Revert "Force 4K ELF alignment on art/odex files."

This reverts commit fcb5c3a0cc8776cfedf8d289c5de19b605afe7ae.

Reason for revert: getting ready to reland, as fixes are in place:
- b/376814207#comment91

This is not a clean revert, only due to oat.h version requirement.

Test: TH, is revert
Bug: 376814207
Bug: 378792349

Change-Id: Ieb9672ba07149bfd2c4b20c3afa17eb19f663c6b

8 files changed, 2 insertions, 44 deletions

diff --git a/artd/artd.cc b/artd/artd.cc
index 56a410487e..b72dc114b6 100644
--- a/artd/artd.cc
+++ b/artd/artd.cc
@@ -1629,7 +1629,6 @@ ScopedAStatus Artd::checkPreRebootSystemRequirements(const std::string& in_chroo
 Result<void> Artd::Start() {
   OR_RETURN(SetLogVerbosity());
   MemMap::Init();
-  Runtime::AllowPageSizeAccess();
 
   ScopedAStatus status = ScopedAStatus::fromStatus(AServiceManager_registerLazyService(
       this->asBinder().get(), options_.is_pre_reboot ? kPreRebootServiceName : kServiceName));
diff --git a/libartbase/base/globals.h b/libartbase/base/globals.h
index 7348444e1c..cab7fab63d 100644
--- a/libartbase/base/globals.h
+++ b/libartbase/base/globals.h
@@ -53,9 +53,7 @@ static constexpr size_t kMaxPageSize = kMinPageSize;
 // to be able to generate OAT (ELF) and other image files with alignment other than the host page
 // size. kElfSegmentAlignment needs to be equal to the largest page size supported. Effectively,
 // this is the value to be used in images files for aligning contents to page size.
-// However, it's temporarily set to 4096 now, to prevent dex2oat from creating sparse files.
-// TODO(b/378794327): Fix this.
-static constexpr size_t kElfSegmentAlignment = kMinPageSize;
+static constexpr size_t kElfSegmentAlignment = kMaxPageSize;
 
 // Clion, clang analyzer, etc can falsely believe that "if (kIsDebugBuild)" always
 // returns the same value. By wrapping into a call to another constexpr function, we force it
diff --git a/runtime/gc/space/image_space.cc b/runtime/gc/space/image_space.cc
index 18f4c4205a..d28a534440 100644
--- a/runtime/gc/space/image_space.cc
+++ b/runtime/gc/space/image_space.cc
@@ -65,7 +65,6 @@
 #include "oat/oat_file.h"
 #include "profile/profile_compilation_info.h"
 #include "runtime.h"
-#include "runtime_globals.h"
 #include "space-inl.h"
 
 namespace art HIDDEN {
@@ -565,11 +564,6 @@ class ImageSpace::Loader {
         REQUIRES(!Locks::mutator_lock_) {
     TimingLogger logger(__PRETTY_FUNCTION__, /*precise=*/ true, VLOG_IS_ON(image));
 
-    if (gPageSize != kMinPageSize) {
-      *error_msg = "Loading app image is only supported on devices with 4K page size";
-      return nullptr;
-    }
-
     std::unique_ptr<ImageSpace> space = Init(image_filename,
                                              image_location,
                                              &logger,
@@ -3249,11 +3243,6 @@ bool ImageSpace::BootImageLoader::LoadFromSystem(
     /*out*/std::string* error_msg) {
   TimingLogger logger(__PRETTY_FUNCTION__, /*precise=*/ true, VLOG_IS_ON(image));
 
-  if (gPageSize != kMinPageSize) {
-    *error_msg = "Loading boot image is only supported on devices with 4K page size";
-    return false;
-  }
-
   BootImageLayout layout(image_locations_,
                          boot_class_path_,
                          boot_class_path_locations_,
diff --git a/runtime/oat/oat.h b/runtime/oat/oat.h
index 2a8607844b..bfda96ec8e 100644
--- a/runtime/oat/oat.h
+++ b/runtime/oat/oat.h
@@ -44,7 +44,7 @@ std::ostream& operator<<(std::ostream& stream, StubType stub_type);
 class EXPORT PACKED(4) OatHeader {
  public:
   static constexpr std::array<uint8_t, 4> kOatMagic { { 'o', 'a', 't', '\n' } };
-  // Last oat version changed reason: move dynamic sections to start of OAT file.
+  // Last oat version changed reason: Restore to 16 KB ELF alignment.
   static constexpr std::array<uint8_t, 4> kOatVersion{{'2', '5', '6', '\0'}};
 
   static constexpr const char* kDex2OatCmdLineKey = "dex2oat-cmdline";
diff --git a/runtime/oat/oat_file_assistant.cc b/runtime/oat/oat_file_assistant.cc
index 7ee65db1a5..151c3a6ca9 100644
--- a/runtime/oat/oat_file_assistant.cc
+++ b/runtime/oat/oat_file_assistant.cc
@@ -51,7 +51,6 @@
 #include "oat.h"
 #include "oat_file_assistant_context.h"
 #include "runtime.h"
-#include "runtime_globals.h"
 #include "scoped_thread_state_change-inl.h"
 #include "vdex_file.h"
 #include "zlib.h"
@@ -1107,12 +1106,6 @@ const OatFile* OatFileAssistant::OatFileInfo::GetFile() {
       executable = LocationIsTrusted(filename_, /*trust_art_apex_data_files=*/true);
     }
     VLOG(oat) << "Loading " << filename_ << " with executable: " << executable;
-
-    if (gPageSize != kMinPageSize) {
-      LOG(WARNING) << "Loading odex files is only supported on devices with 4K page size";
-      return nullptr;
-    }
-
     if (use_fd_) {
       if (oat_fd_ >= 0 && vdex_fd_ >= 0) {
         ArrayRef<const std::string> dex_locations(&oat_file_assistant_->dex_location_,
@@ -1151,13 +1144,6 @@ bool OatFileAssistant::OatFileInfo::ShouldRecompileForFilter(CompilerFilter::Fil
   const OatFile* file = GetFile();
   DCHECK(file != nullptr);
 
-  if (CompilerFilter::IsBetter(target, CompilerFilter::kVerify) && gPageSize != kMinPageSize) {
-    // Prevent infinite recompilations during background dexopt on 16K page devices.
-    VLOG(oat) << "Adjusting target filter to 'verify' because loading odex files is only supported "
-                 "on devices with 4K page size";
-    target = CompilerFilter::kVerify;
-  }
-
   CompilerFilter::Filter current = file->GetCompilerFilter();
   if (dexopt_trigger.targetFilterIsBetter && CompilerFilter::IsBetter(target, current)) {
     VLOG(oat) << ART_FORMAT("Should recompile: targetFilterIsBetter (current: {}, target: {})",
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index b43fa1ca5c..a16bde3469 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -3508,10 +3508,4 @@ void Runtime::DCheckNoTransactionCheckAllowed() {
   }
 }
 
-NO_INLINE void Runtime::AllowPageSizeAccess() {
-#ifdef ART_PAGE_SIZE_AGNOSTIC
-  gPageSize.AllowAccess();
-#endif
-}
-
 }  // namespace art
diff --git a/runtime/runtime.h b/runtime/runtime.h
index 97eac64fa1..e43d1d3432 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -1134,9 +1134,6 @@ class Runtime {
 
   bool AreMetricsInitialized() const { return metrics_reporter_ != nullptr; }
 
-  // For `artd` only.
-  EXPORT static void AllowPageSizeAccess();
-
  private:
   static void InitPlatformSignalHandlers();
 
diff --git a/runtime/runtime_image.cc b/runtime/runtime_image.cc
index 7bfefe5278..1d3007ad3a 100644
--- a/runtime/runtime_image.cc
+++ b/runtime/runtime_image.cc
@@ -1868,11 +1868,6 @@ static bool EnsureDirectoryExists(const std::string& directory, std::string* err
 }
 
 bool RuntimeImage::WriteImageToDisk(std::string* error_msg) {
-  if (gPageSize != kMinPageSize) {
-    *error_msg = "Writing runtime image is only supported on devices with 4K page size";
-    return false;
-  }
-
   gc::Heap* heap = Runtime::Current()->GetHeap();
   if (!heap->HasBootImageSpace()) {
     *error_msg = "Cannot generate an app image without a boot image";