When ProcessMachCore has metadata for a binary, don't scan

Mach-O corefiles have several possible types of metadata for the
binaries that were running when the corefile was written.
ProcessMachCore will try to find these binaries, and load them.
When we have a hint, but could not find the binary, this change
makes ProcessMachCore not fall back to scanning the corefile looking
for ANY binary that it could load.  We sometimes have multiple binaries
present in the memory in a corefile, but only the correct binary
should be loaded, the others are data.

Differential Revision: https://reviews.llvm.org/D157168
rdar://112602508

Author: jasonmolenda

lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp

@@ -223,16 +223,20 @@ void ProcessMachCore::CreateMemoryRegions() {
   }
 }
 
-void ProcessMachCore::LoadBinariesViaMetadata() {
+bool ProcessMachCore::LoadBinariesViaMetadata() {
   Log *log(GetLog(LLDBLog::DynamicLoader | LLDBLog::Process));
   ObjectFile *core_objfile = m_core_module_sp->GetObjectFile();
-  bool found_main_binary_definitively = false;
 
   addr_t objfile_binary_value;
   bool objfile_binary_value_is_offset;
   UUID objfile_binary_uuid;
   ObjectFile::BinaryType type;
 
+  // This will be set to true if we had a metadata hint
+  // specifying a UUID or address -- and we should not fall back
+  // to doing an exhaustive search.
+  bool found_binary_spec_in_metadata = false;
+
   if (core_objfile->GetCorefileMainBinaryInfo(objfile_binary_value,
                                               objfile_binary_value_is_offset,
                                               objfile_binary_uuid, type)) {
@@ -244,14 +248,14 @@ void ProcessMachCore::LoadBinariesViaMetadata() {
                   objfile_binary_uuid.GetAsString().c_str(),
                   objfile_binary_value, objfile_binary_value_is_offset, type);
     }
+    found_binary_spec_in_metadata = true;
 
     // If this is the xnu kernel, don't load it now.  Note the correct
     // DynamicLoader plugin to use, and the address of the kernel, and
     // let the DynamicLoader handle the finding & loading of the binary.
     if (type == ObjectFile::eBinaryTypeKernel) {
       m_mach_kernel_addr = objfile_binary_value;
       m_dyld_plugin_name = DynamicLoaderDarwinKernel::GetPluginNameStatic();
-      found_main_binary_definitively = true;
     } else if (type == ObjectFile::eBinaryTypeUser) {
       m_dyld_addr = objfile_binary_value;
       m_dyld_plugin_name = DynamicLoaderMacOSXDYLD::GetPluginNameStatic();
@@ -265,7 +269,6 @@ void ProcessMachCore::LoadBinariesViaMetadata() {
               objfile_binary_value, objfile_binary_value_is_offset,
               force_symbol_search, notify, set_address_in_target,
               allow_memory_image_last_resort)) {
-        found_main_binary_definitively = true;
         m_dyld_plugin_name = DynamicLoaderStatic::GetPluginNameStatic();
       }
     }
@@ -276,7 +279,6 @@ void ProcessMachCore::LoadBinariesViaMetadata() {
   // load command is present, let's use the contents.
   UUID ident_uuid;
   addr_t ident_binary_addr = LLDB_INVALID_ADDRESS;
-  if (!found_main_binary_definitively) {
     std::string corefile_identifier = core_objfile->GetIdentifierString();
 
     // Search for UUID= and stext= strings in the identifier str.
@@ -287,6 +289,7 @@ void ProcessMachCore::LoadBinariesViaMetadata() {
       if (log)
         log->Printf("Got a UUID from LC_IDENT/kern ver str LC_NOTE: %s",
                     ident_uuid.GetAsString().c_str());
+      found_binary_spec_in_metadata = true;
     }
     if (corefile_identifier.find("stext=") != std::string::npos) {
       size_t p = corefile_identifier.find("stext=") + strlen("stext=");
@@ -297,6 +300,7 @@ void ProcessMachCore::LoadBinariesViaMetadata() {
           log->Printf("Got a load address from LC_IDENT/kern ver str "
                       "LC_NOTE: 0x%" PRIx64,
                       ident_binary_addr);
+        found_binary_spec_in_metadata = true;
       }
     }
 
@@ -309,7 +313,7 @@ void ProcessMachCore::LoadBinariesViaMetadata() {
             "ProcessMachCore::LoadBinariesViaMetadata: Found kernel binary via "
             "LC_IDENT/kern ver str LC_NOTE");
       m_mach_kernel_addr = ident_binary_addr;
-      found_main_binary_definitively = true;
+      found_binary_spec_in_metadata = true;
     } else if (ident_uuid.IsValid()) {
       // We have no address specified, only a UUID.  Load it at the file
       // address.
@@ -322,16 +326,15 @@ void ProcessMachCore::LoadBinariesViaMetadata() {
               this, llvm::StringRef(), ident_uuid, ident_binary_addr,
               value_is_offset, force_symbol_search, notify,
               set_address_in_target, allow_memory_image_last_resort)) {
-        found_main_binary_definitively = true;
+        found_binary_spec_in_metadata = true;
         m_dyld_plugin_name = DynamicLoaderStatic::GetPluginNameStatic();
       }
     }
-  }
 
   // Finally, load any binaries noted by "load binary" LC_NOTEs in the
   // corefile
   if (core_objfile->LoadCoreFileImages(*this)) {
-    found_main_binary_definitively = true;
+    found_binary_spec_in_metadata = true;
     m_dyld_plugin_name = DynamicLoaderStatic::GetPluginNameStatic();
   }
 
@@ -341,6 +344,8 @@ void ProcessMachCore::LoadBinariesViaMetadata() {
   // un-set it later.
   if (m_dyld_up)
     m_dyld_plugin_name = GetDynamicLoader()->GetPluginName();
+
+  return found_binary_spec_in_metadata;
 }
 
 void ProcessMachCore::LoadBinariesViaExhaustiveSearch() {
@@ -417,8 +422,8 @@ void ProcessMachCore::LoadBinariesViaExhaustiveSearch() {
 void ProcessMachCore::LoadBinariesAndSetDYLD() {
   Log *log(GetLog(LLDBLog::DynamicLoader | LLDBLog::Process));
 
-  LoadBinariesViaMetadata();
-  if (m_dyld_plugin_name.empty())
+  bool found_binary_spec_in_metadata = LoadBinariesViaMetadata();
+  if (!found_binary_spec_in_metadata)
     LoadBinariesViaExhaustiveSearch();
 
   if (m_dyld_plugin_name.empty()) {

lldb/source/Plugins/Process/mach-core/ProcessMachCore.h

@@ -86,7 +86,13 @@ class ProcessMachCore : public lldb_private::PostMortemProcess {
 
 private:
   void CreateMemoryRegions();
-  void LoadBinariesViaMetadata();
+
+  /// \return
+  ///   True if any metadata were found indicating the binary that should
+  ///   be loaded, regardless of whether the specified binary could be found.
+  ///   False if no metadata were present.
+  bool LoadBinariesViaMetadata();
+
   void LoadBinariesViaExhaustiveSearch();
   void LoadBinariesAndSetDYLD();
   void CleanupMemoryRegionPermissions();