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[llvm-objdump] support -rebase option for mach-o to dump rebasing info
Similar to my previous -exports-trie option, the -rebase option dumps info from the LC_DYLD_INFO load command. The rebasing info is a list of the the locations that dyld needs to adjust if a mach-o image is not loaded at its preferred address. Since ASLR is now the default, images almost never load at their preferred address, and thus need to be rebased by dyld. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217709 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Kledzik
@ -17,6 +17,7 @@
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#include "llvm/ADT/StringSwitch.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/Support/DataExtractor.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/Format.h"
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#include "llvm/Support/Host.h"
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#include "llvm/Support/LEB128.h"
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@ -1688,6 +1689,177 @@ iterator_range<export_iterator> MachOObjectFile::exports() const {
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}
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MachORebaseEntry::MachORebaseEntry(ArrayRef<uint8_t> Bytes, bool is64Bit)
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: Opcodes(Bytes), Ptr(Bytes.begin()), SegmentOffset(0), SegmentIndex(0),
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RemainingLoopCount(0), AdvanceAmount(0), RebaseType(0),
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PointerSize(is64Bit ? 8 : 4), Malformed(false), Done(false) {}
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void MachORebaseEntry::moveToFirst() {
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Ptr = Opcodes.begin();
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moveNext();
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}
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void MachORebaseEntry::moveToEnd() {
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Ptr = Opcodes.end();
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RemainingLoopCount = 0;
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Done = true;
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}
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void MachORebaseEntry::moveNext() {
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// If in the middle of some loop, move to next rebasing in loop.
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SegmentOffset += AdvanceAmount;
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if (RemainingLoopCount) {
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--RemainingLoopCount;
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return;
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}
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if (Ptr == Opcodes.end()) {
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Done = true;
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return;
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}
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bool More = true;
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while (More && !Malformed) {
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// Parse next opcode and set up next loop.
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uint8_t Byte = *Ptr++;
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uint8_t ImmValue = Byte & MachO::REBASE_IMMEDIATE_MASK;
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uint8_t Opcode = Byte & MachO::REBASE_OPCODE_MASK;
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switch (Opcode) {
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case MachO::REBASE_OPCODE_DONE:
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More = false;
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Done = true;
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moveToEnd();
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DEBUG_WITH_TYPE("mach-o-rebase", llvm::dbgs() << "REBASE_OPCODE_DONE\n");
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break;
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case MachO::REBASE_OPCODE_SET_TYPE_IMM:
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RebaseType = ImmValue;
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DEBUG_WITH_TYPE(
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"mach-o-rebase",
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llvm::dbgs() << "REBASE_OPCODE_SET_TYPE_IMM: "
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<< "RebaseType=" << (int) RebaseType << "\n");
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break;
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case MachO::REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
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SegmentIndex = ImmValue;
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SegmentOffset = readULEB128();
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DEBUG_WITH_TYPE(
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"mach-o-rebase",
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llvm::dbgs() << "REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB: "
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<< "SegmentIndex=" << SegmentIndex << ", "
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<< format("SegmentOffset=0x%06X", SegmentOffset)
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<< "\n");
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break;
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case MachO::REBASE_OPCODE_ADD_ADDR_ULEB:
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SegmentOffset += readULEB128();
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DEBUG_WITH_TYPE("mach-o-rebase",
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llvm::dbgs() << "REBASE_OPCODE_ADD_ADDR_ULEB: "
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<< format("SegmentOffset=0x%06X",
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SegmentOffset) << "\n");
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break;
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case MachO::REBASE_OPCODE_ADD_ADDR_IMM_SCALED:
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SegmentOffset += ImmValue * PointerSize;
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DEBUG_WITH_TYPE("mach-o-rebase",
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llvm::dbgs() << "REBASE_OPCODE_ADD_ADDR_IMM_SCALED: "
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<< format("SegmentOffset=0x%06X",
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SegmentOffset) << "\n");
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break;
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case MachO::REBASE_OPCODE_DO_REBASE_IMM_TIMES:
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AdvanceAmount = PointerSize;
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RemainingLoopCount = ImmValue - 1;
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DEBUG_WITH_TYPE(
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"mach-o-rebase",
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llvm::dbgs() << "REBASE_OPCODE_DO_REBASE_IMM_TIMES: "
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<< format("SegmentOffset=0x%06X", SegmentOffset)
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<< ", AdvanceAmount=" << AdvanceAmount
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<< ", RemainingLoopCount=" << RemainingLoopCount
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<< "\n");
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return;
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case MachO::REBASE_OPCODE_DO_REBASE_ULEB_TIMES:
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AdvanceAmount = PointerSize;
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RemainingLoopCount = readULEB128() - 1;
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DEBUG_WITH_TYPE(
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"mach-o-rebase",
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llvm::dbgs() << "REBASE_OPCODE_DO_REBASE_ULEB_TIMES: "
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<< format("SegmentOffset=0x%06X", SegmentOffset)
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<< ", AdvanceAmount=" << AdvanceAmount
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<< ", RemainingLoopCount=" << RemainingLoopCount
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<< "\n");
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return;
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case MachO::REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB:
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AdvanceAmount = readULEB128() + PointerSize;
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RemainingLoopCount = 0;
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DEBUG_WITH_TYPE(
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"mach-o-rebase",
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llvm::dbgs() << "REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB: "
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<< format("SegmentOffset=0x%06X", SegmentOffset)
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<< ", AdvanceAmount=" << AdvanceAmount
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<< ", RemainingLoopCount=" << RemainingLoopCount
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<< "\n");
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return;
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case MachO::REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB:
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RemainingLoopCount = readULEB128() - 1;
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AdvanceAmount = readULEB128() + PointerSize;
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DEBUG_WITH_TYPE(
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"mach-o-rebase",
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llvm::dbgs() << "REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB: "
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<< format("SegmentOffset=0x%06X", SegmentOffset)
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<< ", AdvanceAmount=" << AdvanceAmount
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<< ", RemainingLoopCount=" << RemainingLoopCount
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<< "\n");
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return;
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default:
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Malformed = true;
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}
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}
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}
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uint64_t MachORebaseEntry::readULEB128() {
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unsigned Count;
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uint64_t Result = decodeULEB128(Ptr, &Count);
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Ptr += Count;
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if (Ptr > Opcodes.end()) {
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Ptr = Opcodes.end();
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Malformed = true;
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}
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return Result;
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}
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uint32_t MachORebaseEntry::segmentIndex() const { return SegmentIndex; }
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uint64_t MachORebaseEntry::segmentOffset() const { return SegmentOffset; }
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StringRef MachORebaseEntry::typeName() const {
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switch (RebaseType) {
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case MachO::REBASE_TYPE_POINTER:
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return "pointer";
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case MachO::REBASE_TYPE_TEXT_ABSOLUTE32:
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return "text abs32";
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case MachO::REBASE_TYPE_TEXT_PCREL32:
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return "text rel32";
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}
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return "unknown";
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}
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bool MachORebaseEntry::operator==(const MachORebaseEntry &Other) const {
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assert(Opcodes == Other.Opcodes && "compare iterators of different files");
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return (Ptr == Other.Ptr) &&
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(RemainingLoopCount == Other.RemainingLoopCount) &&
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(Done == Other.Done);
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}
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iterator_range<rebase_iterator>
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MachOObjectFile::rebaseTable(ArrayRef<uint8_t> Opcodes, bool is64) {
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MachORebaseEntry Start(Opcodes, is64);
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Start.moveToFirst();
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MachORebaseEntry Finish(Opcodes, is64);
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Finish.moveToEnd();
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return iterator_range<rebase_iterator>(rebase_iterator(Start),
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rebase_iterator(Finish));
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}
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iterator_range<rebase_iterator> MachOObjectFile::rebaseTable() const {
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return rebaseTable(getDyldInfoRebaseOpcodes(), is64Bit());
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}
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StringRef
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MachOObjectFile::getSectionFinalSegmentName(DataRefImpl Sec) const {
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ArrayRef<char> Raw = getSectionRawFinalSegmentName(Sec);
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