llvm-project/lld/MachO/Target.h

121 lines
4.2 KiB
C++

//===- Target.h -------------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLD_MACHO_TARGET_H
#define LLD_MACHO_TARGET_H
#include "llvm/ADT/BitmaskEnum.h"
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/Support/MemoryBuffer.h"
#include <cstddef>
#include <cstdint>
namespace lld {
namespace macho {
LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
class Symbol;
class DylibSymbol;
class InputSection;
struct Reloc;
enum : uint64_t {
// We are currently only supporting 64-bit targets since macOS and iOS are
// deprecating 32-bit apps.
WordSize = 8,
PageZeroSize = 1ull << 32, // XXX should be 4096 for 32-bit targets
MaxAlignmentPowerOf2 = 32,
};
enum class RelocAttrBits {
_0 = 0, // invalid
PCREL = 1 << 0, // Value is PC-relative offset
ABSOLUTE = 1 << 1, // Value is an absolute address or fixed offset
BYTE4 = 1 << 2, // 4 byte datum
BYTE8 = 1 << 3, // 8 byte datum
EXTERN = 1 << 4, // Can have an external symbol
LOCAL = 1 << 5, // Can have a local symbol
ADDEND = 1 << 6, // *_ADDEND paired prefix reloc
SUBTRAHEND = 1 << 7, // *_SUBTRACTOR paired prefix reloc
BRANCH = 1 << 8, // Value is branch target
GOT = 1 << 9, // References a symbol in the Global Offset Table
TLV = 1 << 10, // References a thread-local symbol
DYSYM8 = 1 << 11, // Requires DySym width to be 8 bytes
LOAD = 1 << 12, // Relaxable indirect load
POINTER = 1 << 13, // Non-relaxable indirect load (pointer is taken)
UNSIGNED = 1 << 14, // *_UNSIGNED relocs
LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue*/ (1 << 15) - 1),
};
// Note: SUBTRACTOR always pairs with UNSIGNED (a delta between two symbols).
class TargetInfo {
public:
struct RelocAttrs {
llvm::StringRef name;
RelocAttrBits bits;
bool hasAttr(RelocAttrBits b) const { return (bits & b) == b; }
};
static const RelocAttrs invalidRelocAttrs;
virtual ~TargetInfo() = default;
// Validate the relocation structure and get its addend.
virtual uint64_t
getEmbeddedAddend(llvm::MemoryBufferRef, const llvm::MachO::section_64 &,
const llvm::MachO::relocation_info) const = 0;
virtual void relocateOne(uint8_t *loc, const Reloc &, uint64_t va,
uint64_t pc) const = 0;
// Write code for lazy binding. See the comments on StubsSection for more
// details.
virtual void writeStub(uint8_t *buf, const Symbol &) const = 0;
virtual void writeStubHelperHeader(uint8_t *buf) const = 0;
virtual void writeStubHelperEntry(uint8_t *buf, const DylibSymbol &,
uint64_t entryAddr) const = 0;
// Symbols may be referenced via either the GOT or the stubs section,
// depending on the relocation type. prepareSymbolRelocation() will set up the
// GOT/stubs entries, and resolveSymbolVA() will return the addresses of those
// entries. resolveSymbolVA() may also relax the target instructions to save
// on a level of address indirection.
virtual void relaxGotLoad(uint8_t *loc, uint8_t type) const = 0;
virtual const RelocAttrs &getRelocAttrs(uint8_t type) const = 0;
virtual uint64_t getPageSize() const = 0;
bool hasAttr(uint8_t type, RelocAttrBits bit) const {
return getRelocAttrs(type).hasAttr(bit);
}
bool validateRelocationInfo(llvm::MemoryBufferRef,
const llvm::MachO::section_64 &sec,
llvm::MachO::relocation_info);
bool validateSymbolRelocation(const Symbol *, const InputSection *isec,
const Reloc &);
void prepareSymbolRelocation(Symbol *, const InputSection *, const Reloc &);
uint32_t cpuType;
uint32_t cpuSubtype;
size_t stubSize;
size_t stubHelperHeaderSize;
size_t stubHelperEntrySize;
};
TargetInfo *createX86_64TargetInfo();
TargetInfo *createARM64TargetInfo();
extern TargetInfo *target;
} // namespace macho
} // namespace lld
#endif