Grant to allow passing data to scheme handler

arch/x86_64/src/context.rs

@@ -43,6 +43,10 @@ impl Context {
         }
     }
 
+    pub fn get_page_table(&self) -> usize {
+        self.cr3
+    }
+
     pub fn set_page_table(&mut self, address: usize) {
         self.cr3 = address;
     }

arch/x86_64/src/lib.rs

@@ -59,6 +59,9 @@ pub extern crate x86;
     /// Size of user stack
     pub const USER_STACK_SIZE: usize = 1024 * 1024; // 1 MB
 
+    /// Offset to user grants
+    pub const USER_GRANT_OFFSET: usize = USER_STACK_OFFSET + PML4_SIZE;
+
     /// Offset to user temporary image (used when cloning)
     pub const USER_TMP_OFFSET: usize = USER_STACK_OFFSET + PML4_SIZE;
 
@@ -68,6 +71,9 @@ pub extern crate x86;
     /// Offset to user temporary stack (used when cloning)
     pub const USER_TMP_STACK_OFFSET: usize = USER_TMP_HEAP_OFFSET + PML4_SIZE;
 
+    /// Offset to user temporary page for grants
+    pub const USER_TMP_GRANT_OFFSET: usize = USER_TMP_STACK_OFFSET + PML4_SIZE;
+
 
 /// Print to console
 #[macro_export]

arch/x86_64/src/paging/mod.rs

@@ -328,6 +328,10 @@ impl InactivePageTable {
         InactivePageTable { p4_frame: frame }
     }
 
+    pub unsafe fn from_address(cr3: usize) -> InactivePageTable {
+        InactivePageTable { p4_frame: Frame::containing_address(PhysicalAddress::new(cr3)) }
+    }
+
     pub unsafe fn address(&self) -> usize {
         self.p4_frame.start_address().get()
     }

arch/x86_64/src/start.rs

@@ -12,8 +12,8 @@ use externs::memset;
 use gdt;
 use idt;
 use interrupt;
-use memory::{self, Frame};
-use paging::{self, entry, Page, PhysicalAddress, VirtualAddress};
+use memory;
+use paging::{self, entry, Page, VirtualAddress};
 
 /// Test of zero values in BSS.
 static BSS_TEST_ZERO: usize = 0;