Struct ChunkStateMmapper

pub struct ChunkStateMmapper {
    transition_lock: Mutex<()>,
    storage: TwoLevelStateStorage,
}

A Mmapper implementation based on a logical array of chunk states.

The ChunkStateMmapper::storage field holds the state of each chunk, and the ChunkStateMmapper itself actually makes system calls to manage the memory mapping.

As the name suggests, this implementation of Mmapper operates at the granularity of chunks.

Fields

transition_lock: Mutex<()>

Lock for transitioning map states.

storage: TwoLevelStateStorage

This holds the MapState for each chunk.

Implementations

impl ChunkStateMmapper

pub fn new() -> Self

Trait Implementations

impl Mmapper for ChunkStateMmapper

fn log_granularity(&self) -> u8

The logarithm of granularity of this Mmapper, in bytes. Must be at least LOG_BYTES_IN_PAGE.

fn log_mappable_bytes(&self) -> u8

The logarithm of the address space size this Mmapper can handle.

fn mark_as_mapped(&self, start: Address, bytes: usize)

Mark a number of pages as mapped, without making any request to the operating system. Used to mark pages that the VM has already mapped.

fn quarantine_address_range( &self, start: Address, pages: usize, strategy: MmapStrategy, anno: &MmapAnnotation<'_>, ) -> Result<()>

Quarantine/reserve address range. We mmap from the OS with no reserve and with PROT_NONE, which should be little overhead. This ensures that we can reserve certain address range that we can use if needed. Quarantined memory needs to be mapped before it can be used.

fn ensure_mapped( &self, start: Address, pages: usize, strategy: MmapStrategy, anno: &MmapAnnotation<'_>, ) -> Result<()>

Ensure that a range of pages is mmapped (or equivalent). If the pages are not yet mapped, demand-zero map them. Note that mapping occurs at chunk granularity, not page granularity.

fn is_mapped_address(&self, addr: Address) -> bool

Is the page pointed to by this address mapped? Returns true if the page at the given address is mapped.

fn granularity(&self) -> usize

The granularity of Mmapper. Don’t override this method. Override Mmapper::log_granularity instead.