Struct StackBudget 

pub struct StackBudget(/* private fields */);

A native-stack budget a RuntimeContext may be minted with: a u32 proven no larger than STACK_BUDGET_BYTES at construction.

The proof is the point. SHADOW_STACK_SLOTS is sized from STACK_BUDGET_BYTES, on the strength of “a frame spends at least FRAME_BYTES_PER_SLOT per slot it claims, so the slots of every live frame sum to at most budget / FRAME_BYTES_PER_SLOT”. A host that could install a larger budget would make shadow-stack overflow reachable from generated code — silently, because generated code does not check the reservation. It cannot: StackBudget::new is the only constructor and it refuses.

Same shape as SlotCount, and for the same reason: the bound is checked once, where the value is made, and every consumer downstream may assume it.

Implementations

impl StackBudget

pub const DEFAULT: StackBudget

The budget every Runtime starts with: the whole of STACK_BUDGET_BYTES.

pub const fn new(bytes: u32) -> Option<StackBudget>

Some iff bytes is a budget the shadow-stack reservation covers.

const so a caller can prove a literal at compile time.

pub const fn get(self) -> u32

The budget in bytes, which is <= STACK_BUDGET_BYTES by construction.

Trait Implementations

impl Clone for StackBudget

fn clone(&self) -> StackBudget

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for StackBudget

impl Debug for StackBudget

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

Formats the value using the given formatter.

impl Default for StackBudget

fn default() -> Self

Returns the “default value” for a type.

impl Eq for StackBudget

impl PartialEq for StackBudget

fn eq(&self, other: &StackBudget) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for StackBudget