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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/mm/ptl.h>

#define START_STACK     0x7c00  
#define START_STACK_64  $0xffffffff80007c00
                    
#
# This is where we require any SPARTAN-kernel-compatible boot loader
# to pass control in real mode.
#
# Protected mode tables are statically initialised during compile
# time. So we can just load the respective table registers and
# switch to protected mode.
#
.section K_TEXT_START
.code16
.global kernel_image_start
kernel_image_start:
    cli
    xorw %ax,%ax
    movw %ax,%ds
    movw %ax,%ss            # initialize stack segment register
    movl START_STACK,%esp   # initialize stack pointer
    
#   call memmap_arch_init
    
    mov $0x80000000, %eax  
    cpuid
    cmp $0x80000000, %eax   # any function > 80000000h?
    jbe no_long_mode
    mov $0x80000001, %eax   # Extended function code 80000001
    cpuid
    bt $29, %edx        # Test if long mode is supported.
    jnc no_long_mode

    # Load gdtr, idtr
    lgdt gdtr_inst
    lidt idtr_inst
    
    movl %cr0,%eax
    orl $0x1,%eax
    movl %eax,%cr0          # switch to protected mode

    jmpl $40, $now_in_prot

no_long_mode:
1:
    jmp 1b

# Protected 16-bit. We want to reuse the code-seg descriptor,
# the Default operand size must not be 1 when entering long mode    
now_in_prot:  
    # Set up stack & data descriptors
    movw $16, %ax
    movw %ax, %ds
    movw %ax, %fs
    movw %ax, %gs
    movw %ax, %ss

    # Enable 64-bit page transaltion entries - CR4.PAE = 1.
    # Paging is not enabled until after long mode is enabled
    movl %cr4, %eax
    btsl $5, %eax
    movl %eax, %cr4

    # Set up paging tables
    leal ptl_0, %eax
    movl %eax, %cr3
        
    # Enable long mode
    movl $0xc0000080, %ecx   # EFER MSR number
    rdmsr                   # Read EFER
    btsl $8, %eax            # Set LME=1
    wrmsr                   # Write EFER
    
    # Enable paging to activate long mode (set CR0.PG=1)
    movl %cr0, %eax
    btsl $31, %eax
    movl %eax, %cr0
    
    # At this point we are in compatibility mode
    jmpl $8, $start64

.code64
start64:
    movq START_STACK_64, %rsp
    
    lidt idtr_inst
    
    call main_bsp   # never returns
1:
    jmp 1b
            

.section K_DATA_START
.align 4096
.global ptl_2
ptl_2:  
    .quad 0x0 | (PTL_WRITABLE | PTL_PRESENT | PTL_2MB_PAGE)
    .quad 0x200000 | (PTL_WRITABLE | PTL_PRESENT | PTL_2MB_PAGE)
    .quad 0x400000 | (PTL_WRITABLE | PTL_PRESENT | PTL_2MB_PAGE)
    .quad 0x600000 | (PTL_WRITABLE | PTL_PRESENT | PTL_2MB_PAGE)
    .quad 0x800000 | (PTL_WRITABLE | PTL_PRESENT | PTL_2MB_PAGE)
    .quad 0xa00000 | (PTL_WRITABLE | PTL_PRESENT | PTL_2MB_PAGE)
    .quad 0xc00000 | (PTL_WRITABLE | PTL_PRESENT | PTL_2MB_PAGE)
    .quad 0xe00000 | (PTL_WRITABLE | PTL_PRESENT | PTL_2MB_PAGE)
    
.align 4096
.global ptl_1
ptl_1:
    .quad ptl_2 + (PTL_WRITABLE | PTL_PRESENT)
    .fill 509,8,0
    .quad ptl_2 + (PTL_WRITABLE | PTL_PRESENT)
    .fill 2,8,0
    
.align 4096
.global ptl_0
ptl_0:
    .quad ptl_1 + (PTL_WRITABLE | PTL_PRESENT)
    .fill 510,8,0
    .quad ptl_1 + (PTL_WRITABLE | PTL_PRESENT)

.global gdtr_inst               
gdtr_inst:
    .word 7*8  # GDT_ITEMS * 8
    .long gdt + 0x80000000

.global idtr_inst
idtr_inst:
    .word 0
    .long idt + 0x80000000