Grant to allow passing data to scheme handler

kernel/context/context.rs

@@ -5,7 +5,7 @@ use spin::Mutex;
 
 use arch;
 use super::file::File;
-use super::memory::{Memory, SharedMemory};
+use super::memory::{Grant, Memory, SharedMemory};
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum Status {
@@ -33,6 +33,8 @@ pub struct Context {
     pub heap: Option<SharedMemory>,
     /// User stack
     pub stack: Option<Memory>,
+    /// User grants
+    pub grants: Arc<Mutex<Vec<Grant>>>,
     /// The current working directory
     pub cwd: Arc<Mutex<Vec<u8>>>,
     /// The open files in the scheme
@@ -51,6 +53,7 @@ impl Context {
             image: Vec::new(),
             heap: None,
             stack: None,
+            grants: Arc::new(Mutex::new(Vec::new())),
             cwd: Arc::new(Mutex::new(Vec::new())),
             files: Arc::new(Mutex::new(Vec::new()))
         }

kernel/context/list.rs

@@ -1,3 +1,4 @@
+use alloc::arc::Arc;
 use collections::BTreeMap;
 use core::mem;
 use core::sync::atomic::Ordering;
@@ -9,7 +10,7 @@ use super::context::Context;
 
 /// Context list type
 pub struct ContextList {
-    map: BTreeMap<usize, RwLock<Context>>,
+    map: BTreeMap<usize, Arc<RwLock<Context>>>,
     next_id: usize
 }
 
@@ -23,21 +24,21 @@ impl ContextList {
     }
 
     /// Get the nth context.
-    pub fn get(&self, id: usize) -> Option<&RwLock<Context>> {
+    pub fn get(&self, id: usize) -> Option<&Arc<RwLock<Context>>> {
         self.map.get(&id)
     }
 
     /// Get the current context.
-    pub fn current(&self) -> Option<&RwLock<Context>> {
+    pub fn current(&self) -> Option<&Arc<RwLock<Context>>> {
         self.map.get(&super::CONTEXT_ID.load(Ordering::SeqCst))
     }
 
-    pub fn iter(&self) -> ::collections::btree_map::Iter<usize, RwLock<Context>> {
+    pub fn iter(&self) -> ::collections::btree_map::Iter<usize, Arc<RwLock<Context>>> {
         self.map.iter()
     }
 
     /// Create a new context.
-    pub fn new_context(&mut self) -> Result<&RwLock<Context>> {
+    pub fn new_context(&mut self) -> Result<&Arc<RwLock<Context>>> {
         if self.next_id >= super::CONTEXT_MAX_CONTEXTS {
             self.next_id = 1;
         }
@@ -53,13 +54,13 @@ impl ContextList {
         let id = self.next_id;
         self.next_id += 1;
 
-        assert!(self.map.insert(id, RwLock::new(Context::new(id))).is_none());
+        assert!(self.map.insert(id, Arc::new(RwLock::new(Context::new(id)))).is_none());
 
         Ok(self.map.get(&id).expect("Failed to insert new context. ID is out of bounds."))
     }
 
     /// Spawn a context from a function.
-    pub fn spawn(&mut self, func: extern fn()) -> Result<&RwLock<Context>> {
+    pub fn spawn(&mut self, func: extern fn()) -> Result<&Arc<RwLock<Context>>> {
         let context_lock = self.new_context()?;
         {
             let mut context = context_lock.write();
@@ -77,7 +78,7 @@ impl ContextList {
         Ok(context_lock)
     }
 
-    pub fn remove(&mut self, id: usize) -> Option<RwLock<Context>> {
+    pub fn remove(&mut self, id: usize) -> Option<Arc<RwLock<Context>>> {
         self.map.remove(&id)
     }
 }

kernel/context/memory.rs

@@ -1,4 +1,5 @@
 use alloc::arc::{Arc, Weak};
+use collections::VecDeque;
 use spin::Mutex;
 
 use arch::externs::memset;
@@ -7,12 +8,66 @@ use arch::paging::entry::{self, EntryFlags};
 use arch::paging::temporary_page::TemporaryPage;
 
 #[derive(Debug)]
-pub struct Memory {
+pub struct Grant {
     start: VirtualAddress,
     size: usize,
     flags: EntryFlags
 }
 
+impl Grant {
+    pub fn new(from: VirtualAddress, to: VirtualAddress, size: usize, flags: EntryFlags, new_table: &mut InactivePageTable, temporary_page: &mut TemporaryPage) -> Grant {
+        let mut active_table = unsafe { ActivePageTable::new() };
+
+        let mut frames = VecDeque::new();
+
+        let start_page = Page::containing_address(from);
+        let end_page = Page::containing_address(VirtualAddress::new(from.get() + size - 1));
+        for page in Page::range_inclusive(start_page, end_page) {
+            let frame = active_table.translate_page(page).expect("grant references unmapped memory");
+            frames.push_back(frame);
+        }
+
+        active_table.with(new_table, temporary_page, |mapper| {
+            let start_page = Page::containing_address(to);
+            let end_page = Page::containing_address(VirtualAddress::new(to.get() + size - 1));
+            for page in Page::range_inclusive(start_page, end_page) {
+                let frame = frames.pop_front().expect("grant did not find enough frames");
+                mapper.map_to(page, frame, flags);
+            }
+        });
+
+        Grant {
+            start: to,
+            size: size,
+            flags: flags
+        }
+    }
+
+    pub fn destroy(self, new_table: &mut InactivePageTable, temporary_page: &mut TemporaryPage) {
+        let mut active_table = unsafe { ActivePageTable::new() };
+
+        active_table.with(new_table, temporary_page, |mapper| {
+            let start_page = Page::containing_address(self.start);
+            let end_page = Page::containing_address(VirtualAddress::new(self.start.get() + self.size - 1));
+            for page in Page::range_inclusive(start_page, end_page) {
+                mapper.unmap_return(page);
+            }
+        });
+    }
+
+    pub fn start_address(&self) -> VirtualAddress {
+        self.start
+    }
+
+    pub fn size(&self) -> usize {
+        self.size
+    }
+
+    pub fn flags(&self) -> EntryFlags {
+        self.flags
+    }
+}
+
 #[derive(Clone, Debug)]
 pub enum SharedMemory {
     Owned(Arc<Mutex<Memory>>),
@@ -42,6 +97,13 @@ impl SharedMemory {
     }
 }
 
+#[derive(Debug)]
+pub struct Memory {
+    start: VirtualAddress,
+    size: usize,
+    flags: EntryFlags
+}
+
 impl Memory {
     pub fn new(start: VirtualAddress, size: usize, flags: EntryFlags, flush: bool, clear: bool) -> Self {
         let mut memory = Memory {