Development

[assembler-0]

Summary by CodeRabbit

• New Features

  • Introduced spinlock primitives for improved concurrency control.
  • Added detailed page fault diagnostics for easier debugging.
  • Kernel now uses a dedicated, mapped virtual stack for improved stability.
  • Global Descriptor Table (GDT) and Task State Segment (TSS) setup enhanced for 64-bit support.
  • Section-wise kernel memory mapping with correct permissions.
  • Added fast memory comparison utility.

• Bug Fixes

  • Improved atomicity in scheduler tick updates to prevent race conditions.
  • Fixed syscall return value handling for more reliable process exits.

• Refactor

  • Updated function signatures for consistency (e.g., initialization functions now return void).
  • Enhanced memory and interrupt handling routines for clarity and maintainability.

• Chores

  • Improved linker script with explicit section alignment and boundary symbols.
  • Updated build configuration to use the correct assembly source files.

• Documentation

  • Added and clarified comments for better code understanding.

[coderabbitai]

Caution

Review failed

The pull request is closed.

Walkthrough

This update introduces significant architectural changes to the kernel, including 64-bit TSS support in the GDT, improved interrupt and syscall handling, a statically allocated kernel stack mapped into higher-half memory, atomic spinlock primitives, and precise kernel section mapping with page-aligned boundaries. Several function signatures are updated for consistency, and new diagnostics for page faults are added.

Changes

File(s)	Change Summary
arch/x86_64/cpu/Cpu.c	Removed conditional EnableSse() call; added comment about SSE being enabled by bootloader.
arch/x86_64/gdt/Gdt.c, arch/x86_64/gdt/Gdt.h, arch/x86_64/gdt/GdtTssFlush.asm	Added 64-bit TSS support: expanded GDT, new TSS struct, SetTssGate, SetTssRsp0, TssFlush function.
arch/x86_64/interrupts/Interrupts.asm	Added ISR_ERRCODE macro, isr_stub_table, explicit error code ISR handlers.
arch/x86_64/interrupts/Interrupts.c, arch/x86_64/interrupts/Interrupts.h	Improved page fault diagnostics, removed itoa, simplified fatal exception handling.
arch/x86_64/syscall/Syscall.c, arch/x86_64/syscall/Syscall.h, arch/x86_64/syscall/SyscallEntry.asm	Changed syscall exit to use KillProcess, updated return types, fixed syscall return value restoration.
drivers/Pic.c, drivers/Pic.h	Changed PicInstall to void, updated PIC masking/unmasking logic.
kernel/atomic/Spinlock.h	Introduced atomic spinlock primitives (SpinLock, SpinUnlock).
kernel/core/Kernel.c, kernel/memory/AsmHelpers.asm, kernel/memory/AsmHelpers.h	Added 16KB kernel stack, mapped to higher-half, updated paging and stack switching logic.
kernel/memory/MemOps.c	Improved SSE2 memset, added FastMemcmp.
kernel/memory/Memory.c	Prepared for spinlock protection of memory bitmap (commented out), improved error handling.
kernel/memory/VMem.c, kernel/memory/VMem.h	Removed inline spinlocks, improved locking discipline, mapped kernel sections individually, removed VMemUnmap.
kernel/process/Process.c	Used atomic increment for scheduler ticks, added periodic log in tracer.
linker.ld	Added 4K alignment and section boundary symbols for all major sections.
meson.build	Switched GDT assembly source to GdtTssFlush.asm.

Sequence Diagram(s)

Kernel Boot: Paging and Stack Initialization

sequenceDiagram
    participant Bootloader
    participant KernelMain
    participant Paging
    participant Stack
    Bootloader->>KernelMain: Jump to KernelMain
    KernelMain->>Paging: Setup page tables, map kernel and stack
    KernelMain->>Stack: Allocate and map 16KB kernel stack
    KernelMain->>Paging: EnablePagingAndJump(pml4_phys, higher_half_entry, new_stack_top)
    Paging->>KernelMain: Switch to higher-half, set new stack pointer

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Syscall Exit Handling

sequenceDiagram
    participant UserProcess
    participant SyscallHandler
    participant KillProcess
    UserProcess->>SyscallHandler: syscall (exit)
    SyscallHandler->>KillProcess: KillProcess(current->pid)
    KillProcess-->>SyscallHandler: (does not return)
    SyscallHandler->>SyscallHandler: hlt (infinite halt)

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GDT and TSS Initialization

sequenceDiagram
    participant KernelMain
    participant GdtInit
    participant SetTssGate
    participant GdtFlush
    participant TssFlush
    KernelMain->>GdtInit: Initialize GDT
    GdtInit->>SetTssGate: Setup TSS descriptor
    GdtInit->>GdtFlush: Load new GDT
    GdtInit->>TssFlush: Load TSS selector

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Possibly related PRs

• Development #31: Introduces and elaborates on KillProcess, which is now used for syscall-based process termination.
• pls kill me #36: Implements AtomicInc, now used for atomic scheduler tick counting.
• Development #39: Refactors fatal exception handling to use KillProcess, paralleling changes in this update.

Poem

In the kernel’s warren, deep and wide,
A stack now mapped, with GDT as guide.
TSS stands tall, interrupts refined,
Atomic locks keep race conditions confined.
Page faults now whisper their tale,
With each aligned section, the system won’t fail.
🐰 Hooray for the code—let’s follow the trail!

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📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 31f20be and 185b9cf.

📒 Files selected for processing (23)

• arch/x86_64/cpu/Cpu.c (1 hunks)
• arch/x86_64/gdt/Gdt.c (1 hunks)
• arch/x86_64/gdt/Gdt.h (2 hunks)
• arch/x86_64/gdt/GdtTssFlush.asm (2 hunks)
• arch/x86_64/interrupts/Interrupts.asm (2 hunks)
• arch/x86_64/interrupts/Interrupts.c (3 hunks)
• arch/x86_64/interrupts/Interrupts.h (0 hunks)
• arch/x86_64/syscall/Syscall.c (3 hunks)
• arch/x86_64/syscall/Syscall.h (1 hunks)
• arch/x86_64/syscall/SyscallEntry.asm (1 hunks)
• drivers/Pic.c (2 hunks)
• drivers/Pic.h (1 hunks)
• kernel/atomic/Spinlock.h (1 hunks)
• kernel/core/Kernel.c (4 hunks)
• kernel/memory/AsmHelpers.asm (1 hunks)
• kernel/memory/AsmHelpers.h (1 hunks)
• kernel/memory/MemOps.c (2 hunks)
• kernel/memory/Memory.c (4 hunks)
• kernel/memory/VMem.c (4 hunks)
• kernel/memory/VMem.h (1 hunks)
• kernel/process/Process.c (2 hunks)
• linker.ld (1 hunks)
• meson.build (1 hunks)

✨ Finishing Touches

• 📝 Generate Docstrings

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