Files
clang-p2996/lldb/source/Plugins/ObjectFile/JIT/ObjectFileJIT.cpp
Ed Maste d13f691f41 Improve FreeBSD kernel debugging
FreeBSD kernel modules are actually relocatable (.o) ELF files and this
previously caused some issues for LLDB. This change addresses these when
using lldb to symbolicate FreeBSD kernel backtraces. 

The major problems:

- Relocations were not being applied to the DWARF debug info despite
  there being code to do this. Several issues prevented it from working:

  - Relocations are computed at the same time as the symbol table, but
    in the case of split debug files, symbol table parsing always
    redirects to the primary object file, meaning that relocations would
    never be applied in the debug file.

  - There's actually no guarantee that the symbol table has been parsed
    yet when trying to parse debug information.

  - When actually applying relocations, it will segfault because the
    object files are not mapped with MAP_PRIVATE and PROT_WRITE.

- LLDB returned invalid results when performing ordinary address-to-
  symbol resolution. It turned out that the addresses specified in the
  section headers were all 0, so LLDB believed all the sections had
  overlapping "file addresses" and would sometimes return a symbol from
  the wrong section.

Patch by Brian Koropoff

Differential Revision:	https://reviews.llvm.org/D38142

llvm-svn: 314672
2017-10-02 14:35:07 +00:00

268 lines
8.6 KiB
C++

//===-- ObjectFileJIT.cpp ---------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/StringRef.h"
#include "ObjectFileJIT.h"
#include "lldb/Core/ArchSpec.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/FileSpecList.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/RangeMap.h"
#include "lldb/Core/Section.h"
#include "lldb/Core/StreamFile.h"
#include "lldb/Host/Host.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Target/Platform.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/SectionLoadList.h"
#include "lldb/Target/Target.h"
#include "lldb/Utility/DataBuffer.h"
#include "lldb/Utility/DataBufferHeap.h"
#include "lldb/Utility/FileSpec.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/StreamString.h"
#include "lldb/Utility/Timer.h"
#include "lldb/Utility/UUID.h"
#ifndef __APPLE__
#include "Utility/UuidCompatibility.h"
#endif
using namespace lldb;
using namespace lldb_private;
void ObjectFileJIT::Initialize() {
PluginManager::RegisterPlugin(GetPluginNameStatic(),
GetPluginDescriptionStatic(), CreateInstance,
CreateMemoryInstance, GetModuleSpecifications);
}
void ObjectFileJIT::Terminate() {
PluginManager::UnregisterPlugin(CreateInstance);
}
lldb_private::ConstString ObjectFileJIT::GetPluginNameStatic() {
static ConstString g_name("jit");
return g_name;
}
const char *ObjectFileJIT::GetPluginDescriptionStatic() {
return "JIT code object file";
}
ObjectFile *ObjectFileJIT::CreateInstance(const lldb::ModuleSP &module_sp,
DataBufferSP &data_sp,
lldb::offset_t data_offset,
const FileSpec *file,
lldb::offset_t file_offset,
lldb::offset_t length) {
// JIT'ed object file is backed by the ObjectFileJITDelegate, never
// read from a file
return NULL;
}
ObjectFile *ObjectFileJIT::CreateMemoryInstance(const lldb::ModuleSP &module_sp,
DataBufferSP &data_sp,
const ProcessSP &process_sp,
lldb::addr_t header_addr) {
// JIT'ed object file is backed by the ObjectFileJITDelegate, never
// read from memory
return NULL;
}
size_t ObjectFileJIT::GetModuleSpecifications(
const lldb_private::FileSpec &file, lldb::DataBufferSP &data_sp,
lldb::offset_t data_offset, lldb::offset_t file_offset,
lldb::offset_t length, lldb_private::ModuleSpecList &specs) {
// JIT'ed object file can't be read from a file on disk
return 0;
}
ObjectFileJIT::ObjectFileJIT(const lldb::ModuleSP &module_sp,
const ObjectFileJITDelegateSP &delegate_sp)
: ObjectFile(module_sp, NULL, 0, 0, DataBufferSP(), 0), m_delegate_wp() {
if (delegate_sp) {
m_delegate_wp = delegate_sp;
m_data.SetByteOrder(delegate_sp->GetByteOrder());
m_data.SetAddressByteSize(delegate_sp->GetAddressByteSize());
}
}
ObjectFileJIT::~ObjectFileJIT() {}
bool ObjectFileJIT::ParseHeader() {
// JIT code is never in a file, nor is it required to have any header
return false;
}
ByteOrder ObjectFileJIT::GetByteOrder() const { return m_data.GetByteOrder(); }
bool ObjectFileJIT::IsExecutable() const { return false; }
uint32_t ObjectFileJIT::GetAddressByteSize() const {
return m_data.GetAddressByteSize();
}
Symtab *ObjectFileJIT::GetSymtab() {
ModuleSP module_sp(GetModule());
if (module_sp) {
std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
if (m_symtab_ap.get() == NULL) {
m_symtab_ap.reset(new Symtab(this));
std::lock_guard<std::recursive_mutex> symtab_guard(
m_symtab_ap->GetMutex());
ObjectFileJITDelegateSP delegate_sp(m_delegate_wp.lock());
if (delegate_sp)
delegate_sp->PopulateSymtab(this, *m_symtab_ap);
// TODO: get symbols from delegate
m_symtab_ap->Finalize();
}
}
return m_symtab_ap.get();
}
bool ObjectFileJIT::IsStripped() {
return false; // JIT code that is in a module is never stripped
}
void ObjectFileJIT::CreateSections(SectionList &unified_section_list) {
if (!m_sections_ap.get()) {
m_sections_ap.reset(new SectionList());
ObjectFileJITDelegateSP delegate_sp(m_delegate_wp.lock());
if (delegate_sp) {
delegate_sp->PopulateSectionList(this, *m_sections_ap);
unified_section_list = *m_sections_ap;
}
}
}
void ObjectFileJIT::Dump(Stream *s) {
ModuleSP module_sp(GetModule());
if (module_sp) {
std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
s->Printf("%p: ", static_cast<void *>(this));
s->Indent();
s->PutCString("ObjectFileJIT");
ArchSpec arch;
if (GetArchitecture(arch))
*s << ", arch = " << arch.GetArchitectureName();
s->EOL();
SectionList *sections = GetSectionList();
if (sections)
sections->Dump(s, NULL, true, UINT32_MAX);
if (m_symtab_ap.get())
m_symtab_ap->Dump(s, NULL, eSortOrderNone);
}
}
bool ObjectFileJIT::GetUUID(lldb_private::UUID *uuid) {
// TODO: maybe get from delegate, not needed for first pass
return false;
}
uint32_t ObjectFileJIT::GetDependentModules(FileSpecList &files) {
// JIT modules don't have dependencies, but they could
// if external functions are called and we know where they are
files.Clear();
return 0;
}
lldb_private::Address ObjectFileJIT::GetEntryPointAddress() {
return Address();
}
lldb_private::Address ObjectFileJIT::GetHeaderAddress() { return Address(); }
ObjectFile::Type ObjectFileJIT::CalculateType() { return eTypeJIT; }
ObjectFile::Strata ObjectFileJIT::CalculateStrata() { return eStrataJIT; }
bool ObjectFileJIT::GetArchitecture(ArchSpec &arch) {
ObjectFileJITDelegateSP delegate_sp(m_delegate_wp.lock());
if (delegate_sp)
return delegate_sp->GetArchitecture(arch);
return false;
}
//------------------------------------------------------------------
// PluginInterface protocol
//------------------------------------------------------------------
lldb_private::ConstString ObjectFileJIT::GetPluginName() {
return GetPluginNameStatic();
}
uint32_t ObjectFileJIT::GetPluginVersion() { return 1; }
bool ObjectFileJIT::SetLoadAddress(Target &target, lldb::addr_t value,
bool value_is_offset) {
size_t num_loaded_sections = 0;
SectionList *section_list = GetSectionList();
if (section_list) {
const size_t num_sections = section_list->GetSize();
// "value" is an offset to apply to each top level segment
for (size_t sect_idx = 0; sect_idx < num_sections; ++sect_idx) {
// Iterate through the object file sections to find all
// of the sections that size on disk (to avoid __PAGEZERO)
// and load them
SectionSP section_sp(section_list->GetSectionAtIndex(sect_idx));
if (section_sp && section_sp->GetFileSize() > 0 &&
section_sp->IsThreadSpecific() == false) {
if (target.GetSectionLoadList().SetSectionLoadAddress(
section_sp, section_sp->GetFileAddress() + value))
++num_loaded_sections;
}
}
}
return num_loaded_sections > 0;
}
size_t ObjectFileJIT::ReadSectionData(lldb_private::Section *section,
lldb::offset_t section_offset, void *dst,
size_t dst_len) {
lldb::offset_t file_size = section->GetFileSize();
if (section_offset < file_size) {
size_t src_len = file_size - section_offset;
if (src_len > dst_len)
src_len = dst_len;
const uint8_t *src =
((uint8_t *)(uintptr_t)section->GetFileOffset()) + section_offset;
memcpy(dst, src, src_len);
return src_len;
}
return 0;
}
size_t ObjectFileJIT::ReadSectionData(
lldb_private::Section *section,
lldb_private::DataExtractor &section_data) {
if (section->GetFileSize()) {
const void *src = (void *)(uintptr_t)section->GetFileOffset();
DataBufferSP data_sp(
new lldb_private::DataBufferHeap(src, section->GetFileSize()));
if (data_sp) {
section_data.SetData(data_sp, 0, data_sp->GetByteSize());
section_data.SetByteOrder(GetByteOrder());
section_data.SetAddressByteSize(GetAddressByteSize());
return section_data.GetByteSize();
}
}
section_data.Clear();
return 0;
}