From 99019721a9e147c49becc466c5427609b937aca8 Mon Sep 17 00:00:00 2001
From: Loic Guegan <manzerbredes@mailbox.org>
Date: Wed, 21 Apr 2021 18:54:50 +0200
Subject: Enable interrupts

---
 src/core/idt.cc  | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/core/idt.hpp | 33 +++++++++++++++++++++++++++++++++
 src/core/int.S   | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 117 insertions(+)
 create mode 100644 src/core/idt.cc
 create mode 100644 src/core/idt.hpp
 create mode 100644 src/core/int.S

(limited to 'src/core')

diff --git a/src/core/idt.cc b/src/core/idt.cc
new file mode 100644
index 0000000..b808625
--- /dev/null
+++ b/src/core/idt.cc
@@ -0,0 +1,51 @@
+#include "idt.hpp"
+#include "libs/string.hpp"
+
+IDT_REGISTER IDTR = {
+    IDT_GATE_SIZE*IDT_MAX_ENTRIES,
+    IDT_ADDR
+};
+
+extern u64 INT_DEFAULT,INT_0,INT_14;
+
+void idt_enable_interrupt(void){
+    IDT_DESCRIPTOR d;
+    d.ign=0;
+    d.ist=0;
+    d.selector=0x08;
+    d.options=IDT_OPT_P|IDT_OPT_PRVL_0|IDT_OPT_TYPE_INT;
+
+    // Write idt entries
+    for(u16 i=0;i<IDT_MAX_ENTRIES;i++){
+        if(i==0){ // Zero-division
+            d.offset=(u64)&INT_0;
+            idt_write_descriptor(d, i);
+        }
+        else if(i==14){ // Page fault
+            d.offset=(u64)&INT_14;
+            idt_write_descriptor(d, i);
+        }
+        else {
+            d.offset=(u64)&INT_DEFAULT;
+            idt_write_descriptor(d, i);
+        }
+    }
+
+    // Enable interrupts
+    asm(
+        "lidt (IDTR)   \n\t"
+        "sti           \n\t"
+    );
+}
+
+void idt_write_descriptor(IDT_DESCRIPTOR desc, u16 index){
+    u32 desc0_31=(desc.selector << 16) | desc.offset&0xFFFF;
+    u32 desc32_63=desc.ist | desc.options | (desc.offset&0xFFFF0000);
+    u32 desc64_95=desc.offset>>32;
+    u32 desc96_127=desc.ign;
+    u32* dst=(u32*)(IDTR.base+index*IDT_GATE_SIZE);
+    *dst=desc0_31;
+    *(dst+1)=desc32_63;
+    *(dst+2)=desc64_95;
+    *(dst+3)=desc96_127;
+}
\ No newline at end of file
diff --git a/src/core/idt.hpp b/src/core/idt.hpp
new file mode 100644
index 0000000..f2aca43
--- /dev/null
+++ b/src/core/idt.hpp
@@ -0,0 +1,33 @@
+#pragma once
+
+#include "types.hpp"
+#include "libs/stdio.hpp"
+
+#define IDT_GATE_SIZE 16
+#define IDT_MAX_ENTRIES 50
+#define IDT_ADDR 0x200000
+
+#define IDT_OPT_P (1 << 15)
+#define IDT_OPT_TYPE_INT 0xE << 8
+#define IDT_OPT_PRVL_0 0
+#define IDT_OPT_PRVL_1 (1 << 13)
+#define IDT_OPT_PRVL_2 (2 << 13)
+#define IDT_OPT_PRVL_3 (3 << 13)
+
+
+
+typedef struct IDT_REGISTER {
+    u16 limit;
+    u64 base;
+} __attribute__((packed)) IDT_REGISTER;
+
+typedef struct IDT_DESCRIPTOR {
+    u64 offset;
+    u16 selector;
+    u16 options;
+    u8 ist;
+    u32 ign;
+} __attribute__((packed)) IDT_DESCRIPTOR;
+
+void idt_enable_interrupt(void);
+void idt_write_descriptor(IDT_DESCRIPTOR desc, u16 index);
\ No newline at end of file
diff --git a/src/core/int.S b/src/core/int.S
new file mode 100644
index 0000000..d5ad643
--- /dev/null
+++ b/src/core/int.S
@@ -0,0 +1,33 @@
+.extern printk
+
+.macro call_printk msg
+    mov \msg, %rdi
+    mov $0, %eax # Required for variadic functions
+    call printk
+.endm
+
+.globl INT_DEFAULT
+INT_DEFAULT:
+    iretq
+
+.globl INT_0
+INT_0:
+    call_printk $MSG_INT_0
+    INT_0_INFINITE:
+    jmp INT_0_INFINITE
+    iretq
+
+.globl INT_14
+INT_14:
+    call_printk $MSG_INT_14
+    mov $0, %eax
+    call printk
+    INT_14_INFINITE:
+    jmp INT_14_INFINITE
+    iretq
+
+
+MSG_INT_0:
+.asciz "Zero Division error!"
+MSG_INT_14:
+.asciz "Page fault!"
-- 
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