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