[LLDB][Minidump] Have Minidumps save off and properly read TLS data (llvm#109477)

This patch adds the support to `Process.cpp` to automatically save off
TLS sections, either via loading the memory region for the module, or
via reading `fs_base` via generic register. Then when Minidumps are
loaded, we now specify we want the dynamic loader to be the `POSIXDYLD`
so we can leverage the same TLS accessor code as `ProcessELFCore`. Being
able to access TLS Data is an important step for LLDB generated
minidumps to have feature parity with ELF Core dumps.

Author: Jlalond

lldb/include/lldb/Target/DynamicLoader.h

@@ -11,6 +11,7 @@
 
 #include "lldb/Core/Address.h"
 #include "lldb/Core/PluginInterface.h"
+#include "lldb/Target/CoreFileMemoryRanges.h"
 #include "lldb/Utility/FileSpec.h"
 #include "lldb/Utility/Status.h"
 #include "lldb/Utility/UUID.h"
@@ -337,6 +338,17 @@ class DynamicLoader : public PluginInterface {
     return std::nullopt;
   }
 
+  /// Returns a list of memory ranges that should be saved in the core file,
+  /// specific for this dynamic loader.
+  ///
+  /// For example, an implementation of this function can save the thread
+  /// local data of a given thread.
+  virtual void CalculateDynamicSaveCoreRanges(
+      lldb_private::Process &process,
+      std::vector<lldb_private::MemoryRegionInfo> &ranges,
+      llvm::function_ref<bool(const lldb_private::Thread &)>
+          save_thread_predicate) {};
+
 protected:
   // Utility methods for derived classes
 

lldb/source/Core/DynamicLoader.cpp

@@ -83,7 +83,11 @@ ModuleSP DynamicLoader::GetTargetExecutable() {
       ModuleSpec module_spec(executable->GetFileSpec(),
                              executable->GetArchitecture());
       auto module_sp = std::make_shared<Module>(module_spec);
-
+      // If we're a coredump and we already have a main executable, we don't
+      // need to reload the module list that target already has
+      if (!m_process->IsLiveDebugSession()) {
+        return executable;
+      }
       // Check if the executable has changed and set it to the target
       // executable if they differ.
       if (module_sp && module_sp->GetUUID().IsValid() &&
@@ -369,4 +373,3 @@ void DynamicLoader::LoadOperatingSystemPlugin(bool flush)
     if (m_process)
         m_process->LoadOperatingSystemPlugin(flush);
 }
-

lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp

@@ -18,6 +18,7 @@
 #include "lldb/Symbol/ObjectFile.h"
 #include "lldb/Target/MemoryRegionInfo.h"
 #include "lldb/Target/Platform.h"
+#include "lldb/Target/RegisterContext.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Target/Thread.h"
 #include "lldb/Target/ThreadPlanRunToAddress.h"
@@ -866,3 +867,82 @@ bool DynamicLoaderPOSIXDYLD::AlwaysRelyOnEHUnwindInfo(
 bool DynamicLoaderPOSIXDYLD::IsCoreFile() const {
   return !m_process->IsLiveDebugSession();
 }
+
+// For our ELF/POSIX builds save off the fs_base/gs_base regions
+static void AddThreadLocalMemoryRegions(Process &process, ThreadSP &thread_sp,
+                                        std::vector<MemoryRegionInfo> &ranges) {
+  lldb::RegisterContextSP reg_ctx = thread_sp->GetRegisterContext();
+  if (!reg_ctx)
+    return;
+
+  const RegisterInfo *reg_info = reg_ctx->GetRegisterInfo(
+      lldb::RegisterKind::eRegisterKindGeneric, LLDB_REGNUM_GENERIC_TP);
+  if (!reg_info)
+    return;
+
+  lldb_private::RegisterValue thread_local_register_value;
+  bool success = reg_ctx->ReadRegister(reg_info, thread_local_register_value);
+  if (!success)
+    return;
+
+  const uint64_t fail_value = UINT64_MAX;
+  bool readSuccess = false;
+  const lldb::addr_t reg_value_addr =
+      thread_local_register_value.GetAsUInt64(fail_value, &readSuccess);
+  if (!readSuccess || reg_value_addr == fail_value)
+    return;
+
+  MemoryRegionInfo thread_local_region;
+  Status err = process.GetMemoryRegionInfo(reg_value_addr, thread_local_region);
+  if (err.Fail())
+    return;
+
+  ranges.push_back(thread_local_region);
+}
+
+// Save off the link map for core files.
+static void AddLinkMapSections(Process &process,
+                               std::vector<MemoryRegionInfo> &ranges) {
+  ModuleList &module_list = process.GetTarget().GetImages();
+  Target *target = &process.GetTarget();
+  for (size_t idx = 0; idx < module_list.GetSize(); idx++) {
+    ModuleSP module_sp = module_list.GetModuleAtIndex(idx);
+    if (!module_sp)
+      continue;
+
+    ObjectFile *obj = module_sp->GetObjectFile();
+    if (!obj)
+      continue;
+    Address addr = obj->GetImageInfoAddress(target);
+    addr_t load_addr = addr.GetLoadAddress(target);
+    if (load_addr == LLDB_INVALID_ADDRESS)
+      continue;
+
+    MemoryRegionInfo link_map_section;
+    Status err = process.GetMemoryRegionInfo(load_addr, link_map_section);
+    if (err.Fail())
+      continue;
+
+    ranges.push_back(link_map_section);
+  }
+}
+
+void DynamicLoaderPOSIXDYLD::CalculateDynamicSaveCoreRanges(
+    lldb_private::Process &process,
+    std::vector<lldb_private::MemoryRegionInfo> &ranges,
+    llvm::function_ref<bool(const lldb_private::Thread &)>
+        save_thread_predicate) {
+  ThreadList &thread_list = process.GetThreadList();
+  for (size_t idx = 0; idx < thread_list.GetSize(); idx++) {
+    ThreadSP thread_sp = thread_list.GetThreadAtIndex(idx);
+    if (!thread_sp)
+      continue;
+
+    if (!save_thread_predicate(*thread_sp))
+      continue;
+
+    AddThreadLocalMemoryRegions(process, thread_sp, ranges);
+  }
+
+  AddLinkMapSections(process, ranges);
+}

lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.h

@@ -60,6 +60,12 @@ class DynamicLoaderPOSIXDYLD : public lldb_private::DynamicLoader {
                                      lldb::addr_t base_addr,
                                      bool base_addr_is_offset) override;
 
+  void CalculateDynamicSaveCoreRanges(
+      lldb_private::Process &process,
+      std::vector<lldb_private::MemoryRegionInfo> &ranges,
+      llvm::function_ref<bool(const lldb_private::Thread &)>
+          save_thread_predicate) override;
+
 protected:
   /// Runtime linker rendezvous structure.
   DYLDRendezvous m_rendezvous;

lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp

@@ -21,11 +21,13 @@
 #include "lldb/Interpreter/CommandReturnObject.h"
 #include "lldb/Interpreter/OptionArgParser.h"
 #include "lldb/Interpreter/OptionGroupBoolean.h"
+#include "lldb/Target/DynamicLoader.h"
 #include "lldb/Target/JITLoaderList.h"
 #include "lldb/Target/MemoryRegionInfo.h"
 #include "lldb/Target/SectionLoadList.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Target/UnixSignals.h"
+#include "lldb/Utility/DataBufferHeap.h"
 #include "lldb/Utility/LLDBAssert.h"
 #include "lldb/Utility/LLDBLog.h"
 #include "lldb/Utility/Log.h"
@@ -34,6 +36,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Threading.h"
 
+#include "Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.h"
 #include "Plugins/ObjectFile/Placeholder/ObjectFilePlaceholder.h"
 #include "Plugins/Process/Utility/StopInfoMachException.h"
 
@@ -333,6 +336,16 @@ ArchSpec ProcessMinidump::GetArchitecture() {
   return ArchSpec(triple);
 }
 
+DataExtractor ProcessMinidump::GetAuxvData() {
+  std::optional<llvm::ArrayRef<uint8_t>> auxv =
+      m_minidump_parser->GetStream(StreamType::LinuxAuxv);
+  if (!auxv)
+    return DataExtractor();
+
+  return DataExtractor(auxv->data(), auxv->size(), GetByteOrder(),
+                       GetAddressByteSize(), GetAddressByteSize());
+}
+
 void ProcessMinidump::BuildMemoryRegions() {
   if (m_memory_regions)
     return;
@@ -534,7 +547,12 @@ void ProcessMinidump::ReadModuleList() {
 
       module_sp = Module::CreateModuleFromObjectFile<ObjectFilePlaceholder>(
           module_spec, load_addr, load_size);
-      GetTarget().GetImages().Append(module_sp, true /* notify */);
+      // If we haven't loaded a main executable yet, set the first module to be
+      // main executable
+      if (!GetTarget().GetExecutableModule())
+        GetTarget().SetExecutableModule(module_sp);
+      else
+        GetTarget().GetImages().Append(module_sp, true /* notify */);
     }
 
     bool load_addr_changed = false;

lldb/source/Plugins/Process/minidump/ProcessMinidump.h

@@ -53,12 +53,11 @@ class ProcessMinidump : public PostMortemProcess {
 
   Status DoLoadCore() override;
 
-  DynamicLoader *GetDynamicLoader() override { return nullptr; }
+  // Returns AUXV structure found in the core file
+  lldb_private::DataExtractor GetAuxvData() override;
 
   llvm::StringRef GetPluginName() override { return GetPluginNameStatic(); }
 
-  SystemRuntime *GetSystemRuntime() override { return nullptr; }
-
   Status DoDestroy() override;
 
   void RefreshStateAfterStop() override;

lldb/source/Plugins/Process/minidump/RegisterContextMinidump_x86_64.cpp

@@ -44,6 +44,17 @@ static void writeRegister(const void *reg_src, uint8_t *context,
   memcpy(reg_dest.data(), reg_src, reg_dest.size());
 }
 
+// TODO: Fix the registers in this file!
+// writeRegister checks x86_64 registers without base registers. This causes
+// an overlap in the register enum values. So we were truncating fs_base.
+// We should standardize to the x86_64_with_base registers.
+static void writeBaseRegister(const void *reg_src, uint8_t *context,
+                              const RegisterInfo &reg) {
+  auto bytes = reg.mutable_data(context);
+  llvm::MutableArrayRef<uint8_t> reg_dest = bytes.take_front(8);
+  memcpy(reg_dest.data(), reg_src, reg_dest.size());
+}
+
 lldb::DataBufferSP lldb_private::minidump::ConvertMinidumpContext_x86_64(
     llvm::ArrayRef<uint8_t> source_data,
     RegisterInfoInterface *target_reg_interface) {
@@ -105,11 +116,12 @@ lldb::DataBufferSP lldb_private::minidump::ConvertMinidumpContext_x86_64(
     writeRegister(&context->r15, result_base, reg_info[lldb_r15_x86_64]);
   }
 
+  // See comment on base regsiter
   if ((context_flags & LLDBSpecificFlag) == LLDBSpecificFlag) {
-    writeRegister(&context->fs_base, result_base,
-                  reg_info[x86_64_with_base::lldb_fs_base]);
-    writeRegister(&context->gs_base, result_base,
-                  reg_info[x86_64_with_base::lldb_gs_base]);
+    writeBaseRegister(&context->fs_base, result_base,
+                      reg_info[x86_64_with_base::lldb_fs_base]);
+    writeBaseRegister(&context->gs_base, result_base,
+                      reg_info[x86_64_with_base::lldb_gs_base]);
   }
 
   // TODO parse the floating point registers

lldb/source/Target/Process.cpp

@@ -6528,6 +6528,29 @@ static void AddRegion(const MemoryRegionInfo &region, bool try_dirty_pages,
                 CreateCoreFileMemoryRange(region));
 }
 
+static void SaveDynamicLoaderSections(Process &process,
+                                      const SaveCoreOptions &options,
+                                      CoreFileMemoryRanges &ranges,
+                                      std::set<addr_t> &stack_ends) {
+  DynamicLoader *dyld = process.GetDynamicLoader();
+  if (!dyld)
+    return;
+
+  std::vector<MemoryRegionInfo> dynamic_loader_mem_regions;
+  std::function<bool(const lldb_private::Thread &)> save_thread_predicate =
+      [&](const lldb_private::Thread &t) -> bool {
+    return options.ShouldThreadBeSaved(t.GetID());
+  };
+  dyld->CalculateDynamicSaveCoreRanges(process, dynamic_loader_mem_regions,
+                                       save_thread_predicate);
+  for (const auto &region : dynamic_loader_mem_regions) {
+    // The Dynamic Loader can give us regions that could include a truncated
+    // stack
+    if (stack_ends.count(region.GetRange().GetRangeEnd()) == 0)
+      AddRegion(region, true, ranges);
+  }
+}
+
 static void SaveOffRegionsWithStackPointers(Process &process,
                                             const SaveCoreOptions &core_options,
                                             const MemoryRegionInfos &regions,
@@ -6559,11 +6582,13 @@ static void SaveOffRegionsWithStackPointers(Process &process,
       // off in other calls
       sp_region.GetRange().SetRangeBase(stack_head);
       sp_region.GetRange().SetByteSize(stack_size);
-      stack_ends.insert(sp_region.GetRange().GetRangeEnd());
+      const addr_t range_end = sp_region.GetRange().GetRangeEnd();
+      stack_ends.insert(range_end);
       // This will return true if the threadlist the user specified is empty,
       // or contains the thread id from thread_sp.
-      if (core_options.ShouldThreadBeSaved(thread_sp->GetID()))
+      if (core_options.ShouldThreadBeSaved(thread_sp->GetID())) {
         AddRegion(sp_region, try_dirty_pages, ranges);
+      }
     }
   }
 }
@@ -6672,9 +6697,14 @@ Status Process::CalculateCoreFileSaveRanges(const SaveCoreOptions &options,
   std::set<addr_t> stack_ends;
   // For fully custom set ups, we don't want to even look at threads if there
   // are no threads specified.
-  if (core_style != lldb::eSaveCoreCustomOnly || options.HasSpecifiedThreads())
+  if (core_style != lldb::eSaveCoreCustomOnly ||
+      options.HasSpecifiedThreads()) {
     SaveOffRegionsWithStackPointers(*this, options, regions, ranges,
                                     stack_ends);
+    // Save off the dynamic loader sections, so if we are on an architecture
+    // that supports Thread Locals, that we include those as well.
+    SaveDynamicLoaderSections(*this, options, ranges, stack_ends);
+  }
 
   switch (core_style) {
   case eSaveCoreUnspecified: