[llvm] 0db3a5a - [llvm-objcopy][MachO] Handle relocation entries where r_extern is zero
Alexander Shaposhnikov via llvm-commits
llvm-commits at lists.llvm.org
Mon Apr 27 18:00:38 PDT 2020
Author: Alexander Shaposhnikov
Date: 2020-04-27T17:59:07-07:00
New Revision: 0db3a5a93e113d681e78ea5f7dd8cd1020d02a7b
URL: https://github.com/llvm/llvm-project/commit/0db3a5a93e113d681e78ea5f7dd8cd1020d02a7b
DIFF: https://github.com/llvm/llvm-project/commit/0db3a5a93e113d681e78ea5f7dd8cd1020d02a7b.diff
LOG: [llvm-objcopy][MachO] Handle relocation entries where r_extern is zero
Fix handling of relocations with r_extern == 0.
If r_extern == 0 then r_symbolnum is an index of a section rather than a symbol index.
Patch by Seiya Nuta and Alexander Shaposhnikov.
Test plan: make check-all
Differential revision: https://reviews.llvm.org/D78946
Added:
llvm/test/tools/llvm-objcopy/MachO/relocations.test
Modified:
llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
llvm/tools/llvm-objcopy/MachO/Object.cpp
llvm/tools/llvm-objcopy/MachO/Object.h
Removed:
################################################################################
diff --git a/llvm/test/tools/llvm-objcopy/MachO/relocations.test b/llvm/test/tools/llvm-objcopy/MachO/relocations.test
new file mode 100644
index 000000000000..8859b9e4ac14
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/MachO/relocations.test
@@ -0,0 +1,95 @@
+# RUN: yaml2obj %s -o %t
+
+## Show that llvm-objcopy copies relocation entries where r_extern = 0.
+# RUN: llvm-objcopy %t %t2
+# RUN: cmp %t %t2
+
+## Show that llvm-objcopy updates section indices properly.
+# RUN: llvm-objcopy --remove-section=__DATA,__foo %t %t3
+# RUN: llvm-objdump --macho --reloc %t3 | FileCheck %s
+
+# CHECK: Relocation information (__DATA,__bar) 2 entries
+# CHECK-NEXT: address pcrel length extern type scattered symbolnum/value
+# CHECK-NEXT: 00000000 False quad False SUB False 2 (__DATA,__bar)
+# CHECK-NEXT: 00000000 False quad False UNSIGND False 1 (__TEXT,__text)
+
+--- !mach-o
+FileHeader:
+ magic: 0xFEEDFACF
+ cputype: 0x01000007
+ cpusubtype: 0x00000003
+ filetype: 0x00000001
+ ncmds: 1
+ sizeofcmds: 312
+ flags: 0x00000000
+ reserved: 0x00000000
+LoadCommands:
+ - cmd: LC_SEGMENT_64
+ cmdsize: 312
+ segname: ''
+ vmaddr: 0
+ vmsize: 24
+ fileoff: 344
+ filesize: 24
+ maxprot: 7
+ initprot: 7
+ nsects: 3
+ flags: 0
+ Sections:
+ - sectname: __text
+ segname: __TEXT
+ addr: 0x0000000000000000
+ size: 8
+ offset: 0x00000158
+ align: 0
+ reloff: 0x00000000
+ nreloc: 0
+ flags: 0x80000000
+ reserved1: 0x00000000
+ reserved2: 0x00000000
+ reserved3: 0x00000000
+ content: '0000000000000000'
+ - sectname: __foo
+ segname: __DATA
+ addr: 0x0000000000000008
+ size: 8
+ offset: 0x00000160
+ align: 0
+ reloff: 0x00000000
+ nreloc: 0
+ flags: 0x00000000
+ reserved1: 0x00000000
+ reserved2: 0x00000000
+ reserved3: 0x00000000
+ content: '0000000000000000'
+ - sectname: __bar
+ segname: __DATA
+ addr: 0x0000000000000010
+ size: 8
+ offset: 0x00000168
+ align: 0
+ reloff: 0x00000170
+ nreloc: 2
+ flags: 0x00000000
+ reserved1: 0x00000000
+ reserved2: 0x00000000
+ reserved3: 0x00000000
+ content: F0FFFFFFFFFFFFFF
+ relocations:
+ - address: 0x00000000
+ symbolnum: 3
+ pcrel: false
+ length: 3
+ extern: false
+ type: 5
+ scattered: false
+ value: 0
+ - address: 0x00000000
+ symbolnum: 1
+ pcrel: false
+ length: 3
+ extern: false
+ type: 0
+ scattered: false
+ value: 0
+...
diff --git a/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp b/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
index b4662ec5b5cd..b12e39ccd488 100644
--- a/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
@@ -103,6 +103,7 @@ extractSections(const object::MachOObjectFile::LoadCommandInfo &LoadCmd,
R.Symbol = nullptr; // We'll fill this field later.
R.Info = MachOObj.getRelocation(RI->getRawDataRefImpl());
R.Scattered = MachOObj.isRelocationScattered(R.Info);
+ R.Extern = !R.Scattered && MachOObj.getPlainRelocationExternal(R.Info);
S.Relocations.push_back(R);
}
@@ -203,12 +204,27 @@ void MachOReader::readSymbolTable(Object &O) const {
}
void MachOReader::setSymbolInRelocationInfo(Object &O) const {
+ std::vector<const Section *> Sections;
+ for (auto &LC : O.LoadCommands)
+ for (std::unique_ptr<Section> &Sec : LC.Sections)
+ Sections.push_back(Sec.get());
+
for (LoadCommand &LC : O.LoadCommands)
for (std::unique_ptr<Section> &Sec : LC.Sections)
for (auto &Reloc : Sec->Relocations)
- if (!Reloc.Scattered)
- Reloc.Symbol = O.SymTable.getSymbolByIndex(
- Reloc.getPlainRelocationSymbolNum(MachOObj.isLittleEndian()));
+ if (!Reloc.Scattered) {
+ const uint32_t SymbolNum =
+ Reloc.getPlainRelocationSymbolNum(MachOObj.isLittleEndian());
+ if (Reloc.Extern) {
+ Reloc.Symbol = O.SymTable.getSymbolByIndex(SymbolNum);
+ } else {
+ // FIXME: Refactor error handling in MachOReader and report an error
+ // if we encounter an invalid relocation.
+ assert(SymbolNum >= 1 && SymbolNum <= Sections.size() &&
+ "Invalid section index.");
+ Reloc.Section = Sections[SymbolNum - 1];
+ }
+ }
}
void MachOReader::readRebaseInfo(Object &O) const {
diff --git a/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp b/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
index db31ef518aa8..4a8d1aeedb11 100644
--- a/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
@@ -239,11 +239,13 @@ void MachOWriter::writeSections() {
memcpy(B.getBufferStart() + Sec->Offset, Sec->Content.data(),
Sec->Content.size());
for (size_t Index = 0; Index < Sec->Relocations.size(); ++Index) {
- auto RelocInfo = Sec->Relocations[Index];
- if (!RelocInfo.Scattered)
- RelocInfo.setPlainRelocationSymbolNum(RelocInfo.Symbol->Index,
- IsLittleEndian);
-
+ RelocationInfo RelocInfo = Sec->Relocations[Index];
+ if (!RelocInfo.Scattered) {
+ const uint32_t SymbolNum = RelocInfo.Extern
+ ? (*RelocInfo.Symbol)->Index
+ : (*RelocInfo.Section)->Index;
+ RelocInfo.setPlainRelocationSymbolNum(SymbolNum, IsLittleEndian);
+ }
if (IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(
reinterpret_cast<MachO::any_relocation_info &>(RelocInfo.Info));
diff --git a/llvm/tools/llvm-objcopy/MachO/Object.cpp b/llvm/tools/llvm-objcopy/MachO/Object.cpp
index 89fe9946c73f..0f28cb054a96 100644
--- a/llvm/tools/llvm-objcopy/MachO/Object.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/Object.cpp
@@ -60,13 +60,13 @@ Error Object::removeSections(
for (const LoadCommand &LC : LoadCommands)
for (const std::unique_ptr<Section> &Sec : LC.Sections)
for (const RelocationInfo &R : Sec->Relocations)
- if (R.Symbol && DeadSymbols.count(R.Symbol))
+ if (R.Symbol && *R.Symbol && DeadSymbols.count(*R.Symbol))
return createStringError(std::errc::invalid_argument,
"symbol '%s' defined in section with index "
"'%u' cannot be removed because it is "
"referenced by a relocation in section '%s'",
- R.Symbol->Name.c_str(),
- *(R.Symbol->section()),
+ (*R.Symbol)->Name.c_str(),
+ *((*R.Symbol)->section()),
Sec->CanonicalName.c_str());
SymTable.removeSymbols(IsDead);
for (std::unique_ptr<SymbolEntry> &S : SymTable.Symbols)
diff --git a/llvm/tools/llvm-objcopy/MachO/Object.h b/llvm/tools/llvm-objcopy/MachO/Object.h
index dc828e66fcbd..703c31fac0e4 100644
--- a/llvm/tools/llvm-objcopy/MachO/Object.h
+++ b/llvm/tools/llvm-objcopy/MachO/Object.h
@@ -162,9 +162,14 @@ struct StringTable {
};
struct RelocationInfo {
- const SymbolEntry *Symbol;
+ // The referenced symbol entry. Set if !Scattered && Extern.
+ Optional<const SymbolEntry *> Symbol;
+ // The referenced section. Set if !Scattered && !Extern.
+ Optional<const Section *> Section;
// True if Info is a scattered_relocation_info.
bool Scattered;
+ // True if the r_symbolnum points to a section number (i.e. r_extern=0).
+ bool Extern;
MachO::any_relocation_info Info;
unsigned getPlainRelocationSymbolNum(bool IsLittleEndian) {
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