Import LLVM 10.0.0 release including clang, lld and lldb.

ok hackroom
tested by plenty

1 files changed, 1595 insertions, 0 deletions

diff --git a/gnu/llvm/lldb/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp b/gnu/llvm/lldb/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp
new file mode 100644
index 00000000000..6019a1cc760
--- /dev/null
+++ b/gnu/llvm/lldb/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp
@@ -0,0 +1,1595 @@
+//===-- DynamicLoaderDarwinKernel.cpp -----------------------------*- C++
+//-*-===//
+//
+// 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 "Plugins/Platform/MacOSX/PlatformDarwinKernel.h"
+#include "lldb/Breakpoint/StoppointCallbackContext.h"
+#include "lldb/Core/Debugger.h"
+#include "lldb/Core/Module.h"
+#include "lldb/Core/ModuleSpec.h"
+#include "lldb/Core/PluginManager.h"
+#include "lldb/Core/Section.h"
+#include "lldb/Core/StreamFile.h"
+#include "lldb/Interpreter/OptionValueProperties.h"
+#include "lldb/Symbol/LocateSymbolFile.h"
+#include "lldb/Symbol/ObjectFile.h"
+#include "lldb/Target/OperatingSystem.h"
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Target/StackFrame.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Target/Thread.h"
+#include "lldb/Target/ThreadPlanRunToAddress.h"
+#include "lldb/Utility/DataBuffer.h"
+#include "lldb/Utility/DataBufferHeap.h"
+#include "lldb/Utility/Log.h"
+#include "lldb/Utility/State.h"
+
+#include "DynamicLoaderDarwinKernel.h"
+
+#include <algorithm>
+#include <memory>
+
+//#define ENABLE_DEBUG_PRINTF // COMMENT THIS LINE OUT PRIOR TO CHECKIN
+#ifdef ENABLE_DEBUG_PRINTF
+#include <stdio.h>
+#define DEBUG_PRINTF(fmt, ...) printf(fmt, ##__VA_ARGS__)
+#else
+#define DEBUG_PRINTF(fmt, ...)
+#endif
+
+using namespace lldb;
+using namespace lldb_private;
+
+// Progressively greater amounts of scanning we will allow For some targets
+// very early in startup, we can't do any random reads of memory or we can
+// crash the device so a setting is needed that can completely disable the
+// KASLR scans.
+
+enum KASLRScanType {
+  eKASLRScanNone = 0,        // No reading into the inferior at all
+  eKASLRScanLowgloAddresses, // Check one word of memory for a possible kernel
+                             // addr, then see if a kernel is there
+  eKASLRScanNearPC, // Scan backwards from the current $pc looking for kernel;
+                    // checking at 96 locations total
+  eKASLRScanExhaustiveScan // Scan through the entire possible kernel address
+                           // range looking for a kernel
+};
+
+static constexpr OptionEnumValueElement g_kaslr_kernel_scan_enum_values[] = {
+    {
+        eKASLRScanNone,
+        "none",
+        "Do not read memory looking for a Darwin kernel when attaching.",
+    },
+    {
+        eKASLRScanLowgloAddresses,
+        "basic",
+        "Check for the Darwin kernel's load addr in the lowglo page "
+        "(boot-args=debug) only.",
+    },
+    {
+        eKASLRScanNearPC,
+        "fast-scan",
+        "Scan near the pc value on attach to find the Darwin kernel's load "
+        "address.",
+    },
+    {
+        eKASLRScanExhaustiveScan,
+        "exhaustive-scan",
+        "Scan through the entire potential address range of Darwin kernel "
+        "(only on 32-bit targets).",
+    },
+};
+
+#define LLDB_PROPERTIES_dynamicloaderdarwinkernel
+#include "DynamicLoaderDarwinKernelProperties.inc"
+
+enum {
+#define LLDB_PROPERTIES_dynamicloaderdarwinkernel
+#include "DynamicLoaderDarwinKernelPropertiesEnum.inc"
+};
+
+class DynamicLoaderDarwinKernelProperties : public Properties {
+public:
+  static ConstString &GetSettingName() {
+    static ConstString g_setting_name("darwin-kernel");
+    return g_setting_name;
+  }
+
+  DynamicLoaderDarwinKernelProperties() : Properties() {
+    m_collection_sp = std::make_shared<OptionValueProperties>(GetSettingName());
+    m_collection_sp->Initialize(g_dynamicloaderdarwinkernel_properties);
+  }
+
+  ~DynamicLoaderDarwinKernelProperties() override {}
+
+  bool GetLoadKexts() const {
+    const uint32_t idx = ePropertyLoadKexts;
+    return m_collection_sp->GetPropertyAtIndexAsBoolean(
+        nullptr, idx,
+        g_dynamicloaderdarwinkernel_properties[idx].default_uint_value != 0);
+  }
+
+  KASLRScanType GetScanType() const {
+    const uint32_t idx = ePropertyScanType;
+    return (KASLRScanType)m_collection_sp->GetPropertyAtIndexAsEnumeration(
+        nullptr, idx,
+        g_dynamicloaderdarwinkernel_properties[idx].default_uint_value);
+  }
+};
+
+typedef std::shared_ptr<DynamicLoaderDarwinKernelProperties>
+    DynamicLoaderDarwinKernelPropertiesSP;
+
+static const DynamicLoaderDarwinKernelPropertiesSP &GetGlobalProperties() {
+  static DynamicLoaderDarwinKernelPropertiesSP g_settings_sp;
+  if (!g_settings_sp)
+    g_settings_sp = std::make_shared<DynamicLoaderDarwinKernelProperties>();
+  return g_settings_sp;
+}
+
+// Create an instance of this class. This function is filled into the plugin
+// info class that gets handed out by the plugin factory and allows the lldb to
+// instantiate an instance of this class.
+DynamicLoader *DynamicLoaderDarwinKernel::CreateInstance(Process *process,
+                                                         bool force) {
+  if (!force) {
+    // If the user provided an executable binary and it is not a kernel, this
+    // plugin should not create an instance.
+    Module *exe_module = process->GetTarget().GetExecutableModulePointer();
+    if (exe_module) {
+      ObjectFile *object_file = exe_module->GetObjectFile();
+      if (object_file) {
+        if (object_file->GetStrata() != ObjectFile::eStrataKernel) {
+          return nullptr;
+        }
+      }
+    }
+
+    // If the target's architecture does not look like an Apple environment,
+    // this plugin should not create an instance.
+    const llvm::Triple &triple_ref =
+        process->GetTarget().GetArchitecture().GetTriple();
+    switch (triple_ref.getOS()) {
+    case llvm::Triple::Darwin:
+    case llvm::Triple::MacOSX:
+    case llvm::Triple::IOS:
+    case llvm::Triple::TvOS:
+    case llvm::Triple::WatchOS:
+    // NEED_BRIDGEOS_TRIPLE case llvm::Triple::BridgeOS:
+      if (triple_ref.getVendor() != llvm::Triple::Apple) {
+        return nullptr;
+      }
+      break;
+    // If we have triple like armv7-unknown-unknown, we should try looking for
+    // a Darwin kernel.
+    case llvm::Triple::UnknownOS:
+      break;
+    default:
+      return nullptr;
+      break;
+    }
+  }
+
+  // At this point if there is an ExecutableModule, it is a kernel and the
+  // Target is some variant of an Apple system. If the Process hasn't provided
+  // the kernel load address, we need to look around in memory to find it.
+
+  const addr_t kernel_load_address = SearchForDarwinKernel(process);
+  if (CheckForKernelImageAtAddress(kernel_load_address, process).IsValid()) {
+    process->SetCanRunCode(false);
+    return new DynamicLoaderDarwinKernel(process, kernel_load_address);
+  }
+  return nullptr;
+}
+
+lldb::addr_t
+DynamicLoaderDarwinKernel::SearchForDarwinKernel(Process *process) {
+  addr_t kernel_load_address = process->GetImageInfoAddress();
+  if (kernel_load_address == LLDB_INVALID_ADDRESS) {
+    kernel_load_address = SearchForKernelAtSameLoadAddr(process);
+    if (kernel_load_address == LLDB_INVALID_ADDRESS) {
+      kernel_load_address = SearchForKernelWithDebugHints(process);
+      if (kernel_load_address == LLDB_INVALID_ADDRESS) {
+        kernel_load_address = SearchForKernelNearPC(process);
+        if (kernel_load_address == LLDB_INVALID_ADDRESS) {
+          kernel_load_address = SearchForKernelViaExhaustiveSearch(process);
+        }
+      }
+    }
+  }
+  return kernel_load_address;
+}
+
+// Check if the kernel binary is loaded in memory without a slide. First verify
+// that the ExecutableModule is a kernel before we proceed. Returns the address
+// of the kernel if one was found, else LLDB_INVALID_ADDRESS.
+lldb::addr_t
+DynamicLoaderDarwinKernel::SearchForKernelAtSameLoadAddr(Process *process) {
+  Module *exe_module = process->GetTarget().GetExecutableModulePointer();
+  if (exe_module == nullptr)
+    return LLDB_INVALID_ADDRESS;
+
+  ObjectFile *exe_objfile = exe_module->GetObjectFile();
+  if (exe_objfile == nullptr)
+    return LLDB_INVALID_ADDRESS;
+
+  if (exe_objfile->GetType() != ObjectFile::eTypeExecutable ||
+      exe_objfile->GetStrata() != ObjectFile::eStrataKernel)
+    return LLDB_INVALID_ADDRESS;
+
+  if (!exe_objfile->GetBaseAddress().IsValid())
+    return LLDB_INVALID_ADDRESS;
+
+  if (CheckForKernelImageAtAddress(
+          exe_objfile->GetBaseAddress().GetFileAddress(), process) ==
+      exe_module->GetUUID())
+    return exe_objfile->GetBaseAddress().GetFileAddress();
+
+  return LLDB_INVALID_ADDRESS;
+}
+
+// If the debug flag is included in the boot-args nvram setting, the kernel's
+// load address will be noted in the lowglo page at a fixed address Returns the
+// address of the kernel if one was found, else LLDB_INVALID_ADDRESS.
+lldb::addr_t
+DynamicLoaderDarwinKernel::SearchForKernelWithDebugHints(Process *process) {
+  if (GetGlobalProperties()->GetScanType() == eKASLRScanNone)
+    return LLDB_INVALID_ADDRESS;
+
+  Status read_err;
+  addr_t kernel_addresses_64[] = {
+      0xfffffff000004010ULL, // newest arm64 devices
+      0xffffff8000004010ULL, // 2014-2015-ish arm64 devices
+      0xffffff8000002010ULL, // oldest arm64 devices
+      LLDB_INVALID_ADDRESS};
+  addr_t kernel_addresses_32[] = {0xffff0110, // 2016 and earlier armv7 devices
+                                  0xffff1010, LLDB_INVALID_ADDRESS};
+
+  uint8_t uval[8];
+  if (process->GetAddressByteSize() == 8) {
+  for (size_t i = 0; kernel_addresses_64[i] != LLDB_INVALID_ADDRESS; i++) {
+      if (process->ReadMemoryFromInferior (kernel_addresses_64[i], uval, 8, read_err) == 8)
+      {
+          DataExtractor data (&uval, 8, process->GetByteOrder(), process->GetAddressByteSize());
+          offset_t offset = 0;
+          uint64_t addr = data.GetU64 (&offset);
+          if (CheckForKernelImageAtAddress(addr, process).IsValid()) {
+              return addr;
+          }
+      }
+  }
+  }
+
+  if (process->GetAddressByteSize() == 4) {
+  for (size_t i = 0; kernel_addresses_32[i] != LLDB_INVALID_ADDRESS; i++) {
+      if (process->ReadMemoryFromInferior (kernel_addresses_32[i], uval, 4, read_err) == 4)
+      {
+          DataExtractor data (&uval, 4, process->GetByteOrder(), process->GetAddressByteSize());
+          offset_t offset = 0;
+          uint32_t addr = data.GetU32 (&offset);
+          if (CheckForKernelImageAtAddress(addr, process).IsValid()) {
+              return addr;
+          }
+      }
+  }
+  }
+
+  return LLDB_INVALID_ADDRESS;
+}
+
+// If the kernel is currently executing when lldb attaches, and we don't have a
+// better way of finding the kernel's load address, try searching backwards
+// from the current pc value looking for the kernel's Mach header in memory.
+// Returns the address of the kernel if one was found, else
+// LLDB_INVALID_ADDRESS.
+lldb::addr_t
+DynamicLoaderDarwinKernel::SearchForKernelNearPC(Process *process) {
+  if (GetGlobalProperties()->GetScanType() == eKASLRScanNone ||
+      GetGlobalProperties()->GetScanType() == eKASLRScanLowgloAddresses) {
+    return LLDB_INVALID_ADDRESS;
+  }
+
+  ThreadSP thread = process->GetThreadList().GetSelectedThread();
+  if (thread.get() == nullptr)
+    return LLDB_INVALID_ADDRESS;
+  addr_t pc = thread->GetRegisterContext()->GetPC(LLDB_INVALID_ADDRESS);
+
+  int ptrsize = process->GetTarget().GetArchitecture().GetAddressByteSize();
+
+  // The kernel is always loaded in high memory, if the top bit is zero,
+  // this isn't a kernel.
+  if (ptrsize == 8) {
+    if ((pc & (1ULL << 63)) == 0) {
+      return LLDB_INVALID_ADDRESS;
+    }
+  } else {
+    if ((pc & (1ULL << 31)) == 0) {
+      return LLDB_INVALID_ADDRESS;
+    }
+  }
+
+  if (pc == LLDB_INVALID_ADDRESS)
+    return LLDB_INVALID_ADDRESS;
+
+  int pagesize = 0x4000;  // 16k pages on 64-bit targets
+  if (ptrsize == 4)
+    pagesize = 0x1000;    // 4k pages on 32-bit targets
+
+  // The kernel will be loaded on a page boundary.
+  // Round the current pc down to the nearest page boundary.
+  addr_t addr = pc & ~(pagesize - 1ULL);
+
+  // Search backwards for 32 megabytes, or first memory read error.
+  while (pc - addr < 32 * 0x100000) {
+    bool read_error;
+    if (CheckForKernelImageAtAddress(addr, process, &read_error).IsValid())
+      return addr;
+
+    // Stop scanning on the first read error we encounter; we've walked
+    // past this executable block of memory.
+    if (read_error == true)
+      break;
+
+    addr -= pagesize;
+  }
+
+  return LLDB_INVALID_ADDRESS;
+}
+
+// Scan through the valid address range for a kernel binary. This is uselessly
+// slow in 64-bit environments so we don't even try it. This scan is not
+// enabled by default even for 32-bit targets. Returns the address of the
+// kernel if one was found, else LLDB_INVALID_ADDRESS.
+lldb::addr_t DynamicLoaderDarwinKernel::SearchForKernelViaExhaustiveSearch(
+    Process *process) {
+  if (GetGlobalProperties()->GetScanType() != eKASLRScanExhaustiveScan) {
+    return LLDB_INVALID_ADDRESS;
+  }
+
+  addr_t kernel_range_low, kernel_range_high;
+  if (process->GetTarget().GetArchitecture().GetAddressByteSize() == 8) {
+    kernel_range_low = 1ULL << 63;
+    kernel_range_high = UINT64_MAX;
+  } else {
+    kernel_range_low = 1ULL << 31;
+    kernel_range_high = UINT32_MAX;
+  }
+
+  // Stepping through memory at one-megabyte resolution looking for a kernel
+  // rarely works (fast enough) with a 64-bit address space -- for now, let's
+  // not even bother.  We may be attaching to something which *isn't* a kernel
+  // and we don't want to spin for minutes on-end looking for a kernel.
+  if (process->GetTarget().GetArchitecture().GetAddressByteSize() == 8)
+    return LLDB_INVALID_ADDRESS;
+
+  addr_t addr = kernel_range_low;
+
+  while (addr >= kernel_range_low && addr < kernel_range_high) {
+    // x86_64 kernels are at offset 0
+    if (CheckForKernelImageAtAddress(addr, process).IsValid())
+      return addr;
+    // 32-bit arm kernels are at offset 0x1000 (one 4k page)
+    if (CheckForKernelImageAtAddress(addr + 0x1000, process).IsValid())
+      return addr + 0x1000;
+    // 64-bit arm kernels are at offset 0x4000 (one 16k page)
+    if (CheckForKernelImageAtAddress(addr + 0x4000, process).IsValid())
+      return addr + 0x4000;
+    addr += 0x100000;
+  }
+  return LLDB_INVALID_ADDRESS;
+}
+
+// Read the mach_header struct out of memory and return it.
+// Returns true if the mach_header was successfully read,
+// Returns false if there was a problem reading the header, or it was not
+// a Mach-O header.
+
+bool
+DynamicLoaderDarwinKernel::ReadMachHeader(addr_t addr, Process *process, llvm::MachO::mach_header &header,
+                                          bool *read_error) {
+  Status error;
+  if (read_error)
+    *read_error = false;
+
+  // Read the mach header and see whether it looks like a kernel
+  if (process->DoReadMemory (addr, &header, sizeof(header), error) !=
+      sizeof(header)) {
+    if (read_error)
+      *read_error = true;
+    return false;
+  }
+
+  const uint32_t magicks[] = { llvm::MachO::MH_MAGIC_64, llvm::MachO::MH_MAGIC, llvm::MachO::MH_CIGAM, llvm::MachO::MH_CIGAM_64};
+
+  bool found_matching_pattern = false;
+  for (size_t i = 0; i < llvm::array_lengthof (magicks); i++)
+    if (::memcmp (&header.magic, &magicks[i], sizeof (uint32_t)) == 0)
+        found_matching_pattern = true;
+
+  if (!found_matching_pattern)
+    return false;
+
+  if (header.magic == llvm::MachO::MH_CIGAM ||
+      header.magic == llvm::MachO::MH_CIGAM_64) {
+    header.magic = llvm::ByteSwap_32(header.magic);
+    header.cputype = llvm::ByteSwap_32(header.cputype);
+    header.cpusubtype = llvm::ByteSwap_32(header.cpusubtype);
+    header.filetype = llvm::ByteSwap_32(header.filetype);
+    header.ncmds = llvm::ByteSwap_32(header.ncmds);
+    header.sizeofcmds = llvm::ByteSwap_32(header.sizeofcmds);
+    header.flags = llvm::ByteSwap_32(header.flags);
+  }
+
+  return true;
+}
+
+// Given an address in memory, look to see if there is a kernel image at that
+// address.
+// Returns a UUID; if a kernel was not found at that address, UUID.IsValid()
+// will be false.
+lldb_private::UUID
+DynamicLoaderDarwinKernel::CheckForKernelImageAtAddress(lldb::addr_t addr,
+                                                        Process *process,
+                                                        bool *read_error) {
+  Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
+  if (addr == LLDB_INVALID_ADDRESS) {
+    if (read_error)
+      *read_error = true;
+    return UUID();
+  }
+
+  LLDB_LOGF(log,
+            "DynamicLoaderDarwinKernel::CheckForKernelImageAtAddress: "
+            "looking for kernel binary at 0x%" PRIx64,
+            addr);
+
+  llvm::MachO::mach_header header;
+
+  if (!ReadMachHeader(addr, process, header, read_error))
+    return UUID();
+
+  // First try a quick test -- read the first 4 bytes and see if there is a
+  // valid Mach-O magic field there
+  // (the first field of the mach_header/mach_header_64 struct).
+  // A kernel is an executable which does not have the dynamic link object flag
+  // set.
+  if (header.filetype == llvm::MachO::MH_EXECUTE &&
+      (header.flags & llvm::MachO::MH_DYLDLINK) == 0) {
+    // Create a full module to get the UUID
+    ModuleSP memory_module_sp =
+        process->ReadModuleFromMemory(FileSpec("temp_mach_kernel"), addr);
+    if (!memory_module_sp.get())
+      return UUID();
+
+    ObjectFile *exe_objfile = memory_module_sp->GetObjectFile();
+    if (exe_objfile == nullptr) {
+      LLDB_LOGF(log,
+                "DynamicLoaderDarwinKernel::CheckForKernelImageAtAddress "
+                "found a binary at 0x%" PRIx64
+                " but could not create an object file from memory",
+                addr);
+      return UUID();
+    }
+
+    if (exe_objfile->GetType() == ObjectFile::eTypeExecutable &&
+        exe_objfile->GetStrata() == ObjectFile::eStrataKernel) {
+      ArchSpec kernel_arch(eArchTypeMachO, header.cputype, header.cpusubtype);
+      if (!process->GetTarget().GetArchitecture().IsCompatibleMatch(
+              kernel_arch)) {
+        process->GetTarget().SetArchitecture(kernel_arch);
+      }
+      if (log) {
+        std::string uuid_str;
+        if (memory_module_sp->GetUUID().IsValid()) {
+          uuid_str = "with UUID ";
+          uuid_str += memory_module_sp->GetUUID().GetAsString();
+        } else {
+          uuid_str = "and no LC_UUID found in load commands ";
+        }
+        LLDB_LOGF(
+            log,
+            "DynamicLoaderDarwinKernel::CheckForKernelImageAtAddress: "
+            "kernel binary image found at 0x%" PRIx64 " with arch '%s' %s",
+            addr, kernel_arch.GetTriple().str().c_str(), uuid_str.c_str());
+      }
+      return memory_module_sp->GetUUID();
+    }
+  }
+
+  return UUID();
+}
+
+// Constructor
+DynamicLoaderDarwinKernel::DynamicLoaderDarwinKernel(Process *process,
+                                                     lldb::addr_t kernel_addr)
+    : DynamicLoader(process), m_kernel_load_address(kernel_addr), m_kernel(),
+      m_kext_summary_header_ptr_addr(), m_kext_summary_header_addr(),
+      m_kext_summary_header(), m_known_kexts(), m_mutex(),
+      m_break_id(LLDB_INVALID_BREAK_ID) {
+  Status error;
+  PlatformSP platform_sp(
+      Platform::Create(PlatformDarwinKernel::GetPluginNameStatic(), error));
+  // Only select the darwin-kernel Platform if we've been asked to load kexts.
+  // It can take some time to scan over all of the kext info.plists and that
+  // shouldn't be done if kext loading is explicitly disabled.
+  if (platform_sp.get() && GetGlobalProperties()->GetLoadKexts()) {
+    process->GetTarget().SetPlatform(platform_sp);
+  }
+}
+
+// Destructor
+DynamicLoaderDarwinKernel::~DynamicLoaderDarwinKernel() { Clear(true); }
+
+void DynamicLoaderDarwinKernel::UpdateIfNeeded() {
+  LoadKernelModuleIfNeeded();
+  SetNotificationBreakpointIfNeeded();
+}
+/// Called after attaching a process.
+///
+/// Allow DynamicLoader plug-ins to execute some code after
+/// attaching to a process.
+void DynamicLoaderDarwinKernel::DidAttach() {
+  PrivateInitialize(m_process);
+  UpdateIfNeeded();
+}
+
+/// Called after attaching a process.
+///
+/// Allow DynamicLoader plug-ins to execute some code after
+/// attaching to a process.
+void DynamicLoaderDarwinKernel::DidLaunch() {
+  PrivateInitialize(m_process);
+  UpdateIfNeeded();
+}
+
+// Clear out the state of this class.
+void DynamicLoaderDarwinKernel::Clear(bool clear_process) {
+  std::lock_guard<std::recursive_mutex> guard(m_mutex);
+
+  if (m_process->IsAlive() && LLDB_BREAK_ID_IS_VALID(m_break_id))
+    m_process->ClearBreakpointSiteByID(m_break_id);
+
+  if (clear_process)
+    m_process = nullptr;
+  m_kernel.Clear();
+  m_known_kexts.clear();
+  m_kext_summary_header_ptr_addr.Clear();
+  m_kext_summary_header_addr.Clear();
+  m_break_id = LLDB_INVALID_BREAK_ID;
+}
+
+bool DynamicLoaderDarwinKernel::KextImageInfo::LoadImageAtFileAddress(
+    Process *process) {
+  if (IsLoaded())
+    return true;
+
+  if (m_module_sp) {
+    bool changed = false;
+    if (m_module_sp->SetLoadAddress(process->GetTarget(), 0, true, changed))
+      m_load_process_stop_id = process->GetStopID();
+  }
+  return false;
+}
+
+void DynamicLoaderDarwinKernel::KextImageInfo::SetModule(ModuleSP module_sp) {
+  m_module_sp = module_sp;
+  if (module_sp.get() && module_sp->GetObjectFile()) {
+    if (module_sp->GetObjectFile()->GetType() == ObjectFile::eTypeExecutable &&
+        module_sp->GetObjectFile()->GetStrata() == ObjectFile::eStrataKernel) {
+      m_kernel_image = true;
+    } else {
+      m_kernel_image = false;
+    }
+  }
+}
+
+ModuleSP DynamicLoaderDarwinKernel::KextImageInfo::GetModule() {
+  return m_module_sp;
+}
+
+void DynamicLoaderDarwinKernel::KextImageInfo::SetLoadAddress(
+    addr_t load_addr) {
+  m_load_address = load_addr;
+}
+
+addr_t DynamicLoaderDarwinKernel::KextImageInfo::GetLoadAddress() const {
+  return m_load_address;
+}
+
+uint64_t DynamicLoaderDarwinKernel::KextImageInfo::GetSize() const {
+  return m_size;
+}
+
+void DynamicLoaderDarwinKernel::KextImageInfo::SetSize(uint64_t size) {
+  m_size = size;
+}
+
+uint32_t DynamicLoaderDarwinKernel::KextImageInfo::GetProcessStopId() const {
+  return m_load_process_stop_id;
+}
+
+void DynamicLoaderDarwinKernel::KextImageInfo::SetProcessStopId(
+    uint32_t stop_id) {
+  m_load_process_stop_id = stop_id;
+}
+
+bool DynamicLoaderDarwinKernel::KextImageInfo::
+operator==(const KextImageInfo &rhs) {
+  if (m_uuid.IsValid() || rhs.GetUUID().IsValid()) {
+    return m_uuid == rhs.GetUUID();
+  }
+
+  return m_name == rhs.GetName() && m_load_address == rhs.GetLoadAddress();
+}
+
+void DynamicLoaderDarwinKernel::KextImageInfo::SetName(const char *name) {
+  m_name = name;
+}
+
+std::string DynamicLoaderDarwinKernel::KextImageInfo::GetName() const {
+  return m_name;
+}
+
+void DynamicLoaderDarwinKernel::KextImageInfo::SetUUID(const UUID &uuid) {
+  m_uuid = uuid;
+}
+
+UUID DynamicLoaderDarwinKernel::KextImageInfo::GetUUID() const {
+  return m_uuid;
+}
+
+// Given the m_load_address from the kext summaries, and a UUID, try to create
+// an in-memory Module at that address.  Require that the MemoryModule have a
+// matching UUID and detect if this MemoryModule is a kernel or a kext.
+//
+// Returns true if m_memory_module_sp is now set to a valid Module.
+
+bool DynamicLoaderDarwinKernel::KextImageInfo::ReadMemoryModule(
+    Process *process) {
+  Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_HOST);
+  if (m_memory_module_sp.get() != nullptr)
+    return true;
+  if (m_load_address == LLDB_INVALID_ADDRESS)
+    return false;
+
+  FileSpec file_spec(m_name.c_str());
+
+  llvm::MachO::mach_header mh;
+  size_t size_to_read = 512;
+  if (ReadMachHeader(m_load_address, process, mh)) {
+    if (mh.magic == llvm::MachO::MH_CIGAM || mh.magic == llvm::MachO::MH_MAGIC)
+      size_to_read = sizeof(llvm::MachO::mach_header) + mh.sizeofcmds;
+    if (mh.magic == llvm::MachO::MH_CIGAM_64 ||
+        mh.magic == llvm::MachO::MH_MAGIC_64)
+      size_to_read = sizeof(llvm::MachO::mach_header_64) + mh.sizeofcmds;
+  }
+
+  ModuleSP memory_module_sp =
+      process->ReadModuleFromMemory(file_spec, m_load_address, size_to_read);
+
+  if (memory_module_sp.get() == nullptr)
+    return false;
+
+  bool is_kernel = false;
+  if (memory_module_sp->GetObjectFile()) {
+    if (memory_module_sp->GetObjectFile()->GetType() ==
+            ObjectFile::eTypeExecutable &&
+        memory_module_sp->GetObjectFile()->GetStrata() ==
+            ObjectFile::eStrataKernel) {
+      is_kernel = true;
+    } else if (memory_module_sp->GetObjectFile()->GetType() ==
+               ObjectFile::eTypeSharedLibrary) {
+      is_kernel = false;
+    }
+  }
+
+  // If this is a kext, and the kernel specified what UUID we should find at
+  // this load address, require that the memory module have a matching UUID or
+  // something has gone wrong and we should discard it.
+  if (m_uuid.IsValid()) {
+    if (m_uuid != memory_module_sp->GetUUID()) {
+      if (log) {
+        LLDB_LOGF(log,
+                  "KextImageInfo::ReadMemoryModule the kernel said to find "
+                  "uuid %s at 0x%" PRIx64
+                  " but instead we found uuid %s, throwing it away",
+                  m_uuid.GetAsString().c_str(), m_load_address,
+                  memory_module_sp->GetUUID().GetAsString().c_str());
+      }
+      return false;
+    }
+  }
+
+  // If the in-memory Module has a UUID, let's use that.
+  if (!m_uuid.IsValid() && memory_module_sp->GetUUID().IsValid()) {
+    m_uuid = memory_module_sp->GetUUID();
+  }
+
+  m_memory_module_sp = memory_module_sp;
+  m_kernel_image = is_kernel;
+  if (is_kernel) {
+    if (log) {
+      // This is unusual and probably not intended
+      LLDB_LOGF(log,
+                "KextImageInfo::ReadMemoryModule read the kernel binary out "
+                "of memory");
+    }
+    if (memory_module_sp->GetArchitecture().IsValid()) {
+      process->GetTarget().SetArchitecture(memory_module_sp->GetArchitecture());
+    }
+    if (m_uuid.IsValid()) {
+      ModuleSP exe_module_sp = process->GetTarget().GetExecutableModule();
+      if (exe_module_sp.get() && exe_module_sp->GetUUID().IsValid()) {
+        if (m_uuid != exe_module_sp->GetUUID()) {
+          // The user specified a kernel binary that has a different UUID than
+          // the kernel actually running in memory.  This never ends well;
+          // clear the user specified kernel binary from the Target.
+
+          m_module_sp.reset();
+
+          ModuleList user_specified_kernel_list;
+          user_specified_kernel_list.Append(exe_module_sp);
+          process->GetTarget().GetImages().Remove(user_specified_kernel_list);
+        }
+      }
+    }
+  }
+
+  return true;
+}
+
+bool DynamicLoaderDarwinKernel::KextImageInfo::IsKernel() const {
+  return m_kernel_image;
+}
+
+void DynamicLoaderDarwinKernel::KextImageInfo::SetIsKernel(bool is_kernel) {
+  m_kernel_image = is_kernel;
+}
+
+bool DynamicLoaderDarwinKernel::KextImageInfo::LoadImageUsingMemoryModule(
+    Process *process) {
+  if (IsLoaded())
+    return true;
+
+  Target &target = process->GetTarget();
+
+  // kexts will have a uuid from the table.
+  // for the kernel, we'll need to read the load commands out of memory to get it.
+  if (m_uuid.IsValid() == false) {
+    if (ReadMemoryModule(process) == false) {
+      Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
+      LLDB_LOGF(log,
+                "Unable to read '%s' from memory at address 0x%" PRIx64
+                " to get the segment load addresses.",
+                m_name.c_str(), m_load_address);
+      return false;
+    }
+  }
+
+  if (IsKernel() && m_uuid.IsValid()) {
+    Stream &s = target.GetDebugger().GetOutputStream();
+    s.Printf("Kernel UUID: %s\n", m_uuid.GetAsString().c_str());
+    s.Printf("Load Address: 0x%" PRIx64 "\n", m_load_address);
+  }
+
+  if (!m_module_sp) {
+    // See if the kext has already been loaded into the target, probably by the
+    // user doing target modules add.
+    const ModuleList &target_images = target.GetImages();
+    m_module_sp = target_images.FindModule(m_uuid);
+
+    // Search for the kext on the local filesystem via the UUID
+    if (!m_module_sp && m_uuid.IsValid()) {
+      ModuleSpec module_spec;
+      module_spec.GetUUID() = m_uuid;
+      module_spec.GetArchitecture() = target.GetArchitecture();
+
+      // For the kernel, we really do need an on-disk file copy of the binary
+      // to do anything useful. This will force a call to dsymForUUID if it
+      // exists, instead of depending on the DebugSymbols preferences being 
+      // set.
+      if (IsKernel()) {
+        if (Symbols::DownloadObjectAndSymbolFile(module_spec, true)) {
+          if (FileSystem::Instance().Exists(module_spec.GetFileSpec())) {
+            m_module_sp = std::make_shared<Module>(module_spec.GetFileSpec(),
+                                                   target.GetArchitecture());
+          }
+        }
+      }
+
+      // If the current platform is PlatformDarwinKernel, create a ModuleSpec
+      // with the filename set to be the bundle ID for this kext, e.g.
+      // "com.apple.filesystems.msdosfs", and ask the platform to find it.
+      // PlatformDarwinKernel does a special scan for kexts on the local
+      // system.
+      PlatformSP platform_sp(target.GetPlatform());
+      if (!m_module_sp && platform_sp) {
+        ConstString platform_name(platform_sp->GetPluginName());
+        static ConstString g_platform_name(
+            PlatformDarwinKernel::GetPluginNameStatic());
+        if (platform_name == g_platform_name) {
+          ModuleSpec kext_bundle_module_spec(module_spec);
+          FileSpec kext_filespec(m_name.c_str());
+          FileSpecList search_paths = target.GetExecutableSearchPaths();
+          kext_bundle_module_spec.GetFileSpec() = kext_filespec;
+          platform_sp->GetSharedModule(kext_bundle_module_spec, process,
+                                       m_module_sp, &search_paths, nullptr,
+                                       nullptr);
+        }
+      }
+
+      // Ask the Target to find this file on the local system, if possible.
+      // This will search in the list of currently-loaded files, look in the
+      // standard search paths on the system, and on a Mac it will try calling
+      // the DebugSymbols framework with the UUID to find the binary via its
+      // search methods.
+      if (!m_module_sp) {
+        m_module_sp = target.GetOrCreateModule(module_spec, true /* notify */);
+      }
+
+      if (IsKernel() && !m_module_sp) {
+        Stream &s = target.GetDebugger().GetOutputStream();
+        s.Printf("WARNING: Unable to locate kernel binary on the debugger "
+                 "system.\n");
+      }
+    }
+
+    // If we managed to find a module, append it to the target's list of
+    // images. If we also have a memory module, require that they have matching
+    // UUIDs
+    if (m_module_sp) {
+      if (m_uuid.IsValid() && m_module_sp->GetUUID() == m_uuid) {
+        target.GetImages().AppendIfNeeded(m_module_sp, false);
+        if (IsKernel() &&
+            target.GetExecutableModulePointer() != m_module_sp.get()) {
+          target.SetExecutableModule(m_module_sp, eLoadDependentsNo);
+        }
+      }
+    }
+  }
+
+  // If we've found a binary, read the load commands out of memory so we
+  // can set the segment load addresses.
+  if (m_module_sp)
+    ReadMemoryModule (process);
+
+  static ConstString g_section_name_LINKEDIT("__LINKEDIT");
+
+  if (m_memory_module_sp && m_module_sp) {
+    if (m_module_sp->GetUUID() == m_memory_module_sp->GetUUID()) {
+      ObjectFile *ondisk_object_file = m_module_sp->GetObjectFile();
+      ObjectFile *memory_object_file = m_memory_module_sp->GetObjectFile();
+
+      if (memory_object_file && ondisk_object_file) {
+        // The memory_module for kexts may have an invalid __LINKEDIT seg; skip
+        // it.
+        const bool ignore_linkedit = !IsKernel();
+
+        SectionList *ondisk_section_list = ondisk_object_file->GetSectionList();
+        SectionList *memory_section_list = memory_object_file->GetSectionList();
+        if (memory_section_list && ondisk_section_list) {
+          const uint32_t num_ondisk_sections = ondisk_section_list->GetSize();
+          // There may be CTF sections in the memory image so we can't always
+          // just compare the number of sections (which are actually segments
+          // in mach-o parlance)
+          uint32_t sect_idx = 0;
+
+          // Use the memory_module's addresses for each section to set the file
+          // module's load address as appropriate.  We don't want to use a
+          // single slide value for the entire kext - different segments may be
+          // slid different amounts by the kext loader.
+
+          uint32_t num_sections_loaded = 0;
+          for (sect_idx = 0; sect_idx < num_ondisk_sections; ++sect_idx) {
+            SectionSP ondisk_section_sp(
+                ondisk_section_list->GetSectionAtIndex(sect_idx));
+            if (ondisk_section_sp) {
+              // Don't ever load __LINKEDIT as it may or may not be actually
+              // mapped into memory and there is no current way to tell.
+              // I filed rdar://problem/12851706 to track being able to tell
+              // if the __LINKEDIT is actually mapped, but until then, we need
+              // to not load the __LINKEDIT
+              if (ignore_linkedit &&
+                  ondisk_section_sp->GetName() == g_section_name_LINKEDIT)
+                continue;
+
+              const Section *memory_section =
+                  memory_section_list
+                      ->FindSectionByName(ondisk_section_sp->GetName())
+                      .get();
+              if (memory_section) {
+                target.SetSectionLoadAddress(ondisk_section_sp,
+                                             memory_section->GetFileAddress());
+                ++num_sections_loaded;
+              }
+            }
+          }
+          if (num_sections_loaded > 0)
+            m_load_process_stop_id = process->GetStopID();
+          else
+            m_module_sp.reset(); // No sections were loaded
+        } else
+          m_module_sp.reset(); // One or both section lists
+      } else
+        m_module_sp.reset(); // One or both object files missing
+    } else
+      m_module_sp.reset(); // UUID mismatch
+  }
+
+  bool is_loaded = IsLoaded();
+
+  if (is_loaded && m_module_sp && IsKernel()) {
+    Stream &s = target.GetDebugger().GetOutputStream();
+    ObjectFile *kernel_object_file = m_module_sp->GetObjectFile();
+    if (kernel_object_file) {
+      addr_t file_address =
+          kernel_object_file->GetBaseAddress().GetFileAddress();
+      if (m_load_address != LLDB_INVALID_ADDRESS &&
+          file_address != LLDB_INVALID_ADDRESS) {
+        s.Printf("Kernel slid 0x%" PRIx64 " in memory.\n",
+                 m_load_address - file_address);
+      }
+    }
+    {
+      s.Printf("Loaded kernel file %s\n",
+               m_module_sp->GetFileSpec().GetPath().c_str());
+    }
+    s.Flush();
+  }
+
+  // Notify the target about the module being added;
+  // set breakpoints, load dSYM scripts, etc. as needed.
+  if (is_loaded && m_module_sp) {
+    ModuleList loaded_module_list;
+    loaded_module_list.Append(m_module_sp);
+    target.ModulesDidLoad(loaded_module_list);
+  }
+
+  return is_loaded;
+}
+
+uint32_t DynamicLoaderDarwinKernel::KextImageInfo::GetAddressByteSize() {
+  if (m_memory_module_sp)
+    return m_memory_module_sp->GetArchitecture().GetAddressByteSize();
+  if (m_module_sp)
+    return m_module_sp->GetArchitecture().GetAddressByteSize();
+  return 0;
+}
+
+lldb::ByteOrder DynamicLoaderDarwinKernel::KextImageInfo::GetByteOrder() {
+  if (m_memory_module_sp)
+    return m_memory_module_sp->GetArchitecture().GetByteOrder();
+  if (m_module_sp)
+    return m_module_sp->GetArchitecture().GetByteOrder();
+  return endian::InlHostByteOrder();
+}
+
+lldb_private::ArchSpec
+DynamicLoaderDarwinKernel::KextImageInfo::GetArchitecture() const {
+  if (m_memory_module_sp)
+    return m_memory_module_sp->GetArchitecture();
+  if (m_module_sp)
+    return m_module_sp->GetArchitecture();
+  return lldb_private::ArchSpec();
+}
+
+// Load the kernel module and initialize the "m_kernel" member. Return true
+// _only_ if the kernel is loaded the first time through (subsequent calls to
+// this function should return false after the kernel has been already loaded).
+void DynamicLoaderDarwinKernel::LoadKernelModuleIfNeeded() {
+  if (!m_kext_summary_header_ptr_addr.IsValid()) {
+    m_kernel.Clear();
+    m_kernel.SetModule(m_process->GetTarget().GetExecutableModule());
+    m_kernel.SetIsKernel(true);
+
+    ConstString kernel_name("mach_kernel");
+    if (m_kernel.GetModule().get() && m_kernel.GetModule()->GetObjectFile() &&
+        !m_kernel.GetModule()
+             ->GetObjectFile()
+             ->GetFileSpec()
+             .GetFilename()
+             .IsEmpty()) {
+      kernel_name =
+          m_kernel.GetModule()->GetObjectFile()->GetFileSpec().GetFilename();
+    }
+    m_kernel.SetName(kernel_name.AsCString());
+
+    if (m_kernel.GetLoadAddress() == LLDB_INVALID_ADDRESS) {
+      m_kernel.SetLoadAddress(m_kernel_load_address);
+      if (m_kernel.GetLoadAddress() == LLDB_INVALID_ADDRESS &&
+          m_kernel.GetModule()) {
+        // We didn't get a hint from the process, so we will try the kernel at
+        // the address that it exists at in the file if we have one
+        ObjectFile *kernel_object_file = m_kernel.GetModule()->GetObjectFile();
+        if (kernel_object_file) {
+          addr_t load_address =
+              kernel_object_file->GetBaseAddress().GetLoadAddress(
+                  &m_process->GetTarget());
+          addr_t file_address =
+              kernel_object_file->GetBaseAddress().GetFileAddress();
+          if (load_address != LLDB_INVALID_ADDRESS && load_address != 0) {
+            m_kernel.SetLoadAddress(load_address);
+            if (load_address != file_address) {
+              // Don't accidentally relocate the kernel to the File address --
+              // the Load address has already been set to its actual in-memory
+              // address. Mark it as IsLoaded.
+              m_kernel.SetProcessStopId(m_process->GetStopID());
+            }
+          } else {
+            m_kernel.SetLoadAddress(file_address);
+          }
+        }
+      }
+    }
+
+    if (m_kernel.GetLoadAddress() != LLDB_INVALID_ADDRESS) {
+      if (!m_kernel.LoadImageUsingMemoryModule(m_process)) {
+        m_kernel.LoadImageAtFileAddress(m_process);
+      }
+    }
+
+    // The operating system plugin gets loaded and initialized in
+    // LoadImageUsingMemoryModule when we discover the kernel dSYM.  For a core
+    // file in particular, that's the wrong place to do this, since  we haven't
+    // fixed up the section addresses yet.  So let's redo it here.
+    LoadOperatingSystemPlugin(false);
+
+    if (m_kernel.IsLoaded() && m_kernel.GetModule()) {
+      static ConstString kext_summary_symbol("gLoadedKextSummaries");
+      const Symbol *symbol =
+          m_kernel.GetModule()->FindFirstSymbolWithNameAndType(
+              kext_summary_symbol, eSymbolTypeData);
+      if (symbol) {
+        m_kext_summary_header_ptr_addr = symbol->GetAddress();
+        // Update all image infos
+        ReadAllKextSummaries();
+      }
+    } else {
+      m_kernel.Clear();
+    }
+  }
+}
+
+// Static callback function that gets called when our DYLD notification
+// breakpoint gets hit. We update all of our image infos and then let our super
+// class DynamicLoader class decide if we should stop or not (based on global
+// preference).
+bool DynamicLoaderDarwinKernel::BreakpointHitCallback(
+    void *baton, StoppointCallbackContext *context, user_id_t break_id,
+    user_id_t break_loc_id) {
+  return static_cast<DynamicLoaderDarwinKernel *>(baton)->BreakpointHit(
+      context, break_id, break_loc_id);
+}
+
+bool DynamicLoaderDarwinKernel::BreakpointHit(StoppointCallbackContext *context,
+                                              user_id_t break_id,
+                                              user_id_t break_loc_id) {
+  Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
+  LLDB_LOGF(log, "DynamicLoaderDarwinKernel::BreakpointHit (...)\n");
+
+  ReadAllKextSummaries();
+
+  if (log)
+    PutToLog(log);
+
+  return GetStopWhenImagesChange();
+}
+
+bool DynamicLoaderDarwinKernel::ReadKextSummaryHeader() {
+  std::lock_guard<std::recursive_mutex> guard(m_mutex);
+
+  // the all image infos is already valid for this process stop ID
+
+  if (m_kext_summary_header_ptr_addr.IsValid()) {
+    const uint32_t addr_size = m_kernel.GetAddressByteSize();
+    const ByteOrder byte_order = m_kernel.GetByteOrder();
+    Status error;
+    // Read enough bytes for a "OSKextLoadedKextSummaryHeader" structure which
+    // is currently 4 uint32_t and a pointer.
+    uint8_t buf[24];
+    DataExtractor data(buf, sizeof(buf), byte_order, addr_size);
+    const size_t count = 4 * sizeof(uint32_t) + addr_size;
+    const bool prefer_file_cache = false;
+    if (m_process->GetTarget().ReadPointerFromMemory(
+            m_kext_summary_header_ptr_addr, prefer_file_cache, error,
+            m_kext_summary_header_addr)) {
+      // We got a valid address for our kext summary header and make sure it
+      // isn't NULL
+      if (m_kext_summary_header_addr.IsValid() &&
+          m_kext_summary_header_addr.GetFileAddress() != 0) {
+        const size_t bytes_read = m_process->GetTarget().ReadMemory(
+            m_kext_summary_header_addr, prefer_file_cache, buf, count, error);
+        if (bytes_read == count) {
+          lldb::offset_t offset = 0;
+          m_kext_summary_header.version = data.GetU32(&offset);
+          if (m_kext_summary_header.version > 128) {
+            Stream &s = m_process->GetTarget().GetDebugger().GetOutputStream();
+            s.Printf("WARNING: Unable to read kext summary header, got "
+                     "improbable version number %u\n",
+                     m_kext_summary_header.version);
+            // If we get an improbably large version number, we're probably
+            // getting bad memory.
+            m_kext_summary_header_addr.Clear();
+            return false;
+          }
+          if (m_kext_summary_header.version >= 2) {
+            m_kext_summary_header.entry_size = data.GetU32(&offset);
+            if (m_kext_summary_header.entry_size > 4096) {
+              // If we get an improbably large entry_size, we're probably
+              // getting bad memory.
+              Stream &s =
+                  m_process->GetTarget().GetDebugger().GetOutputStream();
+              s.Printf("WARNING: Unable to read kext summary header, got "
+                       "improbable entry_size %u\n",
+                       m_kext_summary_header.entry_size);
+              m_kext_summary_header_addr.Clear();
+              return false;
+            }
+          } else {
+            // Versions less than 2 didn't have an entry size, it was hard
+            // coded
+            m_kext_summary_header.entry_size =
+                KERNEL_MODULE_ENTRY_SIZE_VERSION_1;
+          }
+          m_kext_summary_header.entry_count = data.GetU32(&offset);
+          if (m_kext_summary_header.entry_count > 10000) {
+            // If we get an improbably large number of kexts, we're probably
+            // getting bad memory.
+            Stream &s = m_process->GetTarget().GetDebugger().GetOutputStream();
+            s.Printf("WARNING: Unable to read kext summary header, got "
+                     "improbable number of kexts %u\n",
+                     m_kext_summary_header.entry_count);
+            m_kext_summary_header_addr.Clear();
+            return false;
+          }
+          return true;
+        }
+      }
+    }
+  }
+  m_kext_summary_header_addr.Clear();
+  return false;
+}
+
+// We've either (a) just attached to a new kernel, or (b) the kexts-changed
+// breakpoint was hit and we need to figure out what kexts have been added or
+// removed. Read the kext summaries from the inferior kernel memory, compare
+// them against the m_known_kexts vector and update the m_known_kexts vector as
+// needed to keep in sync with the inferior.
+
+bool DynamicLoaderDarwinKernel::ParseKextSummaries(
+    const Address &kext_summary_addr, uint32_t count) {
+  KextImageInfo::collection kext_summaries;
+  Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
+  LLDB_LOGF(log,
+            "Kexts-changed breakpoint hit, there are %d kexts currently.\n",
+            count);
+
+  std::lock_guard<std::recursive_mutex> guard(m_mutex);
+
+  if (!ReadKextSummaries(kext_summary_addr, count, kext_summaries))
+    return false;
+
+  // read the plugin.dynamic-loader.darwin-kernel.load-kexts setting -- if the
+  // user requested no kext loading, don't print any messages about kexts &
+  // don't try to read them.
+  const bool load_kexts = GetGlobalProperties()->GetLoadKexts();
+
+  // By default, all kexts we've loaded in the past are marked as "remove" and
+  // all of the kexts we just found out about from ReadKextSummaries are marked
+  // as "add".
+  std::vector<bool> to_be_removed(m_known_kexts.size(), true);
+  std::vector<bool> to_be_added(count, true);
+
+  int number_of_new_kexts_being_added = 0;
+  int number_of_old_kexts_being_removed = m_known_kexts.size();
+
+  const uint32_t new_kexts_size = kext_summaries.size();
+  const uint32_t old_kexts_size = m_known_kexts.size();
+
+  // The m_known_kexts vector may have entries that have been Cleared, or are a
+  // kernel.
+  for (uint32_t old_kext = 0; old_kext < old_kexts_size; old_kext++) {
+    bool ignore = false;
+    KextImageInfo &image_info = m_known_kexts[old_kext];
+    if (image_info.IsKernel()) {
+      ignore = true;
+    } else if (image_info.GetLoadAddress() == LLDB_INVALID_ADDRESS &&
+               !image_info.GetModule()) {
+      ignore = true;
+    }
+
+    if (ignore) {
+      number_of_old_kexts_being_removed--;
+      to_be_removed[old_kext] = false;
+    }
+  }
+
+  // Scan over the list of kexts we just read from the kernel, note those that
+  // need to be added and those already loaded.
+  for (uint32_t new_kext = 0; new_kext < new_kexts_size; new_kext++) {
+    bool add_this_one = true;
+    for (uint32_t old_kext = 0; old_kext < old_kexts_size; old_kext++) {
+      if (m_known_kexts[old_kext] == kext_summaries[new_kext]) {
+        // We already have this kext, don't re-load it.
+        to_be_added[new_kext] = false;
+        // This kext is still present, do not remove it.
+        to_be_removed[old_kext] = false;
+
+        number_of_old_kexts_being_removed--;
+        add_this_one = false;
+        break;
+      }
+    }
+    // If this "kext" entry is actually an alias for the kernel -- the kext was
+    // compiled into the kernel or something -- then we don't want to load the
+    // kernel's text section at a different address.  Ignore this kext entry.
+    if (kext_summaries[new_kext].GetUUID().IsValid() &&
+        m_kernel.GetUUID().IsValid() &&
+        kext_summaries[new_kext].GetUUID() == m_kernel.GetUUID()) {
+      to_be_added[new_kext] = false;
+      break;
+    }
+    if (add_this_one) {
+      number_of_new_kexts_being_added++;
+    }
+  }
+
+  if (number_of_new_kexts_being_added == 0 &&
+      number_of_old_kexts_being_removed == 0)
+    return true;
+
+  Stream &s = m_process->GetTarget().GetDebugger().GetOutputStream();
+  if (load_kexts) {
+    if (number_of_new_kexts_being_added > 0 &&
+        number_of_old_kexts_being_removed > 0) {
+      s.Printf("Loading %d kext modules and unloading %d kext modules ",
+               number_of_new_kexts_being_added,
+               number_of_old_kexts_being_removed);
+    } else if (number_of_new_kexts_being_added > 0) {
+      s.Printf("Loading %d kext modules ", number_of_new_kexts_being_added);
+    } else if (number_of_old_kexts_being_removed > 0) {
+      s.Printf("Unloading %d kext modules ", number_of_old_kexts_being_removed);
+    }
+  }
+
+  if (log) {
+    if (load_kexts) {
+      LLDB_LOGF(log,
+                "DynamicLoaderDarwinKernel::ParseKextSummaries: %d kexts "
+                "added, %d kexts removed",
+                number_of_new_kexts_being_added,
+                number_of_old_kexts_being_removed);
+    } else {
+      LLDB_LOGF(log,
+                "DynamicLoaderDarwinKernel::ParseKextSummaries kext loading is "
+                "disabled, else would have %d kexts added, %d kexts removed",
+                number_of_new_kexts_being_added,
+                number_of_old_kexts_being_removed);
+    }
+  }
+
+  // Build up a list of <kext-name, uuid> for any kexts that fail to load
+  std::vector<std::pair<std::string, UUID>> kexts_failed_to_load;
+  if (number_of_new_kexts_being_added > 0) {
+    ModuleList loaded_module_list;
+
+    const uint32_t num_of_new_kexts = kext_summaries.size();
+    for (uint32_t new_kext = 0; new_kext < num_of_new_kexts; new_kext++) {
+      if (to_be_added[new_kext]) {
+        KextImageInfo &image_info = kext_summaries[new_kext];
+        bool kext_successfully_added = true;
+        if (load_kexts) {
+          if (!image_info.LoadImageUsingMemoryModule(m_process)) {
+            kexts_failed_to_load.push_back(std::pair<std::string, UUID>(
+                kext_summaries[new_kext].GetName(),
+                kext_summaries[new_kext].GetUUID()));
+            image_info.LoadImageAtFileAddress(m_process);
+            kext_successfully_added = false;
+          }
+        }
+
+        m_known_kexts.push_back(image_info);
+
+        if (image_info.GetModule() &&
+            m_process->GetStopID() == image_info.GetProcessStopId())
+          loaded_module_list.AppendIfNeeded(image_info.GetModule());
+
+        if (load_kexts) {
+          if (kext_successfully_added)
+            s.Printf(".");
+          else
+            s.Printf("-");
+        }
+
+        if (log)
+          kext_summaries[new_kext].PutToLog(log);
+      }
+    }
+    m_process->GetTarget().ModulesDidLoad(loaded_module_list);
+  }
+
+  if (number_of_old_kexts_being_removed > 0) {
+    ModuleList loaded_module_list;
+    const uint32_t num_of_old_kexts = m_known_kexts.size();
+    for (uint32_t old_kext = 0; old_kext < num_of_old_kexts; old_kext++) {
+      ModuleList unloaded_module_list;
+      if (to_be_removed[old_kext]) {
+        KextImageInfo &image_info = m_known_kexts[old_kext];
+        // You can't unload the kernel.
+        if (!image_info.IsKernel()) {
+          if (image_info.GetModule()) {
+            unloaded_module_list.AppendIfNeeded(image_info.GetModule());
+          }
+          s.Printf(".");
+          image_info.Clear();
+          // should pull it out of the KextImageInfos vector but that would
+          // mutate the list and invalidate the to_be_removed bool vector;
+          // leaving it in place once Cleared() is relatively harmless.
+        }
+      }
+      m_process->GetTarget().ModulesDidUnload(unloaded_module_list, false);
+    }
+  }
+
+  if (load_kexts) {
+    s.Printf(" done.\n");
+    if (kexts_failed_to_load.size() > 0 && number_of_new_kexts_being_added > 0) {
+      s.Printf("Failed to load %d of %d kexts:\n",
+               (int)kexts_failed_to_load.size(),
+               number_of_new_kexts_being_added);
+      // print a sorted list of <kext-name, uuid> kexts which failed to load
+      unsigned longest_name = 0;
+      std::sort(kexts_failed_to_load.begin(), kexts_failed_to_load.end());
+      for (const auto &ku : kexts_failed_to_load) {
+        if (ku.first.size() > longest_name)
+          longest_name = ku.first.size();
+      }
+      for (const auto &ku : kexts_failed_to_load) {
+        std::string uuid;
+        if (ku.second.IsValid())
+          uuid = ku.second.GetAsString();
+        s.Printf(" %-*s %s\n", longest_name, ku.first.c_str(), uuid.c_str());
+      }
+    }
+    s.Flush();
+  }
+
+  return true;
+}
+
+uint32_t DynamicLoaderDarwinKernel::ReadKextSummaries(
+    const Address &kext_summary_addr, uint32_t image_infos_count,
+    KextImageInfo::collection &image_infos) {
+  const ByteOrder endian = m_kernel.GetByteOrder();
+  const uint32_t addr_size = m_kernel.GetAddressByteSize();
+
+  image_infos.resize(image_infos_count);
+  const size_t count = image_infos.size() * m_kext_summary_header.entry_size;
+  DataBufferHeap data(count, 0);
+  Status error;
+
+  const bool prefer_file_cache = false;
+  const size_t bytes_read = m_process->GetTarget().ReadMemory(
+      kext_summary_addr, prefer_file_cache, data.GetBytes(), data.GetByteSize(),
+      error);
+  if (bytes_read == count) {
+
+    DataExtractor extractor(data.GetBytes(), data.GetByteSize(), endian,
+                            addr_size);
+    uint32_t i = 0;
+    for (uint32_t kext_summary_offset = 0;
+         i < image_infos.size() &&
+         extractor.ValidOffsetForDataOfSize(kext_summary_offset,
+                                            m_kext_summary_header.entry_size);
+         ++i, kext_summary_offset += m_kext_summary_header.entry_size) {
+      lldb::offset_t offset = kext_summary_offset;
+      const void *name_data =
+          extractor.GetData(&offset, KERNEL_MODULE_MAX_NAME);
+      if (name_data == nullptr)
+        break;
+      image_infos[i].SetName((const char *)name_data);
+      UUID uuid = UUID::fromOptionalData(extractor.GetData(&offset, 16), 16);
+      image_infos[i].SetUUID(uuid);
+      image_infos[i].SetLoadAddress(extractor.GetU64(&offset));
+      image_infos[i].SetSize(extractor.GetU64(&offset));
+    }
+    if (i < image_infos.size())
+      image_infos.resize(i);
+  } else {
+    image_infos.clear();
+  }
+  return image_infos.size();
+}
+
+bool DynamicLoaderDarwinKernel::ReadAllKextSummaries() {
+  std::lock_guard<std::recursive_mutex> guard(m_mutex);
+
+  if (ReadKextSummaryHeader()) {
+    if (m_kext_summary_header.entry_count > 0 &&
+        m_kext_summary_header_addr.IsValid()) {
+      Address summary_addr(m_kext_summary_header_addr);
+      summary_addr.Slide(m_kext_summary_header.GetSize());
+      if (!ParseKextSummaries(summary_addr,
+                              m_kext_summary_header.entry_count)) {
+        m_known_kexts.clear();
+      }
+      return true;
+    }
+  }
+  return false;
+}
+
+// Dump an image info structure to the file handle provided.
+void DynamicLoaderDarwinKernel::KextImageInfo::PutToLog(Log *log) const {
+  if (m_load_address == LLDB_INVALID_ADDRESS) {
+    LLDB_LOG(log, "uuid={0} name=\"{1}\" (UNLOADED)", m_uuid.GetAsString(),
+             m_name);
+  } else {
+    LLDB_LOG(log, "addr={0:x+16} size={1:x+16} uuid={2} name=\"{3}\"",
+        m_load_address, m_size, m_uuid.GetAsString(), m_name);
+  }
+}
+
+// Dump the _dyld_all_image_infos members and all current image infos that we
+// have parsed to the file handle provided.
+void DynamicLoaderDarwinKernel::PutToLog(Log *log) const {
+  if (log == nullptr)
+    return;
+
+  std::lock_guard<std::recursive_mutex> guard(m_mutex);
+  LLDB_LOGF(log,
+            "gLoadedKextSummaries = 0x%16.16" PRIx64
+            " { version=%u, entry_size=%u, entry_count=%u }",
+            m_kext_summary_header_addr.GetFileAddress(),
+            m_kext_summary_header.version, m_kext_summary_header.entry_size,
+            m_kext_summary_header.entry_count);
+
+  size_t i;
+  const size_t count = m_known_kexts.size();
+  if (count > 0) {
+    log->PutCString("Loaded:");
+    for (i = 0; i < count; i++)
+      m_known_kexts[i].PutToLog(log);
+  }
+}
+
+void DynamicLoaderDarwinKernel::PrivateInitialize(Process *process) {
+  DEBUG_PRINTF("DynamicLoaderDarwinKernel::%s() process state = %s\n",
+               __FUNCTION__, StateAsCString(m_process->GetState()));
+  Clear(true);
+  m_process = process;
+}
+
+void DynamicLoaderDarwinKernel::SetNotificationBreakpointIfNeeded() {
+  if (m_break_id == LLDB_INVALID_BREAK_ID && m_kernel.GetModule()) {
+    DEBUG_PRINTF("DynamicLoaderDarwinKernel::%s() process state = %s\n",
+                 __FUNCTION__, StateAsCString(m_process->GetState()));
+
+    const bool internal_bp = true;
+    const bool hardware = false;
+    const LazyBool skip_prologue = eLazyBoolNo;
+    FileSpecList module_spec_list;
+    module_spec_list.Append(m_kernel.GetModule()->GetFileSpec());
+    Breakpoint *bp =
+        m_process->GetTarget()
+            .CreateBreakpoint(&module_spec_list, nullptr,
+                              "OSKextLoadedKextSummariesUpdated",
+                              eFunctionNameTypeFull, eLanguageTypeUnknown, 0,
+                              skip_prologue, internal_bp, hardware)
+            .get();
+
+    bp->SetCallback(DynamicLoaderDarwinKernel::BreakpointHitCallback, this,
+                    true);
+    m_break_id = bp->GetID();
+  }
+}
+
+// Member function that gets called when the process state changes.
+void DynamicLoaderDarwinKernel::PrivateProcessStateChanged(Process *process,
+                                                           StateType state) {
+  DEBUG_PRINTF("DynamicLoaderDarwinKernel::%s(%s)\n", __FUNCTION__,
+               StateAsCString(state));
+  switch (state) {
+  case eStateConnected:
+  case eStateAttaching:
+  case eStateLaunching:
+  case eStateInvalid:
+  case eStateUnloaded:
+  case eStateExited:
+  case eStateDetached:
+    Clear(false);
+    break;
+
+  case eStateStopped:
+    UpdateIfNeeded();
+    break;
+
+  case eStateRunning:
+  case eStateStepping:
+  case eStateCrashed:
+  case eStateSuspended:
+    break;
+  }
+}
+
+ThreadPlanSP
+DynamicLoaderDarwinKernel::GetStepThroughTrampolinePlan(Thread &thread,
+                                                        bool stop_others) {
+  ThreadPlanSP thread_plan_sp;
+  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
+  LLDB_LOGF(log, "Could not find symbol for step through.");
+  return thread_plan_sp;
+}
+
+Status DynamicLoaderDarwinKernel::CanLoadImage() {
+  Status error;
+  error.SetErrorString(
+      "always unsafe to load or unload shared libraries in the darwin kernel");
+  return error;
+}
+
+void DynamicLoaderDarwinKernel::Initialize() {
+  PluginManager::RegisterPlugin(GetPluginNameStatic(),
+                                GetPluginDescriptionStatic(), CreateInstance,
+                                DebuggerInitialize);
+}
+
+void DynamicLoaderDarwinKernel::Terminate() {
+  PluginManager::UnregisterPlugin(CreateInstance);
+}
+
+void DynamicLoaderDarwinKernel::DebuggerInitialize(
+    lldb_private::Debugger &debugger) {
+  if (!PluginManager::GetSettingForDynamicLoaderPlugin(
+          debugger, DynamicLoaderDarwinKernelProperties::GetSettingName())) {
+    const bool is_global_setting = true;
+    PluginManager::CreateSettingForDynamicLoaderPlugin(
+        debugger, GetGlobalProperties()->GetValueProperties(),
+        ConstString("Properties for the DynamicLoaderDarwinKernel plug-in."),
+        is_global_setting);
+  }
+}
+
+lldb_private::ConstString DynamicLoaderDarwinKernel::GetPluginNameStatic() {
+  static ConstString g_name("darwin-kernel");
+  return g_name;
+}
+
+const char *DynamicLoaderDarwinKernel::GetPluginDescriptionStatic() {
+  return "Dynamic loader plug-in that watches for shared library loads/unloads "
+         "in the MacOSX kernel.";
+}
+
+// PluginInterface protocol
+lldb_private::ConstString DynamicLoaderDarwinKernel::GetPluginName() {
+  return GetPluginNameStatic();
+}
+
+uint32_t DynamicLoaderDarwinKernel::GetPluginVersion() { return 1; }
+
+lldb::ByteOrder
+DynamicLoaderDarwinKernel::GetByteOrderFromMagic(uint32_t magic) {
+  switch (magic) {
+  case llvm::MachO::MH_MAGIC:
+  case llvm::MachO::MH_MAGIC_64:
+    return endian::InlHostByteOrder();
+
+  case llvm::MachO::MH_CIGAM:
+  case llvm::MachO::MH_CIGAM_64:
+    if (endian::InlHostByteOrder() == lldb::eByteOrderBig)
+      return lldb::eByteOrderLittle;
+    else
+      return lldb::eByteOrderBig;
+
+  default:
+    break;
+  }
+  return lldb::eByteOrderInvalid;
+}