From 4b0bd4d1334f6b8f892f424d2555a68904803b00 Mon Sep 17 00:00:00 2001
From: Greg Bowne <gbowne144@gmail.com>
Date: Sun, 8 Oct 2023 18:32:10 -0700
Subject: [PATCH] fixing more of the mess

---
 CMakeLists.txt            |  1 +
 linker.ld                 |  6 +++++-
 src/kernel/arch/x86/gdt.c | 19 ++-----------------
 src/kernel/arch/x86/idt.c |  5 +++--
 src/kernel/arch/x86/isr.c | 11 ++---------
 src/kernel/arch/x86/isr.h | 12 +++++++-----
 6 files changed, 20 insertions(+), 34 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 40c9a84..7f11616 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -68,6 +68,7 @@ target_link_libraries(ClassicOS PRIVATE)
 set(CMAKE_C_COMPILER gcc)
 set(CMAKE_LINKER ld)
 set(CMAKE_EXE_LINKER_FLAGS "-g -s")
+set(CMAKE_LINK_FLAGS "${CMAKE_LINK_FLAGS} -e kernel_main")
 set(CMAKE_CXX_FLAGS "-g -Wall")
 set(CMAKE_C_FLAGS "-g -Wall -m32")
 set(CMAKE_BUILD_TYPE Debug)
diff --git a/linker.ld b/linker.ld
index 118455f..6f90a30 100644
--- a/linker.ld
+++ b/linker.ld
@@ -1,4 +1,4 @@
-ENTRY(_start)
+ENTRY(kernel_main)
 
 SECTIONS {
     . = 0x100000;
@@ -7,6 +7,10 @@ SECTIONS {
         *(.text)
     }
 
+    .rodata : {
+        *(.rodata)
+    }
+
     .data : {
         *(.data)
     }
diff --git a/src/kernel/arch/x86/gdt.c b/src/kernel/arch/x86/gdt.c
index 3a49d64..ed5f819 100644
--- a/src/kernel/arch/x86/gdt.c
+++ b/src/kernel/arch/x86/gdt.c
@@ -81,7 +81,7 @@ void gdt_init()
 
 // Exception handlers
 extern void divide_error();
-extern void page_fault();
+extern void page_fault(struct idt_regs *regs);
 extern void general_protection_fault();
 extern void double_fault();
 
@@ -91,27 +91,12 @@ extern void timer();
 extern void keyboard();
 extern void device();
 
-// ISR table
-void (*isr_table[ISR_TABLE_SIZE])(void) = {0};
-
 // Register an ISR
-void isr_register(uint8_t num, void (*handler)(void))
+void isr_register(uint8_t num, void (*handler)(struct idt_regs *))
 {
     isr_table[num] = handler;
 }
 
-// ISR handler
-void isr_handler(struct idt_regs *regs)
-{
-    void (*handler)(void) = isr_table[regs->int_no];
-
-    handler = isr_table[regs->int_no];
-    if (handler)
-    {
-        handler();
-    }
-}
-
 // Initialize the ISR
 void isr_init()
 {
diff --git a/src/kernel/arch/x86/idt.c b/src/kernel/arch/x86/idt.c
index 1cf09f6..b6af69e 100644
--- a/src/kernel/arch/x86/idt.c
+++ b/src/kernel/arch/x86/idt.c
@@ -1,4 +1,5 @@
 #include "idt.h"
+#include "isr.h"
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -21,7 +22,7 @@ const struct idt_ptr idtp = {sizeof(idt) - 1, idt};
 
 // Exception handlers
 extern void divide_error_handler();
-extern void page_fault_handler();
+extern void page_fault(struct idt_regs *regs);
 extern void general_protection_fault_handler();
 extern void double_fault_handler();
 
@@ -57,7 +58,7 @@ void idt_init()
 
     // Set up exception handlers
     idt_set_gate(0, divide_error_handler, 0x08, 0x8E);
-    idt_set_gate(14, page_fault_handler, 0x08, 0x8E);
+    idt_set_gate(14, page_fault, 0x08, 0x8E);
     idt_set_gate(13, general_protection_fault_handler, 0x08, 0x8E);
     idt_set_gate(8, double_fault_handler, 0x08, 0x8E);
 
diff --git a/src/kernel/arch/x86/isr.c b/src/kernel/arch/x86/isr.c
index 5a348d9..5d508a6 100644
--- a/src/kernel/arch/x86/isr.c
+++ b/src/kernel/arch/x86/isr.c
@@ -18,17 +18,10 @@ void dummy_isr(struct isr_regs *regs)
 }
 
 // ISR table
-void (*isr_table[256])(struct isr_regs *regs) = {
-    // initialize the dummy isr_table
-    [TIMER_INTERRUPT]       = dummy_isr, // Timer interrupt
-    [KEYBOARD_INTERRUPT]    = dummy_isr, // Keyboard interrupt
-    [NETWORK_INTERRUPT]     = dummy_isr, // Network interrupt
-    [DISK_INTERRUPT]        = dummy_isr, // Disk interrupt
-    [SERIAL_PORT_INTERRUPT] = dummy_isr  // Serial port interrupt
-};
+extern void (*isr_table[256])(struct isr_regs *regs);
 
 // Register an ISR
-void isr_register(uint8_t num, void (*handler)(struct isr_regs *regs))
+extern void isr_register(uint8_t num, void (*handler)(struct isr_regs *regs))
 {
     isr_table[num] = handler;
 }
diff --git a/src/kernel/arch/x86/isr.h b/src/kernel/arch/x86/isr.h
index 0b98787..989c56b 100644
--- a/src/kernel/arch/x86/isr.h
+++ b/src/kernel/arch/x86/isr.h
@@ -5,11 +5,13 @@
 
 struct isr_regs
 {
-    uint32_t gs, fs, es, ds;      // Segment selectors
-    uint32_t edi, esi, ebp, esp;  // Pushed by pusha instruction
-    uint32_t ebx, edx, ecx, eax;  // Pushed by the interrupt handler
-    uint32_t int_no, err_code;    // Interrupt number and error code (if applicable)
-    uint32_t eip, cs, eflags, esp_at_signal; // Pushed by the processor automatically
+    uint32_t gs, fs, es, ds;     // Segment selectors
+    uint32_t edi, esi, ebp, esp; // Pushed by pusha instruction
+    uint32_t ebx, edx, ecx, eax; // Pushed by the interrupt handler
+    uint32_t int_no,
+        err_code; // Interrupt number and error code (if applicable)
+    uint32_t eip, cs, eflags,
+        esp_at_signal; // Pushed by the processor automatically
 };
 
 // Structure for storing register values during an ISR