173 lines
3.2 KiB
ArmAsm
173 lines
3.2 KiB
ArmAsm
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/*
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* i386 boot code, based on qemu-bmibug.
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*
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* Copyright 2019 Doug Gale
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* Copyright 2019 Linaro
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*
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* This work is licensed under the terms of the GNU GPL, version 3 or later.
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* See the COPYING file in the top-level directory.
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*
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* SPDX-License-Identifier: GPL-3.0-or-later
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*/
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.section .head
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/* Multi-boot header */
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multiboot_st:
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.int 0x1BADB002
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.int 0x10000
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.int -(0x10000+0x1BADB002)
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// Load address
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.int __load_st
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.int __load_st
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.int __load_en
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.int __bss_en
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.int _start
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// mode
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.int 0
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// width
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.int 0
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// height
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.int 0
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// depth
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.int 0
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.code32
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.section .text
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/* Kernel Entry Point */
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.global _start
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_start:
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// Setup stack ASAP
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mov $stack_end,%esp
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// Load GDT ASAP
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lgdt gdtr
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ljmp $0x8,$.Lloadcs
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.Lloadcs:
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mov $0x10,%eax
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mov %eax,%ds
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mov %eax,%es
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mov %eax,%fs
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mov %eax,%gs
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mov %eax,%ss
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// Fixup the IDT to the ridiculous i386 layout
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xor %ebx,%ebx
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.Lnextidt:
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mov idt_00(,%ebx,8),%eax
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shr $16,%eax
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movw $0x8,idt_00+2(,%ebx,8)
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movw $0x8E00,idt_00+4(,%ebx,8)
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movw %ax,idt_00+6(,%ebx,8)
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add $1,%ebx
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cmp $32,%ebx
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jl .Lnextidt
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// Load IDTR
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push $idt_00
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push $((32 * 8 - 1) << 16)
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lidt 2(%esp)
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add $8,%esp
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/*
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* Don't worry about stack frame, assume everthing
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* is garbage when we return, we won't need it.
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*/
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call main
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/* output any non-zero result in eax to isa-debug-exit device */
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test %al, %al
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jz 1f
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out %ax, $0xf4
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1: /* QEMU ACPI poweroff */
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mov $0x604,%edx
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mov $0x2000,%eax
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out %ax,%dx
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hlt
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jmp 1b
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/*
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* Helper Functions
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*/
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/* Output a single character to serial port */
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.global __sys_outc
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__sys_outc:
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pushl %ebp
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movl %esp, %ebp
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out %al,$0xE9
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movl %ebp, %esp
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popl %ebp
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ret
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/* Interrupt Descriptor Table */
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.section .data
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.align 16
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idt_00: .int 0, 0
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idt_01: .int 0, 0
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idt_02: .int 0, 0
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idt_03: .int 0, 0
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idt_04: .int 0, 0
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idt_05: .int 0, 0
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idt_06: .int 0, 0 /* intr_6_opcode, Invalid Opcode */
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idt_07: .int 0, 0
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idt_08: .int 0, 0
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idt_09: .int 0, 0
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idt_0A: .int 0, 0
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idt_0B: .int 0, 0
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idt_0C: .int 0, 0
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idt_0D: .int 0, 0
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idt_0E: .int 0, 0
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idt_0F: .int 0, 0
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idt_10: .int 0, 0
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idt_11: .int 0, 0
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idt_12: .int 0, 0
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idt_13: .int 0, 0
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idt_14: .int 0, 0
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idt_15: .int 0, 0
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idt_16: .int 0, 0
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idt_17: .int 0, 0
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idt_18: .int 0, 0
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idt_19: .int 0, 0
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idt_1A: .int 0, 0
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idt_1B: .int 0, 0
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idt_1C: .int 0, 0
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idt_1D: .int 0, 0
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idt_1E: .int 0, 0
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idt_1F: .int 0, 0
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gdt:
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.short 0
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gdtr:
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.short gdt_en - gdt - 1
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.int gdt
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// Code
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.short 0xFFFF
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.short 0
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.byte 0
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.byte 0x9b
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.byte 0xCF
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.byte 0
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// Data
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.short 0xFFFF
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.short 0
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.byte 0
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.byte 0x93
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.byte 0xCF
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.byte 0
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gdt_en:
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.section .bss
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.align 16
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stack: .space 65536
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stack_end:
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