Add a flat limit to all GDT segments

.github/workflows/build.yml

@@ -51,43 +51,40 @@ jobs:
       name: 'Build Test Kernel'
 
     - name: 'Build Bootloader'
-      run: cargo xbuild --bin bootloader --features binary --release
-      env:
-        KERNEL: "test-kernel/target/x86_64-test-kernel/debug/test-kernel"
-        KERNEL_MANIFEST: "test-kernel/Cargo.toml"
+      run: cargo xbuild --release
 
     - name: 'Convert Bootloader ELF to Binary'
-      run: cargo objcopy -- -I elf64-x86-64 -O binary --binary-architecture=i386:x86-64 target/x86_64-bootloader/release/bootloader target/x86_64-bootloader/release/bootloader.bin
-
-     # install QEMU
-    - name: Install QEMU (Linux)
-      run: sudo apt update && sudo apt install qemu-system-x86
-      if: runner.os == 'Linux'
-    - name: Install QEMU (macOS)
-      run: brew install qemu
-      if: runner.os == 'macOS'
-      env:
-        HOMEBREW_NO_AUTO_UPDATE: 1
-        HOMEBREW_NO_BOTTLE_SOURCE_FALLBACK: 1
-        HOMEBREW_NO_INSTALL_CLEANUP: 1
-    - name: Install Scoop (Windows)
-      run: |
-        Invoke-Expression (New-Object System.Net.WebClient).DownloadString('https://get.scoop.sh')
-        echo ::add-path::$HOME\scoop\shims
-      if: runner.os == 'Windows'
-      shell: pwsh
-    - name: Install QEMU (Windows)
-      run: scoop install qemu
-      if: runner.os == 'Windows'
-      shell: pwsh
-    - name: "Print QEMU Version"
-      run: qemu-system-x86_64 --version
-
-    - name: 'Run Test Kernel with Bootloader'
-      run: |
-        qemu-system-x86_64 -drive format=raw,file=target/x86_64-bootloader/release/bootloader.bin -device isa-debug-exit,iobase=0xf4,iosize=0x04 -display none
-        if [ $? -eq 123 ]; then (exit 0); else (exit 1); fi
-      shell: 'bash {0}'
+      run: cargo objcopy -- -I elf64-i386 -O binary --binary-architecture=i386:x86-64 target/x86_64-real_mode/release/bootsector target/x86_64-real_mode/release/bootsector.bin
+
+    #  # install QEMU
+    # - name: Install QEMU (Linux)
+    #   run: sudo apt update && sudo apt install qemu-system-x86
+    #   if: runner.os == 'Linux'
+    # - name: Install QEMU (macOS)
+    #   run: brew install qemu
+    #   if: runner.os == 'macOS'
+    #   env:
+    #     HOMEBREW_NO_AUTO_UPDATE: 1
+    #     HOMEBREW_NO_BOTTLE_SOURCE_FALLBACK: 1
+    #     HOMEBREW_NO_INSTALL_CLEANUP: 1
+    # - name: Install Scoop (Windows)
+    #   run: |
+    #     Invoke-Expression (New-Object System.Net.WebClient).DownloadString('https://get.scoop.sh')
+    #     echo ::add-path::$HOME\scoop\shims
+    #   if: runner.os == 'Windows'
+    #   shell: pwsh
+    # - name: Install QEMU (Windows)
+    #   run: scoop install qemu
+    #   if: runner.os == 'Windows'
+    #   shell: pwsh
+    # - name: "Print QEMU Version"
+    #   run: qemu-system-x86_64 --version
+
+    # - name: 'Run Test Kernel with Bootloader'
+    #   run: |
+    #     qemu-system-x86_64 -drive format=raw,file=target/x86_64-bootloader/release/bootloader.bin -device isa-debug-exit,iobase=0xf4,iosize=0x04 -display none
+    #     if [ $? -eq 123 ]; then (exit 0); else (exit 1); fi
+    #   shell: 'bash {0}'
 
 
   build_example_kernel:

Cargo.toml

@@ -3,7 +3,9 @@ members = [
   "src/shared",
   "src/v86",
   "src/bootsector",
-  "src/stage_2"
+  "src/stage_2",
+  "example-kernel",
+  "test-kernel",
 ]
 
 [profile.release]

src/v86/src/gdt.rs

@@ -48,7 +48,9 @@ impl GlobalDescriptorTable {
             limit: (self.table.len() * size_of::<u64>() - 1) as u16,
         };
 
-        llvm_asm!("lgdt ($0)" :: "r" (&ptr) : "memory");
+        unsafe {
+            llvm_asm!("lgdt ($0)" :: "r" (&ptr) : "memory");
+        }
     }
 
     #[inline]
@@ -87,6 +89,9 @@ bitflags! {
 
         /// The DPL for this descriptor is Ring 3
         const DPL_RING_3        = 3 << 45;
+
+        /// If set, limit is in 4k pages
+        const GRANULARITY       = 1 << 55;
     }
 }
 
@@ -98,7 +103,7 @@ impl Descriptor {
 
         let flags =
             Flags::USER_SEGMENT | Flags::PRESENT | Flags::EXECUTABLE | Flags::READABLE_WRITABLE;
-        Descriptor(flags.bits())
+        Descriptor(flags.bits()).with_flat_limit()
     }
 
     /// Creates a segment descriptor for a protected mode kernel data segment.
@@ -107,7 +112,7 @@ impl Descriptor {
         use self::DescriptorFlags as Flags;
 
         let flags = Flags::USER_SEGMENT | Flags::PRESENT | Flags::READABLE_WRITABLE;
-        Descriptor(flags.bits())
+        Descriptor(flags.bits()).with_flat_limit()
     }
 
     /// Creates a segment descriptor for a protected mode ring 3 data segment.
@@ -117,7 +122,7 @@ impl Descriptor {
 
         let flags =
             Flags::USER_SEGMENT | Flags::PRESENT | Flags::READABLE_WRITABLE | Flags::DPL_RING_3;
-        Descriptor(flags.bits())
+        Descriptor(flags.bits()).with_flat_limit()
     }
 
     /// Creates a segment descriptor for a protected mode ring 3 code segment.
@@ -130,7 +135,7 @@ impl Descriptor {
             | Flags::EXECUTABLE
             | Flags::DPL_RING_3
             | Flags::READABLE_WRITABLE;
-        Descriptor(flags.bits())
+        Descriptor(flags.bits()).with_flat_limit()
     }
 
     /// Creates a TSS system descriptor for the given TSS.
@@ -152,6 +157,17 @@ impl Descriptor {
 
         Descriptor(val)
     }
+
+    fn with_flat_limit(mut self) -> Self {
+        // limit_low
+        self.0.set_bits(0..16, 0xffff);
+        // limit high
+        self.0.set_bits(48..52, 0xff);
+        // granularity
+        self.0 |= DescriptorFlags::GRANULARITY.bits();
+
+        self
+    }
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -224,7 +240,7 @@ pub struct Stack {
 }
 
 impl Stack {
-    fn zero() -> Self {
+    const fn zero() -> Self {
         Stack { esp: 0, ss: 0 }
     }
 }

src/v86/src/idt.rs

@@ -1,4 +1,5 @@
 use core::marker::PhantomData;
+use bit_field::BitField;
 
 /// An Interrupt Descriptor Table with 32 entries.
 #[derive(Clone)]