maint: sync up other architectures with mmap(file)

kernel/arch/riscv64/src/mem/process.rs

@@ -6,7 +6,7 @@ use core::{
 use libk_mm_interface::{
     address::{AsPhysicalAddress, PhysicalAddress},
     pointer::PhysicalRefMut,
-    process::ProcessAddressSpaceManager,
+    process::{PageAttributeUpdate, ProcessAddressSpaceManager},
     table::{
         EntryLevel, EntryLevelDrop, EntryLevelExt, MapAttributes, NextPageTable, TableAllocator,
     },
@@ -70,7 +70,15 @@ impl<TA: TableAllocator> ProcessAddressSpaceManager<TA> for ProcessAddressSpaceI
         Ok(())
     }
 
-    unsafe fn unmap_page(&mut self, address: usize) -> Result<PhysicalAddress, Error> {
+    unsafe fn update_page_attributes(
+        &mut self,
+        address: usize,
+        update: &PageAttributeUpdate,
+    ) -> Result<(), Error> {
+        self.update_l3_entry(address, |entry| entry.update(update))
+    }
+
+    unsafe fn unmap_page(&mut self, address: usize) -> Result<(PhysicalAddress, bool), Error> {
         self.pop_l3_entry(address)
     }
 
@@ -118,7 +126,11 @@ impl<TA: TableAllocator> ProcessAddressSpaceImpl<TA> {
         Ok(())
     }
 
-    fn pop_l3_entry(&mut self, virt: usize) -> Result<PhysicalAddress, Error> {
+    fn update_l3_entry<F: FnOnce(&mut PageEntry<L3>) -> Result<(), Error>>(
+        &mut self,
+        virt: usize,
+        mapper: F,
+    ) -> Result<(), Error> {
         let l1i = virt.page_index::<L1>();
         let l2i = virt.page_index::<L2>();
         let l3i = virt.page_index::<L3>();
@@ -127,12 +139,33 @@ impl<TA: TableAllocator> ProcessAddressSpaceImpl<TA> {
         let mut l2 = self.l1.get_mut(l1i).ok_or(Error::DoesNotExist)?;
         let mut l3 = l2.get_mut(l2i).ok_or(Error::DoesNotExist)?;
 
-        let page = l3[l3i].as_page().ok_or(Error::DoesNotExist)?;
+        let entry = &mut l3[l3i];
+        if !entry.is_present() {
+            return Err(Error::DoesNotExist);
+        }
+        mapper(entry)?;
+        super::tlb_flush_va_asid(virt, self.asid as usize);
+
+        Ok(())
+    }
+
+    fn pop_l3_entry(&mut self, virt: usize) -> Result<(PhysicalAddress, bool), Error> {
+        let l1i = virt.page_index::<L1>();
+        let l2i = virt.page_index::<L2>();
+        let l3i = virt.page_index::<L3>();
+
+        // TODO somehow drop tables if they're known to be empty?
+        let mut l2 = self.l1.get_mut(l1i).ok_or(Error::DoesNotExist)?;
+        let mut l3 = l2.get_mut(l2i).ok_or(Error::DoesNotExist)?;
+
+        let entry = l3[l3i];
+        let page = entry.as_page().ok_or(Error::DoesNotExist)?;
+        let dirty = entry.is_dirty();
 
         l3[l3i] = PageEntry::INVALID;
         super::tlb_flush_va_asid(virt, self.asid as usize);
 
-        Ok(page)
+        Ok((page, dirty))
     }
 
     fn read_l3_entry(&self, virt: usize) -> Option<(PhysicalAddress, MapAttributes)> {
@@ -178,6 +211,9 @@ fn to_page_attributes(src: MapAttributes) -> PageAttributes {
     if src.intersects(MapAttributes::USER_READ | MapAttributes::USER_WRITE) {
         result |= PageAttributes::U;
     }
+    if src.contains(MapAttributes::DIRTY) {
+        result |= PageAttributes::SW_DIRTY;
+    }
     result
 }
 
@@ -192,5 +228,9 @@ fn to_map_attributes(src: PageAttributes) -> MapAttributes {
         }
     }
 
+    if src.contains(PageAttributes::SW_DIRTY) {
+        result |= MapAttributes::DIRTY;
+    }
+
     result
 }

kernel/arch/riscv64/src/mem/table.rs

@@ -6,6 +6,7 @@ use core::{
 use libk_mm_interface::{
     address::{AsPhysicalAddress, PhysicalAddress},
     pointer::{PhysicalRef, PhysicalRefMut},
+    process::PageAttributeUpdate,
     table::{
         page_index, EntryLevel, EntryLevelDrop, NextPageTable, NonTerminalEntryLevel,
         TableAllocator,
@@ -88,6 +89,8 @@ impl<L: EntryLevel> PageTable<L> {
 }
 
 impl<L: EntryLevel> PageEntry<L> {
+    // Upper + lower 10 bits
+    const ATTR_MASK: u64 = 0xFFC00000000003FF;
     pub const INVALID: Self = Self(0, PhantomData);
 
     /// Constructs a [PageEntry] from its raw representation.
@@ -103,6 +106,23 @@ impl<L: EntryLevel> PageEntry<L> {
         self.0 & PageAttributes::V.bits() != 0
     }
 
+    pub fn update(&mut self, update: &PageAttributeUpdate) -> Result<(), Error> {
+        let mut attrs = self.attributes();
+        if let Some(write) = update.user_write {
+            attrs.set(PageAttributes::W, write);
+        }
+        if let Some(dirty) = update.dirty {
+            attrs.set(PageAttributes::SW_DIRTY, dirty);
+        }
+        self.0 &= !Self::ATTR_MASK;
+        self.0 |= attrs.bits() & Self::ATTR_MASK;
+        Ok(())
+    }
+
+    pub const fn is_dirty(&self) -> bool {
+        self.0 & PageAttributes::SW_DIRTY.bits() != 0
+    }
+
     pub fn attributes(self) -> PageAttributes {
         PageAttributes::from_bits_retain(self.0)
     }
@@ -211,7 +231,7 @@ impl<L: NonTerminalEntryLevel> PageEntry<L> {
             & (PageAttributes::R | PageAttributes::W | PageAttributes::X | PageAttributes::V)
                 .bits()
             == PageAttributes::V.bits())
-        .then_some((self.0 << 2) & !0xFFF)
+        .then_some((self.0 & !Self::ATTR_MASK) << 2)
         .map(PhysicalAddress::from_u64)
     }
 }
@@ -232,7 +252,7 @@ impl PageEntry<L3> {
 
     pub fn as_page(&self) -> Option<PhysicalAddress> {
         (self.0 & PageAttributes::V.bits() != 0)
-            .then_some((self.0 << 2) & !0xFFF)
+            .then_some((self.0 & !Self::ATTR_MASK) << 2)
             .map(PhysicalAddress::from_u64)
     }
 }