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https://git.stationery.faith/corn/corn.git
synced 2024-11-22 05:22:19 +00:00
Added basic long mode setup
This commit is contained in:
Simon
parent
05cf015382
commit
df2c0ee981
4 changed files with 138 additions and 64 deletions
8
Makefile
8
Makefile
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@ -5,10 +5,10 @@ BUILD_DIR=build
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K_BIN_NAME=kernel.bin
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ISO_NAME=os_image.iso
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CC=cc
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CC=gcc
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LD=ld
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CFLAGS=-ffreestanding -g -Wall -Wextra -pedantic -lgcc -isystem $(INCLUDE_DIR)
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CFLAGS= -std=c2x -ffreestanding -g -Wall -Wextra -pedantic -lgcc -isystem $(INCLUDE_DIR)
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C_SRC=$(shell find $(SRC_DIR) -type f -name "*.c")
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@ -31,6 +31,10 @@ $(A_OBJ): $(BUILD_DIR)/%.S.o : %.S
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@mkdir -p $(@D)
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nasm $< -f elf64 -o $@
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$(BUILD_DIR)/$(SRC_DIR)/arch/amd64/shim.o: $(SRC_DIR)/arch/amd64/shim.c
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@mkdir -p $(@D)
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$(CC) -c $(CFLAGS) -o $@ $< -m32
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$(C_OBJ): $(BUILD_DIR)/%.o : %.c
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@mkdir -p $(@D)
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$(CC) -c $(CFLAGS) -o $@ $<
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@ -3,18 +3,6 @@ extern kmain
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extern amd64_shim
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bits 32
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; base, limit, access, flags
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%macro gdt_entry 4
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db %2 & 0xff
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db (%2 >> 8) & 0xff
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db %1 & 0xff
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db (%1 >> 8) & 0xff
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db (%1 >> 16) & 0xff
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db %3
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db ((%2 >> 16) & 0x0f) | (%4 << 4)
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db (%1 >> 24) & 0xff
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%endmacro
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section .multiboot
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align 8
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mb_start:
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@ -38,33 +26,97 @@ stack_end:
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section .rodata
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align 16
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gdt_start:
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gdt_entry 0, 0, 0, 0
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gdt_entry 0, 0xFFFFF, 0x9A, 0xC
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gdt_entry 0, 0xFFFFF, 0x92, 0xC
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gdt_end:
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gdt_descriptor:
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dw gdt_end - gdt_start - 1
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dd gdt_start
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; Access bits
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PRESENT equ 1 << 7
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NOT_SYS equ 1 << 4
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EXEC equ 1 << 3
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DC equ 1 << 2
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RW equ 1 << 1
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ACCESSED equ 1 << 0
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; Flags bits
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GRAN_4K equ 1 << 7
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SZ_32 equ 1 << 6
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LONG_MODE equ 1 << 5
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GDT:
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.Null: equ $ - GDT
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dq 0
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.Code: equ $ - GDT
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dd 0xFFFF ; Limit & Base (low, bits 0-15)
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db 0 ; Base (mid, bits 16-23)
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db PRESENT | NOT_SYS | EXEC | RW ; Access
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db GRAN_4K | LONG_MODE | 0xF ; Flags & Limit (high, bits 16-19)
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db 0 ; Base (high, bits 24-31)
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.Data: equ $ - GDT
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dd 0xFFFF ; Limit & Base (low, bits 0-15)
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db 0 ; Base (mid, bits 16-23)
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db PRESENT | NOT_SYS | RW ; Access
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db GRAN_4K | SZ_32 | 0xF ; Flags & Limit (high, bits 16-19)
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db 0 ; Base (high, bits 24-31)
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.TSS: equ $ - GDT
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dd 0x00000068
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dd 0x00CF8900
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.Pointer:
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dw $ - GDT - 1
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dq GDT
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section .text
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align 8
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start:
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cli
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lgdt [gdt_descriptor]
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jmp 0x08:after_lgdt
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after_lgdt:
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mov ax, 0x10
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mov ds, ax
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mov ss, ax
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mov es, ax
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mov fs, ax
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mov gs, ax
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mov esp, stack_end
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mov ebp, stack_end
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push ebx
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mov edi, 0x1000
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mov cr3, edi
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xor eax, eax
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mov ecx, 4096
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rep stosd
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mov edi, cr3
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mov DWORD [edi], 0x2003 ; Set the uint32_t at the destination index to 0x2003.
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add edi, 0x1000 ; Add 0x1000 to the destination index.
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mov DWORD [edi], 0x3003 ; Set the uint32_t at the destination index to 0x3003.
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add edi, 0x1000 ; Add 0x1000 to the destination index.
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mov DWORD [edi], 0x4003 ; Set the uint32_t at the destination index to 0x4003.
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add edi, 0x1000 ; Add 0x1000 to the destination index.
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mov ebx, 0x00000003 ; Set the B-register to 0x00000003.
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mov ecx, 512 ; Set the C-register to 512.
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.SetEntry:
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mov DWORD [edi], ebx ; Set the uint32_t at the destination index to the B-register.
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add ebx, 0x1000 ; Add 0x1000 to the B-register.
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add edi, 8 ; Add eight to the destination index.
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loop .SetEntry ; Set the next entry.
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;push ebx ; Call our function to set up basic paging
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;call amd64_shim
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mov eax, cr4 ; Enable the PAE bit
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or eax, 1 << 5
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mov cr4, eax
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mov ecx, 0xC0000080 ; Enable long mode
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rdmsr
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or eax, 1 << 8
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wrmsr
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mov eax, cr0 ; Enable paging
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or eax, 1 << 31
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mov cr0, eax
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lgdt [GDT.Pointer]
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jmp GDT.Code:code64
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bits 64
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code64:
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call amd64_shim
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push rax
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call kmain
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cli
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halt:
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@ -1,4 +1,5 @@
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#include <stdint.h>
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#include <cpuid.h>
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#define PG_PRESENT 0x0000'0000'0000'0001
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#define PG_READ_WRITE 0x0000'0000'0000'0002
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@ -8,14 +9,19 @@
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#define PG_ACCESSED 0x0000'0000'0000'0020
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#define PG_EXECUTE_DISABLE 0x8000'0000'0000'0000
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#define F_PRESENT 0b1
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#define F_WRITEABLE 0b10
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#define F_UNPRIVILEGED 0b100
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#define F_WRITETHROUGH 0b1000
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#define F_CACHEDISABLE 0b10000
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#define F_ACCESSED 0b100000
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#define F_DIRTY 0b1000000
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#define F_MEGABYTE 0b10000000
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#define F_GLOBAL 0b100000000
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// PAGE MAP LEVEL 4 ENTRY
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struct pml4 {
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uint64_t present : 1;
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uint64_t rw : 1;
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uint64_t user_supervisor : 1;
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uint64_t write_through : 1;
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uint64_t cache_disable : 1;
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uint64_t accessed : 1;
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struct pml4e {
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uint64_t flags : 6;
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uint64_t _reserved : 6;
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uint64_t address : 40;
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uint64_t _reserved_2 : 11;
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@ -24,12 +30,7 @@ struct pml4 {
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// PAGE DIRECTORY POINTER TABLE ENTRY
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struct pdpte {
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uint64_t present : 1;
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uint64_t rw : 1;
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uint64_t user_supervisor : 1;
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uint64_t write_through : 1;
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uint64_t cache_disable : 1;
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uint64_t accessed : 1;
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uint64_t flags : 6;
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uint64_t _reserved : 1;
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uint64_t page_size : 1;
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uint64_t _reserved_2 : 2;
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@ -40,12 +41,7 @@ struct pdpte {
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// PAGE DIRECTORY ENTRY
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struct pde {
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uint64_t present : 1;
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uint64_t rw : 1;
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uint64_t user_supervisor : 1;
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uint64_t write_through : 1;
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uint64_t cache_disable : 1;
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uint64_t accessed : 1;
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uint64_t flags : 6;
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uint64_t _reserved : 1;
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uint64_t page_size : 1;
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uint64_t _reserved_2 : 2;
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@ -56,15 +52,7 @@ struct pde {
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// PAGE TABLE ENTRY
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struct pte {
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uint64_t present : 1;
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uint64_t rw : 1;
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uint64_t user_supervisor : 1;
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uint64_t write_through : 1;
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uint64_t cache_disable : 1;
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uint64_t accessed : 1;
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uint64_t dirty : 1;
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uint64_t mem_type : 1;
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uint64_t global : 1;
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uint64_t flags : 9;
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uint64_t _reserved : 3;
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uint64_t address : 40;
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uint64_t _reserved_2 : 7;
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@ -72,7 +60,36 @@ struct pte {
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uint64_t execute_disable : 1;
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};
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// entry point for amd64
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void amd64_shim(void *boot_info) {
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struct pml4e pml4[512];
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struct pdpte pdpt[512];
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struct pde pd[512];
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struct pte pt[512];
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static int get_maxphysaddr() {
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uint32_t eax, ebx, ecx, edx;
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__cpuid(0x80000008, eax, ebx, ecx, edx);
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return eax & 0xFF;
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}
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// entry point for amd64
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void* amd64_shim(void *boot_info) {
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for (int i = 0; i < 512; i++) {
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pml4[i].flags = 0;
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}
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for (int i = 0; i < 512; i++) {
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pdpt[i].flags = 0;
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}
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for (int i = 0; i < 512; i++) {
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pd[i].flags = 0;
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}
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pml4[0].flags = F_PRESENT | F_WRITEABLE;
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pml4[0].address = (uint64_t)&pdpt;
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pdpt[0].flags = F_PRESENT | F_WRITEABLE;
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pdpt[0].address = (uint64_t)&pd;
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pd[0].flags = F_PRESENT | F_WRITEABLE;
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pd[0].address = (uint64_t)&pt;
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for (int i = 0; i < 512; i++) {
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pt[i].flags = F_PRESENT | F_WRITEABLE;
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pt[i].address = i * 4096;
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}
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}
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@ -1,5 +1,6 @@
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void kmain() {
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*(char*)0xB8000 = 'c';
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while(1) {
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asm("cli; hlt");
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__asm("cli; hlt");
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}
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}
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