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115 lines
4.2 KiB
Rust
115 lines
4.2 KiB
Rust
// SPDX-License-Identifier: MIT OR Apache-2.0
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//
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// Copyright (c) 2018-2022 Andre Richter <andre.o.richter@gmail.com>
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//! BSP Memory Management Unit.
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use super::map as memory_map;
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use crate::memory::mmu::*;
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use core::ops::RangeInclusive;
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//--------------------------------------------------------------------------------------------------
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// Public Definitions
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//--------------------------------------------------------------------------------------------------
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/// The kernel's address space defined by this BSP.
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pub type KernelAddrSpace = AddressSpace<{ memory_map::END_INCLUSIVE + 1 }>;
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const NUM_MEM_RANGES: usize = 2;
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/// The virtual memory layout.
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///
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/// The layout must contain only special ranges, aka anything that is _not_ normal cacheable DRAM.
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/// It is agnostic of the paging granularity that the architecture's MMU will use.
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pub static LAYOUT: KernelVirtualLayout<NUM_MEM_RANGES> = KernelVirtualLayout::new(
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memory_map::END_INCLUSIVE,
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[
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TranslationDescriptor {
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name: "Kernel code and RO data",
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virtual_range: code_range_inclusive,
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physical_range_translation: Translation::Identity,
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attribute_fields: AttributeFields {
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mem_attributes: MemAttributes::CacheableDRAM,
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acc_perms: AccessPermissions::ReadOnly,
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execute_never: false,
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},
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},
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TranslationDescriptor {
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name: "Device MMIO",
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virtual_range: mmio_range_inclusive,
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physical_range_translation: Translation::Identity,
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attribute_fields: AttributeFields {
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mem_attributes: MemAttributes::Device,
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acc_perms: AccessPermissions::ReadWrite,
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execute_never: true,
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},
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},
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],
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);
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//--------------------------------------------------------------------------------------------------
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// Private Code
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//--------------------------------------------------------------------------------------------------
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fn code_range_inclusive() -> RangeInclusive<usize> {
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// Notice the subtraction to turn the exclusive end into an inclusive end.
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#[allow(clippy::range_minus_one)]
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RangeInclusive::new(super::code_start(), super::code_end_exclusive() - 1)
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}
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fn mmio_range_inclusive() -> RangeInclusive<usize> {
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RangeInclusive::new(memory_map::mmio::START, memory_map::mmio::END_INCLUSIVE)
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}
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//--------------------------------------------------------------------------------------------------
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// Public Code
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//--------------------------------------------------------------------------------------------------
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/// Return a reference to the virtual memory layout.
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pub fn virt_mem_layout() -> &'static KernelVirtualLayout<NUM_MEM_RANGES> {
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&LAYOUT
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}
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//--------------------------------------------------------------------------------------------------
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// Testing
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//--------------------------------------------------------------------------------------------------
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#[cfg(test)]
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mod tests {
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use super::*;
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use test_macros::kernel_test;
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/// Check alignment of the kernel's virtual memory layout sections.
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#[kernel_test]
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fn virt_mem_layout_sections_are_64KiB_aligned() {
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const SIXTYFOUR_KIB: usize = 65536;
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for i in LAYOUT.inner().iter() {
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let start: usize = *(i.virtual_range)().start();
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let end: usize = *(i.virtual_range)().end() + 1;
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assert_eq!(start % SIXTYFOUR_KIB, 0);
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assert_eq!(end % SIXTYFOUR_KIB, 0);
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assert!(end >= start);
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}
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}
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/// Ensure the kernel's virtual memory layout is free of overlaps.
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#[kernel_test]
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fn virt_mem_layout_has_no_overlaps() {
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let layout = virt_mem_layout().inner();
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for (i, first) in layout.iter().enumerate() {
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for second in layout.iter().skip(i + 1) {
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let first_range = first.virtual_range;
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let second_range = second.virtual_range;
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assert!(!first_range().contains(second_range().start()));
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assert!(!first_range().contains(second_range().end()));
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assert!(!second_range().contains(first_range().start()));
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assert!(!second_range().contains(first_range().end()));
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}
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}
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}
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}
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