                # initialize stack pointer
    
    lgdt protected_bootstrap_gdtr - 0x80000000          # initialize Global Descriptor Table register

    movw $KDATA, %cx
    movw %cx, %es
    movw %cx, %gs
    movw %cx, %fs
    movw %cx, %ds                           # kernel data + stack
    movw %cx, %ss
    
    jmpl $KTEXT, $multiboot_meeting_point + BOOT_OFFSET
    multiboot_meeting_point:
    
    pushl %ebx                          # save parameters from GRUB
    pushl %eax
    
    movl $BOOTSTRAP_OFFSET + BOOT_OFFSET, %esi
    movl $BOOTSTRAP_OFFSET, %edi
    movl $_hardcoded_unmapped_size, %ecx
    cld
    rep movsb
    
    call map_kernel                         # map kernel and turn paging on
    
    popl %eax
    popl %ebx
    cmpl $MULTIBOOT_LOADER_MAGIC, %eax              # compare GRUB signature
    je valid_boot
        
        xorl %ecx, %ecx                         # no memory size or map available
        movl %ecx, e801memorysize
        movl %ecx, e820counter
        
        jmp invalid_boot
        
    valid_boot:
        
        movl (%ebx), %eax                       # ebx = physical address of struct multiboot_info
        
        bt $0, %eax                             # mbi->flags[0] (mem_lower, mem_upper valid)
        jc mem_valid
            
            xorl %ecx, %ecx
            jmp mem_invalid
            
        mem_valid:
        movl 4(%ebx), %ecx                      # mbi->mem_lower
        addl 8(%ebx), %ecx                      # mbi->mem_upper
        
        mem_invalid:
        movl %ecx, e801memorysize
        
        bt $3, %eax                             # mbi->flags[3] (mods_count, mods_addr valid)   
        jc mods_valid
            
            xorl %ecx, %ecx
            xorl %edx, %edx
            jmp mods_invalid
        
        mods_valid:
        movl 20(%ebx), %ecx                     # mbi->mods_count
        cmpl $0, %ecx
        je mods_invalid
        
        movl 24(%ebx), %esi                     # mbi->mods_addr
        movl 0(%esi), %edx                      # mods->mod_start
        movl 4(%esi), %ecx                      # mods->mod_end
        subl %edx, %ecx
        addl $0x80000000, %edx
        
        mods_invalid:
        movl %ecx, init_size
        movl %edx, init_addr
        
        bt $6, %eax                             # mbi->flags[6] (mmap_length, mmap_addr valid)  
        jc mmap_valid
            
            xorl %edx, %edx
            jmp mmap_invalid
            
        mmap_valid:
        movl 44(%ebx), %ecx                     # mbi->mmap_length
        movl 48(%ebx), %esi                     # mbi->mmap_addr
        movl $e820table, %edi
        xorl %edx, %edx
        
        mmap_loop:
            cmpl $0, %ecx
            jle mmap_end
            
            movl 4(%esi), %eax                  # mmap->base_addr_low
            movl %eax, (%edi)
            
            movl 8(%esi), %eax                  # mmap->base_addr_high
            movl %eax, 4(%edi)
            
            movl 12(%esi), %eax                 # mmap->length_low
            movl %eax, 8(%edi)
            
            movl 16(%esi), %eax                 # mmap->length_high
            movl %eax, 12(%edi)
            
            movl 20(%esi), %eax                 # mmap->type
            movl %eax, 16(%edi)
            
            movl (%esi), %eax                   # mmap->size
            addl $0x4, %eax
            addl %eax, %esi
            subl %eax, %ecx
            addl $MEMMAP_E820_RECORD_SIZE, %edi
            incl %edx
            jmp mmap_loop
        
        mmap_end:
        
        mmap_invalid:
        movl %edx, e820counter
        
    invalid_boot:
    
    call main_bsp - BOOT_OFFSET                 # never returns

    cli
    hlt

.global map_kernel
map_kernel:
    #
    # Here we setup mapping for both the unmapped and mapped sections of the kernel.
    # For simplicity, we map the entire 4G space.
    #
    movl %cr4, %ecx
    orl $(1<<4), %ecx
    movl %ecx, %cr4                         # turn PSE on
    
    movl $(page_directory+0), %esi
    movl $(page_directory+2048), %edi
    xorl %ecx, %ecx
    xorl %ebx, %ebx
0:
    movl $((1<<7)|(1<<0)), %eax
    orl %ebx, %eax
    movl %eax, (%esi,%ecx,4)                    # mapping 0x00000000+%ecx*4M => 0x00000000+%ecx*4M
    movl %eax, (%edi,%ecx,4)                    # mapping 0x80000000+%ecx*4M => 0x00000000+%ecx*4M
    addl $(4*1024*1024), %ebx

    incl %ecx
    cmpl $512, %ecx
    jl 0b

    movl %esi, %cr3
    
    # turn paging on
    movl %cr0, %ebx
    orl $(1<<31), %ebx
    movl %ebx, %cr0
    ret


.section K_DATA_START, "aw", @progbits

.align 4096
page_directory:
    .space 4096, 0

.global real_bootstrap_gdtr_boot
real_bootstrap_gdtr_boot:
    .word selector(GDT_ITEMS)
    .long KA2PA(gdt)-BOOT_OFFSET