Struct aarch64_paging::Mapping

pub struct Mapping<T: Translation + Clone> { /* private fields */ }

Manages a level 1 page table and associated state.

Mappings should be added with map_range before calling activate to start using the new page table. To make changes which may require break-before-make semantics you must first call deactivate to switch back to a previous static page table, and then activate again after making the desired changes.

Implementations

impl<T: Translation + Clone> Mapping<T>

pub fn new( translation: T, asid: usize, rootlevel: usize, va_range: VaRange ) -> Self

Creates a new page table with the given ASID, root level and translation mapping.

pub fn active(&self) -> bool

Returns whether this mapping is currently active.

pub unsafe fn activate(&mut self)

Activates the page table by setting TTBRn_EL1 to point to it, and saves the previous value of TTBRn_EL1 so that it may later be restored by deactivate.

Panics if a previous value of TTBRn_EL1 is already saved and not yet used by a call to deactivate.

In test builds or builds that do not target aarch64, the TTBRn_EL1 access is omitted.

Safety

The caller must ensure that the page table doesn’t unmap any memory which the program is using, or introduce aliases which break Rust’s aliasing rules. The page table must not be dropped as long as its mappings are required, as it will automatically be deactivated when it is dropped.

pub unsafe fn deactivate(&mut self)

Deactivates the page table, by setting TTBRn_EL1 back to the value it had before activate was called, and invalidating the TLB for this page table’s configured ASID.

Panics if there is no saved TTBRn_EL1 value because activate has not previously been called.

In test builds or builds that do not target aarch64, the TTBRn_EL1 access is omitted.

Safety

The caller must ensure that the previous page table which this is switching back to doesn’t unmap any memory which the program is using.

pub fn map_range( &mut self, range: &MemoryRegion, pa: PhysicalAddress, flags: Attributes, constraints: Constraints ) -> Result<(), MapError>

Maps the given range of virtual addresses to the corresponding range of physical addresses starting at pa, with the given flags, taking the given constraints into account.

This should generally only be called while the page table is not active. In particular, any change that may require break-before-make per the architecture must be made while the page table is inactive. Mapping a previously unmapped memory range may be done while the page table is active. This function writes block and page entries, but only maps them if flags contains Attributes::VALID, otherwise the entries remain invalid.

Errors

Returns MapError::RegionBackwards if the range is backwards.

Returns MapError::AddressRange if the largest address in the range is greater than the largest virtual address covered by the page table given its root level.

Returns MapError::InvalidFlags if the flags argument has unsupported attributes set.

Returns [`MapError::BreakBeforeMakeViolation’] if the range intersects with live mappings, and modifying those would violate architectural break-before-make (BBM) requirements.

pub fn modify_range<F>( &mut self, range: &MemoryRegion, f: &F ) -> Result<(), MapError>where F: Fn(&MemoryRegion, &mut Descriptor, usize) -> Result<(), ()> + ?Sized,

Applies the provided updater function to a number of PTEs corresponding to a given memory range.

This may involve splitting block entries if the provided range is not currently mapped down to its precise boundaries. For visiting all the descriptors covering a memory range without potential splitting (and no descriptor updates), use walk_range instead.

This should generally only be called while the page table is not active. In particular, any change that may require break-before-make per the architecture must be made while the page table is inactive. Mapping a previously unmapped memory range may be done while the page table is active.

Errors

Returns MapError::PteUpdateFault if the updater function returns an error.

Returns MapError::RegionBackwards if the range is backwards.

Returns MapError::AddressRange if the largest address in the range is greater than the largest virtual address covered by the page table given its root level.

Returns [`MapError::BreakBeforeMakeViolation’] if the range intersects with live mappings, and modifying those would violate architectural break-before-make (BBM) requirements.

pub fn walk_range<F>( &self, range: &MemoryRegion, f: &mut F ) -> Result<(), MapError>where F: FnMut(&MemoryRegion, &Descriptor, usize) -> Result<(), ()>,

Applies the provided function to a number of PTEs corresponding to a given memory range.

The virtual address range passed to the callback function may be expanded compared to the range parameter, due to alignment to block boundaries.

Errors

Returns MapError::PteUpdateFault if the callback function returns an error.

Returns MapError::RegionBackwards if the range is backwards.

Returns MapError::AddressRange if the largest address in the range is greater than the largest virtual address covered by the page table given its root level.

Trait Implementations

impl<T: Debug + Translation + Clone> Debug for Mapping<T>

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

Formats the value using the given formatter.

impl<T: Translation + Clone> Drop for Mapping<T>

fn drop(&mut self)

Executes the destructor for this type.