From bfd58944a64b0997a310b95fbe0423338961e71c Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <iant@google.com>
Date: Sat, 22 Sep 2007 04:42:09 +0000
Subject: [PATCH] Define __start and __stop symbols.

---
 gold/gold.cc   |  4 ++++
 gold/layout.cc | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++
 gold/layout.h  |  4 ++++
 3 files changed, 60 insertions(+)

diff --git a/gold/gold.cc b/gold/gold.cc
index e7b7ae2939d..2d334625e83 100644
--- a/gold/gold.cc
+++ b/gold/gold.cc
@@ -148,6 +148,10 @@ queue_middle_tasks(const General_options& options,
   // bother to create a task for it.
   define_standard_symbols(symtab, layout, input_objects->target());
 
+  // Define __start and __stop symbols for output sections where
+  // appropriate.
+  layout->define_section_symbols(symtab, input_objects->target());
+
   // Read the relocations of the input files.  We do this to find
   // which symbols are used by relocations which require a GOT and/or
   // a PLT entry, or a COPY reloc.  When we implement garbage
diff --git a/gold/layout.cc b/gold/layout.cc
index 9d4b644d112..d72b7e70c0d 100644
--- a/gold/layout.cc
+++ b/gold/layout.cc
@@ -337,6 +337,58 @@ Layout::create_initial_dynamic_sections(const Input_objects* input_objects,
   this->dynamic_section_->add_output_section_data(this->dynamic_data_);
 }
 
+// For each output section whose name can be represented as C symbol,
+// define __start and __stop symbols for the section.  This is a GNU
+// extension.
+
+void
+Layout::define_section_symbols(Symbol_table* symtab, const Target* target)
+{
+  for (Section_list::const_iterator p = this->section_list_.begin();
+       p != this->section_list_.end();
+       ++p)
+    {
+      const char* const name = (*p)->name();
+      if (name[strspn(name,
+		      ("0123456789"
+		       "ABCDEFGHIJKLMNOPWRSTUVWXYZ"
+		       "abcdefghijklmnopqrstuvwxyz"
+		       "_"))]
+	  == '\0')
+	{
+	  const std::string name_string(name);
+	  const std::string start_name("__start_" + name_string);
+	  const std::string stop_name("__stop_" + name_string);
+
+	  symtab->define_in_output_data(target,
+					start_name.c_str(),
+					NULL, // version
+					*p,
+					0, // value
+					0, // symsize
+					elfcpp::STT_NOTYPE,
+					elfcpp::STB_GLOBAL,
+					elfcpp::STV_DEFAULT,
+					0, // nonvis
+					false, // offset_is_from_end
+					false); // only_if_ref
+
+	  symtab->define_in_output_data(target,
+					stop_name.c_str(),
+					NULL, // version
+					*p,
+					0, // value
+					0, // symsize
+					elfcpp::STT_NOTYPE,
+					elfcpp::STB_GLOBAL,
+					elfcpp::STV_DEFAULT,
+					0, // nonvis
+					true, // offset_is_from_end
+					false); // only_if_ref
+	}
+    }
+}
+
 // Find the first read-only PT_LOAD segment, creating one if
 // necessary.
 
diff --git a/gold/layout.h b/gold/layout.h
index 8b349cc0a4b..ecb0490a589 100644
--- a/gold/layout.h
+++ b/gold/layout.h
@@ -85,6 +85,10 @@ class Layout
   void
   create_initial_dynamic_sections(const Input_objects*, Symbol_table*);
 
+  // Define __start and __stop symbols for output sections.
+  void
+  define_section_symbols(Symbol_table*, const Target*);
+
   // Return the Stringpool used for symbol names.
   const Stringpool*
   sympool() const
-- 
2.30.2