Paging, Testing and VMM

.clangd

@@ -0,0 +1,2 @@
+CompileFlags:
+  Add: [-DUNIT_TEST_ENABLED]

.github/workflows/makefile.yml

@@ -0,0 +1,27 @@
+name: Makefile CI
+
+on:
+  push:
+    branches: ["nightly", "dev", "beta", "stable"]
+  pull_request:
+    branches: ["nightly", "dev", "beta", "stable"]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+        with:
+          submodules: "recursive"
+
+      - name: Install Dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y clang nasm make xorriso git curl qemu-system-x86
+
+      - name: Generate Configuration
+        run: make defconfig
+
+      - name: Test Kernel
+        run: make test

.vscode/launch.json

@@ -0,0 +1,36 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Debug",
+      "type": "cppdbg",
+      "request": "launch",
+      "program": "${workspaceFolder}/kernel/bin/kernel",
+      "cwd": "${workspaceFolder}",
+
+      "MIMode": "gdb",
+      "setupCommands": [
+        {
+          "description": "Load Kernel ELF Symbols",
+          "text": "symbol-file ${workspaceFolder}/kernel/bin/kernel",
+          "ignoreFailures": false
+        },
+        {
+          "description": "Use Intel syntax",
+          "text": "set disassembly-flavor intel",
+          "ignoreFailures": false
+        },
+        {
+          "description": "Use hexadecimal values",
+          "text": "set output-radix 16",
+          "ignoreFailures": false
+        },
+        {
+          "description": "Remote QEMU target",
+          "text": "target remote localhost:1234",
+          "ignoreFailures": false
+        }
+      ]
+    }
+  ]
+}

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+  "editor.formatOnSave": true
+}

.vscode/tasks.json

@@ -0,0 +1,15 @@
+{
+  "version": "2.0.0",
+  "tasks": [
+    {
+      "label": "Build Kernel",
+      "type": "shell",
+      "command": "make",
+      "args": ["all"],
+      "group": {
+        "kind": "build",
+        "isDefault": true
+      }
+    }
+  ]
+}

Kconfig

@@ -1 +1,9 @@
 mainmenu "Zeronix Kernel"
+
+menu "Debugging"
+
+config PAGING_DEBUG
+    bool "Enable Paging Debugging"
+    default n
+
+endmenu # Debugging

Makefile

@@ -4,6 +4,7 @@ include tools/utils.mk
 
 $(call USER_VARIABLE, KARCH, x86_64)
 $(call USER_VARIABLE, QEMUFLAGS, -m 128M -M smm=off -serial stdio -d int -D qemu.log -no-reboot -no-shutdown)
+$(call USER_VARIABLE, TEST_QEMUFLAGS, -m 128M -M smm=off -d int -D qemu.log -no-reboot)
 
 override OUTPUT := zeronix.iso
 
@@ -17,7 +18,7 @@ override XORRISO_FLAGS += \
 all: disk
 
 kernel:
-	$(MAKE) -C kernel
+	$(MAKE) -C kernel $(KERNEL_TARGET)
 
 bootloader:
 	$(MAKE) -C limine
@@ -45,6 +46,32 @@ run: ovmf disk
 		-cdrom $(OUTPUT) \
 		$(QEMUFLAGS)
 
+test: KERNEL_TARGET=test
+test: ovmf disk
+	qemu-system-$(KARCH) \
+		-M q35 \
+		-drive if=pflash,unit=0,format=raw,file=ovmf/ovmf-code-$(KARCH).fd,readonly=on \
+		-drive if=pflash,unit=1,format=raw,file=ovmf/ovmf-vars-$(KARCH).fd \
+		-cdrom $(OUTPUT) \
+		-nographic \
+		$(TEST_QEMUFLAGS) \
+		-device isa-debug-exit,iobase=0xf4,iosize=0x04 \
+		|| [ $$? -eq 33 ]
+
+debug: KERNEL_TARGET=debug
+debug: ovmf disk
+	qemu-system-$(KARCH) \
+		-M q35 \
+		-drive if=pflash,unit=0,format=raw,file=ovmf/ovmf-code-$(KARCH).fd,readonly=on \
+		-drive if=pflash,unit=1,format=raw,file=ovmf/ovmf-vars-$(KARCH).fd \
+		-cdrom $(OUTPUT) \
+		$(QEMUFLAGS) \
+		-s -S
+
+defconfig:
+	cp ./kernel/cfgs/$(KARCH)/default_config .config
+	./tools/kconfig.sh
+
 menuconfig:
 	kconfig-mconf Kconfig
 	./tools/kconfig.sh
@@ -59,12 +86,13 @@ clean:
 	rm -rf $(OUTPUT) qemu.log
 
 distclean: clean
-	rm -rf limine/ compile_commands.json ovmf/
+	$(MAKE) -C kernel distclean
+	rm -rf limine/ compile_commands.json ovmf/ .config
 
 ovmf/ovmf-code-$(KARCH).fd:
 	mkdir -p ovmf
 	curl -Lo $@ https://github.com/osdev0/edk2-ovmf-nightly/releases/latest/download/ovmf-code-$(KARCH).fd
 
 ovmf/ovmf-vars-$(KARCH).fd:
 	mkdir -p ovmf
-	curl -Lo $@ https://github.com/osdev0/edk2-ovmf-nightly/releases/latest/download/ovmf-vars-$(KARCH).fd
+	curl -Lo $@ https://github.com/osdev0/edk2-ovmf-nightly/releases/latest/download/ovmf-vars-$(KARCH).fd

README.md

@@ -36,6 +36,12 @@ cd zeronix
 git submodule update --init
 ```
 
+### Generating a Configuration
+
+```sh
+make defconfig
+```
+
 ### Building the ISO
 
 ```sh

kernel/Makefile

@@ -28,9 +28,14 @@ override KCFLAGS += \
 	-mno-sse2 \
 	-fno-omit-frame-pointer \
 	-mno-red-zone \
-	-O3 \
 	-mcmodel=kernel
 
+ifneq ($(filter debug,$(MAKECMDGOALS)),)
+override KCFLAGS += -O0
+else
+override KCFLAGS += -O3
+endif
+
 override KCPPFLAGS += \
 	-I src \
 	-I libs/flanterm/src \
@@ -62,6 +67,11 @@ override HEADER_DEPS := $(addprefix obj/,$(CFILES:.c=.c.d) $(ASFILES:.S=.S.d))
 
 all: bin/$(OUTPUT)
 
+test: override KCPPFLAGS += -DUNIT_TEST_ENABLED
+test: clean bin/$(OUTPUT)
+
+debug: all
+
 bin/$(OUTPUT): linker.lds $(OBJ)
 	mkdir -p "$$(dirname $@)"
 	$(KLD) $(OBJ) $(KLDFLAGS) -o $@
@@ -82,4 +92,7 @@ obj/%.asm.o: src/%.asm
 	nasm $(KNASMFLAGS) $< -o $@
 
 clean:
-	rm -rf bin/ obj/
+	rm -rf bin/ obj/
+
+distclean:
+	rm -rf libs/ src/gen/autoconf.h

kernel/cfgs/x86_64/default_config

@@ -0,0 +1 @@
+# CONFIG_PAGING_DEBUG is not set

kernel/linker.lds

@@ -12,23 +12,30 @@ PHDRS
 SECTIONS
 {
     . = 0xffffffff80000000;
+    __kernel_start = .;
 
     .limine_requests : {
+        __limine_requests_start = .;
         KEEP(*(.limine_requests_start))
         KEEP(*(.limine_requests))
         KEEP(*(.limine_requests_end))
+        __limine_requests_end = .;
     } :limine_requests
 
     . = ALIGN(CONSTANT(MAXPAGESIZE));
 
     .text : {
+        __kernel_text_start = .;
         *(.text .text.*)
+        __kernel_text_end = .;
     } :text
 
     . = ALIGN(CONSTANT(MAXPAGESIZE));
 
     .rodata : {
+        __kernel_rodata_start = .;
         *(.rodata .rodata.*)
+        __kernel_rodata_end = .;
     } :rodata
 
     .note.gnu.build-id : {
@@ -38,16 +45,26 @@ SECTIONS
     . = ALIGN(CONSTANT(MAXPAGESIZE));
 
     .data : {
+        __kernel_data_start = .;
         *(.data .data.*)
+        __kernel_data_end = .;
     } :data
 
     .bss : {
         *(.bss .bss.*)
         *(COMMON)
     } :data
 
+    .testcases : {
+        __start_testcases = .;
+        KEEP(*(.testcases))
+        __end_testcases = .;
+    }
+
     /DISCARD/ : {
         *(.eh_frame*)
         *(.note .note.*)
     }
+
+    __kernel_end = .;
 }

kernel/src/arch/amd64/exceptions/exceptions.h

@@ -1,5 +1,8 @@
 #pragma once
 
+/**
+ * @brief Registers the exception handlers.
+ */
 void amd64_exceptions_init();
 
 void amd64_paging_fault_handler(void *context);

kernel/src/arch/amd64/gdt/gdt.h

@@ -3,4 +3,7 @@
 #define GDT_CODE_SEGMENT 0x8
 #define GDT_DATA_SEGMENT 0x10
 
+/**
+ * @brief Loads the Global Descriptor Table.
+ */
 void amd64_gdt_init();

kernel/src/arch/amd64/idt/idt.h

@@ -3,8 +3,36 @@
 
 #define IDT_MAX_DESCRIPTORS 256
 
+/**
+ * @brief Loads the Interrupt Descriptor Table.
+ *
+ * Sets all vectors to point to their corresponding entry in the ISR stub table and loads the IDT.
+ */
 void amd64_idt_init();
+
+/**
+ * @brief Sets an entry in the IDT.
+ *
+ * @param index The index of the entry.
+ * @param base The base pointer of the function.
+ * @param selector The selector thats used.
+ * @param flags Raw IDT entry flags.
+ *
+ * @note Do not call this directly for registering handlers. Instead use
+ * `amd64_isr_register_handler`.
+ */
 void amd64_idt_set_gate(uint8_t index, void *base, uint16_t selector, uint8_t flags);
 
+/**
+ * @brief Enables an interrupt gate.
+ *
+ * @param interrupt The index of the entry to enable.
+ */
 void amd64_idt_gate_enable(int interrupt);
+
+/**
+ * @brief Disables an interrupt gate.
+ *
+ * @param interrupt The index of the entry to disable.
+ */
 void amd64_idt_gate_disable(int interrupt);

kernel/src/arch/amd64/isr/isr.h

@@ -3,6 +3,9 @@
 
 extern void *amd64_isr_stub_table[];
 
+/**
+ * @brief Interrupt Stack Frame.
+ */
 typedef struct
 {
     // Pushed by `isr_commom`
@@ -35,7 +38,20 @@ typedef struct
 
 } __attribute__((packed)) amd64_interrupt_frame_t;
 
+/**
+ * @brief Interrupt Service Routine Handler Function
+ */
 typedef void (*amd64_isr_handler_fn)(void *ctx);
 
+/**
+ * @brief Enables all IDT gates/entries.
+ */
 void amd64_isr_init();
+
+/**
+ * @brief Registers an ISR Handler
+ *
+ * @param interrupt The IDT/ISR index to register.
+ * @param handler The function that gets registered.
+ */
 void amd64_isr_register_handler(int interrupt, amd64_isr_handler_fn handler);

kernel/src/arch/amd64/paging/paging.asm

@@ -0,0 +1,9 @@
+global get_pml4
+get_pml4:
+	mov rax, cr3
+	ret
+
+global load_pml4
+load_pml4:
+	mov cr3, rdi
+	ret