Module tlb 

TLB (Translation Lookaside Buffer) shootdown for SMP.

When a page table entry is modified on one CPU, all other CPUs that might have cached that entry in their TLB must be notified to invalidate it.

This implementation uses a per-CPU mailbox system inspired by Asterinas :

1. Each CPU has its own queue of pending TLB operations.
2. The initiator pushes an operation into each target’s queue.
3. The initiator sends a TLB shootdown IPI to all targets.
4. The targets process their own queue and set an ACK flag.
5. The initiator waits for all ACK flags to become true.

This avoids global lock contention and race conditions on global counters.

Structs

TlbOp 🔒

A single TLB operation.

TlbQueue 🔒

Per-CPU queue of pending TLB operations.

Enums

TlbShootdownKind 🔒

Type of TLB shootdown operation.

Constants

TLB_RANGE_THRESHOLD_PAGES

Page-count threshold above which a ranged shootdown falls back to a full CR3 reload (shootdown_all) rather than issuing one invlpg per page.

Statics

TLB_ACKS 🔒

Global array of per-CPU acknowledgement flags.

TLB_QUEUES 🔒

Global array of per-CPU TLB queues.

Functions

collect_tlb_targets 🔒

Collect target APIC IDs into a pre-allocated buffer.

current_cpu_index 🔒

Current CPU index.

dispatch_op 🔒

Internal helper to dispatch an operation to target CPUs.

flush_tlb_all 🔒 ^⚠

Flush all TLB entries by reloading CR3 (local CPU only).

init

Initialize TLB shootdown system.

invlpg 🔒 ^⚠

Invalidate a single TLB entry (local CPU only).

local_page

Invalidate a single page on the current CPU only.

local_range

Invalidate a range on the current CPU only.

send_tlb_ipi 🔒

Send TLB IPI.

shootdown_all

Flush all TLB entries on all CPUs.

shootdown_page

Invalidate a single page on all CPUs.

shootdown_range

Invalidate a range of pages on all CPUs.

tlb_shootdown_ipi_handler

IPI handler for TLB shootdown (called on receiving CPU).

wait_for_acks 🔒

Wait for ACKs from specific APIC IDs.