Interrupts

src/kernel/Makefile

@@ -4,8 +4,8 @@ endif
 
 CC := ${TARGET}-gcc
 
-SRC := $(wildcard **/*.[cS])
-OBJ := $(patsubst %, %.o, $(basename $(SRC)))
+SRC := $(wildcard **/*.[cS]*)
+OBJ := $(patsubst %, %.o, $(basename $(basename $(SRC))))
 
 CFLAGS := -Wall -Wextra -pedantic -ffreestanding -mcmodel=large
 CFLAGS += -ggdb -O0
@@ -16,6 +16,9 @@ LDFLAGS := -n -nostdlib -lgcc -T Link.ld
 kernel: $(OBJ)
 	$(LINK.c) $^ -o $@
 
+%.o: %.S.py
+	python3 $^ | $(COMPILE.S) $(DEPFLAGS) -x assembler-with-cpp - -o $@
+
 # Automatic dependency tracking
 DEP := $(OBJ:.o=.d)
 DEPFLAGS = -MT $@ -MMD -MP -MF $*.d

src/kernel/boot/kmain.c

@@ -3,9 +3,15 @@
 #include <vga.h>
 #include <debug.h>
 #include <multiboot.h>
+#include <interrupts.h>
 
 struct kernel_boot_data_st kernel_boot_data;
 
+int divide(int a, int b)
+{
+    return a/b;
+}
+
 void kmain(uint64_t multiboot_magic, void *multiboot_data)
 {
     vga_init();
@@ -22,15 +28,17 @@ void kmain(uint64_t multiboot_magic, void *multiboot_data)
     size_t index = 0;
     uintptr_t start, end;
     uint32_t type;
-    while(!multiboot_get_memory_ara(index, &start, &end, &type))
+    while(!multiboot_get_memory_area(index++, &start, &end, &type))
     {
         debug_info("%d %x-%x\n", type, start, end);
-        index++;
     }
 
+    interrupt_init();
+
     debug("Hello, world!");
-    int value = 123;
-    debug_info("dec: %d hex: %x, binary: %b", value, value, value);
+
+    // Force a divide by zero error
+    divide(5, 0);
 
     PANIC("End of kernel function!");
     

src/kernel/boot/multiboot.c

@@ -83,7 +83,7 @@ int multiboot_init(uint64_t magic, void *mboot_info)
     return 0;
 }
 
-int multiboot_get_memory_ara(size_t index, uintptr_t *start, uintptr_t *end, uint32_t *type)
+int multiboot_get_memory_area(size_t index, uintptr_t *start, uintptr_t *end, uint32_t *type)
 {
     if(index >= kernel_boot_data.mmap_len) return 1;
 

src/kernel/cpu/interrupts.c

@@ -0,0 +1,54 @@
+#include <interrupts.h>
+#include <stdint.h>
+#include <memory.h>
+#include <cpu.h>
+#include <debug.h>
+
+#define IDT_INTERRUPT 0xE
+#define IDT_DPL0 0x0
+#define IDT_PRESENT 0x80
+
+#define NUM_INTERRUPTS 256
+
+struct idt {
+    uint16_t base_l;
+    uint16_t cs;
+    uint8_t ist;
+    uint8_t flags;
+    uint16_t base_m;
+    uint32_t base_h;
+    uint32_t _;
+}__attribute__((packed)) idt[NUM_INTERRUPTS];
+
+struct {
+    uint16_t len;
+    struct idt *addr;
+}__attribute__((packed)) idtr;
+
+extern uintptr_t isr_table[];
+
+void interrupt_init()
+{
+    memset(idt, 0, sizeof(idt));
+    for(int i=0; i < NUM_INTERRUPTS; i++)
+    {
+        idt[i].base_l = isr_table[i] & 0xFFFF;
+        idt[i].base_m = (isr_table[i] >> 16) & 0xFFFF;
+        idt[i].base_h = (isr_table[i] >> 32) & 0xFFFFFFFF;
+        idt[i].cs = 0x8;
+        idt[i].ist = 0;
+        idt[i].flags = IDT_PRESENT | IDT_DPL0 | IDT_INTERRUPT;
+    }
+
+    idtr.addr = idt;
+    idtr.len = sizeof(idt)-1;
+    load_idt(&idtr);
+}
+
+registers *int_handler(registers *r)
+{
+    debug_error("Unhandled interrupt occurred\n");
+    debug_error("Interrupt number: %d, Error code: %d\n", r->int_no, r->err_code);
+    PANIC("Unhandled interrupt");
+    for(;;);
+}

src/kernel/cpu/isr.S.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python
+
+num_isr = 256
+pushes_error = [8, 10, 11, 12, 13, 14, 17]
+
+print("""
+.intel_syntax noprefix
+.extern isr_common
+""")
+
+print("// Interrupt Service Routines")
+for i in range(num_isr):
+    print(f"""isr{i}:
+    cli
+    {"push 0" if i in pushes_error else "nop"}
+    push {i}
+    jmp isr_common""")
+
+print("")
+print("// Vector table")
+
+print("""
+.section .data
+.global isr_table
+isr_table:""")
+for i in range(num_isr):
+    print(f""".quad isr{i}""")

src/kernel/cpu/isr_common.S

@@ -0,0 +1,45 @@
+.intel_syntax noprefix
+
+.extern int_handler
+.global isr_common
+.global isr_return
+
+isr_common:
+    push r15
+    push r14
+    push r13
+    push r12
+    push r11
+    push r10
+    push r9
+    push r8
+    push rbp
+    push rdi
+    push rsi
+    push rdx
+    push rcx
+    push rbx
+    push rax
+    mov rdi, rsp
+    call int_handler
+
+    mov rdi, rax
+isr_return:
+    mov rsp, rdi
+    pop rax
+    pop rbx
+    pop rcx
+    pop rdx
+    pop rsi
+    pop rdi
+    pop rbp
+    pop r8
+    pop r9
+    pop r10
+    pop r11
+    pop r12
+    pop r13
+    pop r14
+    pop r15
+    add rsp, 0x10
+    iretq

src/kernel/cpu/registers.S

@@ -0,0 +1,6 @@
+.intel_syntax noprefix
+
+.global load_idt
+load_idt:
+    lidt [rdi]
+    ret

src/kernel/include/cpu.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void load_idt(void *);

src/kernel/include/interrupts.h

@@ -0,0 +1,32 @@
+#pragma once
+#include <stdint.h>
+
+typedef struct {
+    uint64_t rax;
+    uint64_t rbx;
+    uint64_t rcx;
+    uint64_t rdx;
+    uint64_t rsi;
+    uint64_t rdi;
+    uint64_t rbp;
+    uint64_t r8;
+    uint64_t r9;
+    uint64_t r10;
+    uint64_t r11;
+    uint64_t r12;
+    uint64_t r13;
+    uint64_t r14;
+    uint64_t r15;
+
+    uint64_t int_no;
+    uint64_t err_code;
+
+    uint64_t rip;
+    uint64_t cs;
+    uint64_t rflags;
+    uint64_t rsp;
+    uint64_t ss;
+} registers;
+
+void interrupt_init();
+void isr_return(registers *);

src/kernel/include/multiboot.h

@@ -25,5 +25,5 @@ struct kernel_boot_data_st{
 extern struct kernel_boot_data_st kernel_boot_data;
 
 int multiboot_init(uint64_t magic, void *mboot_info);
-int multiboot_get_memory_ara(size_t index, uintptr_t *start, uintptr_t *end, uint32_t *type);
+int multiboot_get_memory_area(size_t index, uintptr_t *start, uintptr_t *end, uint32_t *type);
 #endif

toolchain/build-toolchain.sh

@@ -5,6 +5,7 @@ apk add gmp-dev mpfr-dev mpc1-dev
 
 apk add make
 apk add grub-bios xorriso
+apk add python3
 
 rm -rf /var/cache/apk/*