bzimage: Align start of initrd to page boundary

We use 2MiB pages so align the start of the address for the initrd to
the page boundary to prevent the kernel trying to access memory outside
of the accessible memory (initrd is placed a the top of usable RAM.)

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

Author: rbradford

src/bzimage.rs

@@ -73,7 +73,8 @@ pub fn load_initrd(f: &mut dyn Read) -> Result<(), Error> {
         top_of_usable_ram = max_load_address;
     }
 
-    let initrd_address = top_of_usable_ram - u64::from(f.get_size());
+    // Align address to 2MiB boundary as we use 2 MiB pages
+    let initrd_address = (top_of_usable_ram - u64::from(f.get_size())) & !((2 << 20) - 1);
     let mut initrd_region = crate::mem::MemoryRegion::new(initrd_address, u64::from(f.get_size()));
 
     let mut offset = 0;
@@ -94,7 +95,6 @@ pub fn load_initrd(f: &mut dyn Read) -> Result<(), Error> {
         }
 
         let dst = initrd_region.as_mut_slice(u64::from(offset), 512);
-
         match f.read(dst) {
             Err(crate::fat::Error::EndOfFile) => break,
             Err(_) => return Err(Error::FileError),