| 1 | #
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| 2 | # Copyright (C) 2001-2004 Jakub Jermar
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| 3 | # All rights reserved.
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| 4 | #
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| 5 | # Redistribution and use in source and binary forms, with or without
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| 6 | # modification, are permitted provided that the following conditions
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| 7 | # are met:
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| 8 | #
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| 9 | # - Redistributions of source code must retain the above copyright
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| 10 | # notice, this list of conditions and the following disclaimer.
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| 11 | # - Redistributions in binary form must reproduce the above copyright
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| 12 | # notice, this list of conditions and the following disclaimer in the
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| 13 | # documentation and/or other materials provided with the distribution.
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| 14 | # - The name of the author may not be used to endorse or promote products
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| 15 | # derived from this software without specific prior written permission.
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| 16 | #
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| 17 | # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | #
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| 28 |
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| 29 | .section K_TEXT_START
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| 30 | .global kernel_image_start
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| 31 |
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| 32 | .code16
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| 33 | #
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| 34 | # This is where we require any SPARTAN-kernel-compatible boot loader
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| 35 | # to pass control in real mode.
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| 36 | #
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| 37 | # Protected mode tables are statically initialised during compile
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| 38 | # time. So we can just load the respective table registers and
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| 39 | # switch to protected mode.
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| 40 | #
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| 41 | kernel_image_start:
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| 42 | cli
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| 43 | call memmap_arch_init
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| 44 | xorw %ax,%ax
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| 45 | movw %ax,%ds
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| 46 | lgdt gdtr
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| 47 | movl %cr0,%eax
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| 48 | orl $0x1,%eax
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| 49 | movl %eax,%cr0
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| 50 | jmpl $8,$meeting_point
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| 51 | meeting_point:
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| 52 | .code32
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| 53 |
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| 54 | movw $16,%ax
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| 55 | movw %ax,%es
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| 56 | movw %ax,%gs
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| 57 | movw %ax,%fs
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| 58 | movw %ax,%ds # kernel data + stack
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| 59 | movw %ax,%ss
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| 60 | movl $0x7c00,%esp
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| 61 |
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| 62 | lidt idtr
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| 63 |
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| 64 | call map_kernel
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| 65 |
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| 66 | movl $_hardcoded_ktext_size, hardcoded_ktext_size
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| 67 | movl $_hardcoded_kdata_size, hardcoded_kdata_size
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| 68 | movl $_hardcoded_load_address, hardcoded_load_address
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| 69 |
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| 70 | call main_bsp # never returns
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| 71 |
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| 72 | cli
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| 73 | hlt
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| 74 |
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| 75 | .global map_kernel
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| 76 | map_kernel:
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| 77 | #
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| 78 | # Here we setup mapping for both the unmapped and mapped sections of the kernel.
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| 79 | # For simplicity, we set only one 4M page for 0x00000000 and one for 0x80000000.
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| 80 | #
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| 81 | movl %cr4, %ecx
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| 82 | orl $(1<<4), %ecx
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| 83 | movl %ecx, %cr4 # turn PSE on
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| 84 |
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| 85 | movl $((1<<7)|(1<<0)), %eax
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| 86 | movl %eax, page_directory # mapping 0x00000000 => 0x00000000
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| 87 |
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| 88 | movl $(page_directory+(4096/2)), %edx
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| 89 | movl %eax, (%edx) # mapping 0x80000000 => 0x00000000
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| 90 |
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| 91 | leal page_directory, %eax
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| 92 | movl %eax, %cr3
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| 93 |
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| 94 | # turn on paging
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| 95 | movl %cr0, %ebx
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| 96 | orl $(1<<31), %ebx
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| 97 | movl %ebx, %cr0
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| 98 | ret
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| 99 |
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| 100 |
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| 101 | .section K_DATA_START
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| 102 |
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| 103 | .align 4096
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| 104 | page_directory:
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| 105 | .space 4096, 0
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