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Update llvm-objdump’s Mach-O symbolizer code to print the name of symbol stubs.

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So in fully linked images when a call is made through a stub it now gets a
comment like the following in the disassembly:

    callq	0x100000f6c             ## symbol stub for: _printf

indicating the call is to a symbol stub and which symbol it is for.  This is
done for branch reference types and seeing if the branch target is in a stub
section and if so using the indirect symbol table entry for that stub and
using that symbol table entries symbol name.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218546 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kevin Enderby 2014-09-26 22:20:44 +00:00
parent aeb9ee0261
commit 7118c73867
2 changed files with 97 additions and 1 deletions
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1
test/tools/llvm-objdump/X86/macho-symbolized-disassembly.test
View File

@ -5,3 +5,4 @@ OBJ: 0000000000000008 leaq L_.str(%rip), %rax ## literal pool for: "Hello w
OBJ: 0000000000000026 callq _printf
EXE: 0000000100000f38 leaq 0x4f(%rip), %rax ## literal pool for: "Hello world\n"
EXE: 0000000100000f56 callq 0x100000f6c ## symbol stub for: _printf

97
tools/llvm-objdump/MachODump.cpp
View File

@ -413,6 +413,94 @@ const char *GuessCstringPointer(uint64_t ReferenceValue,
return nullptr;
}
// GuessIndirectSymbol returns the name of the indirect symbol for the
// ReferenceValue passed in or nullptr. This is used when ReferenceValue maybe
// an address of a symbol stub or a lazy or non-lazy pointer to associate the
// symbol name being referenced by the stub or pointer.
static const char *GuessIndirectSymbol(uint64_t ReferenceValue,
struct DisassembleInfo *info) {
uint32_t LoadCommandCount = info->O->getHeader().ncmds;
MachOObjectFile::LoadCommandInfo Load = info->O->getFirstLoadCommandInfo();
MachO::dysymtab_command Dysymtab = info->O->getDysymtabLoadCommand();
MachO::symtab_command Symtab = info->O->getSymtabLoadCommand();
for (unsigned I = 0;; ++I) {
if (Load.C.cmd == MachO::LC_SEGMENT_64) {
MachO::segment_command_64 Seg = info->O->getSegment64LoadCommand(Load);
for (unsigned J = 0; J < Seg.nsects; ++J) {
MachO::section_64 Sec = info->O->getSection64(Load, J);
uint32_t section_type = Sec.flags & MachO::SECTION_TYPE;
if ((section_type == MachO::S_NON_LAZY_SYMBOL_POINTERS ||
section_type == MachO::S_LAZY_SYMBOL_POINTERS ||
section_type == MachO::S_LAZY_DYLIB_SYMBOL_POINTERS ||
section_type == MachO::S_THREAD_LOCAL_VARIABLE_POINTERS ||
section_type == MachO::S_SYMBOL_STUBS) &&
ReferenceValue >= Sec.addr &&
ReferenceValue < Sec.addr + Sec.size) {
uint32_t stride;
if (section_type == MachO::S_SYMBOL_STUBS)
stride = Sec.reserved2;
else
stride = 8;
if (stride == 0)
return nullptr;
uint32_t index = Sec.reserved1 + (ReferenceValue - Sec.addr) / stride;
if (index < Dysymtab.nindirectsyms) {
uint32_t indirect_symbol =
info->O->getIndirectSymbolTableEntry(Dysymtab, index);
if (indirect_symbol < Symtab.nsyms) {
symbol_iterator Sym = info->O->getSymbolByIndex(indirect_symbol);
SymbolRef Symbol = *Sym;
StringRef SymName;
Symbol.getName(SymName);
const char *name = SymName.data();
return name;
}
}
}
}
} else if (Load.C.cmd == MachO::LC_SEGMENT) {
MachO::segment_command Seg = info->O->getSegmentLoadCommand(Load);
for (unsigned J = 0; J < Seg.nsects; ++J) {
MachO::section Sec = info->O->getSection(Load, J);
uint32_t section_type = Sec.flags & MachO::SECTION_TYPE;
if ((section_type == MachO::S_NON_LAZY_SYMBOL_POINTERS ||
section_type == MachO::S_LAZY_SYMBOL_POINTERS ||
section_type == MachO::S_LAZY_DYLIB_SYMBOL_POINTERS ||
section_type == MachO::S_THREAD_LOCAL_VARIABLE_POINTERS ||
section_type == MachO::S_SYMBOL_STUBS) &&
ReferenceValue >= Sec.addr &&
ReferenceValue < Sec.addr + Sec.size) {
uint32_t stride;
if (section_type == MachO::S_SYMBOL_STUBS)
stride = Sec.reserved2;
else
stride = 4;
if (stride == 0)
return nullptr;
uint32_t index = Sec.reserved1 + (ReferenceValue - Sec.addr) / stride;
if (index < Dysymtab.nindirectsyms) {
uint32_t indirect_symbol =
info->O->getIndirectSymbolTableEntry(Dysymtab, index);
if (indirect_symbol < Symtab.nsyms) {
symbol_iterator Sym = info->O->getSymbolByIndex(indirect_symbol);
SymbolRef Symbol = *Sym;
StringRef SymName;
Symbol.getName(SymName);
const char *name = SymName.data();
return name;
}
}
}
}
}
if (I == LoadCommandCount - 1)
break;
else
Load = info->O->getNextLoadCommandInfo(Load);
}
return nullptr;
}
// GuessLiteralPointer returns a string which for the item in the Mach-O file
// for the address passed in as ReferenceValue for printing as a comment with
// the instruction and also returns the corresponding type of that item
@ -531,7 +619,14 @@ const char *SymbolizerSymbolLookUp(void *DisInfo, uint64_t ReferenceValue,
if (!name.empty())
SymbolName = name.data();
if (*ReferenceType == LLVMDisassembler_ReferenceType_In_PCrel_Load) {
if (*ReferenceType == LLVMDisassembler_ReferenceType_In_Branch) {
*ReferenceName = GuessIndirectSymbol(ReferenceValue, info);
if (*ReferenceName)
*ReferenceType = LLVMDisassembler_ReferenceType_Out_SymbolStub;
else
*ReferenceType = LLVMDisassembler_ReferenceType_InOut_None;
}
else if (*ReferenceType == LLVMDisassembler_ReferenceType_In_PCrel_Load) {
*ReferenceName = GuessLiteralPointer(ReferenceValue, ReferencePC,
ReferenceType, info);
if (*ReferenceName == nullptr)