Struct Process 

pub struct Process {
    pub file_struct: FileStruct,
    pub mm_struct: MmStruct<EagerPager>,
}

A process state of project 2, which contains file struct and mm struct.

Fields

file_struct: FileStruct

mm_struct: MmStruct<EagerPager>

Implementations

impl Process

pub fn from_mm_struct(mm_struct: MmStruct<EagerPager>) -> Self

Create a process with given MmStruct.

pub fn exit(&self, abi: &SyscallAbi<'_>) -> Result<usize, KernelError>

Exit a process.

This function terminates the calling thread by invoking exit on the current thread. The exit code is provided as the first argument (arg1) of the system call.

Syscall API

int exit(int status);

• status: The thread’s exit code.

Parameters

• abi: A reference to SyscallAbi, which holds the arguments passed to the system call.

Returns

• Never returns.

Behavior

Example

syscall!(SyscallNumber::Exit as usize, 0); // Exit with code 0

Notes

• This function does not return in normal execution, as it terminates the thread.
• If an error occurs, it returns a KernelError

Trait Implementations

impl Default for Process

fn default() -> Self

Returns the “default value” for a type.

impl Task for Process

fn syscall(&mut self, regs: &mut Registers)

Handles a system call request from a user program.

This function is the entry point for system call handling. It retrieves the system call ABI from the provided Registers structure, which includes the system call number and its arguments. Based on the system call number (sysno), it looks up the appropriate handler function in a predefined list. If a handler is found, it is invoked with the ABI, otherwise, an error (KernelError::NoSuchSyscall) is returned.

After the handler function processes the system call, the return value (either a success or error) is set back into the CPU registers via the set_return_value method. The return value is stored in the %rax register as per the x86-64 system call convention.

Parameters

• regs: A mutable reference to the Registers struct, which contains the current state of the CPU registers. This structure will be used to retrieve the system call number and its arguments, and also to set the return value.

Functionality

The function processes the system call as follows:

1. Extracts the system call number and arguments using the SyscallAbi::from_registers.
2. Looks up the corresponding handler function from a predefined list of system calls. The handler function is selected based on the system call number (sysno).
3. If a handler is found, it is executed with the ABI as an argument. If no handler is found, the function returns a KernelError::NoSuchSyscall error.

The result of the system call handler (either success or error) is then returned via the SyscallAbi::set_return_value method, which modifies the CPU registers accordingly.

fn access_ok(&self, addr: Range<Va>, is_write: bool) -> bool

Validates whether the given memory range is accessible for the process.

This function checks if a memory region is safe to read or write before performing a memory-related operation. It ensures that user-provided addresses do not access restricted memory regions, preventing potential security vulnerabilities or crashes.

Parameters

• addr: A range of virtual addresses to be accessed.
• is_write: true if the access involves writing to memory, false for read-only access.

Returns

• true if the memory range is valid and accessible.
• false if access is denied due to invalid address range or insufficient permissions.

fn with_page_table_pa(&self, f: &fn(Pa))

Run a closure with physical address of the page table.

fn page_fault(&mut self, ec: PFErrorCode, cr2: Va)

Handles a page fault that occurs when accessing an unmapped memory page.