feat: implement configure_protection and map_shared with real page mapping, remove dead context_switch from Platform trait

crates/adapter-riscv/src/mmu/mod.rs

@@ -2,4 +2,4 @@ pub mod allocator;
 pub mod page_table;
 
 pub use allocator::init_allocator;
-pub use page_table::{activate, init_kernel_page_table, create_user_page_table, PageTable, PAGE_SIZE};
+pub use page_table::{activate, init_kernel_page_table, create_user_page_table, map_range, PageTable, PAGE_SIZE};

crates/adapter-riscv/src/mmu/page_table.rs

@@ -88,7 +88,7 @@ fn map_page(root: &mut PageTable, va: usize, pa: usize, read: bool, write: bool,
     l0.entries[vpn0] = PageTableEntry::new_leaf(ppn, read, write, exec, user, global);
 }
 
-fn map_range(root: &mut PageTable, va_start: usize, pa_start: usize, pages: usize, read: bool, write: bool, exec: bool, user: bool, global: bool) {
+pub fn map_range(root: &mut PageTable, va_start: usize, pa_start: usize, pages: usize, read: bool, write: bool, exec: bool, user: bool, global: bool) {
     for i in 0..pages {
         let offset = i * PAGE_SIZE;
         map_page(root, va_start + offset, pa_start + offset, read, write, exec, user, global);

crates/adapter-riscv/src/platform.rs

@@ -1,12 +1,11 @@
 use domain::memory::MemoryRegion;
 use domain::process::MAX_PROCESSES;
-use domain::thread::SavedContext;
 use platform::Platform;
 use types::{
     address::{EntryPoint, PhysicalAddress, StackPointer},
     bounded::PageCount,
     id::{CoreId, IrqId, ProcessId},
-    permission::PermissionSet,
+    permission::{Permission, PermissionSet},
     time::{Ticks, TimerDuration},
 };
 
@@ -30,23 +29,28 @@ impl RiscVPlatform {
     pub fn page_table_for(&self, pid: ProcessId) -> usize {
         self.page_tables[pid.raw() as usize]
     }
+
+    fn ensure_page_table(&mut self, pid: ProcessId) -> &mut mmu::PageTable {
+        let idx = pid.raw() as usize;
+        if self.page_tables[idx] == 0 {
+            let kernel_pt = unsafe { &*(self.page_tables[0] as *const mmu::PageTable) };
+            let user_pt = mmu::create_user_page_table(kernel_pt, 0, 0, 0x10000);
+            self.page_tables[idx] = user_pt as *const mmu::PageTable as usize;
+        }
+        unsafe { &mut *(self.page_tables[idx] as *mut mmu::PageTable) }
+    }
 }
 
 impl Platform for RiscVPlatform {
-    fn configure_protection(&mut self, process: ProcessId, _regions: &[MemoryRegion]) {
-        if self.page_tables[process.raw() as usize] == 0 {
-            let kernel_pt_addr = self.page_tables[0];
-            let kernel_pt = unsafe { &*(kernel_pt_addr as *const mmu::PageTable) };
-            let user_pt = mmu::create_user_page_table(kernel_pt, 0, 0, 0x10000);
-            self.page_tables[process.raw() as usize] = user_pt as *const mmu::PageTable as usize;
+    fn configure_protection(&mut self, process: ProcessId, regions: &[MemoryRegion]) {
+        let pt = self.ensure_page_table(process);
+        for region in regions {
+            let base_pa = region.base().raw();
+            let pages = region.size().value() as usize;
+            mmu::map_range(pt, base_pa, base_pa, pages, true, true, true, true, false);
         }
     }
 
-    fn context_switch(&mut self, from: &mut SavedContext, to: &SavedContext) {
-        let _ = from;
-        let _ = to;
-    }
-
     fn enable_user_mode(&mut self, entry: EntryPoint, stack: StackPointer) -> ! {
         let kernel_sp: usize;
         unsafe { core::arch::asm!("mv {0}, sp", out(reg) kernel_sp) };
@@ -97,10 +101,17 @@ impl Platform for RiscVPlatform {
 
     fn map_shared(
         &mut self,
-        _process: ProcessId,
-        _base: PhysicalAddress,
-        _size: PageCount,
-        _permissions: PermissionSet,
+        process: ProcessId,
+        base: PhysicalAddress,
+        size: PageCount,
+        permissions: PermissionSet,
     ) {
+        let pt = self.ensure_page_table(process);
+        let pa = base.raw();
+        let pages = size.value() as usize;
+        let read = permissions.allows(Permission::Read);
+        let write = permissions.allows(Permission::Write);
+        let exec = permissions.allows(Permission::Execute);
+        mmu::map_range(pt, pa, pa, pages, read, write, exec, true, false);
     }
 }

crates/kernel/src/tests/mock_platform.rs

@@ -1,5 +1,4 @@
 use domain::memory::MemoryRegion;
-use domain::thread::SavedContext;
 use platform::Platform;
 use types::{
     address::{EntryPoint, PhysicalAddress, StackPointer},
@@ -31,7 +30,6 @@ impl MockPlatform {
 
 impl Platform for MockPlatform {
     fn configure_protection(&mut self, _process: ProcessId, _regions: &[MemoryRegion]) {}
-    fn context_switch(&mut self, _from: &mut SavedContext, _to: &SavedContext) {}
     fn enable_user_mode(&mut self, _entry: EntryPoint, _stack: StackPointer) -> ! {
         loop {}
     }

crates/platform/src/lib.rs

@@ -1,6 +1,6 @@
 #![no_std]
 
-use domain::{memory::MemoryRegion, thread::SavedContext};
+use domain::memory::MemoryRegion;
 use types::{
     address::{EntryPoint, PhysicalAddress, StackPointer},
     bounded::PageCount,
@@ -9,11 +9,8 @@ use types::{
     time::{Ticks, TimerDuration},
 };
 
-pub trait PlatformContext: Copy + Default {}
-
 pub trait Platform {
     fn configure_protection(&mut self, process: ProcessId, regions: &[MemoryRegion]);
-    fn context_switch(&mut self, from: &mut SavedContext, to: &SavedContext);
     fn enable_user_mode(&mut self, entry: EntryPoint, stack: StackPointer) -> !;
     fn set_timer(&mut self, duration: TimerDuration);
     fn current_ticks(&self) -> Ticks;