From 138424b31d9c2af158e8ae619248b035b5a280d9 Mon Sep 17 00:00:00 2001 From: Nic Gaffney Date: Thu, 21 Dec 2023 03:32:06 -0600 Subject: set up bochs for debugging and started working on interrupts. --- src/boot/boot.s | 14 ++++++++++ src/include/asm.h | 15 +++++++++++ src/include/gdt.h | 12 +++++---- src/include/idt.h | 17 ++++++++++++ src/kernel/gdt.c | 52 +++++++++++++++++++++++++++++++++++++ src/kernel/gdt/compile_flags.txt | 1 - src/kernel/gdt/gdt.c | 56 ---------------------------------------- src/kernel/idt.c | 28 ++++++++++++++++++++ src/kernel/keyboard/pic.c | 1 + src/utils/compile_flags.txt | 1 + 10 files changed, 135 insertions(+), 62 deletions(-) create mode 100644 src/include/asm.h create mode 100644 src/include/idt.h create mode 100644 src/kernel/gdt.c delete mode 100644 src/kernel/gdt/compile_flags.txt delete mode 100644 src/kernel/gdt/gdt.c create mode 100644 src/kernel/idt.c create mode 100644 src/kernel/keyboard/pic.c create mode 100644 src/utils/compile_flags.txt (limited to 'src') diff --git a/src/boot/boot.s b/src/boot/boot.s index aba32ff..22d32f3 100644 --- a/src/boot/boot.s +++ b/src/boot/boot.s @@ -19,10 +19,17 @@ resb 16384 stack_top: section .text + global gdtr gdtr: dw 0 dd 0 + +global idtr +idtr: + dw 0 + dd 0 + global _start:function (_start.end - _start) _start: mov esp, stack_top @@ -37,10 +44,17 @@ _start: call reloadSegments + extern get_idtr + call get_idtr + lidt [idtr] + [bits 32] extern kernel_main call kernel_main + ; BOCHS + xchg bx, bx + cli .hang: hlt diff --git a/src/include/asm.h b/src/include/asm.h new file mode 100644 index 0000000..97ea45a --- /dev/null +++ b/src/include/asm.h @@ -0,0 +1,15 @@ +#pragma once +#include + +// IO +static inline void outb(uint16_t port, uint8_t val) { + asm volatile("outb %0, %1" : : "a"(val), "Nd"(port) : "memory"); +} + +static inline uint8_t inb(uint16_t port) { + uint8_t ret; + asm volatile("inb %1, %0" : "=a"(ret) : "Nd"(port) : "memory"); + return ret; +} + +static inline void io_wait(void) { outb(0x80, 0); } diff --git a/src/include/gdt.h b/src/include/gdt.h index 06a0d96..8cc2542 100644 --- a/src/include/gdt.h +++ b/src/include/gdt.h @@ -16,11 +16,13 @@ typedef struct GDTR { uint32_t offset; } __attribute__((packed)) GDTR_t; -typedef struct GDT { - Segment_Descriptor_t nulldesc; - Segment_Descriptor_t codedesc; - Segment_Descriptor_t datadesc; -} __attribute__((packed)) GDT_t; +// typedef struct GDT { +// Segment_Descriptor_t nulldesc; +// Segment_Descriptor_t codedesc; +// Segment_Descriptor_t datadesc; +// } __attribute__((packed)) GDT_t; + +typedef Segment_Descriptor_t *GDT_t; uint16_t make_code(uint8_t priv, uint8_t dc, uint8_t rw); uint16_t make_data(uint8_t priv, uint8_t dc, uint8_t rw); diff --git a/src/include/idt.h b/src/include/idt.h new file mode 100644 index 0000000..b8413b8 --- /dev/null +++ b/src/include/idt.h @@ -0,0 +1,17 @@ +#pragma once +#include + +typedef struct Gate_Descriptor { + uint16_t offset_low; + uint16_t segment_selector; + uint8_t reserved; + uint8_t attrs; + uint16_t offset_high; +} __attribute__((packed)) Gate_Descriptor_t; + +typedef Gate_Descriptor_t *IDT_t; + +Gate_Descriptor_t make_gate(uint32_t offset, uint8_t segment_selector, + uint8_t attrs); + +void get_idtr(); diff --git a/src/kernel/gdt.c b/src/kernel/gdt.c new file mode 100644 index 0000000..406b40c --- /dev/null +++ b/src/kernel/gdt.c @@ -0,0 +1,52 @@ +#include "gdt.h" +#include + +GDT_t table = 0x0; +extern GDTR_t gdtr; +void get_gdtr() { + uint32_t base = 0x0000; + + table[0] = make_descriptor(0, 0, 0); + table[1] = make_descriptor(base, 0x3FFFF, make_code(0, 0, 1)); + table[2] = make_descriptor(base, 0x3FFFF, make_data(0, 0, 1)); + + gdtr.size = sizeof(Segment_Descriptor_t) * 3 - 1; + gdtr.offset = base; +} + +uint16_t make_code(uint8_t priv, uint8_t dc, uint8_t rw) { + uint16_t access = 0; + access |= (1 << 7); + access |= (priv << 5); + access |= (0b11 << 3); + access |= (dc << 2); + access |= (rw << 1); // 10 + access <<= 8; + access |= FLAG; + return access; +} + +uint16_t make_data(uint8_t priv, uint8_t dc, uint8_t rw) { + uint16_t access = 0; + access |= (1 << 7); + access |= (priv << 5); + access |= (0b10 << 3); + access |= (dc << 2); + access |= (rw << 1); // 10 + access <<= 8; + access |= FLAG; + return access; +} + +Segment_Descriptor_t make_descriptor(uint32_t base, uint32_t limit, + uint16_t access_flag) { + uint16_t lim_low = limit; + uint16_t base_low = base; + uint8_t base_mid = (base >> 16); + uint8_t access_byte = access_flag >> 8; + uint8_t lim_flag = ((access_flag << 4) | (limit >> 16)); + uint8_t base_high = (base >> 24); + return (Segment_Descriptor_t){ + lim_low, base_low, base_mid, access_byte, lim_flag, base_high, + }; +} diff --git a/src/kernel/gdt/compile_flags.txt b/src/kernel/gdt/compile_flags.txt deleted file mode 100644 index 2af49c7..0000000 --- a/src/kernel/gdt/compile_flags.txt +++ /dev/null @@ -1 +0,0 @@ --I../../include/ diff --git a/src/kernel/gdt/gdt.c b/src/kernel/gdt/gdt.c deleted file mode 100644 index 4886dc3..0000000 --- a/src/kernel/gdt/gdt.c +++ /dev/null @@ -1,56 +0,0 @@ -#include "gdt.h" -#include - -GDT_t *table = 0x0; -extern GDTR_t gdtr; -void get_gdtr() { - uint32_t base = 0x0000; - - *table = (GDT_t){ - // NULL - make_descriptor(0, 0, 0), - // Code segment, read - make_descriptor(base, 0x8FFFF, make_code(0, 0, 1)), - // Data segment, read write - make_descriptor(base, 0x8FFFF, make_data(0, 0, 1)), - }; - gdtr.size = sizeof(Segment_Descriptor_t) * 3 - 1; - gdtr.offset = base; -} - -uint16_t make_code(uint8_t priv, uint8_t dc, uint8_t rw) { - uint16_t access = 0; - access |= (1 << 7); - access |= (priv << 5); - access |= (0b11 << 3); - access |= (dc << 2); - access |= (rw << 1); // 10 - access <<= 8; - access |= FLAG; - return access; -} - -uint16_t make_data(uint8_t priv, uint8_t dc, uint8_t rw) { - uint16_t access = 0; - access |= (1 << 7); - access |= (priv << 5); - access |= (0b10 << 3); - access |= (dc << 2); - access |= (rw << 1); // 10 - access <<= 8; - access |= FLAG; - return access; -} - -Segment_Descriptor_t make_descriptor(uint32_t base, uint32_t limit, - uint16_t access_flag) { - uint16_t lim_low = limit; - uint16_t base_low = base; - uint8_t base_mid = (base >> 16); - uint8_t access_byte = access_flag >> 8; - uint8_t lim_flag = ((access_flag << 4) | (limit >> 16)); - uint8_t base_high = (base >> 24); - return (Segment_Descriptor_t){ - lim_low, base_low, base_mid, access_byte, lim_flag, base_high, - }; -} diff --git a/src/kernel/idt.c b/src/kernel/idt.c new file mode 100644 index 0000000..f3fea4f --- /dev/null +++ b/src/kernel/idt.c @@ -0,0 +1,28 @@ +#include "idt.h" +#include "gdt.h" +#include + +IDT_t idt = (IDT_t)0x7fffe; +extern GDTR_t idtr; + +void get_idtr() { + int base = 0x7fffe; + uint8_t code_seg = (0b1000 << 3) | 0b000; + + // idtr.size = sizeof(Gate_Descriptor_t) * n - 1; + idtr.size = 0; + idtr.offset = base; +} + +Gate_Descriptor_t make_gate(uint32_t offset, uint8_t segment_selector, + uint8_t type) { + Gate_Descriptor_t ret = (Gate_Descriptor_t){ + .offset_low = offset, + .reserved = 0, + .attrs = (0b1000 << 4) | type, + .offset_high = offset >> 16, + .segment_selector = segment_selector, + }; + + return ret; +} diff --git a/src/kernel/keyboard/pic.c b/src/kernel/keyboard/pic.c new file mode 100644 index 0000000..0c81629 --- /dev/null +++ b/src/kernel/keyboard/pic.c @@ -0,0 +1 @@ +#include "asm.h" diff --git a/src/utils/compile_flags.txt b/src/utils/compile_flags.txt new file mode 100644 index 0000000..b02b210 --- /dev/null +++ b/src/utils/compile_flags.txt @@ -0,0 +1 @@ +-I../include -- cgit v1.2.3