[llvm-objcopy] [COFF] Add support for removing symbols
Differential Revision: https://reviews.llvm.org/D55881
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350893 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/tools/llvm-objcopy/COFF/Inputs/strip-symbols.yaml b/test/tools/llvm-objcopy/COFF/Inputs/strip-symbols.yaml
new file mode 100644
index 0000000..1d652691
--- /dev/null
+++ b/test/tools/llvm-objcopy/COFF/Inputs/strip-symbols.yaml
@@ -0,0 +1,53 @@
+--- !COFF
+header:
+ Machine: IMAGE_FILE_MACHINE_AMD64
+ Characteristics: [ ]
+sections:
+ - Name: .text
+ Characteristics: [ ]
+ Alignment: 4
+ SectionData: 488B0500000000488B0500000000488B0500000000
+ Relocations:
+ - VirtualAddress: 3
+ SymbolTableIndex: 0
+ Type: IMAGE_REL_AMD64_REL32
+ - VirtualAddress: 10
+ SymbolTableIndex: 1
+ Type: IMAGE_REL_AMD64_REL32
+ - VirtualAddress: 17
+ SymbolName: foo
+ Type: IMAGE_REL_AMD64_REL32
+ - Name: .rdata
+ Characteristics: [ ]
+ Alignment: 1
+ SectionData: '00'
+ - Name: .rdata
+ Characteristics: [ ]
+ Alignment: 1
+ SectionData: '01'
+symbols:
+ - Name: .rdata
+ Value: 0
+ SectionNumber: 2
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_STATIC
+ - Name: .rdata
+ Value: 0
+ SectionNumber: 3
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_STATIC
+ - Name: mainfunc
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_EXTERNAL
+ - Name: foo
+ Value: 0
+ SectionNumber: 3
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_EXTERNAL
+...
diff --git a/test/tools/llvm-objcopy/COFF/strip-reloc-symbol.test b/test/tools/llvm-objcopy/COFF/strip-reloc-symbol.test
new file mode 100644
index 0000000..50740d9
--- /dev/null
+++ b/test/tools/llvm-objcopy/COFF/strip-reloc-symbol.test
@@ -0,0 +1,5 @@
+# RUN: yaml2obj %p/Inputs/strip-symbols.yaml > %t.o
+# RUN: not llvm-objcopy -N foo %t.o 2>&1 | FileCheck %s --check-prefix=ERROR
+# RUN: not llvm-objcopy --strip-symbol foo %t.o 2>&1 | FileCheck %s --check-prefix=ERROR
+
+# ERROR: error: '{{.*}}/strip-reloc-symbol.test.tmp.o': not stripping symbol 'foo' because it is named in a relocation.
diff --git a/test/tools/llvm-objcopy/COFF/strip-symbol.test b/test/tools/llvm-objcopy/COFF/strip-symbol.test
new file mode 100644
index 0000000..5355b22
--- /dev/null
+++ b/test/tools/llvm-objcopy/COFF/strip-symbol.test
@@ -0,0 +1,32 @@
+# RUN: yaml2obj %p/Inputs/strip-symbols.yaml > %t.in.o
+
+# RUN: llvm-readobj -relocations %t.in.o | FileCheck %s --check-prefixes=RELOCS,RELOCS-PRE
+# RUN: llvm-objdump -t %t.in.o | FileCheck %s --check-prefixes=SYMBOLS,SYMBOLS-PRE
+
+# RUN: llvm-objcopy -N mainfunc %t.in.o %t.out.o
+# RUN: llvm-readobj -relocations %t.out.o | FileCheck %s --check-prefixes=RELOCS,RELOCS-POST
+# RUN: llvm-objdump -t %t.out.o | FileCheck %s --check-prefix=SYMBOLS
+
+# RUN: llvm-objcopy --strip-symbol mainfunc %t.in.o %t.out.o
+# RUN: llvm-readobj -relocations %t.out.o | FileCheck %s --check-prefixes=RELOCS,RELOCS-POST
+# RUN: llvm-objdump -t %t.out.o | FileCheck %s --check-prefix=SYMBOLS
+
+# Explicitly listing the relocations for the input as well, to show
+# that the symbol index of the symbol foo is updated in the relocations,
+# while keeping relocations to two distinct .rdata symbols separate.
+
+# RELOCS: Relocations [
+# RELOCS-NEXT: Section (1) .text {
+# RELOCS-NEXT: 0x3 IMAGE_REL_AMD64_REL32 .rdata (0)
+# RELOCS-NEXT: 0xA IMAGE_REL_AMD64_REL32 .rdata (1)
+# RELOCS-PRE-NEXT: 0x11 IMAGE_REL_AMD64_REL32 foo (3)
+# RELOCS-POST-NEXT: 0x11 IMAGE_REL_AMD64_REL32 foo (2)
+# RELOCS-NEXT: }
+# RELOCS-NEXT: ]
+
+# SYMBOLS: SYMBOL TABLE:
+# SYMBOLS-NEXT: .rdata
+# SYMBOLS-NEXT: .rdata
+# SYMBOLS-PRE-NEXT: mainfunc
+# SYMBOLS-NEXT: foo
+# SYMBOLS-EMPTY:
diff --git a/tools/llvm-objcopy/CMakeLists.txt b/tools/llvm-objcopy/CMakeLists.txt
index 3b6c345..1beb737 100644
--- a/tools/llvm-objcopy/CMakeLists.txt
+++ b/tools/llvm-objcopy/CMakeLists.txt
@@ -18,6 +18,7 @@
CopyConfig.cpp
llvm-objcopy.cpp
COFF/COFFObjcopy.cpp
+ COFF/Object.cpp
COFF/Reader.cpp
COFF/Writer.cpp
ELF/ELFObjcopy.cpp
diff --git a/tools/llvm-objcopy/COFF/COFFObjcopy.cpp b/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
index 9ed965c..9087cf6 100644
--- a/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
+++ b/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
@@ -17,6 +17,7 @@
#include "llvm/Object/Binary.h"
#include "llvm/Object/COFF.h"
+#include "llvm/Support/Errc.h"
#include <cassert>
namespace llvm {
@@ -26,6 +27,30 @@
using namespace object;
using namespace COFF;
+static Error handleArgs(const CopyConfig &Config, Object &Obj) {
+ // If we need to do per-symbol removals, initialize the Referenced field.
+ if (!Config.SymbolsToRemove.empty())
+ if (Error E = Obj.markSymbols())
+ return E;
+
+ // Actually do removals of symbols.
+ Obj.removeSymbols([&](const Symbol &Sym) {
+ if (is_contained(Config.SymbolsToRemove, Sym.Name)) {
+ // Explicitly removing a referenced symbol is an error.
+ if (Sym.Referenced)
+ reportError(Config.OutputFilename,
+ make_error<StringError>(
+ "not stripping symbol '" + Sym.Name +
+ "' because it is named in a relocation.",
+ llvm::errc::invalid_argument));
+ return true;
+ }
+
+ return false;
+ });
+ return Error::success();
+}
+
void executeObjcopyOnBinary(const CopyConfig &Config,
object::COFFObjectFile &In, Buffer &Out) {
COFFReader Reader(In);
@@ -34,6 +59,8 @@
reportError(Config.InputFilename, ObjOrErr.takeError());
Object *Obj = ObjOrErr->get();
assert(Obj && "Unable to deserialize COFF object");
+ if (Error E = handleArgs(Config, *Obj))
+ reportError(Config.InputFilename, std::move(E));
COFFWriter Writer(*Obj, Out);
if (Error E = Writer.write())
reportError(Config.OutputFilename, std::move(E));
diff --git a/tools/llvm-objcopy/COFF/Object.cpp b/tools/llvm-objcopy/COFF/Object.cpp
new file mode 100644
index 0000000..315d3a7
--- /dev/null
+++ b/tools/llvm-objcopy/COFF/Object.cpp
@@ -0,0 +1,70 @@
+//===- Object.cpp ---------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Object.h"
+#include <algorithm>
+
+namespace llvm {
+namespace objcopy {
+namespace coff {
+
+using namespace object;
+
+void Object::addSymbols(ArrayRef<Symbol> NewSymbols) {
+ for (Symbol S : NewSymbols) {
+ S.UniqueId = NextSymbolUniqueId++;
+ Symbols.emplace_back(S);
+ }
+ updateSymbols();
+}
+
+void Object::updateSymbols() {
+ SymbolMap = DenseMap<size_t, Symbol *>(Symbols.size());
+ size_t RawSymIndex = 0;
+ for (Symbol &Sym : Symbols) {
+ SymbolMap[Sym.UniqueId] = &Sym;
+ Sym.RawIndex = RawSymIndex;
+ RawSymIndex += 1 + Sym.Sym.NumberOfAuxSymbols;
+ }
+}
+
+const Symbol *Object::findSymbol(size_t UniqueId) const {
+ auto It = SymbolMap.find(UniqueId);
+ if (It == SymbolMap.end())
+ return nullptr;
+ return It->second;
+}
+
+void Object::removeSymbols(function_ref<bool(const Symbol &)> ToRemove) {
+ Symbols.erase(
+ std::remove_if(std::begin(Symbols), std::end(Symbols),
+ [ToRemove](const Symbol &Sym) { return ToRemove(Sym); }),
+ std::end(Symbols));
+ updateSymbols();
+}
+
+Error Object::markSymbols() {
+ for (Symbol &Sym : Symbols)
+ Sym.Referenced = false;
+ for (const Section &Sec : Sections) {
+ for (const Relocation &R : Sec.Relocs) {
+ auto It = SymbolMap.find(R.Target);
+ if (It == SymbolMap.end())
+ return make_error<StringError>("Relocation target " + Twine(R.Target) +
+ " not found",
+ object_error::invalid_symbol_index);
+ It->second->Referenced = true;
+ }
+ }
+ return Error::success();
+}
+
+} // end namespace coff
+} // end namespace objcopy
+} // end namespace llvm
diff --git a/tools/llvm-objcopy/COFF/Object.h b/tools/llvm-objcopy/COFF/Object.h
index 89f9903..ca1ff7f 100644
--- a/tools/llvm-objcopy/COFF/Object.h
+++ b/tools/llvm-objcopy/COFF/Object.h
@@ -11,7 +11,9 @@
#define LLVM_TOOLS_OBJCOPY_COFF_OBJECT_H
#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/iterator_range.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/Object/COFF.h"
#include <cstddef>
@@ -22,10 +24,16 @@
namespace objcopy {
namespace coff {
+struct Relocation {
+ object::coff_relocation Reloc;
+ size_t Target;
+ StringRef TargetName; // Used for diagnostics only
+};
+
struct Section {
object::coff_section Header;
ArrayRef<uint8_t> Contents;
- std::vector<object::coff_relocation> Relocs;
+ std::vector<Relocation> Relocs;
StringRef Name;
};
@@ -33,6 +41,9 @@
object::coff_symbol32 Sym;
StringRef Name;
ArrayRef<uint8_t> AuxData;
+ size_t UniqueId;
+ size_t RawIndex;
+ bool Referenced;
};
struct Object {
@@ -49,7 +60,31 @@
std::vector<object::data_directory> DataDirectories;
std::vector<Section> Sections;
+
+ ArrayRef<Symbol> getSymbols() const { return Symbols; }
+ // This allows mutating individual Symbols, but not mutating the list
+ // of symbols itself.
+ iterator_range<std::vector<Symbol>::iterator> getMutableSymbols() {
+ return make_range(Symbols.begin(), Symbols.end());
+ }
+
+ const Symbol *findSymbol(size_t UniqueId) const;
+
+ void addSymbols(ArrayRef<Symbol> NewSymbols);
+ void removeSymbols(function_ref<bool(const Symbol &)> ToRemove);
+
+ // Set the Referenced field on all Symbols, based on relocations in
+ // all sections.
+ Error markSymbols();
+
+private:
std::vector<Symbol> Symbols;
+ DenseMap<size_t, Symbol *> SymbolMap;
+
+ size_t NextSymbolUniqueId = 0;
+
+ // Update SymbolMap and RawIndex in each Symbol.
+ void updateSymbols();
};
// Copy between coff_symbol16 and coff_symbol32.
diff --git a/tools/llvm-objcopy/COFF/Reader.cpp b/tools/llvm-objcopy/COFF/Reader.cpp
index 5d80596..76b3f73 100644
--- a/tools/llvm-objcopy/COFF/Reader.cpp
+++ b/tools/llvm-objcopy/COFF/Reader.cpp
@@ -73,7 +73,7 @@
return errorCodeToError(EC);
ArrayRef<coff_relocation> Relocs = COFFObj.getRelocations(Sec);
for (const coff_relocation &R : Relocs)
- S.Relocs.push_back(R);
+ S.Relocs.push_back(Relocation{R});
if (auto EC = COFFObj.getSectionName(Sec, S.Name))
return errorCodeToError(EC);
if (Sec->hasExtendedRelocations())
@@ -84,14 +84,16 @@
}
Error COFFReader::readSymbols(Object &Obj, bool IsBigObj) const {
+ std::vector<Symbol> Symbols;
+ Symbols.reserve(COFFObj.getRawNumberOfSymbols());
for (uint32_t I = 0, E = COFFObj.getRawNumberOfSymbols(); I < E;) {
Expected<COFFSymbolRef> SymOrErr = COFFObj.getSymbol(I);
if (!SymOrErr)
return SymOrErr.takeError();
COFFSymbolRef SymRef = *SymOrErr;
- Obj.Symbols.push_back(Symbol());
- Symbol &Sym = Obj.Symbols.back();
+ Symbols.push_back(Symbol());
+ Symbol &Sym = Symbols.back();
// Copy symbols from the original form into an intermediate coff_symbol32.
if (IsBigObj)
copySymbol(Sym.Sym,
@@ -106,6 +108,30 @@
(IsBigObj ? sizeof(coff_symbol32) : sizeof(coff_symbol16))) == 0);
I += 1 + SymRef.getNumberOfAuxSymbols();
}
+ Obj.addSymbols(Symbols);
+ return Error::success();
+}
+
+Error COFFReader::setRelocTargets(Object &Obj) const {
+ std::vector<const Symbol *> RawSymbolTable;
+ for (const Symbol &Sym : Obj.getSymbols()) {
+ RawSymbolTable.push_back(&Sym);
+ for (size_t I = 0; I < Sym.Sym.NumberOfAuxSymbols; I++)
+ RawSymbolTable.push_back(nullptr);
+ }
+ for (Section &Sec : Obj.Sections) {
+ for (Relocation &R : Sec.Relocs) {
+ if (R.Reloc.SymbolTableIndex >= RawSymbolTable.size())
+ return make_error<StringError>("SymbolTableIndex out of range",
+ object_error::parse_failed);
+ const Symbol *Sym = RawSymbolTable[R.Reloc.SymbolTableIndex];
+ if (Sym == nullptr)
+ return make_error<StringError>("Invalid SymbolTableIndex",
+ object_error::parse_failed);
+ R.Target = Sym->UniqueId;
+ R.TargetName = Sym->Name;
+ }
+ }
return Error::success();
}
@@ -136,6 +162,8 @@
return std::move(E);
if (Error E = readSymbols(*Obj, IsBigObj))
return std::move(E);
+ if (Error E = setRelocTargets(*Obj))
+ return std::move(E);
return std::move(Obj);
}
diff --git a/tools/llvm-objcopy/COFF/Reader.h b/tools/llvm-objcopy/COFF/Reader.h
index f2b7f78..c972a14 100644
--- a/tools/llvm-objcopy/COFF/Reader.h
+++ b/tools/llvm-objcopy/COFF/Reader.h
@@ -35,6 +35,7 @@
Error readExecutableHeaders(Object &Obj) const;
Error readSections(Object &Obj) const;
Error readSymbols(Object &Obj, bool IsBigObj) const;
+ Error setRelocTargets(Object &Obj) const;
public:
explicit COFFReader(const COFFObjectFile &O) : COFFObj(O) {}
diff --git a/tools/llvm-objcopy/COFF/Writer.cpp b/tools/llvm-objcopy/COFF/Writer.cpp
index 388c62c..d7a5224 100644
--- a/tools/llvm-objcopy/COFF/Writer.cpp
+++ b/tools/llvm-objcopy/COFF/Writer.cpp
@@ -27,6 +27,21 @@
Writer::~Writer() {}
+Error COFFWriter::finalizeRelocTargets() {
+ for (Section &Sec : Obj.Sections) {
+ for (Relocation &R : Sec.Relocs) {
+ const Symbol *Sym = Obj.findSymbol(R.Target);
+ if (Sym == nullptr)
+ return make_error<StringError>("Relocation target " + R.TargetName +
+ " (" + Twine(R.Target) +
+ ") not found",
+ object_error::invalid_symbol_index);
+ R.Reloc.SymbolTableIndex = Sym->RawIndex;
+ }
+ }
+ return Error::success();
+}
+
void COFFWriter::layoutSections() {
for (auto &S : Obj.Sections) {
if (S.Header.SizeOfRawData > 0)
@@ -48,7 +63,7 @@
if (S.Name.size() > COFF::NameSize)
StrTabBuilder.add(S.Name);
- for (const auto &S : Obj.Symbols)
+ for (const auto &S : Obj.getSymbols())
if (S.Name.size() > COFF::NameSize)
StrTabBuilder.add(S.Name);
@@ -62,7 +77,7 @@
strncpy(S.Header.Name, S.Name.data(), COFF::NameSize);
}
}
- for (auto &S : Obj.Symbols) {
+ for (auto &S : Obj.getMutableSymbols()) {
if (S.Name.size() > COFF::NameSize) {
S.Sym.Name.Offset.Zeroes = 0;
S.Sym.Name.Offset.Offset = StrTabBuilder.getOffset(S.Name);
@@ -75,13 +90,16 @@
template <class SymbolTy>
std::pair<size_t, size_t> COFFWriter::finalizeSymbolTable() {
- size_t SymTabSize = Obj.Symbols.size() * sizeof(SymbolTy);
- for (const auto &S : Obj.Symbols)
+ size_t SymTabSize = Obj.getSymbols().size() * sizeof(SymbolTy);
+ for (const auto &S : Obj.getSymbols())
SymTabSize += S.AuxData.size();
return std::make_pair(SymTabSize, sizeof(SymbolTy));
}
-void COFFWriter::finalize(bool IsBigObj) {
+Error COFFWriter::finalize(bool IsBigObj) {
+ if (Error E = finalizeRelocTargets())
+ return E;
+
size_t SizeOfHeaders = 0;
FileAlignment = 1;
size_t PeHeaderSize = 0;
@@ -149,6 +167,8 @@
Obj.CoffFileHeader.NumberOfSymbols = NumRawSymbols;
FileSize += SymTabSize + StrTabSize;
FileSize = alignTo(FileSize, FileAlignment);
+
+ return Error::success();
}
void COFFWriter::writeHeaders(bool IsBigObj) {
@@ -225,14 +245,16 @@
S.Header.SizeOfRawData - S.Contents.size());
Ptr += S.Header.SizeOfRawData;
- std::copy(S.Relocs.begin(), S.Relocs.end(),
- reinterpret_cast<coff_relocation *>(Ptr));
+ for (const auto &R : S.Relocs) {
+ memcpy(Ptr, &R.Reloc, sizeof(R.Reloc));
+ Ptr += sizeof(R.Reloc);
+ }
}
}
template <class SymbolTy> void COFFWriter::writeSymbolStringTables() {
uint8_t *Ptr = Buf.getBufferStart() + Obj.CoffFileHeader.PointerToSymbolTable;
- for (const auto &S : Obj.Symbols) {
+ for (const auto &S : Obj.getSymbols()) {
// Convert symbols back to the right size, from coff_symbol32.
copySymbol<SymbolTy, coff_symbol32>(*reinterpret_cast<SymbolTy *>(Ptr),
S.Sym);
@@ -248,7 +270,8 @@
}
Error COFFWriter::write(bool IsBigObj) {
- finalize(IsBigObj);
+ if (Error E = finalize(IsBigObj))
+ return E;
Buf.allocate(FileSize);
diff --git a/tools/llvm-objcopy/COFF/Writer.h b/tools/llvm-objcopy/COFF/Writer.h
index f2e814a..a2612ca 100644
--- a/tools/llvm-objcopy/COFF/Writer.h
+++ b/tools/llvm-objcopy/COFF/Writer.h
@@ -40,11 +40,12 @@
size_t SizeOfInitializedData;
StringTableBuilder StrTabBuilder;
+ Error finalizeRelocTargets();
void layoutSections();
size_t finalizeStringTable();
template <class SymbolTy> std::pair<size_t, size_t> finalizeSymbolTable();
- void finalize(bool IsBigObj);
+ Error finalize(bool IsBigObj);
void writeHeaders(bool IsBigObj);
void writeSections();
