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🆕 切换为grub2引导，能进入Start_Kernel函数（未能完成初始化）
This commit is contained in:
fslongjin
275
kernel/head.S
275
kernel/head.S
@ -4,11 +4,247 @@
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#include "common/asm.h"
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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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.section .text
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.global _start
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_start:
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.code64
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.global _start64
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.type _start64, @function
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.extern Start_Kernel
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ENTRY(_start64)
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// 初始化寄存器
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mov $0x10, %ax
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mov %ax, %ds
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@ -28,14 +264,26 @@ _start:
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mov %ax, %fs
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mov %ax, %ss
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mov %ax, %gs
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movq $0x7e00, %rsp
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// 2. 设置临时页表
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// 最高级
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mov $__PML4E, %eax
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mov $__PDPTE, %ebx
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or $0x7, %ebx
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mov %ebx, 0(%eax)
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// 次级
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mov $__PDPTE, %eax
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mov $__PDE, %ebx
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or $0x7, %ebx
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mov %ebx, 0(%eax)
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// ==== 加载CR3寄存器
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movq $0x101000, %rax //设置页目录基地址
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movq $__PML4E, %rax //设置页目录基地址
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movq %rax, %cr3
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movq switch_seg(%rip), %rax
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movq switch_seg(%rip), %rax
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// 由于ljmp和lcall在GAS中不受支持，因此我们需要先伪造函数调用现场，通过lret的方式，给它跳转过去。才能更新cs寄存器
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// 实在是太妙了！Amazing！
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pushq $0x08 //段选择子
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@ -44,9 +292,11 @@ _start:
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// 64位模式的代码
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switch_seg:
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.quad entry64
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entry64:
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movq $0x10, %rax
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movq %rax, %ds
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movq %rax, %es
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@ -119,11 +369,8 @@ SetUp_TSS64:
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// mov $0x50, %ax // 设置起始地址为80
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// ltr %ax
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// 切换到内核主程序
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movq go_to_kernel(%rip), %rax
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pushq $0x08
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pushq %rax
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lretq
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call Start_Kernel
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go_to_kernel:
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.quad Start_Kernel
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@ -148,13 +395,14 @@ ENTRY(_stack_start)
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// 初始化页表
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.align 8 //设置为8byte对齐
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.align 0x1000 //设置为8byte对齐
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.org 0x1000 //设置页表位置为内核执行头程序的0x1000处
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__PML4E:
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.quad 0x102007 // 用户访问，可读写，已存在， 地址在31~12位
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.fill 255,8,0
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.quad 0x102007
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.quad 0x102007
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.fill 255,8,0
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.org 0x2000
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@ -185,6 +433,7 @@ __PDE:
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// GDT表
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.section .data
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.align 16
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.global GDT_Table // 使得GDT可以被外部程序引用或者访问
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GDT_Table:
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