mirror of
https://github.com/DragonOS-Community/DragonOS.git
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226 lines
5.5 KiB
ArmAsm
226 lines
5.5 KiB
ArmAsm
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// 以下是来自 multiboot2 规范的定义
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// How many bytes from the start of the file we search for the header.
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#define MULTIBOOT_SEARCH 32768
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#define MULTIBOOT_HEADER_ALIGN 8
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// The magic field should contain this.
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#define MULTIBOOT2_HEADER_MAGIC 0xe85250d6
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// This should be in %eax.
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#define MULTIBOOT2_BOOTLOADER_MAGIC 0x36d76289
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// Alignment of multiboot modules.
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#define MULTIBOOT_MOD_ALIGN 0x00001000
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// Alignment of the multiboot info structure.
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#define MULTIBOOT_INFO_ALIGN 0x00000008
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// Flags set in the 'flags' member of the multiboot header.
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#define MULTIBOOT_TAG_ALIGN 8
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#define MULTIBOOT_TAG_TYPE_END 0
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#define MULTIBOOT_TAG_TYPE_CMDLINE 1
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#define MULTIBOOT_TAG_TYPE_BOOT_LOADER_NAME 2
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#define MULTIBOOT_TAG_TYPE_MODULE 3
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#define MULTIBOOT_TAG_TYPE_BASIC_MEMINFO 4
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#define MULTIBOOT_TAG_TYPE_BOOTDEV 5
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#define MULTIBOOT_TAG_TYPE_MMAP 6
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#define MULTIBOOT_TAG_TYPE_VBE 7
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#define MULTIBOOT_TAG_TYPE_FRAMEBUFFER 8
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#define MULTIBOOT_TAG_TYPE_ELF_SECTIONS 9
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#define MULTIBOOT_TAG_TYPE_APM 10
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#define MULTIBOOT_TAG_TYPE_EFI32 11
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#define MULTIBOOT_TAG_TYPE_EFI64 12
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#define MULTIBOOT_TAG_TYPE_SMBIOS 13
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#define MULTIBOOT_TAG_TYPE_ACPI_OLD 14
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#define MULTIBOOT_TAG_TYPE_ACPI_NEW 15
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#define MULTIBOOT_TAG_TYPE_NETWORK 16
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#define MULTIBOOT_TAG_TYPE_EFI_MMAP 17
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#define MULTIBOOT_TAG_TYPE_EFI_BS 18
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#define MULTIBOOT_TAG_TYPE_EFI32_IH 19
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#define MULTIBOOT_TAG_TYPE_EFI64_IH 20
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#define MULTIBOOT_TAG_TYPE_LOAD_BASE_ADDR 21
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#define MULTIBOOT_HEADER_TAG_END 0
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#define MULTIBOOT_HEADER_TAG_INFORMATION_REQUEST 1
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#define MULTIBOOT_HEADER_TAG_ADDRESS 2
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#define MULTIBOOT_HEADER_TAG_ENTRY_ADDRESS 3
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#define MULTIBOOT_HEADER_TAG_CONSOLE_FLAGS 4
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#define MULTIBOOT_HEADER_TAG_FRAMEBUFFER 5
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#define MULTIBOOT_HEADER_TAG_MODULE_ALIGN 6
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#define MULTIBOOT_HEADER_TAG_EFI_BS 7
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#define MULTIBOOT_HEADER_TAG_ENTRY_ADDRESS_EFI32 8
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#define MULTIBOOT_HEADER_TAG_ENTRY_ADDRESS_EFI64 9
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#define MULTIBOOT_HEADER_TAG_RELOCATABLE 10
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#define MULTIBOOT_ARCHITECTURE_I386 0
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#define MULTIBOOT_ARCHITECTURE_MIPS32 4
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#define MULTIBOOT_HEADER_TAG_OPTIONAL 1
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#define MULTIBOOT_LOAD_PREFERENCE_NONE 0
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#define MULTIBOOT_LOAD_PREFERENCE_LOW 1
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#define MULTIBOOT_LOAD_PREFERENCE_HIGH 2
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#define MULTIBOOT_CONSOLE_FLAGS_CONSOLE_REQUIRED 1
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#define MULTIBOOT_CONSOLE_FLAGS_EGA_TEXT_SUPPORTED 2
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// 直接用 -m64 编译出来的是 64 位代码,
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// 但是启动后的机器是 32 位的,相当于在 32 位机器上跑 64 位程序。
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// 得加一层跳转到 64 位的 -m32 代码,开启 long 模式后再跳转到以 -m64 编译的代码中
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// 对于 x86_64,需要在启动阶段进入长模式(IA32E),这意味着需要一个临时页表
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// See https://wiki.osdev.org/Creating_a_64-bit_kernel:
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// With a 32-bit bootstrap in your kernel
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// 这部分是从保护模式启动 long 模式的代码
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// 工作在 32bit
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// 声明这一段代码以 32 位模式编译
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.code32
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// multiboot2 文件头
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// 计算头长度
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.SET HEADER_LENGTH, multiboot_header_end - multiboot_header
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// 计算校验和
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.SET CHECKSUM, -(MULTIBOOT2_HEADER_MAGIC + MULTIBOOT_ARCHITECTURE_I386 + HEADER_LENGTH)
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// 8 字节对齐
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.align MULTIBOOT_HEADER_ALIGN
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// 声明所属段
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.section .multiboot_header
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multiboot_header:
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// 魔数
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.long MULTIBOOT2_HEADER_MAGIC
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// 架构
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.long MULTIBOOT_ARCHITECTURE_I386
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// 头长度
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.long HEADER_LENGTH
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// 校验和
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.long CHECKSUM
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// 添加其它内容在此,详细信息见 Multiboot2 Specification version 2.0.pdf
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.short MULTIBOOT_HEADER_TAG_END
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// 结束标记
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.short 0
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.long 8
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multiboot_header_end:
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// 临时页表 4KB/页
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.section .data
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.align 0x1000
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pml4:
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.skip 0x1000
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pdpt:
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.skip 0x1000
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pd:
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.skip 0x1000
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pt:
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.skip 0x1000
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// 临时 GDT
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.align 16
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gdt64:
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null_desc:
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.short 0xFFFF
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.short 0
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.byte 0
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.byte 0
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.byte 0
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.byte 0
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code_desc:
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.short 0
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.short 0
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.byte 0
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.byte 0x9A
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.byte 0x20
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.byte 0
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data_desc:
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.short 0
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.short 0
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.byte 0
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.byte 0x92
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.byte 0
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.byte 0
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user_code_desc:
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.short 0
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.short 0
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.byte 0
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.byte 0xFA
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.byte 0x20
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.byte 0
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user_data_desc:
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.short 0
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.short 0
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.byte 0
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.byte 0xF2
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.byte 0
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.byte 0
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gdt64_pointer:
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.short gdt64_pointer-gdt64-1
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.quad gdt64
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gdt64_pointer64:
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.short gdt64_pointer-gdt64-1
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.quad gdt64
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.section .text
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.global _start
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.type _start, @function
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# 在 multiboot2.cpp 中定义
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.extern boot_info_addr
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.extern multiboot2_magic
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_start:
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// 关中断
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cli
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// multiboot2_info 结构体指针
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//mov %ebx, boot_info_addr
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// 魔数
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// mov %eax, multiboot2_magic
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// 从保护模式跳转到长模式
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// 1. 允许 PAE
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mov %cr4, %eax
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or $(1<<5), %eax
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mov %eax, %cr4
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// 2. 设置临时页表
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// 最高级
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mov $pml4, %eax
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mov $pdpt, %ebx
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or $0x3, %ebx
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mov %ebx, 0(%eax)
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// 次级
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mov $pdpt, %eax
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mov $pd, %ebx
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or $0x3, %ebx
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mov %ebx, 0(%eax)
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// 次低级
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mov $pd, %eax
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mov $pt, %ebx
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or $0x3, %ebx
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mov %ebx, 0(%eax)
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// 最低级
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// 循环 512 次,填满一页
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mov $512, %ecx
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mov $pt, %eax
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mov $0x3, %ebx
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.fill_pt:
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mov %ebx, 0(%eax)
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add $0x1000, %ebx
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add $8, %eax
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loop .fill_pt
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// 填写 CR3
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mov $pml4, %eax
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mov %eax, %cr3
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// 3. 切换到 long 模式
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mov $0xC0000080, %ecx
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rdmsr
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or $(1<<8), %eax
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wrmsr
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// 4. 开启分页
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mov %cr0, %eax
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or $(1<<31), %eax
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mov %eax, %cr0
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// 5. 重新设置 GDT
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mov $gdt64_pointer, %eax
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lgdt 0(%eax)
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// 6. 跳转到 64 位代码执行
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jmp $0x8, $_start64
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hlt
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ret
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