amd64: barely boot into kernel code

7 files changed, 250 insertions, 0 deletions

diff --git a/src/kernel/arch/amd64/interrupts/idt.c b/src/kernel/arch/amd64/interrupts/idt.c
new file mode 100644
index 0000000..9c71000
--- /dev/null
+++ b/src/kernel/arch/amd64/interrupts/idt.c
@@ -0,0 +1,71 @@
+#include <kernel/arch/amd64/32/gdt.h>
+#include <kernel/arch/amd64/interrupts/idt.h>
+#include <kernel/arch/amd64/interrupts/isr.h>
+#include <kernel/panic.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+struct idt_entry {
+	uint16_t offset_low;
+	uint16_t seg;
+	uint8_t ist;
+	uint8_t type    : 4; // 0xE - interrupt, 0xF - trap
+	uint8_t zero1   : 1;
+	uint8_t ring    : 2;
+	uint8_t present : 1;
+	uint16_t offset_mid;
+	uint32_t offset_high;
+	uint32_t zero2;
+} __attribute__((packed));
+
+// is exactly the same as lgdt_arg, i should combine them into a single struct
+// later
+struct lidt_arg {
+	uint16_t limit;
+	uintptr_t base;
+} __attribute__((packed));
+
+__attribute__((section(".shared")))
+static struct idt_entry IDT[256];
+static struct lidt_arg lidt_arg;
+
+static void idt_prepare(void);
+static void idt_load(void);
+static void idt_test(void);
+
+
+static void idt_prepare(void) {
+	for (int i = 0; i < 256; i++) {
+		uintptr_t offset = (uintptr_t) &_isr_stubs + i * 8;
+
+		IDT[i] = (struct idt_entry) {
+			.offset_low  = offset,
+			.offset_mid  = offset >> 16,
+			.offset_high = offset >> 32,
+			.seg = SEG_r0code << 3,
+			.present = 1,
+			.type = 0xE,
+			.ist = 1,
+		};
+	}
+}
+
+static void idt_load(void) {
+	lidt_arg.limit = sizeof(IDT) - 1;
+	lidt_arg.base = (uintptr_t) &IDT;
+	asm("lidt (%0)" : : "r" (&lidt_arg) : "memory");
+}
+
+static void idt_test(void) {
+	kprintf("idt test?\n");
+	asm("xchgw %%bx, %%bx" ::: "memory");
+	asm("int $0x34" : : : "memory");
+	assert(isr_test_interrupt_called);
+	kprintf("done.\n");
+}
+
+void idt_init(void) {
+	idt_prepare();
+	idt_load();
+	idt_test();
+}
diff --git a/src/kernel/arch/amd64/interrupts/idt.h b/src/kernel/arch/amd64/interrupts/idt.h
new file mode 100644
index 0000000..6576cf9
--- /dev/null
+++ b/src/kernel/arch/amd64/interrupts/idt.h
@@ -0,0 +1,3 @@
+#pragma once
+
+void idt_init(void);
diff --git a/src/kernel/arch/amd64/interrupts/irq.c b/src/kernel/arch/amd64/interrupts/irq.c
new file mode 100644
index 0000000..74bc48c
--- /dev/null
+++ b/src/kernel/arch/amd64/interrupts/irq.c
@@ -0,0 +1,33 @@
+#include <kernel/arch/amd64/interrupts/irq.h>
+#include <kernel/arch/amd64/port_io.h>
+#include <stdint.h>
+
+static const int PIC1 = 0x20;
+static const int PIC2 = 0xA0;
+
+void irq_init(void) {
+	port_out8(PIC1, 0x11);   /* start init sequence */
+	port_out8(PIC2, 0x11);
+
+	port_out8(PIC1+1, 0x20); /* interrupt offsets */
+	port_out8(PIC2+1, 0x30);
+
+	port_out8(PIC1+1, 0x4);  /* just look at the osdev wiki lol */
+	port_out8(PIC2+1, 0x2);
+
+	port_out8(PIC1+1, 0x1);  /* 8086 mode */
+	port_out8(PIC2+1, 0x1);
+
+	uint8_t mask = 0xff;
+	mask &= ~(1 << 1); // keyboard
+	mask &= ~(1 << 4); // COM1
+
+	port_out8(PIC1+1, mask);
+	port_out8(PIC2+1, 0xff);
+}
+
+void irq_eoi(uint8_t line) {
+	port_out8(PIC1, 0x20);
+	if (line >= 8)
+		port_out8(PIC2, 0x20);
+}
diff --git a/src/kernel/arch/amd64/interrupts/irq.h b/src/kernel/arch/amd64/interrupts/irq.h
new file mode 100644
index 0000000..f523154
--- /dev/null
+++ b/src/kernel/arch/amd64/interrupts/irq.h
@@ -0,0 +1,6 @@
+#pragma once
+#include <stdbool.h>
+#include <stdint.h>
+
+void irq_init(void);
+void irq_eoi(uint8_t line);
diff --git a/src/kernel/arch/amd64/interrupts/isr.c b/src/kernel/arch/amd64/interrupts/isr.c
new file mode 100644
index 0000000..b55bc8b
--- /dev/null
+++ b/src/kernel/arch/amd64/interrupts/isr.c
@@ -0,0 +1,48 @@
+#include <kernel/arch/amd64/driver/ps2.h>
+#include <kernel/arch/amd64/driver/serial.h>
+#include <kernel/arch/amd64/interrupts/irq.h>
+#include <kernel/arch/amd64/interrupts/isr.h>
+#include <kernel/arch/amd64/port_io.h>
+#include <kernel/arch/generic.h>
+#include <kernel/panic.h>
+#include <kernel/proc.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+bool isr_test_interrupt_called = false;
+
+void isr_stage3(int interrupt, uint64_t *stackframe) {
+	if (interrupt == 0xe) stackframe++;
+	kprintf("interrupt %x, rip = k/%08x, cs 0x%x\n", interrupt, stackframe[0], stackframe[1]);
+	switch (interrupt) {
+		case 0x08: // double fault
+			kprintf("#DF");
+			panic_invalid_state();
+
+		case 0xe:
+			uint64_t addr = 0x69;
+			asm("mov %%cr2, %0" : "=r"(addr));
+			kprintf("error code 0x%x, addr 0x%x\n", stackframe[-1], addr);
+			panic_unimplemented();
+
+		case 0x34:
+			asm("nop" ::: "memory");
+			isr_test_interrupt_called = true;
+			return;
+
+		case 0x21: // keyboard irq
+			ps2_recv(port_in8(0x60));
+			irq_eoi(1);
+			return;
+
+		case 0x24: // COM1 irq
+			serial_irq();
+			irq_eoi(1);
+			return;
+
+		default:
+			// TODO check if the exception was in the kernel
+			process_kill(process_current, interrupt);
+			process_switch_any();
+	}
+}
diff --git a/src/kernel/arch/amd64/interrupts/isr.h b/src/kernel/arch/amd64/interrupts/isr.h
new file mode 100644
index 0000000..01f5236
--- /dev/null
+++ b/src/kernel/arch/amd64/interrupts/isr.h
@@ -0,0 +1,8 @@
+#pragma once
+#include <stdbool.h>
+#include <stdint.h>
+
+extern bool isr_test_interrupt_called; // used in the self-test in idt.c
+extern const char _isr_stubs;
+
+void isr_stage3(int interrupt, uint64_t *stackframe);
diff --git a/src/kernel/arch/amd64/interrupts/isr_stub.s b/src/kernel/arch/amd64/interrupts/isr_stub.s
new file mode 100644
index 0000000..e45c1c1
--- /dev/null
+++ b/src/kernel/arch/amd64/interrupts/isr_stub.s
@@ -0,0 +1,81 @@
+.section .shared
+
+.global _isr_stubs
+_isr_stubs:
+.rept 256
+	.set _stub_start, .
+
+	cli
+	call _isr_stage2
+
+	.if . - _stub_start > 8
+		.error "isr stubs over maximum size"
+		.abort
+	.endif
+	.align 8
+.endr
+
+_isr_stage2:
+	// pushal order, without %esp
+	push %rax
+	push %rcx
+	push %rdx
+	push %rbx
+	push %rbp
+	push %rsi
+	push %rdi
+	push %r8
+	push %r9
+	push %r10
+	push %r11
+	push %r12
+	push %r13
+	push %r14
+	push %r15
+
+	// convert the return address into the vector nr
+	mov 120(%rsp), %rdi
+	sub $_isr_stubs, %rdi
+	shr $3, %rdi
+
+	lea 128(%rsp), %rsi // second argument - IRET stack frame
+
+	// load kernel paging
+	mov %cr3, %rbx
+	push %rbx
+	mov $pml4_identity, %rbx
+	mov %rbx, %cr3
+
+	mov %rsp, %rbp
+	mov $_isr_big_stack, %rsp
+	call isr_stage3
+
+	mov %rbp, %rsp
+	pop %rax // restore old cr3
+	mov %rax, %cr3
+
+	// restore registers
+	pop %r15
+	pop %r14
+	pop %r13
+	pop %r12
+	pop %r11
+	pop %r10
+	pop %r9
+	pop %r8
+	pop %rdi
+	pop %rsi
+	pop %rbp
+	pop %rbx
+	pop %rdx
+	pop %rcx
+	pop %rax
+
+	add $8, %rsp // skip call's return address
+	iretq
+
+.align 8
+// TODO overflow check
+.skip 256 // seems to be enough
+.global _isr_mini_stack
+_isr_mini_stack: