Share .debug_line and .debug_line_str among dwp file and main binary file.

The debug info in the dwp file needs to refer to the .debug_line and
.debug_line_str sections in the main binary.

This fixes dump_syms not generating LINE records for dwp in split dwarf.

Bug: chromium:1448979
Change-Id: I71923f12cea72caae081c1406e2cbca55e95859e
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/4576346
Reviewed-by: Joshua Peraza <jperaza@chromium.org>

src/common/dwarf/dwarf2reader.cc

@@ -82,7 +82,8 @@ CompilationUnit::CompilationUnit(const string& path,
       is_split_dwarf_(false), is_type_unit_(false), dwo_id_(0), dwo_name_(),
       skeleton_dwo_id_(0), addr_base_(0),
       str_offsets_base_(0), have_checked_for_dwp_(false),
-      should_process_split_dwarf_(false) {}
+      should_process_split_dwarf_(false), low_pc_(0),
+      has_source_line_info_(false), source_line_offset_(0) {}
 
 // Initialize a compilation unit from a .dwo or .dwp file.
 // In this case, we need the .debug_addr section from the
@@ -91,8 +92,7 @@ CompilationUnit::CompilationUnit(const string& path,
 // the executable file, and call it as if we were still
 // processing the original compilation unit.
 
-void CompilationUnit::SetSplitDwarf(
+void CompilationUnit::SetSplitDwarf(uint64_t addr_base,
-                                    uint64_t addr_base,
                                     uint64_t dwo_id) {
   is_split_dwarf_ = true;
   addr_base_ = addr_base;
@@ -435,6 +435,12 @@ uint64_t CompilationUnit::Start() {
     string_buffer_length_ = iter->second.second;
   }
 
+  iter = GetSectionByName(sections_, ".debug_line");
+  if (iter != sections_.end()) {
+    line_buffer_ = iter->second.first;
+    line_buffer_length_ = iter->second.second;
+  }
+
   // Set the line string section if we have one.
   iter = GetSectionByName(sections_, ".debug_line_str");
   if (iter != sections_.end()) {

src/common/dwarf/dwarf2reader.h

@@ -496,6 +496,18 @@ class CompilationUnit {
 
   uint64_t GetDWOID() { return dwo_id_; }
 
+  const uint8_t* GetLineBuffer() { return line_buffer_; }
+
+  uint64_t GetLineBufferLen() { return line_buffer_length_; }
+
+  const uint8_t* GetLineStrBuffer() { return line_string_buffer_; }
+
+  uint64_t GetLineStrBufferLen() { return line_string_buffer_length_; }
+
+  bool HasSourceLineInfo() { return has_source_line_info_; }
+
+  uint64_t GetSourceLineOffset() { return source_line_offset_; }
+
   bool ShouldProcessSplitDwarf() { return should_process_split_dwarf_; }
 
  private:
@@ -585,6 +597,10 @@ class CompilationUnit {
     else if (attr == DW_AT_low_pc) {
       low_pc_ = data;
     }
+    else if (attr == DW_AT_stmt_list) {
+      has_source_line_info_ = true;
+      source_line_offset_ = data;
+    }
     handler_->ProcessAttributeUnsigned(offset, attr, form, data);
   }
 
@@ -696,7 +712,7 @@ class CompilationUnit {
   const uint8_t* string_buffer_;
   uint64_t string_buffer_length_;
 
-  // Similarly for .debug_line_string.
+  // Similarly for .debug_line_str.
   const uint8_t* line_string_buffer_;
   uint64_t line_string_buffer_length_;
 
@@ -710,6 +726,10 @@ class CompilationUnit {
   const uint8_t* addr_buffer_;
   uint64_t addr_buffer_length_;
 
+  // .debug_line section buffer and length.
+  const uint8_t* line_buffer_;
+  uint64_t line_buffer_length_;
+
   // Flag indicating whether this compilation unit is part of a .dwo
   // or .dwp file.  If true, we are reading this unit because a
   // skeleton compilation unit in an executable file had a
@@ -757,6 +777,10 @@ class CompilationUnit {
 
   // The value of the DW_AT_low_pc attribute, if any.
   uint64_t low_pc_;
+
+  // The value of DW_AT_stmt_list attribute if any.
+  bool has_source_line_info_;
+  uint64_t source_line_offset_;
 };
 
 // A Reader for a .dwp file.  Supports the fetching of DWARF debug

src/common/dwarf_cu_to_module.cc

@@ -1075,7 +1075,9 @@ DwarfCUToModule::DwarfCUToModule(FileContext* file_context,
                                  WarningReporter* reporter,
                                  bool handle_inline,
                                  uint64_t low_pc,
-                                 uint64_t addr_base)
+                                 uint64_t addr_base,
+                                 bool has_source_line_info,
+                                 uint64_t source_line_offset)
     : RootDIEHandler(handle_inline),
       line_reader_(line_reader),
       cu_context_(new CUContext(file_context,
@@ -1084,7 +1086,8 @@ DwarfCUToModule::DwarfCUToModule(FileContext* file_context,
                                 low_pc,
                                 addr_base)),
       child_context_(new DIEContext()),
-      has_source_line_info_(false) {}
+      has_source_line_info_(has_source_line_info),
+      source_line_offset_(source_line_offset) {}
 
 DwarfCUToModule::~DwarfCUToModule() {
 }

src/common/dwarf_cu_to_module.h

@@ -266,7 +266,9 @@ class DwarfCUToModule: public RootDIEHandler {
                   WarningReporter* reporter,
                   bool handle_inline = false,
                   uint64_t low_pc = 0,
-                  uint64_t addr_base = 0);
+                  uint64_t addr_base = 0,
+                  bool has_source_line_info = false,
+                  uint64_t source_line_offset = 0);
   ~DwarfCUToModule();
 
   void ProcessAttributeSigned(enum DwarfAttribute attr,

src/common/linux/dump_symbols.cc

@@ -351,19 +351,29 @@ void StartProcessSplitDwarf(google_breakpad::CompilationUnit* reader,
   for (auto section : split_sections)
     file_context.AddSectionToSectionMap(section.first, section.second.first,
                                         section.second.second);
-  // Because DWP/DWO file doesn't have .debug_addr/.debug_line, its debug info
+  // Because DWP/DWO file doesn't have .debug_addr/.debug_line/.debug_line_str,
-  // will refer to .debug_addr/.debug_line in the main binary.
+  // its debug info will refer to .debug_addr/.debug_line in the main binary.
   if (file_context.section_map().find(".debug_addr") ==
       file_context.section_map().end())
     file_context.AddSectionToSectionMap(".debug_addr", reader->GetAddrBuffer(),
                                         reader->GetAddrBufferLen());
+  if (file_context.section_map().find(".debug_line") ==
+      file_context.section_map().end())
+    file_context.AddSectionToSectionMap(".debug_line", reader->GetLineBuffer(),
+                                        reader->GetLineBufferLen());
+  if (file_context.section_map().find(".debug_line_str") ==
+      file_context.section_map().end())
+    file_context.AddSectionToSectionMap(".debug_line_str",
+                                        reader->GetLineStrBuffer(),
+                                        reader->GetLineStrBufferLen());
 
   DumperRangesHandler ranges_handler(&split_byte_reader);
   DumperLineToModule line_to_module(&split_byte_reader);
   DwarfCUToModule::WarningReporter reporter(split_file, cu_offset);
-  DwarfCUToModule root_handler(&file_context, &line_to_module, &ranges_handler,
+  DwarfCUToModule root_handler(
-                               &reporter, handle_inline, reader->GetLowPC(),
+      &file_context, &line_to_module, &ranges_handler, &reporter, handle_inline,
-                               reader->GetAddrBase());
+      reader->GetLowPC(), reader->GetAddrBase(), reader->HasSourceLineInfo(),
+      reader->GetSourceLineOffset());
   google_breakpad::DIEDispatcher die_dispatcher(&root_handler);
   google_breakpad::CompilationUnit split_reader(
       split_file, file_context.section_map(), cu_offset, &split_byte_reader,

src/common/mac/dump_syms.cc

@@ -442,18 +442,28 @@ void DumpSymbols::StartProcessSplitDwarf(
   for (auto section : split_sections)
     file_context.AddSectionToSectionMap(section.first, section.second.first,
                                         section.second.second);
-  // If DWP/DWO file doesn't have .debug_addr, its debug info will refer to
+  // Because DWP/DWO file doesn't have .debug_addr/.debug_line/.debug_line_str,
-  // .debug_addr in the main binary.
+  // its debug info will refer to .debug_addr/.debug_line in the main binary.
   if (file_context.section_map().find(".debug_addr") ==
       file_context.section_map().end())
     file_context.AddSectionToSectionMap(".debug_addr", reader->GetAddrBuffer(),
                                         reader->GetAddrBufferLen());
+  if (file_context.section_map().find(".debug_line") ==
+      file_context.section_map().end())
+    file_context.AddSectionToSectionMap(".debug_line", reader->GetLineBuffer(),
+                                        reader->GetLineBufferLen());
+  if (file_context.section_map().find(".debug_line_str") ==
+      file_context.section_map().end())
+    file_context.AddSectionToSectionMap(".debug_line_str",
+                                        reader->GetLineStrBuffer(),
+                                        reader->GetLineStrBufferLen());
   DumperRangesHandler ranges_handler(&split_byte_reader);
   DumperLineToModule line_to_module(&split_byte_reader);
   DwarfCUToModule::WarningReporter reporter(split_file, cu_offset);
-  DwarfCUToModule root_handler(&file_context, &line_to_module, &ranges_handler,
+  DwarfCUToModule root_handler(
-                               &reporter, handle_inline, reader->GetLowPC(),
+      &file_context, &line_to_module, &ranges_handler, &reporter, handle_inline,
-                               reader->GetAddrBase());
+      reader->GetLowPC(), reader->GetAddrBase(), reader->HasSourceLineInfo(),
+      reader->GetSourceLineOffset());
   google_breakpad::DIEDispatcher die_dispatcher(&root_handler);
   google_breakpad::CompilationUnit split_reader(
       split_file, file_context.section_map(), cu_offset, &split_byte_reader,