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14f94de1ee6487f2f254709383258aaa095b4cfe
clang-p2996/lldb/source/Symbol/Symbol.cpp
Pavel Labath c6ae7eaa7b Correctly resolve symbol names containing linker annotations 
Summary:
Symbols in ELF files can be versioned, but LLDB currently does not understand these. This problem
becomes apparent once one loads glibc with debug info. Here (in the .symtab section) the versions
are embedded in the name (name@VERSION), which causes issues when evaluating expressions
referencing memcpy for example (current glibc contains memcpy@@GLIBC_2.14 and
memcpy@GLIBC_2.2.5).

This problem was not evident without debug symbols as the .dynsym section
stores the bare names and the actual versions are present in a separate section (.gnu.version_d),
which LLDB ignores. This resulted in two definitions of memcpy in the symbol table.

This patch adds support for storing annotated names to the Symbol class. If
Symbol.m_contains_linker_annotations is true then this symbol is annotated. Unannotated name can
be obtained by calling StripLinkerAnnotations on the corresponding ObjectFile. ObjectFileELF
implements this to strip @VERSION suffixes when requested. Symtab uses this function to add the
bare name as well as the annotated name to the name lookup table.

To preserve the size of the Symbol class, I had to steal one bit from the m_type field.

Test Plan:
This fixes TestExprHelpExamples.py when run with a glibc with debug symbols. Writing
an environment agnostic test case would require building a custom shared library with symbol
versions and testing symbol resolution against that, which is somewhat challenging.

Reviewers: clayborg, jingham

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D8036

llvm-svn: 231228
2015-03-04 10:25:22 +00:00

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//===-- Symbol.cpp ----------------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "lldb/Symbol/Symbol.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Core/Section.h"
#include "lldb/Core/Stream.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/Symtab.h"
#include "lldb/Symbol/Function.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/Target.h"
#include "lldb/Symbol/SymbolVendor.h"
using namespace lldb;
using namespace lldb_private;
Symbol::Symbol() :
SymbolContextScope (),
m_uid (UINT32_MAX),
m_type_data (0),
m_type_data_resolved (false),
m_is_synthetic (false),
m_is_debug (false),
m_is_external (false),
m_size_is_sibling (false),
m_size_is_synthesized (false),
m_size_is_valid (false),
m_demangled_is_synthesized (false),
m_contains_linker_annotations (false),
m_type (eSymbolTypeInvalid),
m_mangled (),
m_addr_range (),
m_flags ()
{
}
Symbol::Symbol
(
uint32_t symID,
const char *name,
bool name_is_mangled,
SymbolType type,
bool external,
bool is_debug,
bool is_trampoline,
bool is_artificial,
const lldb::SectionSP &section_sp,
addr_t offset,
addr_t size,
bool size_is_valid,
bool contains_linker_annotations,
uint32_t flags
) :
SymbolContextScope (),
m_uid (symID),
m_type_data (0),
m_type_data_resolved (false),
m_is_synthetic (is_artificial),
m_is_debug (is_debug),
m_is_external (external),
m_size_is_sibling (false),
m_size_is_synthesized (false),
m_size_is_valid (size_is_valid || size > 0),
m_demangled_is_synthesized (false),
m_contains_linker_annotations (contains_linker_annotations),
m_type (type),
m_mangled (ConstString(name), name_is_mangled),
m_addr_range (section_sp, offset, size),
m_flags (flags)
{
}
Symbol::Symbol
(
uint32_t symID,
const Mangled &mangled,
SymbolType type,
bool external,
bool is_debug,
bool is_trampoline,
bool is_artificial,
const AddressRange &range,
bool size_is_valid,
bool contains_linker_annotations,
uint32_t flags
) :
SymbolContextScope (),
m_uid (symID),
m_type_data (0),
m_type_data_resolved (false),
m_is_synthetic (is_artificial),
m_is_debug (is_debug),
m_is_external (external),
m_size_is_sibling (false),
m_size_is_synthesized (false),
m_size_is_valid (size_is_valid || range.GetByteSize() > 0),
m_demangled_is_synthesized (false),
m_contains_linker_annotations (contains_linker_annotations),
m_type (type),
m_mangled (mangled),
m_addr_range (range),
m_flags (flags)
{
}
Symbol::Symbol(const Symbol& rhs):
SymbolContextScope (rhs),
m_uid (rhs.m_uid),
m_type_data (rhs.m_type_data),
m_type_data_resolved (rhs.m_type_data_resolved),
m_is_synthetic (rhs.m_is_synthetic),
m_is_debug (rhs.m_is_debug),
m_is_external (rhs.m_is_external),
m_size_is_sibling (rhs.m_size_is_sibling),
m_size_is_synthesized (false),
m_size_is_valid (rhs.m_size_is_valid),
m_demangled_is_synthesized (rhs.m_demangled_is_synthesized),
m_contains_linker_annotations (rhs.m_contains_linker_annotations),
m_type (rhs.m_type),
m_mangled (rhs.m_mangled),
m_addr_range (rhs.m_addr_range),
m_flags (rhs.m_flags)
{
}
const Symbol&
Symbol::operator= (const Symbol& rhs)
{
if (this != &rhs)
{
SymbolContextScope::operator= (rhs);
m_uid = rhs.m_uid;
m_type_data = rhs.m_type_data;
m_type_data_resolved = rhs.m_type_data_resolved;
m_is_synthetic = rhs.m_is_synthetic;
m_is_debug = rhs.m_is_debug;
m_is_external = rhs.m_is_external;
m_size_is_sibling = rhs.m_size_is_sibling;
m_size_is_synthesized = rhs.m_size_is_sibling;
m_size_is_valid = rhs.m_size_is_valid;
m_demangled_is_synthesized = rhs.m_demangled_is_synthesized;
m_contains_linker_annotations = rhs.m_contains_linker_annotations;
m_type = rhs.m_type;
m_mangled = rhs.m_mangled;
m_addr_range = rhs.m_addr_range;
m_flags = rhs.m_flags;
}
return *this;
}
void
Symbol::Clear()
{
m_uid = UINT32_MAX;
m_mangled.Clear();
m_type_data = 0;
m_type_data_resolved = false;
m_is_synthetic = false;
m_is_debug = false;
m_is_external = false;
m_size_is_sibling = false;
m_size_is_synthesized = false;
m_size_is_valid = false;
m_demangled_is_synthesized = false;
m_contains_linker_annotations = false;
m_type = eSymbolTypeInvalid;
m_flags = 0;
m_addr_range.Clear();
}
bool
Symbol::ValueIsAddress() const
{
return m_addr_range.GetBaseAddress().GetSection().get() != nullptr;
}
ConstString
Symbol::GetReExportedSymbolName() const
{
if (m_type == eSymbolTypeReExported)
{
// For eSymbolTypeReExported, the "const char *" from a ConstString
// is used as the offset in the address range base address. We can
// then make this back into a string that is the re-exported name.
intptr_t str_ptr = m_addr_range.GetBaseAddress().GetOffset();
if (str_ptr != 0)
return ConstString((const char *)str_ptr);
else
return GetName();
}
return ConstString();
}
FileSpec
Symbol::GetReExportedSymbolSharedLibrary() const
{
if (m_type == eSymbolTypeReExported)
{
// For eSymbolTypeReExported, the "const char *" from a ConstString
// is used as the offset in the address range base address. We can
// then make this back into a string that is the re-exported name.
intptr_t str_ptr = m_addr_range.GetByteSize();
if (str_ptr != 0)
return FileSpec((const char *)str_ptr, false);
}
return FileSpec();
}
void
Symbol::SetReExportedSymbolName(const ConstString &name)
{
SetType (eSymbolTypeReExported);
// For eSymbolTypeReExported, the "const char *" from a ConstString
// is used as the offset in the address range base address.
m_addr_range.GetBaseAddress().SetOffset((uintptr_t)name.GetCString());
}
bool
Symbol::SetReExportedSymbolSharedLibrary(const FileSpec &fspec)
{
if (m_type == eSymbolTypeReExported)
{
// For eSymbolTypeReExported, the "const char *" from a ConstString
// is used as the offset in the address range base address.
m_addr_range.SetByteSize((uintptr_t)ConstString(fspec.GetPath().c_str()).GetCString());
return true;
}
return false;
}
uint32_t
Symbol::GetSiblingIndex() const
{
return m_size_is_sibling ? m_addr_range.GetByteSize() : UINT32_MAX;
}
bool
Symbol::IsTrampoline () const
{
return m_type == eSymbolTypeTrampoline;
}
bool
Symbol::IsIndirect () const
{
return m_type == eSymbolTypeResolver;
}
void
Symbol::GetDescription (Stream *s, lldb::DescriptionLevel level, Target *target) const
{
s->Printf("id = {0x%8.8x}", m_uid);
if (m_addr_range.GetBaseAddress().GetSection())
{
if (ValueIsAddress())
{
const lldb::addr_t byte_size = GetByteSize();
if (byte_size > 0)
{
s->PutCString (", range = ");
m_addr_range.Dump(s, target, Address::DumpStyleLoadAddress, Address::DumpStyleFileAddress);
}
else
{
s->PutCString (", address = ");
m_addr_range.GetBaseAddress().Dump(s, target, Address::DumpStyleLoadAddress, Address::DumpStyleFileAddress);
}
}
else
s->Printf (", value = 0x%16.16" PRIx64, m_addr_range.GetBaseAddress().GetOffset());
}
else
{
if (m_size_is_sibling)
s->Printf (", sibling = %5" PRIu64, m_addr_range.GetBaseAddress().GetOffset());
else
s->Printf (", value = 0x%16.16" PRIx64, m_addr_range.GetBaseAddress().GetOffset());
}
if (m_mangled.GetDemangledName())
s->Printf(", name=\"%s\"", m_mangled.GetDemangledName().AsCString());
if (m_mangled.GetMangledName())
s->Printf(", mangled=\"%s\"", m_mangled.GetMangledName().AsCString());
}
void
Symbol::Dump(Stream *s, Target *target, uint32_t index) const
{
s->Printf("[%5u] %6u %c%c%c %-15s ",
index,
GetID(),
m_is_debug ? 'D' : ' ',
m_is_synthetic ? 'S' : ' ',
m_is_external ? 'X' : ' ',
GetTypeAsString());
// Make sure the size of the symbol is up to date before dumping
GetByteSize();
if (ValueIsAddress())
{
if (!m_addr_range.GetBaseAddress().Dump(s, nullptr, Address::DumpStyleFileAddress))
s->Printf("%*s", 18, "");
s->PutChar(' ');
if (!m_addr_range.GetBaseAddress().Dump(s, target, Address::DumpStyleLoadAddress))
s->Printf("%*s", 18, "");
const char *format = m_size_is_sibling ?
" Sibling -> [%5llu] 0x%8.8x %s\n":
" 0x%16.16" PRIx64 " 0x%8.8x %s\n";
s->Printf( format,
GetByteSize(),
m_flags,
m_mangled.GetName().AsCString(""));
}
else if (m_type == eSymbolTypeReExported)
{
s->Printf (" 0x%8.8x %s",
m_flags,
m_mangled.GetName().AsCString(""));
ConstString reexport_name = GetReExportedSymbolName();
intptr_t shlib = m_addr_range.GetByteSize();
if (shlib)
s->Printf(" -> %s`%s\n", (const char *)shlib, reexport_name.GetCString());
else
s->Printf(" -> %s\n", reexport_name.GetCString());
}
else
{
const char *format = m_size_is_sibling ?
"0x%16.16" PRIx64 " Sibling -> [%5llu] 0x%8.8x %s\n":
"0x%16.16" PRIx64 " 0x%16.16" PRIx64 " 0x%8.8x %s\n";
s->Printf( format,
m_addr_range.GetBaseAddress().GetOffset(),
GetByteSize(),
m_flags,
m_mangled.GetName().AsCString(""));
}
}
uint32_t
Symbol::GetPrologueByteSize ()
{
if (m_type == eSymbolTypeCode || m_type == eSymbolTypeResolver)
{
if (!m_type_data_resolved)
{
m_type_data_resolved = true;
const Address &base_address = m_addr_range.GetBaseAddress();
Function *function = base_address.CalculateSymbolContextFunction();
if (function)
{
// Functions have line entries which can also potentially have end of prologue information.
// So if this symbol points to a function, use the prologue information from there.
m_type_data = function->GetPrologueByteSize();
}
else
{
ModuleSP module_sp (base_address.GetModule());
SymbolContext sc;
if (module_sp)
{
uint32_t resolved_flags = module_sp->ResolveSymbolContextForAddress (base_address,
eSymbolContextLineEntry,
sc);
if (resolved_flags & eSymbolContextLineEntry)
{
// Default to the end of the first line entry.
m_type_data = sc.line_entry.range.GetByteSize();
// Set address for next line.
Address addr (base_address);
addr.Slide (m_type_data);
// Check the first few instructions and look for one that has a line number that is
// different than the first entry. This is also done in Function::GetPrologueByteSize().
uint16_t total_offset = m_type_data;
for (int idx = 0; idx < 6; ++idx)
{
SymbolContext sc_temp;
resolved_flags = module_sp->ResolveSymbolContextForAddress (addr, eSymbolContextLineEntry, sc_temp);
// Make sure we got line number information...
if (!(resolved_flags & eSymbolContextLineEntry))
break;
// If this line number is different than our first one, use it and we're done.
if (sc_temp.line_entry.line != sc.line_entry.line)
{
m_type_data = total_offset;
break;
}
// Slide addr up to the next line address.
addr.Slide (sc_temp.line_entry.range.GetByteSize());
total_offset += sc_temp.line_entry.range.GetByteSize();
// If we've gone too far, bail out.
if (total_offset >= m_addr_range.GetByteSize())
break;
}
// Sanity check - this may be a function in the middle of code that has debug information, but
// not for this symbol. So the line entries surrounding us won't lie inside our function.
// In that case, the line entry will be bigger than we are, so we do that quick check and
// if that is true, we just return 0.
if (m_type_data >= m_addr_range.GetByteSize())
m_type_data = 0;
}
else
{
// TODO: expose something in Process to figure out the
// size of a function prologue.
m_type_data = 0;
}
}
}
}
return m_type_data;
}
return 0;
}
bool
Symbol::Compare(const ConstString& name, SymbolType type) const
{
if (type == eSymbolTypeAny || m_type == type)
return m_mangled.GetMangledName() == name || m_mangled.GetDemangledName() == name;
return false;
}
#define ENUM_TO_CSTRING(x) case eSymbolType##x: return #x;
const char *
Symbol::GetTypeAsString() const
{
switch (m_type)
{
ENUM_TO_CSTRING(Invalid);
ENUM_TO_CSTRING(Absolute);
ENUM_TO_CSTRING(Code);
ENUM_TO_CSTRING(Resolver);
ENUM_TO_CSTRING(Data);
ENUM_TO_CSTRING(Trampoline);
ENUM_TO_CSTRING(Runtime);
ENUM_TO_CSTRING(Exception);
ENUM_TO_CSTRING(SourceFile);
ENUM_TO_CSTRING(HeaderFile);
ENUM_TO_CSTRING(ObjectFile);
ENUM_TO_CSTRING(CommonBlock);
ENUM_TO_CSTRING(Block);
ENUM_TO_CSTRING(Local);
ENUM_TO_CSTRING(Param);
ENUM_TO_CSTRING(Variable);
ENUM_TO_CSTRING(VariableType);
ENUM_TO_CSTRING(LineEntry);
ENUM_TO_CSTRING(LineHeader);
ENUM_TO_CSTRING(ScopeBegin);
ENUM_TO_CSTRING(ScopeEnd);
ENUM_TO_CSTRING(Additional);
ENUM_TO_CSTRING(Compiler);
ENUM_TO_CSTRING(Instrumentation);
ENUM_TO_CSTRING(Undefined);
ENUM_TO_CSTRING(ObjCClass);
ENUM_TO_CSTRING(ObjCMetaClass);
ENUM_TO_CSTRING(ObjCIVar);
ENUM_TO_CSTRING(ReExported);
default:
break;
}
return "<unknown SymbolType>";
}
void
Symbol::CalculateSymbolContext (SymbolContext *sc)
{
// Symbols can reconstruct the symbol and the module in the symbol context
sc->symbol = this;
if (ValueIsAddress())
sc->module_sp = GetAddress().GetModule();
else
sc->module_sp.reset();
}
ModuleSP
Symbol::CalculateSymbolContextModule ()
{
if (ValueIsAddress())
return GetAddress().GetModule();
return ModuleSP();
}
Symbol *
Symbol::CalculateSymbolContextSymbol ()
{
return this;
}
void
Symbol::DumpSymbolContext (Stream *s)
{
bool dumped_module = false;
if (ValueIsAddress())
{
ModuleSP module_sp (GetAddress().GetModule());
if (module_sp)
{
dumped_module = true;
module_sp->DumpSymbolContext(s);
}
}
if (dumped_module)
s->PutCString(", ");
s->Printf("Symbol{0x%8.8x}", GetID());
}
lldb::addr_t
Symbol::GetByteSize () const
{
return m_addr_range.GetByteSize();
}
Symbol *
Symbol::ResolveReExportedSymbolInModuleSpec (Target &target,
ConstString &reexport_name,
ModuleSpec &module_spec,
ModuleList &seen_modules) const
{
ModuleSP module_sp;
if (module_spec.GetFileSpec())
{
// Try searching for the module file spec first using the full path
module_sp = target.GetImages().FindFirstModule(module_spec);
if (!module_sp)
{
// Next try and find the module by basename in case environment
// variables or other runtime trickery causes shared libraries
// to be loaded from alternate paths
module_spec.GetFileSpec().GetDirectory().Clear();
module_sp = target.GetImages().FindFirstModule(module_spec);
}
}
if (module_sp)
{
// There should not be cycles in the reexport list, but we don't want to crash if there are so make sure
// we haven't seen this before:
if (!seen_modules.AppendIfNeeded(module_sp))
return nullptr;
lldb_private::SymbolContextList sc_list;
module_sp->FindSymbolsWithNameAndType(reexport_name, eSymbolTypeAny, sc_list);
const size_t num_scs = sc_list.GetSize();
if (num_scs > 0)
{
for (size_t i=0; i<num_scs; ++i)
{
lldb_private::SymbolContext sc;
if (sc_list.GetContextAtIndex(i, sc))
{
if (sc.symbol->IsExternal())
return sc.symbol;
}
}
}
// If we didn't find the symbol in this module, it may be because this module re-exports some
// whole other library. We have to search those as well:
seen_modules.Append(module_sp);
FileSpecList reexported_libraries = module_sp->GetObjectFile()->GetReExportedLibraries();
size_t num_reexported_libraries = reexported_libraries.GetSize();
for (size_t idx = 0; idx < num_reexported_libraries; idx++)
{
ModuleSpec reexported_module_spec;
reexported_module_spec.GetFileSpec() = reexported_libraries.GetFileSpecAtIndex(idx);
Symbol *result_symbol = ResolveReExportedSymbolInModuleSpec(target,
reexport_name,
reexported_module_spec,
seen_modules);
if (result_symbol)
return result_symbol;
}
}
return nullptr;
}
Symbol *
Symbol::ResolveReExportedSymbol (Target &target) const
{
ConstString reexport_name (GetReExportedSymbolName());
if (reexport_name)
{
ModuleSpec module_spec;
ModuleList seen_modules;
module_spec.GetFileSpec() = GetReExportedSymbolSharedLibrary();
if (module_spec.GetFileSpec())
{
return ResolveReExportedSymbolInModuleSpec(target, reexport_name, module_spec, seen_modules);
}
}
return nullptr;
}
lldb::addr_t
Symbol::ResolveCallableAddress(Target &target) const
{
if (GetType() == lldb::eSymbolTypeUndefined)
return LLDB_INVALID_ADDRESS;
Address func_so_addr;
bool is_indirect = IsIndirect();
if (GetType() == eSymbolTypeReExported)
{
Symbol *reexported_symbol = ResolveReExportedSymbol(target);
if (reexported_symbol)
{
func_so_addr = reexported_symbol->GetAddress();
is_indirect = reexported_symbol->IsIndirect();
}
}
else
{
func_so_addr = GetAddress();
is_indirect = IsIndirect();
}
if (func_so_addr.IsValid())
{
if (!target.GetProcessSP() && is_indirect)
{
// can't resolve indirect symbols without calling a function...
return LLDB_INVALID_ADDRESS;
}
lldb::addr_t load_addr = func_so_addr.GetCallableLoadAddress (&target, is_indirect);
if (load_addr != LLDB_INVALID_ADDRESS)
{
return load_addr;
}
}
return LLDB_INVALID_ADDRESS;
}
lldb::DisassemblerSP
Symbol::GetInstructions (const ExecutionContext &exe_ctx,
const char *flavor,
bool prefer_file_cache)
{
ModuleSP module_sp (m_addr_range.GetBaseAddress().GetModule());
if (module_sp)
{
const bool prefer_file_cache = false;
return Disassembler::DisassembleRange (module_sp->GetArchitecture(),
nullptr,
flavor,
exe_ctx,
m_addr_range,
prefer_file_cache);
}
return lldb::DisassemblerSP();
}
bool
Symbol::GetDisassembly (const ExecutionContext &exe_ctx,
const char *flavor,
bool prefer_file_cache,
Stream &strm)
{
lldb::DisassemblerSP disassembler_sp = GetInstructions (exe_ctx, flavor, prefer_file_cache);
if (disassembler_sp)
{
const bool show_address = true;
const bool show_bytes = false;
disassembler_sp->GetInstructionList().Dump (&strm, show_address, show_bytes, &exe_ctx);
return true;
}
return false;
}
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