Combine checksum of all boot images.

Allows a change to be detected in more than just the first image.
Combines checksums of all boot images using xor. A better hash is left
as TODO.

Bug: 28054110
Change-Id: Ifbdd6cbb0104c95e8926ba4f8a207cc72dbb7f79

diff --git a/dex2oat/dex2oat.cc b/dex2oat/dex2oat.cc
index 0889098..370583e 100644 (file)
--- a/dex2oat/dex2oat.cc
+++ b/dex2oat/dex2oat.cc
@@ -68,6 +68,7 @@
 #include "mirror/class_loader.h"
 #include "mirror/object-inl.h"
 #include "mirror/object_array-inl.h"
+#include "oat_file_assistant.h"
 #include "oat_writer.h"
 #include "os.h"
 #include "runtime.h"
@@ -1325,7 +1326,7 @@ class Dex2Oat FINAL {
         TimingLogger::ScopedTiming t3("Loading image checksum", timings_);
         std::vector<gc::space::ImageSpace*> image_spaces =
             Runtime::Current()->GetHeap()->GetBootImageSpaces();
-        image_file_location_oat_checksum_ = image_spaces[0]->GetImageHeader().GetOatChecksum();
+        image_file_location_oat_checksum_ = OatFileAssistant::CalculateCombinedImageChecksum();
         image_file_location_oat_data_begin_ =
             reinterpret_cast<uintptr_t>(image_spaces[0]->GetImageHeader().GetOatDataBegin());
         image_patch_delta_ = image_spaces[0]->GetImageHeader().GetPatchDelta();

diff --git a/runtime/oat_file_assistant.cc b/runtime/oat_file_assistant.cc
index ce892f3..de30dc8 100644 (file)
--- a/runtime/oat_file_assistant.cc
+++ b/runtime/oat_file_assistant.cc
@@ -495,7 +495,7 @@ bool OatFileAssistant::GivenOatFileIsOutOfDate(const OatFile& file) {
       return true;
     }
 
-    if (file.GetOatHeader().GetImageFileLocationOatChecksum() != image_info->oat_checksum) {
+    if (file.GetOatHeader().GetImageFileLocationOatChecksum() != GetCombinedImageChecksum()) {
       VLOG(oat) << "Oat image checksum does not match image checksum.";
       return true;
     }
@@ -931,8 +931,7 @@ const OatFileAssistant::ImageInfo* OatFileAssistant::GetImageInfo() {
         cached_image_info_.patch_delta = image_header.GetPatchDelta();
       } else {
         std::unique_ptr<ImageHeader> image_header(
-            gc::space::ImageSpace::ReadImageHeaderOrDie(
-                cached_image_info_.location.c_str(), isa_));
+            gc::space::ImageSpace::ReadImageHeaderOrDie(cached_image_info_.location.c_str(), isa_));
         cached_image_info_.oat_checksum = image_header->GetOatChecksum();
         cached_image_info_.oat_data_begin = reinterpret_cast<uintptr_t>(
             image_header->GetOatDataBegin());
@@ -940,10 +939,30 @@ const OatFileAssistant::ImageInfo* OatFileAssistant::GetImageInfo() {
       }
     }
     image_info_load_succeeded_ = (!image_spaces.empty());
+
+    combined_image_checksum_ = CalculateCombinedImageChecksum();
   }
   return image_info_load_succeeded_ ? &cached_image_info_ : nullptr;
 }
 
+// TODO: Use something better than xor.
+uint32_t OatFileAssistant::CalculateCombinedImageChecksum() {
+  uint32_t checksum = 0;
+  std::vector<gc::space::ImageSpace*> image_spaces =
+      Runtime::Current()->GetHeap()->GetBootImageSpaces();
+  for (gc::space::ImageSpace* image_space : image_spaces) {
+    checksum ^= image_space->GetImageHeader().GetOatChecksum();
+  }
+  return checksum;
+}
+
+uint32_t OatFileAssistant::GetCombinedImageChecksum() {
+  if (!image_info_load_attempted_) {
+    GetImageInfo();
+  }
+  return combined_image_checksum_;
+}
+
 gc::space::ImageSpace* OatFileAssistant::OpenImageSpace(const OatFile* oat_file) {
   DCHECK(oat_file != nullptr);
   std::string art_file = ArtFileName(oat_file);

diff --git a/runtime/oat_file_assistant.h b/runtime/oat_file_assistant.h
index 17f72fe..63b1573 100644 (file)
--- a/runtime/oat_file_assistant.h
+++ b/runtime/oat_file_assistant.h
@@ -279,6 +279,8 @@ class OatFileAssistant {
   static bool DexFilenameToOdexFilename(const std::string& location,
       InstructionSet isa, std::string* odex_filename, std::string* error_msg);
 
+  static uint32_t CalculateCombinedImageChecksum();
+
  private:
   struct ImageInfo {
     uint32_t oat_checksum = 0;
@@ -352,6 +354,8 @@ class OatFileAssistant {
   // The caller shouldn't clean up or free the returned pointer.
   const ImageInfo* GetImageInfo();
 
+  uint32_t GetCombinedImageChecksum();
+
   // To implement Lock(), we lock a dummy file where the oat file would go
   // (adding ".flock" to the target file name) and retain the lock for the
   // remaining lifetime of the OatFileAssistant object.
@@ -423,6 +427,7 @@ class OatFileAssistant {
   bool image_info_load_attempted_ = false;
   bool image_info_load_succeeded_ = false;
   ImageInfo cached_image_info_;
+  uint32_t combined_image_checksum_ = 0;
 
   // For debugging only.
   // If this flag is set, the oat or odex file has been released to the user

diff --git a/runtime/oat_file_assistant_test.cc b/runtime/oat_file_assistant_test.cc
index bddfa4f..f50d1cb 100644 (file)
--- a/runtime/oat_file_assistant_test.cc
+++ b/runtime/oat_file_assistant_test.cc
@@ -239,7 +239,8 @@ class OatFileAssistantTest : public CommonRuntimeTest {
       ASSERT_TRUE(!image_spaces.empty() && image_spaces[0] != nullptr);
       const ImageHeader& image_header = image_spaces[0]->GetImageHeader();
       const OatHeader& oat_header = odex_file->GetOatHeader();
-      EXPECT_EQ(image_header.GetOatChecksum(), oat_header.GetImageFileLocationOatChecksum());
+      uint32_t combined_checksum = OatFileAssistant::CalculateCombinedImageChecksum();
+      EXPECT_EQ(combined_checksum, oat_header.GetImageFileLocationOatChecksum());
       EXPECT_NE(reinterpret_cast<uintptr_t>(image_header.GetOatDataBegin()),
           oat_header.GetImageFileLocationOatDataBegin());
       EXPECT_NE(image_header.GetPatchDelta(), oat_header.GetImagePatchDelta());