From 6411831e67a6a74bbe55105297ec02468bc3a2ba Mon Sep 17 00:00:00 2001 From: Jack Halford Date: Sun, 4 Feb 2018 17:32:46 +0000 Subject: [PATCH] readme, also paging is enabled --- kernel-rs/Makefile | 11 ++- kernel-rs/README.md | 13 +++ kernel-rs/src/arch/x86_64/boot.asm | 136 ++++++++++++++++++++++++++++- kernel-rs/src/arch/x86_64/grub.cfg | 7 ++ 4 files changed, 159 insertions(+), 8 deletions(-) create mode 100644 kernel-rs/README.md create mode 100644 kernel-rs/src/arch/x86_64/grub.cfg diff --git a/kernel-rs/Makefile b/kernel-rs/Makefile index 464c7329..19b2e1b3 100644 --- a/kernel-rs/Makefile +++ b/kernel-rs/Makefile @@ -6,8 +6,7 @@ linker_script := src/arch/$(arch)/linker.ld grub.cfg := src/arch/$(arch)/grub.cfg asm_source_files := $(wildcard src/arch/$(arch)/*.asm) asm_object_files := $(patsubst src/arch/$(arch)/%.asm, \ - build/arch/$(arch)/%.o, $(asm_source_files)) - + build/arch/$(arch)/%.o, $(asm_source_files)) .PHONY: all clean run iso all: $(kernel) @@ -22,10 +21,10 @@ iso: $(iso) $(iso): $(kernel) $(grub.cfg) @mkdir -p build/isofiles/boot/grub - @cp $(kernel) build/isofiles/boot/kernel.bin - @cp $(grub.cfg) build/isofiles/boot/grub - @grub-mkrescue -o $(iso) build/isofiles 2>/dev/null - @rm -r build/isofiles + cp $(kernel) build/isofiles/boot/kernel.bin + cp $(grub.cfg) build/isofiles/boot/grub + grub-mkrescue -o $(iso) build/isofiles 2>/dev/null + rm -r build/isofiles $(kernel): $(asm_object_files) $(linker_script) @ld -n -T $(linker_script) -o $(kernel) $(asm_object_files) diff --git a/kernel-rs/README.md b/kernel-rs/README.md new file mode 100644 index 00000000..342e5999 --- /dev/null +++ b/kernel-rs/README.md @@ -0,0 +1,13 @@ +# compiling + +a standard development environment can be invoked: + +``` +docker run jzck/arch-kernel -it /usr/bin/zsh +``` + +clone the repo and `make iso` + +# running + +`make run` in your host operating system to launch qemu gtk window diff --git a/kernel-rs/src/arch/x86_64/boot.asm b/kernel-rs/src/arch/x86_64/boot.asm index ec460075..f717b7dd 100644 --- a/kernel-rs/src/arch/x86_64/boot.asm +++ b/kernel-rs/src/arch/x86_64/boot.asm @@ -3,6 +3,138 @@ global start section .text bits 32 start: - ; print OK to screen - mov dword [0xb8000], 0x2f4b2f4f + mov esp, stack_top + + call check_multiboot + call check_cpuid + call check_long_mode + + call set_up_page_tables + call enable_paging + + ; print 'OK' to screen + mov dword [0xb8000], 0x2f4b2f4f + hlt +error: + ; print 'ERR: ' and the given error code to screen and hangs + mov dword [0xb8000], 0x4f524f45 + mov dword [0xb8004], 0x4f3a4f52 + mov dword [0xb8008], 0x4f204f20 + mov byte [0xb800a], al hlt + +check_multiboot: + cmp eax, 0x36d76289 + jne .no_multiboot + ret +.no_multiboot: + mov al, "0" + jmp error + +check_cpuid: + ; Check if CPUID is supported by attempting to flip the ID bit (bit 21) + ; in the FLAGS register. If we can flip it, CPUID is available. + + ; Copy FLAGS in to EAX via stack + pushfd + pop eax + ; Copy to ECX as well for comparing later on + mov ecx, eax + ; Flip the ID bit + xor eax, 1 << 21 + ; Copy EAX to FLAGS via the stack + push eax + popfd + ; Copy FLAGS back to EAX (with the flipped bit if CPUID is supported) + pushfd + pop eax + ; Restore FLAGS from the old version stored in ECX (i.e. flipping the + ; ID bit back if it was ever flipped). + push ecx + popfd + + ; Compare EAX and ECX. If they are equal then that means the bit + ; wasn't flipped, and CPUID isn't supported. + cmp eax, ecx + je .no_cpuid + ret +.no_cpuid: + mov al, "1" + jmp error + +check_long_mode: + ; test if extended processor info in available + mov eax, 0x80000000 ; implicit argument for cpuid + cpuid ; get highest supported argument + cmp eax, 0x80000001 ; it needs to be at least 0x80000001 + jb .no_long_mode ; if it's less, the CPU is too old for long mode + + ; use extended info to test if long mode is available + mov eax, 0x80000001 ; argument for extended processor info + cpuid ; returns various feature bits in ecx and edx + test edx, 1 << 29 ; test if the LM-bit is set in the D-register + jz .no_long_mode ; If it's not set, there is no long mode + ret +.no_long_mode: + mov al, "2" + jmp error + +set_up_page_tables: + ; map first P4 entry to P3 table + mov eax, p3_table + or eax, 0b11 ; present + writeable + mov [p4_table], eax + + ; map first P3 entry to P2 table + mov eax, p2_table + or eax, 0b11 ; present + writeable + mov [p3_table], eax + + mov ecx, 0 ;counter variable +.map_p2_table: + ; map ecx-th P2 entry to a huge page that start at address 2MiB*ecx + mov eax, 0x200000 ; 2MiB + mul ecx ; start address of ecx-th page + or eax, 0b10000011 ; present + writeable + huge + mov [p2_table + ecx * 8], eax ; map ecx-th entry + + inc ecx ; increase counter + cmp ecx, 512 ; if counter == 512, the whole P2 table is mapped + jne .map_p2_table ; else map the next entry + + ret + +enable_paging: + ; load P4 to cr3 register (cpu uses this to acces the P4 table) + mov eax, p4_table + mov cr3, eax + + ; enable PAE-flag in cr4 (Physical Address Extension) + mov eax, cr4 + or eax, 1 << 5 + mov cr4, eax + + ; set the long mode bit in the EFER MSR (model specific register) + mov ecx, 0xC0000080 + rdmsr + or eax, 1 << 8 + wrmsr + + ; enable paging in the cr0 register + mov eax, cr0 + or eax, 1 << 31 + mov cr0, eax + + ret + +section .bss + align 4096 +p4_table: + resb 4096 +p3_table: + resb 4096 +p2_table: + resb 4096 +stack_bottom: + resb 64 +stack_top: diff --git a/kernel-rs/src/arch/x86_64/grub.cfg b/kernel-rs/src/arch/x86_64/grub.cfg new file mode 100644 index 00000000..a1f38c91 --- /dev/null +++ b/kernel-rs/src/arch/x86_64/grub.cfg @@ -0,0 +1,7 @@ +set timeout=0 +set default=0 + +menuentry "my os" { + multiboot2 /boot/kernel.bin + boot +}