From 97cd6cdd987084e5a37347765d555148b71075ed Mon Sep 17 00:00:00 2001 From: vanten-s Date: Tue, 26 Mar 2024 15:15:06 +0100 Subject: [PATCH] First version --- .cargo/config.toml | 2 - .gitignore | 6 +- Makefile | 23 +++++++ boot.s | 109 ++++++++++++++++++++++++++++++++++ grub.cfg | 3 + kernel/.cargo/config.toml | 9 +++ kernel/Cargo.lock | 7 +++ kernel/Cargo.toml | 6 ++ kernel/i686-unknown-bare.json | 25 ++++++++ kernel/src/main.rs | 23 +++++++ linker.ld | 52 ++++++++++++++++ rust-toolchain | 1 - shell.nix | 21 ++++++- 13 files changed, 280 insertions(+), 7 deletions(-) delete mode 100644 .cargo/config.toml create mode 100644 Makefile create mode 100644 boot.s create mode 100644 grub.cfg create mode 100644 kernel/.cargo/config.toml create mode 100644 kernel/Cargo.lock create mode 100644 kernel/Cargo.toml create mode 100644 kernel/i686-unknown-bare.json create mode 100644 kernel/src/main.rs create mode 100644 linker.ld delete mode 100644 rust-toolchain diff --git a/.cargo/config.toml b/.cargo/config.toml deleted file mode 100644 index dfa84e8..0000000 --- a/.cargo/config.toml +++ /dev/null @@ -1,2 +0,0 @@ -[unstable] -bindeps = true diff --git a/.gitignore b/.gitignore index ea8c4bf..3fce5f8 100644 --- a/.gitignore +++ b/.gitignore @@ -1 +1,5 @@ -/target +/kernel/target +/build +/binutils +/gcc +/opt diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..d2477a1 --- /dev/null +++ b/Makefile @@ -0,0 +1,23 @@ +.PHONY: all build test clean + +all: build + +build: + rm -rf build + rm -rf kernel/target + mkdir build + i686-elf-as -o build/boot.o boot.s + cd kernel; cargo build + cp kernel/target/i686-unknown-bare/debug/kernel.elf build/geos.bin + mkdir -p build/isodir/boot/grub + cp build/geos.bin build/isodir/boot/geos.bin + cp grub.cfg build/isodir/boot/grub/grub.cfg + grub-mkrescue -o build/geos.iso build/isodir + +test: build + qemu-system-i386 -cdrom build/geos.iso + +clean: + rm -rf kernel/target + rm -rf build + diff --git a/boot.s b/boot.s new file mode 100644 index 0000000..66c98bc --- /dev/null +++ b/boot.s @@ -0,0 +1,109 @@ +/* Declare constants for the multiboot header. */ +.set ALIGN, 1<<0 /* align loaded modules on page boundaries */ +.set MEMINFO, 1<<1 /* provide memory map */ +.set FLAGS, ALIGN | MEMINFO /* this is the Multiboot 'flag' field */ +.set MAGIC, 0x1BADB002 /* 'magic number' lets bootloader find the header */ +.set CHECKSUM, -(MAGIC + FLAGS) /* 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 +.long MAGIC +.long FLAGS +.long CHECKSUM + +/* +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: +.skip 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. +*/ +.section .text +.global _start +.type _start, @function +_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 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. + */ + + /* + To set up a stack, we set the esp register to point to the top of the + 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 $stack_top, %esp + + /* + 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 pushed a multiple of 16 bytes to the + stack since (pushed 0 bytes so far), so the alignment has thus been + preserved and the call is well defined. + */ + 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. + */ + cli +1: hlt + jmp 1b + +/* +Set the size of the _start symbol to the current location '.' minus its start. +This is useful when debugging or when you implement call tracing. +*/ +.size _start, . - _start diff --git a/grub.cfg b/grub.cfg new file mode 100644 index 0000000..dbc242d --- /dev/null +++ b/grub.cfg @@ -0,0 +1,3 @@ +menuentry "geos" { + multiboot /boot/geos.bin +} diff --git a/kernel/.cargo/config.toml b/kernel/.cargo/config.toml new file mode 100644 index 0000000..9b79ad8 --- /dev/null +++ b/kernel/.cargo/config.toml @@ -0,0 +1,9 @@ +[build] +target = "i686-unknown-bare.json" + +[unstable] +build-std-features = ["compiler-builtins-mem"] +build-std = ["core", "compiler_builtins"] + +[target."i686-unknown-bare"] +linker = "i686-elf-gcc" diff --git a/kernel/Cargo.lock b/kernel/Cargo.lock new file mode 100644 index 0000000..0dd1539 --- /dev/null +++ b/kernel/Cargo.lock @@ -0,0 +1,7 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +version = 3 + +[[package]] +name = "kernel" +version = "0.1.0" diff --git a/kernel/Cargo.toml b/kernel/Cargo.toml new file mode 100644 index 0000000..f84cf70 --- /dev/null +++ b/kernel/Cargo.toml @@ -0,0 +1,6 @@ +[package] +name = "kernel" +version = "0.1.0" +edition = "2021" + +[dependencies] diff --git a/kernel/i686-unknown-bare.json b/kernel/i686-unknown-bare.json new file mode 100644 index 0000000..500f009 --- /dev/null +++ b/kernel/i686-unknown-bare.json @@ -0,0 +1,25 @@ +{ + "llvm-target": "i686-unknown-none", + "data-layout": "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i128:128-f64:32:64-f80:32-n8:16:32-S128", + "arch": "x86", + "target-endian": "little", + "target-pointer-width": "32", + "target-c-int-width": "32", + "os": "none", + "executables": true, + "linker-flavor": "gcc", + "linker": "i686-elf-gcc", + "panic-strategy": "abort", + "disable-redzone": true, + "features": "-sse,+soft-float", + "dynamic-linking": false, + "relocation-model": "pic", + "code-model": "kernel", + "exe-suffix": ".elf", + "has-rpath": false, + "no-default-libraries": true, + "position-independent-executables": false, + "pre-link-args": { + "gcc": ["-T", "../linker.ld", "-ffreestanding", "-nostdlib", "-lgcc", "../build/boot.o"] + } +} diff --git a/kernel/src/main.rs b/kernel/src/main.rs new file mode 100644 index 0000000..2f11094 --- /dev/null +++ b/kernel/src/main.rs @@ -0,0 +1,23 @@ +#![no_std] +#![no_main] + +#[no_mangle] +pub extern "C" fn kernel_main() -> ! { + let vga_buffer = 0xb8000 as *mut u8; + + let string: &[u8] = b":3"; + for (i, &byte) in string.iter().enumerate() { + unsafe { + *vga_buffer.offset(i as isize * 2) = byte; + *vga_buffer.offset(i as isize * 2 + 1) = 0xf; + } + } + + + loop {} +} + +#[panic_handler] +fn panic(_info: &core::panic::PanicInfo) -> ! { + loop {} +} diff --git a/linker.ld b/linker.ld new file mode 100644 index 0000000..66c0802 --- /dev/null +++ b/linker.ld @@ -0,0 +1,52 @@ +/* The bootloader will look at this image and start execution at the symbol + designated as the entry point. */ +ENTRY(_start) + +/* Tell where the various sections of the object files will be put in the final + kernel image. */ +SECTIONS +{ + /* It used to be universally recommended to use 1M as a start offset, + as it was effectively guaranteed to be available under BIOS systems. + However, UEFI has made things more complicated, and experimental data + strongly suggests that 2M is a safer place to load. In 2016, a new + feature was introduced to the multiboot2 spec to inform bootloaders + that a kernel can be loaded anywhere within a range of addresses and + will be able to relocate itself to run from such a loader-selected + address, in order to give the loader freedom in selecting a span of + memory which is verified to be available by the firmware, in order to + work around this issue. This does not use that feature, so 2M was + chosen as a safer option than the traditional 1M. */ + . = 2M; + + /* First put the multiboot header, as it is required to be put very early + in the image or the bootloader won't recognize the file format. + Next we'll put the .text section. */ + .text BLOCK(4K) : ALIGN(4K) + { + *(.multiboot) + *(.text) + } + + /* Read-only data. */ + .rodata BLOCK(4K) : ALIGN(4K) + { + *(.rodata) + } + + /* Read-write data (initialized) */ + .data BLOCK(4K) : ALIGN(4K) + { + *(.data) + } + + /* Read-write data (uninitialized) and stack */ + .bss BLOCK(4K) : ALIGN(4K) + { + *(COMMON) + *(.bss) + } + + /* The compiler may produce other sections, by default it will put them in + a segment with the same name. Simply add stuff here as needed. */ +} diff --git a/rust-toolchain b/rust-toolchain deleted file mode 100644 index bf867e0..0000000 --- a/rust-toolchain +++ /dev/null @@ -1 +0,0 @@ -nightly diff --git a/shell.nix b/shell.nix index 16e00dc..152b0de 100644 --- a/shell.nix +++ b/shell.nix @@ -1,20 +1,35 @@ { pkgs ? import {} }: -pkgs.mkShell rec { + +let + crossPkgs = pkgs.pkgsCross.aarch64-multiplatform; +in pkgs.mkShell rec { buildInputs = with pkgs; [ clang llvmPackages_17.bintools rustup qemu + grub2 + libisoburn + bison + flex + gmp + libmpc + mpfr + texinfo + isl ]; - RUSTC_VERSION = pkgs.lib.readFile ./rust-toolchain; + RUSTC_VERSION = "nightly"; + hardeningDisable = [ "all" ]; # https://github.com/rust-lang/rust-bindgen#environment-variables LIBCLANG_PATH = pkgs.lib.makeLibraryPath [ pkgs.llvmPackages_latest.libclang.lib ]; shellHook = '' + rustup default nightly rustup component add llvm-tools-preview rustup component add rust-analyzer rustup target add x86_64-unknown-none export PATH=$PATH:''${CARGO_HOME:-~/.cargo}/bin - export PATH=$PATH:''${RUSTUP_HOME:-~/.rustup}/toolchains/$RUSTC_VERSION-x86_64-unknown-linux-gnu/bin/ + export PATH=$PATH:''${RUSTUP_HOME:-~/.rustup}/toolchains/nightly-x86_64-unknown-linux-gnu/bin/ + export PATH=$PATH:$PWD/opt/bin ''; # Add precompiled library to rustc search path RUSTFLAGS = (builtins.map (a: ''-L ${a}/lib'') [