Struct TaskContext 

pub struct TaskContext { /* private fields */ }

Saved hardware states of a task.

The context usually includes:

• Callee-saved registers
• Stack pointer register
• Thread pointer register (for kernel-space thread-local storage)
• FP/SIMD registers

On context switch, current task saves its context from CPU to memory, and the next task restores its context from memory to CPU.

On x86_64, callee-saved registers are saved to the kernel stack by the PUSH instruction. So that rsp is the RSP after callee-saved registers are pushed, and kstack_top is the top of the kernel stack (RSP before any push).

Implementations

impl TaskContext

pub fn new() -> Self

Creates a dummy context for a new task.

Note the context is not initialized, it will be filled by switch_to_prepared (for initial tasks) and init (for regular tasks) methods.

pub fn init( &mut self, entry: usize, kstack_top: VirtAddr, kernel_tls: KernelTlsBase, )

Initializes the context for a new task, with the given entry point and kernel stack.

pub fn set_context_header(&mut self, header: NonNull<ExecutionContextHeader>)

Sets the pinned task-owned execution-context header restored by the raw switch tail in LinuxCurrent images.

pub const fn context_header(&self) -> Option<NonNull<ExecutionContextHeader>>

Returns the configured task-owned execution-context header.

pub fn prepare_switch_to(&mut self, _next_ctx: &Self)

Completes every helper operation that must precede current publication.

pub fn prepare_user_return_fp(&self)

Restores this task’s userspace FPU image at the final IRQ-off return boundary.

pub fn clone_user_fp_state_into(&self, child: &mut Self)

Available on crate features fp-simd and uspace only.

Saves the current task’s user FPU image directly into an unpublished clone.

pub fn capture_user_fp_state(&self) -> UserXstate

Available on crate features fp-simd and uspace only.

Captures the current task’s complete hardware user xstate.

pub fn replace_user_fp_state(&mut self, state: UserXstate)

Available on crate features fp-simd and uspace only.

Installs a complete user xstate into the current task and hardware owner.

pub fn reset_user_fp_state(&mut self)

Replaces this task’s user FPU state with the architecture initial image.

pub unsafe fn switch_to_prepared( &mut self, next_ctx: &Self, prepared: PreparedContextSwitch<'_>, )

Commits current-context publication and performs the raw transfer.

Safety

The caller must have serialized scheduling, prepared FP/SIMD state, and prepared must belong to next_ctx. No fallible Rust work may be placed between its commit and the naked switch tail.

Trait Implementations

impl Debug for TaskContext

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.