text: //===-- DynamicLoaderHexagonDYLD.cpp --------------------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  
  #include "lldb/Breakpoint/BreakpointLocation.h"
  #include "lldb/Core/Module.h"
  #include "lldb/Core/ModuleSpec.h"
  #include "lldb/Core/PluginManager.h"
  #include "lldb/Core/Section.h"
  #include "lldb/Symbol/ObjectFile.h"
  #include "lldb/Target/Process.h"
  #include "lldb/Target/Target.h"
  #include "lldb/Target/Thread.h"
  #include "lldb/Target/ThreadPlanRunToAddress.h"
  #include "lldb/Utility/Log.h"
  
  #include "DynamicLoaderHexagonDYLD.h"
  
  #include <memory>
  
  using namespace lldb;
  using namespace lldb_private;
  
  LLDB_PLUGIN_DEFINE(DynamicLoaderHexagonDYLD)
  
  // Aidan 21/05/2014
  //
  // Notes about hexagon dynamic loading:
  //
  //      When we connect to a target we find the dyld breakpoint address.  We put
  //      a
  //      breakpoint there with a callback 'RendezvousBreakpointHit()'.
  //
  //      It is possible to find the dyld structure address from the ELF symbol
  //      table,
  //      but in the case of the simulator it has not been initialized before the
  //      target calls dlinit().
  //
  //      We can only safely parse the dyld structure after we hit the dyld
  //      breakpoint
  //      since at that time we know dlinit() must have been called.
  //
  
  // Find the load address of a symbol
  static lldb::addr_t findSymbolAddress(Process *proc, ConstString findName) {
    assert(proc != nullptr);
  
    ModuleSP module = proc->GetTarget().GetExecutableModule();
    assert(module.get() != nullptr);
  
    ObjectFile *exe = module->GetObjectFile();
    assert(exe != nullptr);
  
    lldb_private::Symtab *symtab = exe->GetSymtab();
    assert(symtab != nullptr);
  
    for (size_t i = 0; i < symtab->GetNumSymbols(); i++) {
      const Symbol *sym = symtab->SymbolAtIndex(i);
      assert(sym != nullptr);
      ConstString symName = sym->GetName();
  
      if (ConstString::Compare(findName, symName) == 0) {
        Address addr = sym->GetAddress();
        return addr.GetLoadAddress(&proc->GetTarget());
      }
    }
    return LLDB_INVALID_ADDRESS;
  }
  
  void DynamicLoaderHexagonDYLD::Initialize() {
    PluginManager::RegisterPlugin(GetPluginNameStatic(),
                                  GetPluginDescriptionStatic(), CreateInstance);
  }
  
  void DynamicLoaderHexagonDYLD::Terminate() {}
  
  llvm::StringRef DynamicLoaderHexagonDYLD::GetPluginDescriptionStatic() {
    return "Dynamic loader plug-in that watches for shared library "
           "loads/unloads in Hexagon processes.";
  }
  
  DynamicLoader *DynamicLoaderHexagonDYLD::CreateInstance(Process *process,
                                                          bool force) {
    bool create = force;
    if (!create) {
      const llvm::Triple &triple_ref =
          process->GetTarget().GetArchitecture().GetTriple();
      if (triple_ref.getArch() == llvm::Triple::hexagon)
        create = true;
    }
  
    if (create)
      return new DynamicLoaderHexagonDYLD(process);
    return nullptr;
  }
  
  DynamicLoaderHexagonDYLD::DynamicLoaderHexagonDYLD(Process *process)
      : DynamicLoader(process), m_rendezvous(process),
        m_load_offset(LLDB_INVALID_ADDRESS), m_entry_point(LLDB_INVALID_ADDRESS),
        m_dyld_bid(LLDB_INVALID_BREAK_ID) {}
  
  DynamicLoaderHexagonDYLD::~DynamicLoaderHexagonDYLD() {
    if (m_dyld_bid != LLDB_INVALID_BREAK_ID) {
      m_process->GetTarget().RemoveBreakpointByID(m_dyld_bid);
      m_dyld_bid = LLDB_INVALID_BREAK_ID;
    }
  }
  
  void DynamicLoaderHexagonDYLD::DidAttach() {
    ModuleSP executable;
    addr_t load_offset;
  
    executable = GetTargetExecutable();
  
    // Find the difference between the desired load address in the elf file and
    // the real load address in memory
    load_offset = ComputeLoadOffset();
  
    // Check that there is a valid executable
    if (executable.get() == nullptr)
      return;
  
    // Disable JIT for hexagon targets because its not supported
    m_process->SetCanJIT(false);
  
    // Enable Interpreting of function call expressions
    m_process->SetCanInterpretFunctionCalls(true);
  
    // Add the current executable to the module list
    ModuleList module_list;
    module_list.Append(executable);
  
    // Map the loaded sections of this executable
    if (load_offset != LLDB_INVALID_ADDRESS)
      UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_offset, true);
  
    // AD: confirm this?
    // Load into LLDB all of the currently loaded executables in the stub
    LoadAllCurrentModules();
  
    // AD: confirm this?
    // Callback for the target to give it the loaded module list
    m_process->GetTarget().ModulesDidLoad(module_list);
  
    // Try to set a breakpoint at the rendezvous breakpoint. DidLaunch uses
    // ProbeEntry() instead.  That sets a breakpoint, at the dyld breakpoint
    // address, with a callback so that when hit, the dyld structure can be
    // parsed.
    if (!SetRendezvousBreakpoint()) {
      // fail
    }
  }
  
  void DynamicLoaderHexagonDYLD::DidLaunch() {}
  
  /// Checks to see if the target module has changed, updates the target
  /// accordingly and returns the target executable module.
  ModuleSP DynamicLoaderHexagonDYLD::GetTargetExecutable() {
    Target &target = m_process->GetTarget();
    ModuleSP executable = target.GetExecutableModule();
  
    // There is no executable
    if (!executable.get())
      return executable;
  
    // The target executable file does not exits
    if (!FileSystem::Instance().Exists(executable->GetFileSpec()))
      return executable;
  
    // Prep module for loading
    ModuleSpec module_spec(executable->GetFileSpec(),
                           executable->GetArchitecture());
    ModuleSP module_sp(new Module(module_spec));
  
    // Check if the executable has changed and set it to the target executable if
    // they differ.
    if (module_sp.get() && module_sp->GetUUID().IsValid() &&
        executable->GetUUID().IsValid()) {
      // if the executable has changed ??
      if (module_sp->GetUUID() != executable->GetUUID())
        executable.reset();
    } else if (executable->FileHasChanged())
      executable.reset();
  
    if (executable.get())
      return executable;
  
    // TODO: What case is this code used?
    executable = target.GetOrCreateModule(module_spec, true /* notify */);
    if (executable.get() != target.GetExecutableModulePointer()) {
      // Don't load dependent images since we are in dyld where we will know and
      // find out about all images that are loaded
      target.SetExecutableModule(executable, eLoadDependentsNo);
    }
  
    return executable;
  }
  
  // AD: Needs to be updated?
  Status DynamicLoaderHexagonDYLD::CanLoadImage() { return Status(); }
  
  void DynamicLoaderHexagonDYLD::UpdateLoadedSections(ModuleSP module,
                                                      addr_t link_map_addr,
                                                      addr_t base_addr,
                                                      bool base_addr_is_offset) {
    Target &target = m_process->GetTarget();
    const SectionList *sections = GetSectionListFromModule(module);
  
    assert(sections && "SectionList missing from loaded module.");
  
    m_loaded_modules[module] = link_map_addr;
  
    const size_t num_sections = sections->GetSize();
  
    for (unsigned i = 0; i < num_sections; ++i) {
      SectionSP section_sp(sections->GetSectionAtIndex(i));
      lldb::addr_t new_load_addr = section_sp->GetFileAddress() + base_addr;
  
      // AD: 02/05/14
      //   since our memory map starts from address 0, we must not ignore
      //   sections that load to address 0.  This violates the reference
      //   ELF spec, however is used for Hexagon.
  
      // If the file address of the section is zero then this is not an
      // allocatable/loadable section (property of ELF sh_addr).  Skip it.
      //      if (new_load_addr == base_addr)
      //          continue;
  
      target.SetSectionLoadAddress(section_sp, new_load_addr);
    }
  }
  
  /// Removes the loaded sections from the target in \p module.
  ///
  /// \param module The module to traverse.
  void DynamicLoaderHexagonDYLD::UnloadSections(const ModuleSP module) {
    Target &target = m_process->GetTarget();
    const SectionList *sections = GetSectionListFromModule(module);
  
    assert(sections && "SectionList missing from unloaded module.");
  
    m_loaded_modules.erase(module);
  
    const size_t num_sections = sections->GetSize();
    for (size_t i = 0; i < num_sections; ++i) {
      SectionSP section_sp(sections->GetSectionAtIndex(i));
      target.SetSectionUnloaded(section_sp);
    }
  }
  
  // Place a breakpoint on <_rtld_debug_state>
  bool DynamicLoaderHexagonDYLD::SetRendezvousBreakpoint() {
    Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
  
    // This is the original code, which want to look in the rendezvous structure
    // to find the breakpoint address.  Its backwards for us, since we can easily
    // find the breakpoint address, since it is exported in our executable. We
    // however know that we cant read the Rendezvous structure until we have hit
    // the breakpoint once.
    const ConstString dyldBpName("_rtld_debug_state");
    addr_t break_addr = findSymbolAddress(m_process, dyldBpName);
  
    Target &target = m_process->GetTarget();
  
    // Do not try to set the breakpoint if we don't know where to put it
    if (break_addr == LLDB_INVALID_ADDRESS) {
      LLDB_LOGF(log, "Unable to locate _rtld_debug_state breakpoint address");
  
      return false;
    }
  
    // Save the address of the rendezvous structure
    m_rendezvous.SetBreakAddress(break_addr);
  
    // If we haven't set the breakpoint before then set it
    if (m_dyld_bid == LLDB_INVALID_BREAK_ID) {
      Breakpoint *dyld_break =
          target.CreateBreakpoint(break_addr, true, false).get();
      dyld_break->SetCallback(RendezvousBreakpointHit, this, true);
      dyld_break->SetBreakpointKind("shared-library-event");
      m_dyld_bid = dyld_break->GetID();
  
      // Make sure our breakpoint is at the right address.
      assert(target.GetBreakpointByID(m_dyld_bid)
                 ->FindLocationByAddress(break_addr)
                 ->GetBreakpoint()
                 .GetID() == m_dyld_bid);
  
      if (log && dyld_break == nullptr)
        LLDB_LOGF(log, "Failed to create _rtld_debug_state breakpoint");
  
      // check we have successfully set bp
      return (dyld_break != nullptr);
    } else
      // rendezvous already set
      return true;
  }
  
  // We have just hit our breakpoint at <_rtld_debug_state>
  bool DynamicLoaderHexagonDYLD::RendezvousBreakpointHit(
      void *baton, StoppointCallbackContext *context, user_id_t break_id,
      user_id_t break_loc_id) {
    Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
  
    LLDB_LOGF(log, "Rendezvous breakpoint hit!");
  
    DynamicLoaderHexagonDYLD *dyld_instance = nullptr;
    dyld_instance = static_cast<DynamicLoaderHexagonDYLD *>(baton);
  
    // if the dyld_instance is still not valid then try to locate it on the
    // symbol table
    if (!dyld_instance->m_rendezvous.IsValid()) {
      Process *proc = dyld_instance->m_process;
  
      const ConstString dyldStructName("_rtld_debug");
      addr_t structAddr = findSymbolAddress(proc, dyldStructName);
  
      if (structAddr != LLDB_INVALID_ADDRESS) {
        dyld_instance->m_rendezvous.SetRendezvousAddress(structAddr);
  
        LLDB_LOGF(log, "Found _rtld_debug structure @ 0x%08" PRIx64, structAddr);
      } else {
        LLDB_LOGF(log, "Unable to resolve the _rtld_debug structure");
      }
    }
  
    dyld_instance->RefreshModules();
  
    // Return true to stop the target, false to just let the target run.
    return dyld_instance->GetStopWhenImagesChange();
  }
  
  /// Helper method for RendezvousBreakpointHit.  Updates LLDB's current set
  /// of loaded modules.
  void DynamicLoaderHexagonDYLD::RefreshModules() {
    Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
  
    if (!m_rendezvous.Resolve())
      return;
  
    HexagonDYLDRendezvous::iterator I;
    HexagonDYLDRendezvous::iterator E;
  
    ModuleList &loaded_modules = m_process->GetTarget().GetImages();
  
    if (m_rendezvous.ModulesDidLoad()) {
      ModuleList new_modules;
  
      E = m_rendezvous.loaded_end();
      for (I = m_rendezvous.loaded_begin(); I != E; ++I) {
        FileSpec file(I->path);
        FileSystem::Instance().Resolve(file);
        ModuleSP module_sp =
            LoadModuleAtAddress(file, I->link_addr, I->base_addr, true);
        if (module_sp.get()) {
          loaded_modules.AppendIfNeeded(module_sp);
          new_modules.Append(module_sp);
        }
  
        if (log) {
          LLDB_LOGF(log, "Target is loading '%s'", I->path.c_str());
          if (!module_sp.get())
            LLDB_LOGF(log, "LLDB failed to load '%s'", I->path.c_str());
          else
            LLDB_LOGF(log, "LLDB successfully loaded '%s'", I->path.c_str());
        }
      }
      m_process->GetTarget().ModulesDidLoad(new_modules);
    }
  
    if (m_rendezvous.ModulesDidUnload()) {
      ModuleList old_modules;
  
      E = m_rendezvous.unloaded_end();
      for (I = m_rendezvous.unloaded_begin(); I != E; ++I) {
        FileSpec file(I->path);
        FileSystem::Instance().Resolve(file);
        ModuleSpec module_spec(file);
        ModuleSP module_sp = loaded_modules.FindFirstModule(module_spec);
  
        if (module_sp.get()) {
          old_modules.Append(module_sp);
          UnloadSections(module_sp);
        }
  
        LLDB_LOGF(log, "Target is unloading '%s'", I->path.c_str());
      }
      loaded_modules.Remove(old_modules);
      m_process->GetTarget().ModulesDidUnload(old_modules, false);
    }
  }
  
  // AD:	This is very different to the Static Loader code.
  //		It may be wise to look over this and its relation to stack
  //		unwinding.
  ThreadPlanSP
  DynamicLoaderHexagonDYLD::GetStepThroughTrampolinePlan(Thread &thread,
                                                         bool stop) {
    ThreadPlanSP thread_plan_sp;
  
    StackFrame *frame = thread.GetStackFrameAtIndex(0).get();
    const SymbolContext &context = frame->GetSymbolContext(eSymbolContextSymbol);
    Symbol *sym = context.symbol;
  
    if (sym == nullptr || !sym->IsTrampoline())
      return thread_plan_sp;
  
    const ConstString sym_name =
        sym->GetMangled().GetName(Mangled::ePreferMangled);
    if (!sym_name)
      return thread_plan_sp;
  
    SymbolContextList target_symbols;
    Target &target = thread.GetProcess()->GetTarget();
    const ModuleList &images = target.GetImages();
  
    images.FindSymbolsWithNameAndType(sym_name, eSymbolTypeCode, target_symbols);
    size_t num_targets = target_symbols.GetSize();
    if (!num_targets)
      return thread_plan_sp;
  
    typedef std::vector<lldb::addr_t> AddressVector;
    AddressVector addrs;
    for (size_t i = 0; i < num_targets; ++i) {
      SymbolContext context;
      AddressRange range;
      if (target_symbols.GetContextAtIndex(i, context)) {
        context.GetAddressRange(eSymbolContextEverything, 0, false, range);
        lldb::addr_t addr = range.GetBaseAddress().GetLoadAddress(&target);
        if (addr != LLDB_INVALID_ADDRESS)
          addrs.push_back(addr);
      }
    }
  
    if (addrs.size() > 0) {
      AddressVector::iterator start = addrs.begin();
      AddressVector::iterator end = addrs.end();
  
      llvm::sort(start, end);
      addrs.erase(std::unique(start, end), end);
      thread_plan_sp =
          std::make_shared<ThreadPlanRunToAddress>(thread, addrs, stop);
    }
  
    return thread_plan_sp;
  }
  
  /// Helper for the entry breakpoint callback.  Resolves the load addresses
  /// of all dependent modules.
  void DynamicLoaderHexagonDYLD::LoadAllCurrentModules() {
    HexagonDYLDRendezvous::iterator I;
    HexagonDYLDRendezvous::iterator E;
    ModuleList module_list;
  
    if (!m_rendezvous.Resolve()) {
      Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
      LLDB_LOGF(
          log,
          "DynamicLoaderHexagonDYLD::%s unable to resolve rendezvous address",
          __FUNCTION__);
      return;
    }
  
    // The rendezvous class doesn't enumerate the main module, so track that
    // ourselves here.
    ModuleSP executable = GetTargetExecutable();
    m_loaded_modules[executable] = m_rendezvous.GetLinkMapAddress();
  
    for (I = m_rendezvous.begin(), E = m_rendezvous.end(); I != E; ++I) {
      const char *module_path = I->path.c_str();
      FileSpec file(module_path);
      ModuleSP module_sp =
          LoadModuleAtAddress(file, I->link_addr, I->base_addr, true);
      if (module_sp.get()) {
        module_list.Append(module_sp);
      } else {
        Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
        LLDB_LOGF(log,
                  "DynamicLoaderHexagonDYLD::%s failed loading module %s at "
                  "0x%" PRIx64,
                  __FUNCTION__, module_path, I->base_addr);
      }
    }
  
    m_process->GetTarget().ModulesDidLoad(module_list);
  }
  
  /// Computes a value for m_load_offset returning the computed address on
  /// success and LLDB_INVALID_ADDRESS on failure.
  addr_t DynamicLoaderHexagonDYLD::ComputeLoadOffset() {
    // Here we could send a GDB packet to know the load offset
    //
    // send:    $qOffsets#4b
    // get:     Text=0;Data=0;Bss=0
    //
    // Currently qOffsets is not supported by pluginProcessGDBRemote
    //
    return 0;
  }
  
  // Here we must try to read the entry point directly from the elf header.  This
  // is possible if the process is not relocatable or dynamically linked.
  //
  // an alternative is to look at the PC if we can be sure that we have connected
  // when the process is at the entry point.
  // I dont think that is reliable for us.
  addr_t DynamicLoaderHexagonDYLD::GetEntryPoint() {
    if (m_entry_point != LLDB_INVALID_ADDRESS)
      return m_entry_point;
    // check we have a valid process
    if (m_process == nullptr)
      return LLDB_INVALID_ADDRESS;
    // Get the current executable module
    Module &module = *(m_process->GetTarget().GetExecutableModule().get());
    // Get the object file (elf file) for this module
    lldb_private::ObjectFile &object = *(module.GetObjectFile());
    // Check if the file is executable (ie, not shared object or relocatable)
    if (object.IsExecutable()) {
      // Get the entry point address for this object
      lldb_private::Address entry = object.GetEntryPointAddress();
      // Return the entry point address
      return entry.GetFileAddress();
    }
    // No idea so back out
    return LLDB_INVALID_ADDRESS;
  }
  
  const SectionList *DynamicLoaderHexagonDYLD::GetSectionListFromModule(
      const ModuleSP module) const {
    SectionList *sections = nullptr;
    if (module.get()) {
      ObjectFile *obj_file = module->GetObjectFile();
      if (obj_file) {
        sections = obj_file->GetSectionList();
      }
    }
    return sections;
  }
  
  static int ReadInt(Process *process, addr_t addr) {
    Status error;
    int value = (int)process->ReadUnsignedIntegerFromMemory(
        addr, sizeof(uint32_t), 0, error);
    if (error.Fail())
      return -1;
    else
      return value;
  }
  
  lldb::addr_t
  DynamicLoaderHexagonDYLD::GetThreadLocalData(const lldb::ModuleSP module,
                                               const lldb::ThreadSP thread,
                                               lldb::addr_t tls_file_addr) {
    auto it = m_loaded_modules.find(module);
    if (it == m_loaded_modules.end())
      return LLDB_INVALID_ADDRESS;
  
    addr_t link_map = it->second;
    if (link_map == LLDB_INVALID_ADDRESS)
      return LLDB_INVALID_ADDRESS;
  
    const HexagonDYLDRendezvous::ThreadInfo &metadata =
        m_rendezvous.GetThreadInfo();
    if (!metadata.valid)
      return LLDB_INVALID_ADDRESS;
  
    // Get the thread pointer.
    addr_t tp = thread->GetThreadPointer();
    if (tp == LLDB_INVALID_ADDRESS)
      return LLDB_INVALID_ADDRESS;
  
    // Find the module's modid.
    int modid = ReadInt(m_process, link_map + metadata.modid_offset);
    if (modid == -1)
      return LLDB_INVALID_ADDRESS;
  
    // Lookup the DTV structure for this thread.
    addr_t dtv_ptr = tp + metadata.dtv_offset;
    addr_t dtv = ReadPointer(dtv_ptr);
    if (dtv == LLDB_INVALID_ADDRESS)
      return LLDB_INVALID_ADDRESS;
  
    // Find the TLS block for this module.
    addr_t dtv_slot = dtv + metadata.dtv_slot_size * modid;
    addr_t tls_block = ReadPointer(dtv_slot + metadata.tls_offset);
  
    Module *mod = module.get();
    Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
    LLDB_LOGF(log,
              "DynamicLoaderHexagonDYLD::Performed TLS lookup: "
              "module=%s, link_map=0x%" PRIx64 ", tp=0x%" PRIx64
              ", modid=%i, tls_block=0x%" PRIx64,
              mod->GetObjectName().AsCString(""), link_map, tp, modid, tls_block);
  
    if (tls_block == LLDB_INVALID_ADDRESS)
      return LLDB_INVALID_ADDRESS;
    else
      return tls_block + tls_file_addr;
  }
  