From 912d2e3c7eb1baa71dda2c0a28aa5809eaa96f27 Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Sat, 16 Jul 2022 13:33:00 +0200
Subject: amd64: barely boot into kernel code

---
 src/kernel/arch/amd64/interrupts/idt.c | 71 ++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 src/kernel/arch/amd64/interrupts/idt.c

(limited to 'src/kernel/arch/amd64/interrupts/idt.c')

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();
+}
-- 
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