Update readme

mrgian · Mar 30, 2023 · b69dd4c · b69dd4c
1 parent af06203
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diff --git a/README.md b/README.md
@@ -51,6 +51,22 @@ You can run it in QEMU using this command: `qemu-system-i386 -drive id=disk,file
 
 Or you can run it on a real x86 computer by copying the disk image to a USB drive using this command: `sudo dd if=build/disk.img of=/dev/sdX status=progress` and then booting from USB.
 
+## Features
+
+### Bootloader
+ - boots (you don't say!)
+ - BIOS compatible (also works on UEFI with CSM enabled)
+ - loads a basic Global Descriptor Table
+ - switches to Unreal Mode (to use 32bit addresses in 16bit Real Mode)
+ - copies kernel from disk to protected memory
+ - switches to 32bit Protected Mode
+ - jumps to kernel
+
+ ### Kernel
+ - prints formatted text to screen by writing to VGA text buffer
+ - loads a basic Interrupt Descriptor Table
+ - has a basic handler for CPU exceptions
+
 ## Progress
 - *22/10/22* - Project start
 - *27/01/23* - Bootloader can print to screen
@@ -60,6 +76,7 @@ Or you can run it on a real x86 computer by copying the disk image to a USB driv
 - *01/03/23* - Rewritten kernel loading code in Rust
 - *08/03/23* - Implemented println macro
 - *20/03/23* - Switch to 32bit protected mode
+- *30/03/23* - Basic CPU exception handler
 
 ## Credits
 This project is entirely developed by **Gianmatteo Palmieri** ([mrgian](https://github.com/mrgian)).
diff --git a/kernel/src/idt.rs b/kernel/src/idt.rs
@@ -98,7 +98,7 @@ impl IdtEntry {
 
 //handle excpetion based on interrupt number
 #[no_mangle]
-pub extern "C" fn exception_handler(int: u32) {
+pub extern "C" fn exception_handler(int: u32, eip: u32, cs: u32, eflags: u32) {
     match int {
         0x00 => {
             println!("DIVISION ERROR!");
@@ -122,46 +122,83 @@ pub extern "C" fn exception_handler(int: u32) {
             println!("EXCEPTION!");
         }
     }
+    println!("EIP: {:X}, CS: {:X}, EFLAGS: {:b}", eip, cs, eflags);
 }
 
 #[naked]
 pub extern "C" fn div_error() {
     unsafe {
-        asm!("push 0x00", "call exception_handler","add esp, 4","iretd", options(noreturn));
+        asm!(
+            "push 0x00",
+            "call exception_handler",
+            "add esp, 4",
+            "iretd",
+            options(noreturn)
+        );
     }
 }
 
 #[naked]
 pub extern "C" fn invalid_opcode() {
     unsafe {
-        asm!("push 0x06", "call exception_handler", "add esp, 4","iretd", options(noreturn));
+        asm!(
+            "push 0x06",
+            "call exception_handler",
+            "add esp, 4",
+            "iretd",
+            options(noreturn)
+        );
     }
 }
 
 #[naked]
 pub extern "C" fn double_fault() {
     unsafe {
-        asm!("push 0x08", "call exception_handler", options(noreturn));
+        asm!(
+            "push 0x08",
+            "call exception_handler",
+            "add esp, 4",
+            "iretd",
+            options(noreturn)
+        );
     }
 }
 
 #[naked]
 pub extern "C" fn general_protection_fault() {
     unsafe {
-        asm!("push 0x0d", "call exception_handler", options(noreturn));
+        asm!(
+            "push 0x0d",
+            "call exception_handler",
+            "add esp, 4",
+            "iretd",
+            options(noreturn)
+        );
     }
 }
 
 #[naked]
 pub extern "C" fn page_fault() {
     unsafe {
-        asm!("push 0x0e", "call exception_handler", options(noreturn));
+        asm!(
+            "push 0x0e",
+            "call exception_handler",
+            "add esp, 4",
+            "iretd",
+            options(noreturn)
+        );
     }
 }
 
 #[naked]
 pub extern "C" fn generic_handler() {
     unsafe {
-        asm!("push 0xff", "call exception_handler", options(noreturn));
+        asm!(
+            "push 0xff",
+            "call exception_handler",
+            "add esp, 4",
+            "iretd",
+            options(noreturn)
+        );
     }
-}
+}
diff --git a/kernel/src/main.rs b/kernel/src/main.rs
@@ -34,16 +34,10 @@ pub extern "C" fn _start() -> ! {
     idt.add_exceptions();
     idt.load();
 
-    //generates invalid opcode exception
     unsafe {
-        asm!("int 0x0");
+        asm!("int 0xff");
     }
 
-    //generates division error exception
-    /*unsafe {
-        asm!("div bl", in("al") 0x00 as u8, in("bl") 0x00 as u8);
-    }*/
-
     println!("Not crashed!");
 
     loop {}
@@ -55,5 +49,3 @@ fn panic(info: &PanicInfo) -> ! {
 
     loop {}
 }
-
-