Add patchoat tool to Art.
Add a new executable called patchoat to art. This tool takes already
compiled images and oat files and changes their base address, acting as
a cheap form of relocation.
Add a --include-patch-information flag to dex2oat and code to add
required patch information to oat files created with the quick compiler.
Bug: 15358152
Change-Id: Ie0c580db45bb14ec180deb84930def6c3628d97d
diff --git a/compiler/image_writer.cc b/compiler/image_writer.cc
index 6e5f19a..2d25b7a 100644
--- a/compiler/image_writer.cc
+++ b/compiler/image_writer.cc
@@ -27,6 +27,8 @@
#include "compiled_method.h"
#include "dex_file-inl.h"
#include "driver/compiler_driver.h"
+#include "elf_file.h"
+#include "elf_utils.h"
#include "elf_writer.h"
#include "gc/accounting/card_table-inl.h"
#include "gc/accounting/heap_bitmap.h"
@@ -138,7 +140,8 @@
ElfWriter::GetOatElfInformation(oat_file.get(), oat_loaded_size, oat_data_offset);
CalculateNewObjectOffsets(oat_loaded_size, oat_data_offset);
CopyAndFixupObjects();
- PatchOatCodeAndMethods();
+
+ PatchOatCodeAndMethods(oat_file.get());
Thread::Current()->TransitionFromRunnableToSuspended(kNative);
std::unique_ptr<File> image_file(OS::CreateEmptyFile(image_filename.c_str()));
@@ -782,7 +785,25 @@
return klass;
}
-void ImageWriter::PatchOatCodeAndMethods() {
+void ImageWriter::PatchOatCodeAndMethods(File* elf_file) {
+ std::vector<uintptr_t> patches;
+ std::set<uintptr_t> patches_set;
+ auto maybe_push = [&patches, &patches_set] (uintptr_t p) {
+ if (patches_set.find(p) == patches_set.end()) {
+ patches.push_back(p);
+ patches_set.insert(p);
+ }
+ };
+ const bool add_patches = compiler_driver_.GetCompilerOptions().GetIncludePatchInformation();
+ if (add_patches) {
+ // TODO if we are adding patches the resulting ELF file might have a
+ // potentially rather large amount of free space where patches might have been
+ // placed. We should adjust the ELF file to get rid of this excess space.
+ patches.reserve(compiler_driver_.GetCodeToPatch().size() +
+ compiler_driver_.GetMethodsToPatch().size() +
+ compiler_driver_.GetClassesToPatch().size());
+ }
+ uintptr_t loc = 0;
Thread* self = Thread::Current();
ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
const char* old_cause = self->StartAssertNoThreadSuspension("ImageWriter");
@@ -828,14 +849,20 @@
} else {
value = PointerToLowMemUInt32(GetOatAddress(code_offset));
}
- SetPatchLocation(patch, value);
+ SetPatchLocation(patch, value, &loc);
+ if (add_patches && !patch->AsCall()->IsRelative()) {
+ maybe_push(loc);
+ }
}
const CallPatches& methods_to_patch = compiler_driver_.GetMethodsToPatch();
for (size_t i = 0; i < methods_to_patch.size(); i++) {
const CompilerDriver::CallPatchInformation* patch = methods_to_patch[i];
ArtMethod* target = GetTargetMethod(patch);
- SetPatchLocation(patch, PointerToLowMemUInt32(GetImageAddress(target)));
+ SetPatchLocation(patch, PointerToLowMemUInt32(GetImageAddress(target)), &loc);
+ if (add_patches && !patch->AsCall()->IsRelative()) {
+ maybe_push(loc);
+ }
}
const std::vector<const CompilerDriver::TypePatchInformation*>& classes_to_patch =
@@ -843,16 +870,51 @@
for (size_t i = 0; i < classes_to_patch.size(); i++) {
const CompilerDriver::TypePatchInformation* patch = classes_to_patch[i];
Class* target = GetTargetType(patch);
- SetPatchLocation(patch, PointerToLowMemUInt32(GetImageAddress(target)));
+ SetPatchLocation(patch, PointerToLowMemUInt32(GetImageAddress(target)), &loc);
+ if (add_patches) {
+ maybe_push(loc);
+ }
}
// Update the image header with the new checksum after patching
ImageHeader* image_header = reinterpret_cast<ImageHeader*>(image_->Begin());
image_header->SetOatChecksum(oat_file_->GetOatHeader().GetChecksum());
self->EndAssertNoThreadSuspension(old_cause);
+
+ // Update the ElfFiles SHT_OAT_PATCH section to include the patches.
+ if (add_patches) {
+ std::string err;
+ // TODO we are mapping in the contents of this file twice. We should be able
+ // to do it only once, which would be better.
+ std::unique_ptr<ElfFile> file(ElfFile::Open(elf_file, true, false, &err));
+ if (file == nullptr) {
+ LOG(ERROR) << err;
+ }
+ Elf32_Shdr* shdr = file->FindSectionByName(".oat_patches");
+ if (shdr != nullptr) {
+ DCHECK_EQ(shdr, file->FindSectionByType(SHT_OAT_PATCH))
+ << "Incorrect type for .oat_patches section";
+ CHECK_LE(patches.size() * sizeof(uintptr_t), shdr->sh_size)
+ << "We got more patches than anticipated";
+ CHECK_LE(reinterpret_cast<uintptr_t>(file->Begin()) + shdr->sh_offset + shdr->sh_size,
+ reinterpret_cast<uintptr_t>(file->End())) << "section is too large";
+ CHECK(shdr == &file->GetSectionHeader(file->GetSectionHeaderNum() - 1) ||
+ shdr->sh_offset + shdr->sh_size <= (shdr + 1)->sh_offset)
+ << "Section overlaps onto next section";
+ // It's mmap'd so we can just memcpy.
+ memcpy(file->Begin() + shdr->sh_offset, patches.data(), patches.size()*sizeof(uintptr_t));
+ // TODO We should fill in the newly empty space between the last patch and
+ // the start of the next section by moving the following sections down if
+ // possible.
+ shdr->sh_size = patches.size() * sizeof(uintptr_t);
+ } else {
+ LOG(ERROR) << "Unable to find section header for SHT_OAT_PATCH";
+ }
+ }
}
-void ImageWriter::SetPatchLocation(const CompilerDriver::PatchInformation* patch, uint32_t value) {
+void ImageWriter::SetPatchLocation(const CompilerDriver::PatchInformation* patch, uint32_t value,
+ uintptr_t* patched_ptr) {
ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
const void* quick_oat_code = class_linker->GetQuickOatCodeFor(patch->GetDexFile(),
patch->GetReferrerClassDefIdx(),
@@ -885,6 +947,14 @@
}
*patch_location = value;
oat_header.UpdateChecksum(patch_location, sizeof(value));
+
+ uintptr_t loc = reinterpret_cast<uintptr_t>(patch_location) -
+ (reinterpret_cast<uintptr_t>(oat_file_->Begin()) + oat_header.GetExecutableOffset());
+ CHECK_GT(reinterpret_cast<uintptr_t>(patch_location),
+ reinterpret_cast<uintptr_t>(oat_file_->Begin()) + oat_header.GetExecutableOffset());
+ CHECK_LT(loc, oat_file_->Size() - oat_header.GetExecutableOffset());
+
+ *patched_ptr = loc;
}
} // namespace art