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keyboard support + switch bootstrap to nasm

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This commit is contained in:
hippoz 2022-02-24 21:16:28 +02:00
parent eae0e5e345
commit c1bac7864f
Signed by: hippoz
GPG key ID: 7C52899193467641
10 changed files with 213 additions and 141 deletions
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7
Makefile
View file

@ -1,14 +1,15 @@
CC=i686-elf-gcc
NASM=nasm
.PHONY: iso run clean
%.o: %.c
$(CC) -c $< -o $@ -std=gnu99 -mgeneral-regs-only -ffreestanding -O2 -Wall -Wextra -pedantic -I.
bootstrap.o: bootstrap.s
i686-elf-as bootstrap.s -o bootstrap.o
bootstrap.o: bootstrap.asm
$(NASM) -felf32 bootstrap.asm -o bootstrap.o
kernel.bin: bootstrap.o gfx/terminal.o std/std.o std/kstd.o cpu/idt.o cpu/pic.o cpu/exception.o kernel.o
kernel.bin: bootstrap.o gfx/terminal.o ps2/keyboard.o std/std.o std/kstd.o cpu/idt.o cpu/pic.o cpu/exception.o kernel.o
$(CC) -T linker.ld -o $@ -ffreestanding -O2 -nostdlib -lgcc $^
iso: kernel.bin

118
bootstrap.asm Normal file
View file

@ -0,0 +1,118 @@
; Declare constants for the multiboot header.
MBALIGN equ 1 << 0 ; align loaded modules on page boundaries
MEMINFO equ 1 << 1 ; provide memory map
FLAGS equ MBALIGN | MEMINFO ; this is the Multiboot 'flag' field
MAGIC equ 0x1BADB002 ; 'magic number' lets bootloader find the header
CHECKSUM equ -(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
dd MAGIC
dd FLAGS
dd 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:
resb 16384 ; 16 KiB
stack_top:
section .data
gdt_ptr:
dw gdt_end - gdt - 1
dq gdt
gdt:
; generated using https://wiki.osdev.org/GDT_Tutorial#Some_stuff_to_make_your_life_easy
; signature for create_descriptor function: void create_descriptor(uint32_t base, uint32_t limit, uint16_t flag)
dq 0x0000000000000000 ; create_descriptor(0, 0, 0);
dq 0x00CF9A000000FFFF ; create_descriptor(0, 0x000FFFFF, (GDT_CODE_PL0));
dq 0x00CF92000000FFFF ; create_descriptor(0, 0x000FFFFF, (GDT_DATA_PL0));
gdt_end:
; 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 _start:function (_start.end - _start)
load_gdt:
lgdt [gdt_ptr]
; Reload CS register containing code selector:
JMP 0x08:.reload_CS ; 0x08 is a stand-in for your code segment
.reload_CS:
; Reload data segment registers:
MOV AX, 0x10 ; 0x10 is a stand-in for your data segment
MOV DS, AX
MOV ES, AX
MOV FS, AX
MOV GS, AX
MOV SS, AX
RET
_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.
; 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 esp, 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.
call load_gdt
; 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: _kmain
extern kmain
call kmain
; 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
; kmain (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
.hang: hlt
jmp .hang
.end:

126
bootstrap.s
View file

@ -1,126 +0,0 @@
/* 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:
.section .data
gdt_ptr:
.word gdt_end - gdt - 1
.long gdt
gdt:
// generated using https://wiki.osdev.org/GDT_Tutorial#Some_stuff_to_make_your_life_easy
// signature for create_descriptor function: void create_descriptor(uint32_t base, uint32_t limit, uint16_t flag)
.quad 0x0000000000000000 // create_descriptor(0, 0, 0);
.quad 0x00CF9A000000FFFF // create_descriptor(0, 0x000FFFFF, (GDT_CODE_PL0));
.quad 0x00CF92000000FFFF // create_descriptor(0, 0x000FFFFF, (GDT_DATA_PL0));
.quad 0x00CFFA000000FFFF // create_descriptor(0, 0x000FFFFF, (GDT_CODE_PL3));
.quad 0x00CFF2000000FFFF // create_descriptor(0, 0x000FFFFF, (GDT_DATA_PL3));
gdt_end:
/*
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 <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.
*/
/*
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.
*/
lgdt gdt_ptr
/*
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 kmain
/*
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
kmain (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

3
cpu/exception.c
View file

@ -7,6 +7,7 @@ void generic_exception_handler(struct interrupt_descriptor_32 *frame, uint8_t ir
kprintf("---- PANIC -------------\n");
kprintf("Kernel panic due to exception\n");
kprintf("IRQ %d\n", (int)irq);
kprintf("selector %d\n", (int)frame->selector);
kprintf("------------------------\n");
kabort();
}
@ -103,7 +104,7 @@ static void isr17(struct interrupt_descriptor_32 *frame) {
__attribute__((interrupt))
static void isr18(struct interrupt_descriptor_32 *frame) {
generic_exception_handler(frame, 17);
generic_exception_handler(frame, 18);
}

8
cpu/pic.c
View file

@ -4,9 +4,6 @@
void pic_remap(uint8_t offset1, uint8_t offset2) {
uint8_t a1, a2;
a1 = inb(PIC1_DATA); // save masks
a2 = inb(PIC2_DATA);
outb(PIC1_COMMAND, ICW1_INIT | ICW1_ICW4); // starts the initialization sequence (in cascade mode)
io_wait();
outb(PIC2_COMMAND, ICW1_INIT | ICW1_ICW4);
@ -25,8 +22,9 @@ void pic_remap(uint8_t offset1, uint8_t offset2) {
outb(PIC2_DATA, ICW4_8086);
io_wait();
outb(PIC1_DATA, a1); // restore saved masks.
outb(PIC2_DATA, a2);
// mask all irqs
outb(PIC1_DATA, 0xFF);
outb(PIC2_DATA, 0xFF);
}
void pic_send_eoi(uint8_t irq)

15
kernel.c
View file

@ -1,10 +1,14 @@
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include "std/kstd.h"
#include "gfx/terminal.h"
#include "cpu/pic.h"
#include "cpu/io.h"
#include "cpu/idt.h"
#include "std/kstd.h"
#include "cpu/exception.h"
#include "ps2/keyboard.h"
#if defined(__linux__)
#error "You are not using a cross-compiler, you will most certainly run into trouble"
@ -27,10 +31,15 @@ void kmain(void) {
exception_handlers_init();
kprintf("\r[ OK ]\n");
kprintf("[ ] Initializing keyboard");
keyboard_init();
kprintf("\r[ OK ]\n");
kprintf("[ ] Initializing IDT");
idt_init();
kprintf("\r[ OK ]\n");
terminal_writestring("Initialization finished.\n");
}
kprintf("Initialization finished.\n\n");
for (;;) {}
}

65
ps2/keyboard.c Normal file
View file

@ -0,0 +1,65 @@
#include <stdint.h>
#include "std/kstd.h"
#include "ps2/keyboard.h"
#include "cpu/pic.h"
#include "cpu/idt.h"
#include "cpu/io.h"
const char us_map[128] = {
0, 27, '1', '2', '3', '4', '5', '6', '7', '8',
'9', '0', '-', '=', '\b',
'\t',
'q', 'w', 'e', 'r',
't', 'y', 'u', 'i', 'o', 'p', '[', ']', '\n',
0, // 29 ctrl
'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', ';',
'\'', '`', 0, // 42 left shift
'\\', 'z', 'x', 'c', 'v', 'b', 'n',
'm', ',', '.', '/', 0, // 54 right shift
'*',
0, // 56 alt
' ',
0, // 58 caps lock
0, // 59 F1 key
0, 0, 0, 0, 0, 0, 0, 0,
0, // 68 F10 key
0, // 69 num lock
0, // 70 scroll lock
0, // 71 home key
0, // 72 up arrow
0, // 73 page up
'-',
0, // 75 left arrow
0,
0, // 77 right arrow
'+',
0, // 79 end key
0, // 80 down arrow
0, // 81 page down
0, // 82 insert key
0, // 83 delete key
0, 0, 0,
0, // 87 F11 key
0, // 88 F12 key
0
};
__attribute__((interrupt))
static void irq(struct interrupt_descriptor_32 *frame) {
char scancode = inb(0x60);
if (scancode & 128) {
goto end; // ignore release scancode
}
terminal_putchar(us_map[scancode]);
end:
pic_send_eoi(1);
}
void keyboard_init() {
pic_irq_clear_mask(1);
idt_register_handler(33, (size_t)irq);
inb(0x60);
}

6
ps2/keyboard.h Normal file
View file

@ -0,0 +1,6 @@
#ifndef _KEYBOARD_H
#define _KEYBOARD_H
void keyboard_init();
#endif

4
std/kstd.c
View file

@ -4,7 +4,7 @@
#include "std/std.h"
#include "gfx/terminal.h"
int putchar(int ic) {
int kputchar(int ic) {
char c = (char) ic;
terminal_write(&c, sizeof(c));
return ic;
@ -13,7 +13,7 @@ int putchar(int ic) {
static bool print(const char* data, size_t length) {
const unsigned char* bytes = (const unsigned char*) data;
for (size_t i = 0; i < length; i++) {
if (putchar(bytes[i]) == (-1)) { // EOF??
if (kputchar(bytes[i]) == (-1)) { // EOF??
return false;
}
}

2
std/kstd.h
View file

@ -3,7 +3,7 @@
#include <stdbool.h>
int putchar(int ic);
int kputchar(int ic);
int kprintf(const char* restrict format, ...);
void kputs(const char* data);
void kabort();