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/// Failure to construct, install, or observe CPU-local state.
#[derive(Clone, Copy, Debug, Eq, PartialEq, thiserror::Error)]
pub enum CpuLocalError {
/// No runtime CPU area has been installed in the architecture register.
#[error("CPU-local area is not installed")]
AreaNotInstalled,
/// A runtime CPU-area address is null or does not meet prefix alignment.
#[error("CPU-local area base {base:#x} is null or misaligned")]
InvalidAreaBase {
/// Rejected runtime address.
base: usize,
},
/// Address arithmetic for the fixed CPU-area prefix overflowed.
#[error("CPU-local prefix address calculation overflowed")]
AddressOverflow,
/// The immutable area header does not describe its actual address.
#[error("CPU-local area header does not match its runtime address")]
AreaIdentityMismatch,
/// The kernel is running at an exception level unsupported by this backend.
#[error("CPU-local registers do not support host exception level {level}")]
UnsupportedHostLevel {
/// Architecture-specific live exception level.
level: usize,
},
/// The selected current-context source does not identify a valid context.
#[error("current-context source does not identify this CPU's execution context")]
CurrentContextMismatch,
}
/// Failure while preparing or completing an execution-context switch.
#[derive(Clone, Copy, Debug, Eq, PartialEq, thiserror::Error)]
pub enum ContextSwitchError {
/// CPU-local state could not be validated.
#[error(transparent)]
CpuLocal(#[from] CpuLocalError),
/// The outgoing header is not the context currently selected on this CPU.
#[error("outgoing context does not match the selected current context")]
CurrentContextMismatch,
/// The switch tail was paired with another previous context.
#[error("previous-context token does not match the supplied context header")]
PreviousContextMismatch,
/// The next context is already running or is in another binding transition.
#[error("next context is already bound to a CPU")]
NextContextAlreadyBound,
/// The incoming switch tail attempted to consume an obsolete binding epoch.
#[error("previous-context binding epoch is stale")]
StalePreviousBinding,
}