diff --git a/src/idt.zig b/src/idt.zig new file mode 100644 index 0000000..f19dc37 --- /dev/null +++ b/src/idt.zig @@ -0,0 +1,142 @@ +const std = @import("std"); + +pub const InterruptStackFrame = extern struct { + instruction_ptr: u64, + code_segment: u64, + cpu_flags: u64, + stack_ptr: u64, + stack_segment: u64, +}; + +const HandlerFunction = *const fn (_: *InterruptStackFrame) callconv(.{ .x86_interrupt = .{} }) void; + +fn HandlerFunctionWithErrorCode(comptime Return: type) type { + if (Return != void and Return != noreturn) { + @compileError("Return should either be void or noreturn"); + } + + return *const fn (_: *InterruptStackFrame, error_code: u32) callconv(.{ .x86_interrupt = .{} }) Return; +} + +pub const InterruptDescriptorTableEntryType = enum(u8) { + division_error = 0, + debug = 1, + non_maskable_interrupt = 2, + breakpoint = 3, + overflow = 4, + bound_range_exceeded = 5, + invalid_opcode = 6, + device_not_available = 7, + double_fault = 8, + coprocessor_segment_overrun = 9, + invalid_tss = 10, + segment_not_present = 11, + stack_segment_fault = 12, + general_protection_fault = 13, + page_fault = 14, + x87_floating_point_exception = 16, + alignment_check = 17, + machine_check = 18, + simd_floating_point = 19, + virtualization = 20, + control_protection_exception = 21, + hypervisor_injection_exception = 28, + vmm_communication_exception = 29, + security_exception = 30, + + const Self = @This(); + + pub fn HandlerFunctionType(self: Self) type { + return switch (self) { + .double_fault, .machine_check => HandlerFunctionWithErrorCode(noreturn), + .invalid_tss, .segment_not_present, .stack_segment_fault, .general_protection_fault, .page_fault, .alignment_check, .control_protection_exception, .vmm_communication_exception, .security_exception => HandlerFunctionWithErrorCode(void), + else => HandlerFunction, + }; + } +}; + +pub const InterruptDescriptorTable = extern struct { + table: [Length]Entry, + + const Length = std.math.maxInt(u8) + 1; + + const Entry = packed struct { + ptr_low: u16, + options: Options, + ptr_mid: u16, + ptr_high: u32, + reserved: u32, + + pub const missing: Entry = .{ + .ptr_low = 0, + .options = .minimal, + .ptr_mid = 0, + .ptr_high = 0, + .reserved = 0, + }; + + const Options = packed struct { + code_segment: u16, + bit_set: std.bit_set.IntegerBitSet(16), + + pub const minimal: Options = .{ + .code_segment = 0, + .bit_set = .{ .mask = 0b1110_0000_0000 }, + }; + + pub fn setCodeSelector(self: *align(2) Options, segment: u16) void { + self.code_segment = segment; + } + + pub fn setPresent(self: *align(2) Options, present: bool) void { + self.bit_set.setValue(15, present); + } + }; + + fn setHandler(self: *Entry, handler_addr: u64) void { + self.ptr_low = @truncate(handler_addr); + self.ptr_mid = @truncate(handler_addr >> 16); + self.ptr_high = @truncate(handler_addr >> 32); + + self.options = .minimal; + const segment = asm volatile ( + \\ mov %%cs, %[segment] + : [segment] "=&r" (-> u16) + : + ); + self.options.setCodeSelector(segment); + self.options.setPresent(true); + + std.log.info("Setting handler {any}\n", .{ self.* }); + } + }; + + pub const empty: InterruptDescriptorTable = .{ + .table = [_]Entry{.missing} ** Length, + }; + + pub fn setEntry( + self: *InterruptDescriptorTable, + comptime entry_type: InterruptDescriptorTableEntryType, + handler: InterruptDescriptorTableEntryType.HandlerFunctionType(entry_type), + ) void { + self.table[@intFromEnum(entry_type)].setHandler(@intFromPtr(handler)); + } + + pub fn load(self: *InterruptDescriptorTable) void { + const DescriptorTablePointer = packed struct { + limit: u16, + base: u64, + }; + const idt: DescriptorTablePointer = .{ + .limit = @sizeOf(@TypeOf(self.*)) - 1, + .base = @intFromPtr(self), + }; + + asm volatile ( + \\ lidt (%[idt]) + : + : [idt] "r" (idt), + ); + } +}; diff --git a/src/main.zig b/src/main.zig index dd4f020..256ff39 100644 --- a/src/main.zig +++ b/src/main.zig @@ -1,7 +1,11 @@ const lazy = @import("utils/Lazy.zig").lazy; const Console = @import("Console.zig"); + const MultibootInfo = @import("multiboot.zig").Info; +const InterruptDescriptorTable = @import("idt.zig").InterruptDescriptorTable; +const InterruptStackFrame = @import("idt.zig").InterruptStackFrame; + const MultibootHeader = packed struct { magic: i32, flags: i32, @@ -37,6 +41,8 @@ export fn _start() callconv(.naked) noreturn { var console = lazy(Console, .init); +var idt: InterruptDescriptorTable = .empty; + fn kmain(magic: u32, info: *const MultibootInfo) callconv(.c) void { std.debug.assert(magic == MAGIC); @@ -49,9 +55,24 @@ fn kmain(magic: u32, info: *const MultibootInfo) callconv(.c) void { std.log.info("Booted with cmdline \"{s}\"", .{info.cmdline}); } + idt.setEntry(.breakpoint, breakpointHandler); + idt.load(); + + //asm volatile ( + // \\ int3 + // : + // : + //); + hang(); } +fn breakpointHandler(stack_frame: *InterruptStackFrame) callconv(.{ .x86_interrupt = .{} }) void { + _ = stack_frame; + + std.log.err("breakpoint\n", .{}); +} + fn hang() noreturn { while (true) asm volatile ("hlt"); }