Grant to allow passing data to scheme handler

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()))
         }

context/list.rs

+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)
     }
 }

context/memory.rs

 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 {

scheme/root.rs

@@ -4,6 +4,7 @@ use collections::BTreeMap;
 use core::sync::atomic::{AtomicUsize, Ordering};
 use spin::RwLock;
 
+use context;
 use syscall::{Error, Result};
 use scheme::{self, Scheme};
 use scheme::user::{UserInner, UserScheme};
@@ -24,12 +25,18 @@ impl RootScheme {
 
 impl Scheme for RootScheme {
     fn open(&self, path: &[u8], _flags: usize) -> Result<usize> {
+        let context = {
+            let contexts = context::contexts();
+            let context = contexts.current().ok_or(Error::NoProcess)?;
+            Arc::downgrade(&context)
+        };
+
         let inner = {
             let mut schemes = scheme::schemes_mut();
             if schemes.get_name(path).is_some() {
                 return Err(Error::FileExists);
             }
-            let inner = Arc::new(UserInner::new());
+            let inner = Arc::new(UserInner::new(context));
             schemes.insert(path.to_vec().into_boxed_slice(), Arc::new(Box::new(UserScheme::new(Arc::downgrade(&inner))))).expect("failed to insert user scheme");
             inner
         };

scheme/user.rs

@@ -2,9 +2,13 @@ use alloc::arc::Weak;
 use collections::{BTreeMap, VecDeque};
 use core::sync::atomic::{AtomicUsize, Ordering};
 use core::{mem, usize};
-use spin::Mutex;
+use spin::{Mutex, RwLock};
 
-use context;
+use arch;
+use arch::paging::{InactivePageTable, Page, VirtualAddress, entry};
+use arch::paging::temporary_page::TemporaryPage;
+use context::{self, Context};
+use context::memory::Grant;
 use syscall::{convert_to_result, Call, Error, Result};
 
 use super::Scheme;
@@ -21,14 +25,16 @@ pub struct Packet {
 
 pub struct UserInner {
     next_id: AtomicUsize,
+    context: Weak<RwLock<Context>>,
     todo: Mutex<VecDeque<Packet>>,
     done: Mutex<BTreeMap<usize, usize>>
 }
 
 impl UserInner {
-    pub fn new() -> UserInner {
+    pub fn new(context: Weak<RwLock<Context>>) -> UserInner {
         UserInner {
             next_id: AtomicUsize::new(0),
+            context: context,
             todo: Mutex::new(VecDeque::new()),
             done: Mutex::new(BTreeMap::new())
         }
@@ -59,6 +65,87 @@ impl UserInner {
         }
     }
 
+    pub fn capture(&self, buf: &[u8]) -> Result<usize> {
+        self.capture_inner(buf.as_ptr() as usize, buf.len(), false)
+    }
+
+    pub fn capture_mut(&self, buf: &mut [u8]) -> Result<usize> {
+        self.capture_inner(buf.as_mut_ptr() as usize, buf.len(), true)
+    }
+
+    fn capture_inner(&self, address: usize, size: usize, writable: bool) -> Result<usize> {
+        let context_lock = self.context.upgrade().ok_or(Error::NoProcess)?;
+        let context = context_lock.read();
+
+        let mut grants = context.grants.lock();
+
+        let mut new_table = unsafe { InactivePageTable::from_address(context.arch.get_page_table()) };
+        let mut temporary_page = TemporaryPage::new(Page::containing_address(VirtualAddress::new(arch::USER_TMP_GRANT_OFFSET)));
+
+        let from_address = (address/4096) * 4096;
+        let offset = address - from_address;
+        let full_size = ((offset + size + 4095)/4096) * 4096;
+        let mut to_address = arch::USER_GRANT_OFFSET;
+
+        let mut flags = entry::PRESENT | entry::NO_EXECUTE;
+        if writable {
+            flags |= entry::WRITABLE;
+        }
+
+        for i in 0 .. grants.len() {
+            let start = grants[i].start_address().get();
+            if to_address + full_size < start {
+                grants.insert(i, Grant::new(
+                    VirtualAddress::new(from_address),
+                    VirtualAddress::new(to_address),
+                    full_size,
+                    flags,
+                    &mut new_table,
+                    &mut temporary_page
+                ));
+
+                return Ok(to_address + offset);
+            } else {
+                let pages = (grants[i].size() + 4095) / 4096;
+                let end = start + pages * 4096;
+                to_address = end;
+            }
+        }
+
+        grants.push(Grant::new(
+            VirtualAddress::new(from_address),
+            VirtualAddress::new(to_address),
+            full_size,
+            flags,
+            &mut new_table,
+            &mut temporary_page
+        ));
+
+        return Ok(to_address + offset);
+    }
+
+    pub fn release(&self, address: usize) -> Result<()> {
+        let context_lock = self.context.upgrade().ok_or(Error::NoProcess)?;
+        let context = context_lock.read();
+
+        let mut grants = context.grants.lock();
+
+        let mut new_table = unsafe { InactivePageTable::from_address(context.arch.get_page_table()) };
+        let mut temporary_page = TemporaryPage::new(Page::containing_address(VirtualAddress::new(arch::USER_TMP_GRANT_OFFSET)));
+
+        for i in 0 .. grants.len() {
+            let start = grants[i].start_address().get();
+            let end = start + grants[i].size();
+            if address >= start && address < end {
+                grants.remove(i).destroy(&mut new_table, &mut temporary_page);
+
+                return Ok(());
+            }
+        }
+
+        Err(Error::Fault)
+    }
+
     pub fn read(&self, buf: &mut [u8]) -> Result<usize> {
         let packet_size = mem::size_of::<Packet>();
         let len = buf.len()/packet_size;
@@ -115,7 +202,10 @@ impl UserScheme {
 impl Scheme for UserScheme {
     fn open(&self, path: &[u8], flags: usize) -> Result<usize> {
         let inner = self.inner.upgrade().ok_or(Error::NoDevice)?;
-        inner.call(Call::Open, path.as_ptr() as usize, path.len(), flags)
+        let address = inner.capture(path)?;
+        let result = inner.call(Call::Open, address, path.len(), flags);
+        let _ = inner.release(address);
+        result
     }
 
     fn dup(&self, file: usize) -> Result<usize> {
@@ -125,12 +215,18 @@ impl Scheme for UserScheme {
 
     fn read(&self, file: usize, buf: &mut [u8]) -> Result<usize> {
         let inner = self.inner.upgrade().ok_or(Error::NoDevice)?;
-        inner.call(Call::Read, file, buf.as_mut_ptr() as usize, buf.len())
+        let address = inner.capture_mut(buf)?;
+        let result = inner.call(Call::Read, file, address, buf.len());
+        let _ = inner.release(address);
+        result
     }
 
     fn write(&self, file: usize, buf: &[u8]) -> Result<usize> {
         let inner = self.inner.upgrade().ok_or(Error::NoDevice)?;
-        inner.call(Call::Write, file, buf.as_ptr() as usize, buf.len())
+        let address = inner.capture(buf)?;
+        let result = inner.call(Call::Write, file, buf.as_ptr() as usize, buf.len());
+        let _ = inner.release(address);
+        result
     }
 
     fn fsync(&self, file: usize) -> Result<()> {