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- add tools/doc_translator.py - translated docs into English Signed-off-by: longjin <longjin@DragonOS.org>
108 lines
3.0 KiB
ReStructuredText
108 lines
3.0 KiB
ReStructuredText
.. note:: AI Translation Notice
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This document was automatically translated by `Qwen/Qwen3-8B` model, for reference only.
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- Source document: kernel/syscall/syscall_table.rst
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- Translation time: 2025-05-19 01:41:32
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- Translation model: `Qwen/Qwen3-8B`
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Please report issues via `Community Channel <https://github.com/DragonOS-Community/DragonOS/issues>`_
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System Call Table Implementation Plan
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=====================================
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.. note::
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Author: longjin <longjin@dragonos.org>
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Date: 2025/05/13
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Overview
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--------
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.. mermaid::
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:align: center
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:caption: System Call Table Architecture
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classDiagram
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class Syscall {
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<<trait>>
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+num_args() usize
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+handle(args, from_user) Result<usize, SystemError>
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+entry_format(args) Vec<FormattedSyscallParam>
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}
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class SyscallHandle {
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+nr: usize
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+inner_handle: &dyn Syscall
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}
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class SyscallTable {
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-entries: [Option<&SyscallHandle>; 512]
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+get(nr) Option<&dyn Syscall>
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}
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Syscall <|.. SysXXXXXXHandle
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SyscallHandle "1" *-- "1" Syscall
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SyscallTable "1" *-- "512" SyscallHandle
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Compared to the original approach of dispatching system calls in a single large match statement, this approach uses a trait-based and system call table-based implementation. The main advantages include:
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- Reduced stack memory usage: Avoids a single large function consuming excessive stack space
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- Support for parameter printing: Through a unified parameter formatting interface
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- Better extensibility: Adding new system calls does not require modifying the dispatch logic
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Core Design
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-----------
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Syscall Trait
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~~~~~~~~~~~~~
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All system call handler functions must implement the `Syscall` trait:
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.. code-block:: rust
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pub trait Syscall: Send + Sync + 'static {
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fn num_args(&self) -> usize;
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fn handle(&self, args: &[usize], from_user: bool) -> Result<usize, SystemError>;
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fn entry_format(&self, args: &[usize]) -> Vec<FormattedSyscallParam>;
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}
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- `num_args()`: Returns the number of arguments required by the system call
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- `handle()`: Executes the actual system call handling
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- `entry_format()`: Formats the parameters for debugging printing
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SyscallHandle
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~~~~~~~~~~~~~
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The `SyscallHandle` struct associates a system call number with its handler:
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.. code-block:: rust
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pub struct SyscallHandle {
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pub nr: usize, // System call number
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pub inner_handle: &'static dyn Syscall, // Handler function
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pub name: &'static str,
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}
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SyscallTable
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~~~~~~~~~~~~
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The `SyscallTable` manages all system calls:
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- Fixed size of 512 entries
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- Initialized at compile time
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- Allows quick lookup of the handler function by system call number
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Usage
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-----
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Implementing a System Call
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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1. Define the implementation of `Syscall` for the specific system call
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2. Register the system call in the system call table
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3. Load all registered system calls during system initialization
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