Provide a substitute to load command of gdb.

For bare-metal targets, lldb was missing a command like 'load' in gdb
which can be used to create executable image on the target. This was
discussed in
http://lists.llvm.org/pipermail/lldb-dev/2016-December/011752.html

This commits adds an option to "target module load" command to provide
that functionality. It does not set the PC to entry address which will
be done separately.

Reviewed in https://reviews.llvm.org/D28804

llvm-svn: 292499

lldb/include/lldb/Core/Module.h

@@ -962,6 +962,20 @@ public:
   bool RemapSourceFile(llvm::StringRef path, std::string &new_path) const;
   bool RemapSourceFile(const char *, std::string &) const = delete;
 
+  //------------------------------------------------------------------
+  /// Loads this module to memory.
+  ///
+  /// Loads the bits needed to create an executable image to the memory.
+  /// It is useful with bare-metal targets where target does not have the
+  /// ability to start a process itself.
+  ///
+  /// @param[in] target
+  ///     Target where to load the module.
+  ///
+  /// @return
+  //------------------------------------------------------------------
+  Error LoadInMemory(Target &target);
+
   //----------------------------------------------------------------------
   /// @class LookupInfo Module.h "lldb/Core/Module.h"
   /// @brief A class that encapsulates name lookup information.

lldb/include/lldb/Symbol/ObjectFile.h

@@ -774,6 +774,20 @@ public:
       llvm::StringRef name,
       lldb::SymbolType symbol_type_hint = lldb::eSymbolTypeUndefined);
 
+  //------------------------------------------------------------------
+  /// Loads this objfile to memory.
+  ///
+  /// Loads the bits needed to create an executable image to the memory.
+  /// It is useful with bare-metal targets where target does not have the
+  /// ability to start a process itself.
+  ///
+  /// @param[in] target
+  ///     Target where to load.
+  ///
+  /// @return
+  //------------------------------------------------------------------
+  virtual Error LoadInMemory(Target &target);
+
 protected:
   //------------------------------------------------------------------
   // Member variables.

lldb/source/Commands/CommandObjectTarget.cpp

@@ -2567,6 +2567,9 @@ public:
         m_option_group(),
         m_file_option(LLDB_OPT_SET_1, false, "file", 'f', 0, eArgTypeName,
                       "Fullpath or basename for module to load.", ""),
+        m_load_option(LLDB_OPT_SET_1, false, "load", 'l',
+                      "Write file contents to the memory.",
+                      false, true),
         m_slide_option(LLDB_OPT_SET_1, false, "slide", 's', 0, eArgTypeOffset,
                        "Set the load address for all sections to be the "
                        "virtual address in the file plus the offset.",
@@ -2574,6 +2577,7 @@ public:
     m_option_group.Append(&m_uuid_option_group, LLDB_OPT_SET_ALL,
                           LLDB_OPT_SET_1);
     m_option_group.Append(&m_file_option, LLDB_OPT_SET_ALL, LLDB_OPT_SET_1);
+    m_option_group.Append(&m_load_option, LLDB_OPT_SET_ALL, LLDB_OPT_SET_1);
     m_option_group.Append(&m_slide_option, LLDB_OPT_SET_ALL, LLDB_OPT_SET_1);
     m_option_group.Finalize();
   }
@@ -2585,6 +2589,7 @@ public:
 protected:
   bool DoExecute(Args &args, CommandReturnObject &result) override {
     Target *target = m_interpreter.GetDebugger().GetSelectedTarget().get();
+    const bool load = m_load_option.GetOptionValue().GetCurrentValue();
     if (target == nullptr) {
       result.AppendError("invalid target, create a debug target using the "
                          "'target create' command");
@@ -2594,6 +2599,21 @@ protected:
       const size_t argc = args.GetArgumentCount();
       ModuleSpec module_spec;
       bool search_using_module_spec = false;
+
+      // Allow "load" option to work without --file or --uuid
+      // option.
+      if (load) {
+        if (!m_file_option.GetOptionValue().OptionWasSet() &&
+            !m_uuid_option_group.GetOptionValue().OptionWasSet()) {
+          ModuleList &module_list = target->GetImages();
+          if (module_list.GetSize() == 1) {
+            search_using_module_spec = true;
+            module_spec.GetFileSpec() =
+                module_list.GetModuleAtIndex(0)->GetFileSpec();
+          }
+        }
+      }
+
       if (m_file_option.GetOptionValue().OptionWasSet()) {
         search_using_module_spec = true;
         const char *arg_cstr = m_file_option.GetOptionValue().GetCurrentValue();
@@ -2721,6 +2741,13 @@ protected:
                   if (process)
                     process->Flush();
                 }
+                if (load) {
+                  Error error = module->LoadInMemory(*target);
+                  if (error.Fail()) {
+                    result.AppendError(error.AsCString());
+                    return false;
+                  }
+                }
               } else {
                 module->GetFileSpec().GetPath(path, sizeof(path));
                 result.AppendErrorWithFormat(
@@ -2783,6 +2810,7 @@ protected:
   OptionGroupOptions m_option_group;
   OptionGroupUUID m_uuid_option_group;
   OptionGroupString m_file_option;
+  OptionGroupBoolean m_load_option;
   OptionGroupUInt64 m_slide_option;
 };
 

lldb/source/Core/Module.cpp

@@ -1664,3 +1664,7 @@ bool Module::GetIsDynamicLinkEditor() {
 
   return false;
 }
+
+Error Module::LoadInMemory(Target &target) {
+  return m_objfile_sp->LoadInMemory(target);
+}

lldb/source/Symbol/ObjectFile.cpp

@@ -20,6 +20,9 @@
 #include "lldb/Core/Timer.h"
 #include "lldb/Symbol/ObjectContainer.h"
 #include "lldb/Symbol/SymbolFile.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Target/SectionLoadList.h"
 #include "lldb/Target/Process.h"
 #include "lldb/lldb-private.h"
 
@@ -648,3 +651,31 @@ ConstString ObjectFile::GetNextSyntheticSymbolName() {
             file_name.GetCString());
   return ConstString(ss.GetString());
 }
+
+Error ObjectFile::LoadInMemory(Target &target) {
+  Error error;
+  ProcessSP process = target.CalculateProcess();
+  if (!process)
+    return Error("No Process");
+
+  SectionList *section_list = GetSectionList();
+  if (!section_list)
+      return Error("No section in object file");
+  size_t section_count = section_list->GetNumSections(0);
+  for (size_t i = 0; i < section_count; ++i) {
+    SectionSP section_sp = section_list->GetSectionAtIndex(i);
+    addr_t addr = target.GetSectionLoadList().GetSectionLoadAddress(section_sp);
+    if (addr != LLDB_INVALID_ADDRESS) {
+      DataExtractor section_data;
+      // We can skip sections like bss
+      if (section_sp->GetFileSize() == 0)
+        continue;
+      section_sp->GetSectionData(section_data);
+      lldb::offset_t written = process->WriteMemory(
+          addr, section_data.GetDataStart(), section_data.GetByteSize(), error);
+      if (written != section_data.GetByteSize())
+        return error;
+    }
+  }
+  return error;
+}