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-rw-r--r--compiler/Android.bp8
-rw-r--r--compiler/driver/compiler_options.cc6
-rw-r--r--compiler/driver/compiler_options.h5
-rw-r--r--compiler/elf_builder.h62
-rw-r--r--compiler/elf_writer_quick.cc33
-rw-r--r--compiler/elf_writer_test.cc19
6 files changed, 132 insertions, 1 deletions
diff --git a/compiler/Android.bp b/compiler/Android.bp
index 2556178ddf..d9ed0671a3 100644
--- a/compiler/Android.bp
+++ b/compiler/Android.bp
@@ -190,6 +190,14 @@ art_cc_defaults {
],
include_dirs: ["art/disassembler"],
export_include_dirs: ["."],
+
+ // For SHA-1 checksumming of build ID
+ static: {
+ whole_static_libs: ["libcrypto"],
+ },
+ shared: {
+ shared_libs: ["libcrypto"],
+ },
}
gensrcs {
diff --git a/compiler/driver/compiler_options.cc b/compiler/driver/compiler_options.cc
index cbcc169f41..c222f90043 100644
--- a/compiler/driver/compiler_options.cc
+++ b/compiler/driver/compiler_options.cc
@@ -37,6 +37,7 @@ CompilerOptions::CompilerOptions()
debuggable_(false),
generate_debug_info_(kDefaultGenerateDebugInfo),
generate_mini_debug_info_(kDefaultGenerateMiniDebugInfo),
+ generate_build_id_(false),
implicit_null_checks_(true),
implicit_so_checks_(true),
implicit_suspend_checks_(false),
@@ -97,6 +98,7 @@ CompilerOptions::CompilerOptions(CompilerFilter::Filter compiler_filter,
debuggable_(debuggable),
generate_debug_info_(generate_debug_info),
generate_mini_debug_info_(kDefaultGenerateMiniDebugInfo),
+ generate_build_id_(false),
implicit_null_checks_(implicit_null_checks),
implicit_so_checks_(implicit_so_checks),
implicit_suspend_checks_(implicit_suspend_checks),
@@ -196,6 +198,10 @@ bool CompilerOptions::ParseCompilerOption(const StringPiece& option, UsageFn Usa
generate_mini_debug_info_ = true;
} else if (option == "--no-generate-mini-debug-info") {
generate_mini_debug_info_ = false;
+ } else if (option == "--generate-build-id") {
+ generate_build_id_ = true;
+ } else if (option == "--no-generate-build-id") {
+ generate_build_id_ = false;
} else if (option == "--debuggable") {
debuggable_ = true;
} else if (option.starts_with("--top-k-profile-threshold=")) {
diff --git a/compiler/driver/compiler_options.h b/compiler/driver/compiler_options.h
index 8e4a775558..3c920d9601 100644
--- a/compiler/driver/compiler_options.h
+++ b/compiler/driver/compiler_options.h
@@ -187,6 +187,10 @@ class CompilerOptions FINAL {
return generate_mini_debug_info_;
}
+ bool GetGenerateBuildId() const {
+ return generate_build_id_;
+ }
+
bool GetImplicitNullChecks() const {
return implicit_null_checks_;
}
@@ -297,6 +301,7 @@ class CompilerOptions FINAL {
bool debuggable_;
bool generate_debug_info_;
bool generate_mini_debug_info_;
+ bool generate_build_id_;
bool implicit_null_checks_;
bool implicit_so_checks_;
bool implicit_suspend_checks_;
diff --git a/compiler/elf_builder.h b/compiler/elf_builder.h
index 73240bed03..31a75294bc 100644
--- a/compiler/elf_builder.h
+++ b/compiler/elf_builder.h
@@ -36,6 +36,7 @@ namespace art {
// The basic layout of the elf file:
// Elf_Ehdr - The ELF header.
// Elf_Phdr[] - Program headers for the linker.
+// .note.gnu.build-id - Optional build ID section (SHA-1 digest).
// .rodata - DEX files and oat metadata.
// .text - Compiled code.
// .bss - Zero-initialized writeable section.
@@ -75,6 +76,10 @@ template <typename ElfTypes>
class ElfBuilder FINAL {
public:
static constexpr size_t kMaxProgramHeaders = 16;
+ // SHA-1 digest. Not using SHA_DIGEST_LENGTH from openssl/sha.h to avoid
+ // spreading this header dependency for just this single constant.
+ static constexpr size_t kBuildIdLen = 20;
+
using Elf_Addr = typename ElfTypes::Addr;
using Elf_Off = typename ElfTypes::Off;
using Elf_Word = typename ElfTypes::Word;
@@ -458,6 +463,49 @@ class ElfBuilder FINAL {
} abiflags_;
};
+ class BuildIdSection FINAL : public Section {
+ public:
+ BuildIdSection(ElfBuilder<ElfTypes>* owner,
+ const std::string& name,
+ Elf_Word type,
+ Elf_Word flags,
+ const Section* link,
+ Elf_Word info,
+ Elf_Word align,
+ Elf_Word entsize)
+ : Section(owner, name, type, flags, link, info, align, entsize),
+ digest_start_(-1) {
+ }
+
+ void Write() {
+ // The size fields are 32-bit on both 32-bit and 64-bit systems, confirmed
+ // with the 64-bit linker and libbfd code. The size of name and desc must
+ // be a multiple of 4 and it currently is.
+ this->WriteUint32(4); // namesz.
+ this->WriteUint32(kBuildIdLen); // descsz.
+ this->WriteUint32(3); // type = NT_GNU_BUILD_ID.
+ this->WriteFully("GNU", 4); // name.
+ digest_start_ = this->Seek(0, kSeekCurrent);
+ static_assert(kBuildIdLen % 4 == 0, "expecting a mutliple of 4 for build ID length");
+ this->WriteFully(std::string(kBuildIdLen, '\0').c_str(), kBuildIdLen); // desc.
+ }
+
+ off_t GetDigestStart() {
+ CHECK_GT(digest_start_, 0);
+ return digest_start_;
+ }
+
+ private:
+ bool WriteUint32(uint32_t v) {
+ return this->WriteFully(&v, sizeof(v));
+ }
+
+ // File offset where the build ID digest starts.
+ // Populated with zeros first, then updated with the actual value as the
+ // very last thing in the output file creation.
+ off_t digest_start_;
+ };
+
ElfBuilder(InstructionSet isa, const InstructionSetFeatures* features, OutputStream* output)
: isa_(isa),
features_(features),
@@ -479,6 +527,7 @@ class ElfBuilder FINAL {
shstrtab_(this, ".shstrtab", 0, 1),
abiflags_(this, ".MIPS.abiflags", SHT_MIPS_ABIFLAGS, SHF_ALLOC, nullptr, 0, kPageSize, 0,
isa, features),
+ build_id_(this, ".note.gnu.build-id", SHT_NOTE, SHF_ALLOC, nullptr, 0, 4, 0),
started_(false),
write_program_headers_(false),
loaded_size_(0u),
@@ -489,6 +538,7 @@ class ElfBuilder FINAL {
dynamic_.phdr_type_ = PT_DYNAMIC;
eh_frame_hdr_.phdr_type_ = PT_GNU_EH_FRAME;
abiflags_.phdr_type_ = PT_MIPS_ABIFLAGS;
+ build_id_.phdr_type_ = PT_NOTE;
}
~ElfBuilder() {}
@@ -741,6 +791,17 @@ class ElfBuilder FINAL {
abiflags_.End();
}
+ void WriteBuildIdSection() {
+ build_id_.Start();
+ build_id_.Write();
+ build_id_.End();
+ }
+
+ void WriteBuildId(uint8_t build_id[kBuildIdLen]) {
+ stream_.Seek(build_id_.GetDigestStart(), kSeekSet);
+ stream_.WriteFully(build_id, kBuildIdLen);
+ }
+
// Returns true if all writes and seeks on the output stream succeeded.
bool Good() {
return stream_.Good();
@@ -932,6 +993,7 @@ class ElfBuilder FINAL {
Section debug_line_;
StringSection shstrtab_;
AbiflagsSection abiflags_;
+ BuildIdSection build_id_;
std::vector<std::unique_ptr<Section>> other_sections_;
// List of used section in the order in which they were written.
diff --git a/compiler/elf_writer_quick.cc b/compiler/elf_writer_quick.cc
index 36cd2327c4..0d6575cffd 100644
--- a/compiler/elf_writer_quick.cc
+++ b/compiler/elf_writer_quick.cc
@@ -16,6 +16,7 @@
#include "elf_writer_quick.h"
+#include <openssl/sha.h>
#include <unordered_map>
#include <unordered_set>
@@ -126,6 +127,8 @@ class ElfWriterQuick FINAL : public ElfWriter {
std::unique_ptr<DebugInfoTask> debug_info_task_;
std::unique_ptr<ThreadPool> debug_info_thread_pool_;
+ void ComputeFileBuildId(uint8_t (*build_id)[ElfBuilder<ElfTypes>::kBuildIdLen]);
+
DISALLOW_IMPLICIT_CONSTRUCTORS(ElfWriterQuick);
};
@@ -167,6 +170,9 @@ ElfWriterQuick<ElfTypes>::~ElfWriterQuick() {}
template <typename ElfTypes>
void ElfWriterQuick<ElfTypes>::Start() {
builder_->Start();
+ if (compiler_options_->GetGenerateBuildId()) {
+ builder_->WriteBuildIdSection();
+ }
}
template <typename ElfTypes>
@@ -275,11 +281,36 @@ void ElfWriterQuick<ElfTypes>::WritePatchLocations(
template <typename ElfTypes>
bool ElfWriterQuick<ElfTypes>::End() {
builder_->End();
-
+ if (compiler_options_->GetGenerateBuildId()) {
+ uint8_t build_id[ElfBuilder<ElfTypes>::kBuildIdLen];
+ ComputeFileBuildId(&build_id);
+ builder_->WriteBuildId(build_id);
+ }
return builder_->Good();
}
template <typename ElfTypes>
+void ElfWriterQuick<ElfTypes>::ComputeFileBuildId(
+ uint8_t (*build_id)[ElfBuilder<ElfTypes>::kBuildIdLen]) {
+ constexpr int kBufSize = 8192;
+ std::vector<char> buffer(kBufSize);
+ int64_t offset = 0;
+ SHA_CTX ctx;
+ SHA1_Init(&ctx);
+ while (true) {
+ int64_t bytes_read = elf_file_->Read(buffer.data(), kBufSize, offset);
+ CHECK_GE(bytes_read, 0);
+ if (bytes_read == 0) {
+ // End of file.
+ break;
+ }
+ SHA1_Update(&ctx, buffer.data(), bytes_read);
+ offset += bytes_read;
+ }
+ SHA1_Final(*build_id, &ctx);
+}
+
+template <typename ElfTypes>
OutputStream* ElfWriterQuick<ElfTypes>::GetStream() {
return builder_->GetStream();
}
diff --git a/compiler/elf_writer_test.cc b/compiler/elf_writer_test.cc
index d5f16637be..b58004976e 100644
--- a/compiler/elf_writer_test.cc
+++ b/compiler/elf_writer_test.cc
@@ -101,6 +101,25 @@ TEST_F(ElfWriterTest, dlsym) {
}
}
+TEST_F(ElfWriterTest, CheckBuildIdPresent) {
+ std::string elf_location = GetCoreOatLocation();
+ std::string elf_filename = GetSystemImageFilename(elf_location.c_str(), kRuntimeISA);
+ LOG(INFO) << "elf_filename=" << elf_filename;
+
+ std::unique_ptr<File> file(OS::OpenFileForReading(elf_filename.c_str()));
+ ASSERT_TRUE(file.get() != nullptr);
+ {
+ std::string error_msg;
+ std::unique_ptr<ElfFile> ef(ElfFile::Open(file.get(),
+ false,
+ false,
+ /*low_4gb*/false,
+ &error_msg));
+ CHECK(ef.get() != nullptr) << error_msg;
+ EXPECT_TRUE(ef->HasSection(".note.gnu.build-id"));
+ }
+}
+
TEST_F(ElfWriterTest, EncodeDecodeOatPatches) {
const std::vector<std::vector<uintptr_t>> test_data {
{ 0, 4, 8, 15, 128, 200 },
generated by cgit v1.2.3-59-g8ed1b (git 2.39.0) at 2025-10-21 16:15:36 +0000