Added interrupt handling

7 files changed, 441 insertions, 7 deletions

diff --git a/makefile b/makefile
index 7677ff0..288f029 100644
--- a/makefile
+++ b/makefile
@@ -1,4 +1,5 @@
 # MIT License, Copyright (c) 2021 Marvin Borner
+# It's not as complicated as it looks
 
 # Obviously needs cross compiler
 CC = $(PWD)/cross/opt/bin/i686-elf-gcc
@@ -10,8 +11,13 @@ AS = nasm
 BLD = $(PWD)/build
 SRC = $(PWD)/src
 
-SRCS = $(shell find $(SRC)/loader/ -type f -name "*.c")
-OBJS = $(patsubst $(SRC)/%.c,$(BLD)/%.o,$(SRCS))
+# C code
+CSRCS = $(shell find $(SRC)/loader/ -type f -name "*.c")
+COBJS = $(patsubst $(SRC)/%.c,$(BLD)/%_c.o,$(CSRCS))
+
+# Assembly code
+ASRCS = $(shell find $(SRC)/loader/ -type f -name "*.asm")
+AOBJS = $(patsubst $(SRC)/%.asm,$(BLD)/%_asm.o,$(ASRCS))
 
 # Enable many warnings for less bugs :)
 WARNINGS = -Wall -Wextra -Wshadow -Wpointer-arith -Wwrite-strings -Wredundant-decls -Wnested-externs -Wformat=2 -Wmissing-declarations -Wstrict-prototypes -Wmissing-prototypes -Wcast-qual -Wswitch-default -Wswitch-enum -Wunreachable-code -Wundef -Wold-style-definition -Wvla -pedantic-errors
@@ -28,16 +34,19 @@ dir:
 	@mkdir -p $(BLD)/loader/fs/
 
 $(BLD)/boot.bin: $(BLD)/loader.bin
-	@$(AS) -f bin $(SRC)/entry/bootsector.asm -o $@
+	@$(AS) $(ASFLAGS) -f bin $(SRC)/entry/bootsector.asm -o $@
 
-$(BLD)/loader.o: $(OBJS)
+$(BLD)/loader.o: $(COBJS) $(AOBJS)
 	@$(LD) -N -z max-page-size=0x1000 -estart -T$(SRC)/loader/link.ld -o $@ $^
 
 $(BLD)/loader.bin: $(BLD)/loader.o
 	@$(OC) -O binary $^ $@
 
-$(OBJS): $(BLD)/%.o : $(SRC)/%.c
+$(COBJS): $(BLD)/%_c.o : $(SRC)/%.c
 	@$(CC) -c $(CFLAGS) $< -o $@
 
+$(AOBJS): $(BLD)/%_asm.o : $(SRC)/%.asm
+	@$(AS) $(ASFLAGS) $< -o $@
+
 clean:
 	@rm -rf $(BLD)/*
diff --git a/src/loader/inc/int.h b/src/loader/inc/int.h
new file mode 100644
index 0000000..ccd9ea8
--- /dev/null
+++ b/src/loader/inc/int.h
@@ -0,0 +1,49 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#ifndef INT_H
+#define INT_H
+
+#include <def.h>
+
+#define INT_GATE 0x8e
+#define INT_TRAP 0xef
+#define INT_USER 0x60
+#define IDT_ENTRY(offset, selector, type)                                                          \
+	(struct idt_entry)                                                                         \
+	{                                                                                          \
+		.base_low = (u16)((offset)&0xffff), .sel = (selector), .zero = 0, .flags = (type), \
+		.base_high = (u16)(((offset) >> 16) & 0xffff),                                     \
+	}
+
+struct int_frame {
+	u32 gs, fs, es, ds;
+	u32 edi, esi, ebp, esp, ebx, edx, ecx, eax;
+	u32 int_no, err_code;
+	u32 eip, cs, eflags;
+} PACKED;
+
+struct int_frame_user {
+	u32 gs, fs, es, ds;
+	u32 edi, esi, ebp, esp, ebx, edx, ecx, eax;
+	u32 int_no, err_code;
+	u32 eip, cs, eflags;
+	u32 useresp, ss;
+} PACKED;
+
+struct idt_entry {
+	u16 base_low;
+	u16 sel; // Kernel segment
+	u8 zero; // Always 0
+	u8 flags;
+	u16 base_high;
+} PACKED;
+
+struct idt_ptr {
+	u16 size;
+	void *base;
+} PACKED;
+
+void idt_install(void);
+void int_event_handler_add(u32 int_no, void (*handler)(void));
+
+#endif
diff --git a/src/loader/inc/pic.h b/src/loader/inc/pic.h
new file mode 100644
index 0000000..c2a7d87
--- /dev/null
+++ b/src/loader/inc/pic.h
@@ -0,0 +1,11 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#ifndef PIC_H
+#define PIC_H
+
+#include <def.h>
+
+void pic_install(void);
+void pic_ack(u32 int_no);
+
+#endif
diff --git a/src/loader/int.asm b/src/loader/int.asm
new file mode 100644
index 0000000..f6e66ae
--- /dev/null
+++ b/src/loader/int.asm
@@ -0,0 +1,151 @@
+; MIT License, Copyright (c) 2021 Marvin Borner
+
+bits 32
+
+%macro INT_REGISTER 1
+dd int%1
+%endmacro
+
+%macro INT_ERR 1
+int%1:
+	push %1
+	jmp int_common
+%endmacro
+
+%macro INT_NOERR 1
+int%1:
+	push 0
+	push %1
+	jmp int_common
+%endmacro
+
+extern int_handler
+int_common:
+	cld
+
+	pushad
+	push ds
+	push es
+	push fs
+	push gs
+
+	mov ax, 0x10
+	mov ds, ax
+	mov es, ax
+	mov fs, ax
+	mov gs, ax
+
+	push esp
+	call int_handler
+	mov esp, eax
+
+	pop gs
+	pop fs
+	pop es
+	pop ds
+	popad
+
+	add esp, 8
+	iret
+
+INT_NOERR 0
+INT_NOERR 1
+INT_NOERR 2
+INT_NOERR 3
+INT_NOERR 4
+INT_NOERR 5
+INT_NOERR 6
+INT_NOERR 7
+INT_ERR   8
+INT_NOERR 9
+INT_ERR   10
+INT_ERR   11
+INT_ERR   12
+INT_ERR   13
+INT_ERR   14
+INT_NOERR 15
+INT_NOERR 16
+INT_ERR 17
+INT_NOERR 18
+INT_NOERR 19
+INT_NOERR 20
+INT_NOERR 21
+INT_NOERR 22
+INT_NOERR 23
+INT_NOERR 24
+INT_NOERR 25
+INT_NOERR 26
+INT_NOERR 27
+INT_NOERR 28
+INT_NOERR 29
+INT_ERR   30
+INT_NOERR 31
+
+INT_NOERR 32
+INT_NOERR 33
+INT_NOERR 34
+INT_NOERR 35
+INT_NOERR 36
+INT_NOERR 37
+INT_NOERR 38
+INT_NOERR 39
+INT_NOERR 40
+INT_NOERR 41
+INT_NOERR 42
+INT_NOERR 43
+INT_NOERR 44
+INT_NOERR 45
+INT_NOERR 46
+INT_NOERR 47
+
+global int_table
+int_table:
+	INT_REGISTER 0
+	INT_REGISTER 1
+	INT_REGISTER 2
+	INT_REGISTER 3
+	INT_REGISTER 4
+	INT_REGISTER 5
+	INT_REGISTER 6
+	INT_REGISTER 7
+	INT_REGISTER 8
+	INT_REGISTER 9
+	INT_REGISTER 10
+	INT_REGISTER 11
+	INT_REGISTER 12
+	INT_REGISTER 13
+	INT_REGISTER 14
+	INT_REGISTER 15
+	INT_REGISTER 16
+	INT_REGISTER 17
+	INT_REGISTER 18
+	INT_REGISTER 19
+	INT_REGISTER 20
+	INT_REGISTER 21
+	INT_REGISTER 22
+	INT_REGISTER 23
+	INT_REGISTER 24
+	INT_REGISTER 25
+	INT_REGISTER 26
+	INT_REGISTER 27
+	INT_REGISTER 28
+	INT_REGISTER 29
+	INT_REGISTER 30
+	INT_REGISTER 31
+
+	INT_REGISTER 32
+	INT_REGISTER 33
+	INT_REGISTER 34
+	INT_REGISTER 35
+	INT_REGISTER 36
+	INT_REGISTER 37
+	INT_REGISTER 38
+	INT_REGISTER 39
+	INT_REGISTER 40
+	INT_REGISTER 41
+	INT_REGISTER 42
+	INT_REGISTER 43
+	INT_REGISTER 44
+	INT_REGISTER 45
+	INT_REGISTER 46
+	INT_REGISTER 47
diff --git a/src/loader/int.c b/src/loader/int.c
new file mode 100644
index 0000000..67b80f0
--- /dev/null
+++ b/src/loader/int.c
@@ -0,0 +1,144 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <int.h>
+#include <log.h>
+#include <pic.h>
+#include <pnc.h>
+
+/**
+ * IDT
+ */
+
+extern u32 int_table[];
+static struct idt_entry idt[256] = { 0 };
+static struct idt_ptr idt_ptr = { 0 };
+
+void idt_install(void)
+{
+	idt_ptr.size = sizeof(idt) - 1;
+	idt_ptr.base = &idt;
+
+	for (u8 i = 0; i < 3; i++)
+		idt[i] = IDT_ENTRY(int_table[i], 0x08, INT_GATE);
+
+	idt[3] = IDT_ENTRY(int_table[3], 0x08, INT_TRAP);
+	idt[4] = IDT_ENTRY(int_table[4], 0x08, INT_TRAP);
+
+	for (u8 i = 5; i < 48; i++)
+		idt[i] = IDT_ENTRY(int_table[i], 0x08, INT_GATE);
+
+	idt[128] = IDT_ENTRY(int_table[48], 0x08, INT_GATE | INT_USER);
+	idt[129] = IDT_ENTRY(int_table[49], 0x08, INT_GATE);
+
+	// Load table
+	__asm__ volatile("lidt %0" : : "m"(idt_ptr));
+
+	// Enable interrupts
+	__asm__ volatile("sti");
+}
+
+/**
+ * Exception (trap) handling
+ */
+
+const char *int_trap_names[32] = {
+	"Division By Zero",
+	"Debug",
+	"Non Maskable Interrupt",
+	"Breakpoint",
+	"Into Detected Overflow",
+	"Out of Bounds",
+	"Invalid Opcode",
+	"No Coprocessor",
+
+	"Double Fault",
+	"Coprocessor Segment Overrun",
+	"Bad TSS",
+	"Segment Not Present",
+	"Stack Fault",
+	"General Protection Fault",
+	"Page Fault",
+	"Unknown Interrupt",
+
+	"Coprocessor Fault",
+	"Alignment Check",
+	"Machine Check",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+};
+
+static void int_trap_handler(struct int_frame *frame)
+{
+	static u8 faulting = 0;
+	faulting++;
+
+	if (faulting == 2) {
+		// Fall back to serial driver
+		serial_print("Double fault, halting immediatly\n");
+		while (1)
+			__asm__ volatile("cli\nhlt");
+	}
+
+	log("%s Exception (code %x) at 0x%x!\n", int_trap_names[frame->int_no], frame->err_code,
+	    frame->eip);
+
+	while (1)
+		__asm__ volatile("cli\nhlt");
+}
+
+/**
+ * Event handling
+ */
+
+static void (*int_event_handlers[16])(void) = { 0 };
+
+void int_event_handler_add(u32 int_no, void (*handler)(void))
+{
+	assert(int_no < COUNT(int_event_handlers));
+	int_event_handlers[int_no] = handler;
+}
+
+static u32 int_event_handler(struct int_frame *frame)
+{
+	u32 int_no = frame->int_no - 32;
+	assert(int_no < COUNT(int_event_handlers));
+	void (*handler)(void) = int_event_handlers[int_no];
+	if (handler)
+		handler();
+
+	return (u32)frame;
+}
+
+/**
+ * Universal handler
+ */
+
+static u8 int_enabled = 1;
+
+u32 int_handler(u32 esp);
+u32 int_handler(u32 esp)
+{
+	struct int_frame *frame = (struct int_frame *)esp;
+	if (frame->int_no < 32) {
+		int_trap_handler(frame);
+	} else if (int_enabled && frame->int_no < 48) {
+		esp = int_event_handler(frame);
+	} else if (frame->int_no >= 48) {
+		panic("Unknown interrupt\n");
+	}
+
+	pic_ack(frame->int_no);
+	return esp;
+}
diff --git a/src/loader/main.c b/src/loader/main.c
index bf2604e..7c50e62 100644
--- a/src/loader/main.c
+++ b/src/loader/main.c
@@ -3,13 +3,14 @@
 #include <def.h>
 #include <dev.h>
 #include <ide.h>
+#include <int.h>
 #include <log.h>
 #include <pci.h>
+#include <pic.h>
 
 /**
  * Entry
  */
-#include <pnc.h>
 
 int start(void);
 int start(void)
@@ -17,10 +18,15 @@ int start(void)
 	vga_clear();
 	serial_install();
 
+	pic_install();
+	idt_install();
+
 	pci_probe();
 	dev_print();
 
+	// Sleep and wait for interrupts
 	while (1)
-		;
+		__asm__ volatile("hlt");
+
 	return 0;
 }
diff --git a/src/loader/pic.c b/src/loader/pic.c
new file mode 100644
index 0000000..18b248c
--- /dev/null
+++ b/src/loader/pic.c
@@ -0,0 +1,64 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <cpu.h>
+#include <pic.h>
+
+#define PIC1 0x20
+#define PIC1_COMMAND PIC1
+#define PIC1_OFFSET 0x20
+#define PIC1_DATA (PIC1 + 1)
+
+#define PIC2 0xa0
+#define PIC2_COMMAND PIC2
+#define PIC2_OFFSET 0x28
+#define PIC2_DATA (PIC2 + 1)
+
+#define ICW1_ICW4 0x01
+#define ICW1_INIT 0x10
+
+static void pic_wait(void)
+{
+	__asm__ volatile("jmp 1f\n\t"
+			 "1:\n\t"
+			 "    jmp 2f\n\t"
+			 "2:");
+}
+
+void pic_install(void)
+{
+	// Initialize
+	outb(PIC1_COMMAND, ICW1_INIT | ICW1_ICW4);
+	pic_wait();
+	outb(PIC2_COMMAND, ICW1_INIT | ICW1_ICW4);
+	pic_wait();
+
+	// Remap
+	outb(PIC1_DATA, PIC1_OFFSET);
+	pic_wait();
+	outb(PIC2_DATA, PIC2_OFFSET);
+	pic_wait();
+
+	outb(PIC1_DATA, 0x04);
+	pic_wait();
+	outb(PIC2_DATA, 0x02);
+	pic_wait();
+
+	// Set 8086 mode
+	outb(PIC1_DATA, 0x01);
+	pic_wait();
+	outb(PIC2_DATA, 0x01);
+	pic_wait();
+
+	outb(PIC1_DATA, 0x00);
+	pic_wait();
+	outb(PIC2_DATA, 0x00);
+	pic_wait();
+}
+
+void pic_ack(u32 int_no)
+{
+	if (int_no >= 40)
+		outb(PIC2, 0x20);
+
+	outb(PIC1, 0x20);
+}