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Fix handling of mach header and DSO handle symbols. 

The magic file which contained these symbols inherited from archive
which meant that the resolver didn't add the required atoms as archive
members only get added when referenced.  Instead we now inherit from
SimpleFile which always links in the atoms needed.

The second issue was in the handling of these symbols when we emit
the MachO.  The mach header symbol needs to be in the atom list as
it gets an offset (0), and being in the atom list makes sure it is
emitted to the symbol table.  DSO handles are not emitted to the
symbol table.

rdar://problem/24450654

llvm-svn: 259574
This commit is contained in:
Pete Cooper 2016-02-02 21:37:15 +00:00
parent de4208122b
commit d4f414583a
8 changed files with 62 additions and 40 deletions
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1
lld/include/lld/Core/DefinedAtom.h
View File

@ -147,6 +147,7 @@ public:
typeTLVInitialZeroFill, // TLV initial zero fill data [Darwin]
typeTLVInitializerPtr, // pointer to thread local initializer [Darwin]
typeMachHeader, // atom representing mach_header [Darwin]
typeDSOHandle, // atom representing DSO handle [Darwin]
typeThreadZeroFill, // Uninitialized thread local data(TBSS) [ELF]
typeThreadData, // Initialized thread local data(TDATA) [ELF]
typeRONote, // Identifies readonly note sections [ELF]

1
lld/include/lld/Core/File.h
View File

@ -50,6 +50,7 @@ public:
kindMachObject, ///< a MachO object file (.o)
kindELFObject, ///< a ELF object file (.o)
kindCEntryObject, ///< a file for CEntries
kindHeaderObject, ///< a file for file headers
kindEntryObject, ///< a file for the entry
kindUndefinedSymsObject, ///< a file for undefined symbols
kindAliasSymsObject, ///< a file for alias symbols

1
lld/lib/Core/DefinedAtom.cpp
View File

@ -79,6 +79,7 @@ DefinedAtom::ContentPermissions DefinedAtom::permissions(ContentType type) {
case typeUnknown:
case typeTempLTO:
case typeSectCreate:
case typeDSOHandle:
return permUnknown;
}
llvm_unreachable("unknown content type");

1
lld/lib/Core/Resolver.cpp
View File

@ -343,6 +343,7 @@ bool Resolver::resolveUndefines() {
case File::kindMachObject:
case File::kindELFObject:
case File::kindCEntryObject:
case File::kindHeaderObject:
case File::kindEntryObject:
case File::kindUndefinedSymsObject:
case File::kindAliasSymsObject:

83
lld/lib/ReaderWriter/MachO/ExecutableAtoms.h
View File

@ -11,10 +11,10 @@
#define LLD_READER_WRITER_MACHO_EXECUTABLE_ATOMS_H
#include "Atoms.h"
#include "File.h"
#include "llvm/Support/MachO.h"
#include "lld/Core/ArchiveLibraryFile.h"
#include "lld/Core/DefinedAtom.h"
#include "lld/Core/File.h"
#include "lld/Core/LinkingContext.h"
@ -65,45 +65,57 @@ private:
// MachHeaderAliasFile lazily instantiates the magic symbols that mark the start
// of the mach_header for final linked images.
//
class MachHeaderAliasFile : public ArchiveLibraryFile {
class MachHeaderAliasFile : public SimpleFile {
public:
MachHeaderAliasFile(const MachOLinkingContext &context)
: ArchiveLibraryFile("mach_header symbols") {
switch (context.outputMachOType()) {
case llvm::MachO::MH_EXECUTE:
_machHeaderSymbolName = "__mh_execute_header";
break;
case llvm::MachO::MH_DYLIB:
_machHeaderSymbolName = "__mh_dylib_header";
break;
case llvm::MachO::MH_BUNDLE:
_machHeaderSymbolName = "__mh_bundle_header";
break;
case llvm::MachO::MH_DYLINKER:
_machHeaderSymbolName = "__mh_dylinker_header";
break;
case llvm::MachO::MH_PRELOAD:
_machHeaderSymbolName = "__mh_preload_header";
break;
default:
llvm_unreachable("no mach_header symbol for file type");
}
}
std::error_code
parseAllMembers(std::vector<std::unique_ptr<File>> &result) override {
return std::error_code();
}
File *find(StringRef sym, bool dataSymbolOnly) override {
if (sym.equals("___dso_handle") || sym.equals(_machHeaderSymbolName)) {
: SimpleFile("mach_header symbols", kindHeaderObject) {
StringRef machHeaderSymbolName;
StringRef dsoHandleName;
switch (context.outputMachOType()) {
case llvm::MachO::MH_OBJECT:
machHeaderSymbolName = "__mh_object_header";
break;
case llvm::MachO::MH_EXECUTE:
machHeaderSymbolName = "__mh_execute_header";
dsoHandleName = "___dso_handle";
break;
case llvm::MachO::MH_FVMLIB:
llvm_unreachable("no mach_header symbol for file type");
case llvm::MachO::MH_CORE:
llvm_unreachable("no mach_header symbol for file type");
case llvm::MachO::MH_PRELOAD:
llvm_unreachable("no mach_header symbol for file type");
case llvm::MachO::MH_DYLIB:
machHeaderSymbolName = "__mh_dylib_header";
dsoHandleName = "___dso_handle";
break;
case llvm::MachO::MH_DYLINKER:
machHeaderSymbolName = "__mh_dylinker_header";
dsoHandleName = "___dso_handle";
break;
case llvm::MachO::MH_BUNDLE:
machHeaderSymbolName = "__mh_bundle_header";
dsoHandleName = "___dso_handle";
break;
case llvm::MachO::MH_DYLIB_STUB:
llvm_unreachable("no mach_header symbol for file type");
case llvm::MachO::MH_DSYM:
llvm_unreachable("no mach_header symbol for file type");
case llvm::MachO::MH_KEXT_BUNDLE:
dsoHandleName = "___dso_handle";
break;
}
if (!machHeaderSymbolName.empty())
_definedAtoms.push_back(new (allocator()) MachODefinedAtom(
*this, sym, DefinedAtom::scopeLinkageUnit,
*this, machHeaderSymbolName, DefinedAtom::scopeLinkageUnit,
DefinedAtom::typeMachHeader, DefinedAtom::mergeNo, false, false,
ArrayRef<uint8_t>(), DefinedAtom::Alignment(4096)));
return this;
}
return nullptr;
if (!dsoHandleName.empty())
_definedAtoms.push_back(new (allocator()) MachODefinedAtom(
*this, dsoHandleName, DefinedAtom::scopeLinkageUnit,
DefinedAtom::typeDSOHandle, DefinedAtom::mergeNo, false, false,
ArrayRef<uint8_t>(), DefinedAtom::Alignment(1)));
}
const AtomVector<DefinedAtom> &defined() const override {
@ -124,7 +136,6 @@ public:
private:
mutable AtomVector<DefinedAtom> _definedAtoms;
StringRef _machHeaderSymbolName;
};
} // namespace mach_o

8
lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp
View File

@ -242,6 +242,7 @@ struct MachOFinalSectionFromAtomType {
const MachOFinalSectionFromAtomType sectsToAtomType[] = {
ENTRY("__TEXT", "__text", S_REGULAR, typeCode),
ENTRY("__TEXT", "__text", S_REGULAR, typeMachHeader),
ENTRY("__TEXT", "__cstring", S_CSTRING_LITERALS, typeCString),
ENTRY("__TEXT", "__ustring", S_REGULAR, typeUTF16String),
ENTRY("__TEXT", "__const", S_REGULAR, typeConstant),
@ -385,7 +386,12 @@ void Util::processAtomAttributes(const DefinedAtom *atom) {
}
void Util::assignAtomToSection(const DefinedAtom *atom) {
if (atom->contentType() == DefinedAtom::typeMachHeader)
if (atom->contentType() == DefinedAtom::typeMachHeader) {
_machHeaderAliasAtoms.push_back(atom);
// Assign atom to this section with this offset.
AtomInfo ai = {atom, 0};
sectionForAtom(atom)->atomsAndOffsets.push_back(ai);
} else if (atom->contentType() == DefinedAtom::typeDSOHandle)
_machHeaderAliasAtoms.push_back(atom);
else
appendAtom(sectionForAtom(atom), atom);

1
lld/lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
View File

@ -435,6 +435,7 @@ template <> struct ScalarEnumerationTraits<lld::DefinedAtom::ContentType> {
io.enumCase(value, "tlv-initializer-ptr",
DefinedAtom::typeTLVInitializerPtr);
io.enumCase(value, "mach_header", DefinedAtom::typeMachHeader);
io.enumCase(value, "dso_handle", DefinedAtom::typeDSOHandle);
io.enumCase(value, "thread-data", DefinedAtom::typeThreadData);
io.enumCase(value, "thread-zero-fill",DefinedAtom::typeThreadZeroFill);
io.enumCase(value, "ro-note", DefinedAtom::typeRONote);

6
lld/test/mach-o/arm-interworking-movw.yaml
View File

@ -2,7 +2,7 @@
# RUN: lld -flavor darwin -arch armv7 -r -print_atoms %s -o %t | FileCheck %s
# RUN: lld -flavor darwin -arch armv7 -dylib -print_atoms %t -o %t2 \
# RUN: %p/Inputs/libSystem.yaml -sectalign __TEXT __text 0x1000 | FileCheck %s
# RUN: llvm-objdump -d -macho %t2 | FileCheck -check-prefix=CODE %s
# RUN: llvm-objdump -d -macho -no-symbolic-operands %t2 | FileCheck -check-prefix=CODE %s
#
# Test thumb and arm branches round trip through -r.
# Test movw/movt pairs have low bit set properly for thumb vs arm.
@ -330,7 +330,7 @@ local-symbols:
# CODE-NEXT: movt r0, #0
# CODE-NEXT: movw r1, #1
# CODE-NEXT: movt r1, #0
# CODE-NEXT: movw r2, _a2
# CODE-NEXT: movw r2, #4174
# CODE-NEXT: movt r2, #0
# CODE-NEXT: movw r3, #42
# CODE-NEXT: movt r3, #0
@ -341,7 +341,7 @@ local-symbols:
# CODE-NEXT: movt r0, #0
# CODE-NEXT: movw r1, #65495
# CODE-NEXT: movt r1, #65535
# CODE-NEXT: movw r2, _a2
# CODE-NEXT: movw r2, #4174
# CODE-NEXT: movt r2, #0
# CODE-NEXT: movw r3, #0
# CODE-NEXT: movt r3, #0