diff options
Diffstat (limited to 'asm')
| -rw-r--r-- | asm/boot.asm | 161 | ||||
| -rw-r--r-- | asm/long.asm | 171 |
2 files changed, 0 insertions, 332 deletions
diff --git a/asm/boot.asm b/asm/boot.asm deleted file mode 100644 index ae68761..0000000 --- a/asm/boot.asm +++ /dev/null @@ -1,161 +0,0 @@ -[BITS 32] - -; Declare constants for the multiboot header. -MBALIGN equ 1 << 0 ; align loaded modules on page boundaries -MEMINFO equ 1 << 1 ; provide memory map -MBFLAGS equ MBALIGN | MEMINFO ; this is the Multiboot 'flag' field -MAGIC equ 0x1BADB002 ; 'magic number' lets bootloader find the header -CHECKSUM equ -(MAGIC + MBFLAGS) ; checksum of above, to prove we are multiboot - -; Declare a multiboot header that marks the program as a kernel. These are magic -; values that are documented in the multiboot standard. The bootloader will -; search for this signature in the first 8 KiB of the kernel file, aligned at a -; 32-bit boundary. The signature is in its own section so the header can be -; forced to be within the first 8 KiB of the kernel file. -section .multiboot -align 4 - dd MAGIC - dd MBFLAGS - dd CHECKSUM - -section .bootstrap - -present equ 1 << 7 -not_sys equ 1 << 4 -exec equ 1 << 3 -cd equ 1 << 2 -rw equ 1 << 1 -access equ 1 << 0 - -gran_4k equ 1 << 7 -sz_32 equ 1 << 6 -long_m equ 1 << 5 - -global gdt.ptr -gdt: -.null: equ $ - gdt - dq 0 -.code: equ $ - gdt - dd 0xffff - db 0 - db present | not_sys | exec | rw - db gran_4k | long_m | 0xf - db 0 -.data: equ $ - gdt - dd 0xffff - db 0 - db present | not_sys | rw - db gran_4k | sz_32 | 0xf - db 0 -.ptr: - dw $ - gdt - 1 - dq gdt - -global bootstrap -bootstrap: - - mov dword [multiboot_magic], eax - mov dword [multiboot_header], ebx - - mov eax, cr0 - and eax, ~(1 << 31) - mov cr0, eax - - mov edi, pml4 ;0x1000 - mov cr3, edi - xor eax, eax - mov ecx, 1024 - rep stosd - - mov edi, 0x2000 - mov ecx, 4096 - rep stosd - - mov edi, cr3 - - mov dword [edi], 0x2003 - mov edi, 0x2000 - mov dword [edi], 0x3003 - add edi, 0x1000 - mov dword [edi], 0x4003 - mov dword [edi + 8], 0x5003 - add edi, 0x1000 - - mov ebx, 0x00000003 - mov ecx, 512 - -.set_entry: - mov dword [edi], ebx - add ebx, 0x1000 - add edi, 8 - loop .set_entry - - mov edi, 0x5000 - mov ecx, 512 - -.set_entry_2: - mov dword [edi], ebx - add ebx, 0x1000 - add edi, 8 - loop .set_entry_2 - - mov eax, cr4 - or eax, 1 << 5 - mov cr4, eax - - mov ecx, 0xc0000080 - rdmsr - or eax, 1 << 8 | 1 << 0 - wrmsr - - mov eax, cr0 - or eax, 1 << 31 - mov cr0, eax - - lgdt [gdt.ptr] - - mov ax, gdt.data - mov ds, ax - mov es, ax - mov fs, ax - mov gs, ax - mov ss, ax - - extern start - jmp gdt.code:start - -global set_pml4 -set_pml4: - mov ecx, 0xC000080 - rdmsr - and eax, ~(1 << 8) - wrmsr - - mov eax, cr0 - and eax, ~(1 << 31) - mov cr0, eax - - mov cr3, edi - - mov ecx, 0xC000080 - rdmsr - or eax, 1 << 8 - wrmsr - - mov eax, cr0 - or eax, 1 << 31 - mov cr0, eax - - retf - -section .data -align 16 -global multiboot_header -multiboot_header: dq 0 -global multiboot_magic -multiboot_magic: dq 0 - -section .bss -global pml4 -align 4096 -pml4: resq 512 diff --git a/asm/long.asm b/asm/long.asm deleted file mode 100644 index 829d582..0000000 --- a/asm/long.asm +++ /dev/null @@ -1,171 +0,0 @@ -; The multiboot standard does not define the value of the stack pointer register -; (esp) and it is up to the kernel to provide a stack. This allocates room for a -; small stack by creating a symbol at the bottom of it, then allocating 16384 -; bytes for it, and finally creating a symbol at the top. The stack grows -; downwards on x86. The stack is in its own section so it can be marked nobits, -; which means the kernel file is smaller because it does not contain an -; uninitialized stack. The stack on x86 must be 16-byte aligned according to the -; System V ABI standard and de-facto extensions. The compiler will assume the -; stack is properly aligned and failure to align the stack will result in -; undefined behavior. -section .bss - align 16 -stack_bottom: - resb 16384 ; 16 KiB -stack_top: - -; The linker script specifies _start as the entry point to the kernel and the -; bootloader will jump to this position once the kernel has been loaded. It -; doesn't make sense to return from this function as the bootloader is gone. -; Declare _start as a function symbol with the given symbol size. -section .text - -global idt_load -extern idt_ptr -idt_load: - lidt [idt_ptr] - ret - -%macro isr 1-* - %rep %0 - isr_%+%1: - cli - push qword 0 - push qword %1 - jmp isr_common - %rotate 1 - %endrep -%endmacro - -%macro isr_err 1-* - %rep %0 - isr_%+%1: - cli - push qword %1 - jmp isr_common - %rotate 1 - %endrep -%endmacro - -isr 0, 1, 2, 3, 4, 5, 6, 7, 9, 15, 16, 18, 19, 20, 22, 23, 24, 25, 26, 27, 28, 31 -isr_err 8, 10, 11, 12, 13, 14, 17, 21, 29, 30 -isr 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47 - -extern interrupt_handler -isr_common: - push rdi - mov rdi, [rsp + 8] - push rsi - mov rsi, [rsp + 24] - push rax - push rdx - push rcx - push r8 - push r9 - push r10 - push r11 - - call interrupt_handler - - pop r11 - pop r10 - pop r9 - pop r8 - pop rcx - pop rdx - pop rax - pop rsi - pop rdi - - add rsp, 16 - iretq - -global isr_table -isr_table: - %assign i 0 - %rep 48 - dq isr_%+i - %assign i i+1 - %endrep - -global toggle_interrupts -toggle_interrupts: - cmp rdi, 0x0 - je .disable - sti - ret -.disable - cli - ret - -global start:function (start.end - start) -start: - ; The bootloader has loaded us into 32-bit protected mode on a x86 - ; machine. Interrupts are disabled. Paging is disabled. The processor - ; state is as defined in the multiboot standard. The kernel has full - ; control of the CPU. The kernel can only make use of hardware features - ; and any code it provides as part of itself. There's no printf - ; function, unless the kernel provides its own <stdio.h> header and a - ; printf implementation. There are no security restrictions, no - ; safeguards, no debugging mechanisms, only what the kernel provides - ; itself. It has absolute and complete power over the - ; machine. - mov rsp, stack_top - - ; To set up a stack, we set the esp register to point to the top of our - ; stack (as it grows downwards on x86 systems). This is necessarily done - ; in assembly as languages such as C cannot function without a stack. - ;mov rsp, stack_top - - ; This is a good place to initialize crucial processor state before the - ; high-level kernel is entered. It's best to minimize the early - ; environment where crucial features are offline. Note that the - ; processor is not fully initialized yet: Features such as floating - ; point instructions and instruction set extensions are not initialized - ; yet. The GDT should be loaded here. Paging should be enabled here. - ; C++ features such as global constructors and exceptions will require - ; runtime support to work as well. - - ; Enter the high-level kernel. The ABI requires the stack is 16-byte - ; aligned at the time of the call instruction (which afterwards pushes - ; the return pointer of size 4 bytes). The stack was originally 16-byte - ; aligned above and we've since pushed a multiple of 16 bytes to the - ; stack since (pushed 0 bytes so far) and the alignment is thus - ; preserved and the call is well defined. - ; note, that if you are building on Windows, C functions may have "_" prefix in assembly: _kernel_main - - mov rax, 0x1 - cpuid - test edx, 1 << 25 - jz .no_sse - - mov rax, cr0 - and ax, 0xfffb - or ax, 0x2 - mov cr0, rax - mov rax, cr4 - or ax, 3 << 9 - mov cr4, rax - -.no_sse: - extern kernel_main - call kernel_main - - ; If the system has nothing more to do, put the computer into an - ; infinite loop. To do that: - ; 1) Disable interrupts with cli (clear interrupt enable in eflags). - ; They are already disabled by the bootloader, so this is not needed. - ; Mind that you might later enable interrupts and return from - ; kernel_main (which is sort of nonsensical to do). - ; 2) Wait for the next interrupt to arrive with hlt (halt instruction). - ; Since they are disabled, this will lock up the computer. - ; 3) Jump to the hlt instruction if it ever wakes up due to a - ; non-maskable interrupt occurring or due to system management mode. - int 0 -.hang: hlt - jmp .hang -.end: - -section .end -global kernel_end -kernel_end: |