handle mmap of large offsets on 32 bit systems

While only 32 bits of address can be mapped, that 32 bits can be offset
by further than 32 bits in to a large file. As chirantan points out, the
try_mmap call was already casting the usize to u64 on all architectures.

Convert the usize offset in mmap to u64 and address users of the API as
well.

Change-Id: I67aed928ea521049fb51eb7aa61ea4de8b4d096c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2124879
Reviewed-by: Dylan Reid <dgreid@chromium.org>
Tested-by: Dylan Reid <dgreid@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Dylan Reid <dgreid@chromium.org>

1 files changed, 5 insertions, 5 deletions

diff --git a/sys_util/src/guest_memory.rs b/sys_util/src/guest_memory.rs
index 2390b92..e8f620b 100644
--- a/sys_util/src/guest_memory.rs
+++ b/sys_util/src/guest_memory.rs
@@ -84,7 +84,7 @@ impl Display for Error {
 struct MemoryRegion {
     mapping: MemoryMapping,
     guest_base: GuestAddress,
-    memfd_offset: usize,
+    memfd_offset: u64,
 }
 
 fn region_end(region: &MemoryRegion) -> GuestAddress {
@@ -175,7 +175,7 @@ impl GuestMemory {
                 memfd_offset: offset,
             });
 
-            offset += size;
+            offset += size as u64;
         }
 
         Ok(GuestMemory {
@@ -262,7 +262,7 @@ impl GuestMemory {
     ///  * memfd_offset: usize
     pub fn with_regions<F, E>(&self, mut cb: F) -> result::Result<(), E>
     where
-        F: FnMut(usize, GuestAddress, usize, usize, usize) -> result::Result<(), E>,
+        F: FnMut(usize, GuestAddress, usize, usize, u64) -> result::Result<(), E>,
     {
         for (index, region) in self.regions.iter().enumerate() {
             cb(
@@ -584,10 +584,10 @@ impl GuestMemory {
     ///                .expect("failed to get offset");
     /// assert_eq!(offset, 0x3500);
     /// ```
-    pub fn offset_from_base(&self, guest_addr: GuestAddress) -> Result<usize> {
+    pub fn offset_from_base(&self, guest_addr: GuestAddress) -> Result<u64> {
         for region in self.regions.iter() {
             if guest_addr >= region.guest_base && guest_addr < region_end(region) {
-                return Ok(region.memfd_offset + guest_addr.offset_from(region.guest_base) as usize);
+                return Ok(region.memfd_offset + guest_addr.offset_from(region.guest_base) as u64);
             }
         }
         Err(Error::InvalidGuestAddress(guest_addr))