llvm-objcopy: Implement --extract-partition and --extract-main-partition.
This implements the functionality described in
https://lld.llvm.org/Partitions.html. It works as follows:
- Reads the section headers using the ELF header at file offset 0;
- If extracting a loadable partition:
- Finds the section containing the required partition ELF header by looking it up in the section table;
- Reads the ELF and program headers from the section.
- If extracting the main partition:
- Reads the ELF and program headers from file offset 0.
- Filters the section table according to which sections are in the program headers that it read:
- If ParentSegment != nullptr or section is not SHF_ALLOC, then it goes in.
- Sections containing partition ELF headers or program headers are excluded as there are no headers for these in ordinary ELF files.
Differential Revision: https://reviews.llvm.org/D62364
llvm-svn: 362818
diff --git a/llvm/tools/llvm-objcopy/CopyConfig.cpp b/llvm/tools/llvm-objcopy/CopyConfig.cpp
index b138544..8500ff4 100644
--- a/llvm/tools/llvm-objcopy/CopyConfig.cpp
+++ b/llvm/tools/llvm-objcopy/CopyConfig.cpp
@@ -519,6 +519,8 @@
Config.SymbolsPrefix = InputArgs.getLastArgValue(OBJCOPY_prefix_symbols);
Config.AllocSectionsPrefix =
InputArgs.getLastArgValue(OBJCOPY_prefix_alloc_sections);
+ if (auto Arg = InputArgs.getLastArg(OBJCOPY_extract_partition))
+ Config.ExtractPartition = Arg->getValue();
for (auto Arg : InputArgs.filtered(OBJCOPY_redefine_symbol)) {
if (!StringRef(Arg->getValue()).contains('='))
@@ -593,6 +595,8 @@
Config.StripNonAlloc = InputArgs.hasArg(OBJCOPY_strip_non_alloc);
Config.StripUnneeded = InputArgs.hasArg(OBJCOPY_strip_unneeded);
Config.ExtractDWO = InputArgs.hasArg(OBJCOPY_extract_dwo);
+ Config.ExtractMainPartition =
+ InputArgs.hasArg(OBJCOPY_extract_main_partition);
Config.LocalizeHidden = InputArgs.hasArg(OBJCOPY_localize_hidden);
Config.Weaken = InputArgs.hasArg(OBJCOPY_weaken);
if (InputArgs.hasArg(OBJCOPY_discard_all, OBJCOPY_discard_locals))
@@ -697,6 +701,11 @@
errc::invalid_argument,
"LLVM was not compiled with LLVM_ENABLE_ZLIB: cannot decompress");
+ if (Config.ExtractPartition && Config.ExtractMainPartition)
+ return createStringError(errc::invalid_argument,
+ "cannot specify --extract-partition together with "
+ "--extract-main-partition");
+
DC.CopyConfigs.push_back(std::move(Config));
return std::move(DC);
}
diff --git a/llvm/tools/llvm-objcopy/CopyConfig.h b/llvm/tools/llvm-objcopy/CopyConfig.h
index 7607d3b..06b3efd 100644
--- a/llvm/tools/llvm-objcopy/CopyConfig.h
+++ b/llvm/tools/llvm-objcopy/CopyConfig.h
@@ -120,6 +120,7 @@
StringRef BuildIdLinkDir;
Optional<StringRef> BuildIdLinkInput;
Optional<StringRef> BuildIdLinkOutput;
+ Optional<StringRef> ExtractPartition;
StringRef SplitDWO;
StringRef SymbolsPrefix;
StringRef AllocSectionsPrefix;
@@ -155,6 +156,7 @@
bool AllowBrokenLinks = false;
bool DeterministicArchives = true;
bool ExtractDWO = false;
+ bool ExtractMainPartition = false;
bool KeepFileSymbols = false;
bool LocalizeHidden = false;
bool OnlyKeepDebug = false;
diff --git a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
index efb8f05..adc7a95 100644
--- a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
+++ b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
@@ -507,6 +507,16 @@
return (Sec.Flags & SHF_ALLOC) == 0;
};
+ if (Config.ExtractPartition || Config.ExtractMainPartition) {
+ RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
+ if (RemovePred(Sec))
+ return true;
+ if (Sec.Type == SHT_LLVM_PART_EHDR || Sec.Type == SHT_LLVM_PART_PHDR)
+ return true;
+ return (Sec.Flags & SHF_ALLOC) != 0 && !Sec.ParentSegment;
+ };
+ }
+
// Explicit copies:
if (!Config.OnlySection.empty()) {
RemovePred = [&Config, RemovePred, &Obj](const SectionBase &Sec) {
@@ -747,7 +757,7 @@
Error executeObjcopyOnBinary(const CopyConfig &Config,
object::ELFObjectFileBase &In, Buffer &Out) {
- ELFReader Reader(&In);
+ ELFReader Reader(&In, Config.ExtractPartition);
std::unique_ptr<Object> Obj = Reader.create();
// Prefer OutputArch (-O<format>) if set, otherwise infer it from the input.
const ElfType OutputElfType =
diff --git a/llvm/tools/llvm-objcopy/ELF/Object.cpp b/llvm/tools/llvm-objcopy/ELF/Object.cpp
index b654305..89f25a4 100644
--- a/llvm/tools/llvm-objcopy/ELF/Object.cpp
+++ b/llvm/tools/llvm-objcopy/ELF/Object.cpp
@@ -1101,21 +1101,36 @@
}
}
-template <class ELFT> void ELFBuilder<ELFT>::readProgramHeaders() {
+template <class ELFT> void ELFBuilder<ELFT>::findEhdrOffset() {
+ if (!ExtractPartition)
+ return;
+
+ for (const SectionBase &Section : Obj.sections()) {
+ if (Section.Type == SHT_LLVM_PART_EHDR &&
+ Section.Name == *ExtractPartition) {
+ EhdrOffset = Section.Offset;
+ return;
+ }
+ }
+ error("could not find partition named '" + *ExtractPartition + "'");
+}
+
+template <class ELFT>
+void ELFBuilder<ELFT>::readProgramHeaders(const ELFFile<ELFT> &HeadersFile) {
uint32_t Index = 0;
- for (const auto &Phdr : unwrapOrError(ElfFile.program_headers())) {
- if (Phdr.p_offset + Phdr.p_filesz > ElfFile.getBufSize())
+ for (const auto &Phdr : unwrapOrError(HeadersFile.program_headers())) {
+ if (Phdr.p_offset + Phdr.p_filesz > HeadersFile.getBufSize())
error("program header with offset 0x" + Twine::utohexstr(Phdr.p_offset) +
" and file size 0x" + Twine::utohexstr(Phdr.p_filesz) +
" goes past the end of the file");
- ArrayRef<uint8_t> Data{ElfFile.base() + Phdr.p_offset,
+ ArrayRef<uint8_t> Data{HeadersFile.base() + Phdr.p_offset,
(size_t)Phdr.p_filesz};
Segment &Seg = Obj.addSegment(Data);
Seg.Type = Phdr.p_type;
Seg.Flags = Phdr.p_flags;
- Seg.OriginalOffset = Phdr.p_offset;
- Seg.Offset = Phdr.p_offset;
+ Seg.OriginalOffset = Phdr.p_offset + EhdrOffset;
+ Seg.Offset = Phdr.p_offset + EhdrOffset;
Seg.VAddr = Phdr.p_vaddr;
Seg.PAddr = Phdr.p_paddr;
Seg.FileSize = Phdr.p_filesz;
@@ -1135,8 +1150,9 @@
auto &ElfHdr = Obj.ElfHdrSegment;
ElfHdr.Index = Index++;
+ ElfHdr.OriginalOffset = ElfHdr.Offset = EhdrOffset;
- const auto &Ehdr = *ElfFile.getHeader();
+ const auto &Ehdr = *HeadersFile.getHeader();
auto &PrHdr = Obj.ProgramHdrSegment;
PrHdr.Type = PT_PHDR;
PrHdr.Flags = 0;
@@ -1144,7 +1160,7 @@
// Whereas this works automatically for ElfHdr, here OriginalOffset is
// always non-zero and to ensure the equation we assign the same value to
// VAddr as well.
- PrHdr.OriginalOffset = PrHdr.Offset = PrHdr.VAddr = Ehdr.e_phoff;
+ PrHdr.OriginalOffset = PrHdr.Offset = PrHdr.VAddr = EhdrOffset + Ehdr.e_phoff;
PrHdr.PAddr = 0;
PrHdr.FileSize = PrHdr.MemSize = Ehdr.e_phentsize * Ehdr.e_phnum;
// The spec requires us to naturally align all the fields.
@@ -1363,7 +1379,9 @@
ArrayRef<uint8_t>(ElfFile.base() + Shdr.sh_offset,
(Shdr.sh_type == SHT_NOBITS) ? 0 : Shdr.sh_size);
}
+}
+template <class ELFT> void ELFBuilder<ELFT>::readSections() {
// If a section index table exists we'll need to initialize it before we
// initialize the symbol table because the symbol table might need to
// reference it.
@@ -1397,23 +1415,8 @@
initGroupSection(GroupSec);
}
}
-}
-template <class ELFT> void ELFBuilder<ELFT>::build() {
- const auto &Ehdr = *ElfFile.getHeader();
-
- Obj.OSABI = Ehdr.e_ident[EI_OSABI];
- Obj.ABIVersion = Ehdr.e_ident[EI_ABIVERSION];
- Obj.Type = Ehdr.e_type;
- Obj.Machine = Ehdr.e_machine;
- Obj.Version = Ehdr.e_version;
- Obj.Entry = Ehdr.e_entry;
- Obj.Flags = Ehdr.e_flags;
-
- readSectionHeaders();
- readProgramHeaders();
-
- uint32_t ShstrIndex = Ehdr.e_shstrndx;
+ uint32_t ShstrIndex = ElfFile.getHeader()->e_shstrndx;
if (ShstrIndex == SHN_XINDEX)
ShstrIndex = unwrapOrError(ElfFile.getSection(0))->sh_link;
@@ -1423,10 +1426,33 @@
Obj.SectionNames =
Obj.sections().template getSectionOfType<StringTableSection>(
ShstrIndex,
- "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) +
- " in elf header is invalid",
- "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) +
- " in elf header is not a string table");
+ "e_shstrndx field value " + Twine(ShstrIndex) + " in elf header " +
+ " is invalid",
+ "e_shstrndx field value " + Twine(ShstrIndex) + " in elf header " +
+ " is not a string table");
+}
+
+template <class ELFT> void ELFBuilder<ELFT>::build() {
+ readSectionHeaders();
+ findEhdrOffset();
+
+ // The ELFFile whose ELF headers and program headers are copied into the
+ // output file. Normally the same as ElfFile, but if we're extracting a
+ // loadable partition it will point to the partition's headers.
+ ELFFile<ELFT> HeadersFile = unwrapOrError(ELFFile<ELFT>::create(toStringRef(
+ {ElfFile.base() + EhdrOffset, ElfFile.getBufSize() - EhdrOffset})));
+
+ auto &Ehdr = *HeadersFile.getHeader();
+ Obj.OSABI = Ehdr.e_ident[EI_OSABI];
+ Obj.ABIVersion = Ehdr.e_ident[EI_ABIVERSION];
+ Obj.Type = Ehdr.e_type;
+ Obj.Machine = Ehdr.e_machine;
+ Obj.Version = Ehdr.e_version;
+ Obj.Entry = Ehdr.e_entry;
+ Obj.Flags = Ehdr.e_flags;
+
+ readSections();
+ readProgramHeaders(HeadersFile);
}
Writer::~Writer() {}
@@ -1440,19 +1466,19 @@
std::unique_ptr<Object> ELFReader::create() const {
auto Obj = llvm::make_unique<Object>();
if (auto *O = dyn_cast<ELFObjectFile<ELF32LE>>(Bin)) {
- ELFBuilder<ELF32LE> Builder(*O, *Obj);
+ ELFBuilder<ELF32LE> Builder(*O, *Obj, ExtractPartition);
Builder.build();
return Obj;
} else if (auto *O = dyn_cast<ELFObjectFile<ELF64LE>>(Bin)) {
- ELFBuilder<ELF64LE> Builder(*O, *Obj);
+ ELFBuilder<ELF64LE> Builder(*O, *Obj, ExtractPartition);
Builder.build();
return Obj;
} else if (auto *O = dyn_cast<ELFObjectFile<ELF32BE>>(Bin)) {
- ELFBuilder<ELF32BE> Builder(*O, *Obj);
+ ELFBuilder<ELF32BE> Builder(*O, *Obj, ExtractPartition);
Builder.build();
return Obj;
} else if (auto *O = dyn_cast<ELFObjectFile<ELF64BE>>(Bin)) {
- ELFBuilder<ELF64BE> Builder(*O, *Obj);
+ ELFBuilder<ELF64BE> Builder(*O, *Obj, ExtractPartition);
Builder.build();
return Obj;
}
@@ -1732,7 +1758,6 @@
Segment &ElfHdr = Obj.ElfHdrSegment;
ElfHdr.Type = PT_PHDR;
ElfHdr.Flags = 0;
- ElfHdr.OriginalOffset = ElfHdr.Offset = 0;
ElfHdr.VAddr = 0;
ElfHdr.PAddr = 0;
ElfHdr.FileSize = ElfHdr.MemSize = sizeof(Elf_Ehdr);
diff --git a/llvm/tools/llvm-objcopy/ELF/Object.h b/llvm/tools/llvm-objcopy/ELF/Object.h
index fabbb7f..af37a2b 100644
--- a/llvm/tools/llvm-objcopy/ELF/Object.h
+++ b/llvm/tools/llvm-objcopy/ELF/Object.h
@@ -889,17 +889,23 @@
const ELFFile<ELFT> &ElfFile;
Object &Obj;
+ uint64_t EhdrOffset = 0;
+ Optional<StringRef> ExtractPartition;
void setParentSegment(Segment &Child);
- void readProgramHeaders();
+ void readProgramHeaders(const ELFFile<ELFT> &HeadersFile);
void initGroupSection(GroupSection *GroupSec);
void initSymbolTable(SymbolTableSection *SymTab);
void readSectionHeaders();
+ void readSections();
+ void findEhdrOffset();
SectionBase &makeSection(const Elf_Shdr &Shdr);
public:
- ELFBuilder(const ELFObjectFile<ELFT> &ElfObj, Object &Obj)
- : ElfFile(*ElfObj.getELFFile()), Obj(Obj) {}
+ ELFBuilder(const ELFObjectFile<ELFT> &ElfObj, Object &Obj,
+ Optional<StringRef> ExtractPartition)
+ : ElfFile(*ElfObj.getELFFile()), Obj(Obj),
+ ExtractPartition(ExtractPartition) {}
void build();
};
@@ -916,10 +922,12 @@
class ELFReader : public Reader {
Binary *Bin;
+ Optional<StringRef> ExtractPartition;
public:
std::unique_ptr<Object> create() const override;
- explicit ELFReader(Binary *B) : Bin(B) {}
+ explicit ELFReader(Binary *B, Optional<StringRef> ExtractPartition)
+ : Bin(B), ExtractPartition(ExtractPartition) {}
};
class Object {
diff --git a/llvm/tools/llvm-objcopy/ObjcopyOpts.td b/llvm/tools/llvm-objcopy/ObjcopyOpts.td
index 33545a5..c97c356 100644
--- a/llvm/tools/llvm-objcopy/ObjcopyOpts.td
+++ b/llvm/tools/llvm-objcopy/ObjcopyOpts.td
@@ -145,6 +145,13 @@
HelpText<
"Remove all sections that are not DWARF .dwo sections from file">;
+defm extract_partition
+ : Eq<"extract-partition", "Extract named partition from input file">,
+ MetaVarName<"name">;
+def extract_main_partition
+ : Flag<["--"], "extract-main-partition">,
+ HelpText<"Extract main partition from the input file">;
+
def localize_hidden
: Flag<["--"], "localize-hidden">,
HelpText<