Keep input SHF_GNU_RETAIN sections and strip output SHF_GNU_RETAIN for GNU/FreBSD ELFOSABIs.

2020-12-14  H.J. Lu  <hjl.tools@gmail.com>
	    Cary Coutant  <ccoutant@gmail.com>

elfcpp/
	PR gold/27039
	* elfcpp.h (SHF): Add SHF_GNU_RETAIN.

gold/
    	PR gold/27039
	* layout.cc (Layout::layout): Strip SHF_GNU_RETAIN.
	* object.cc (Sized_relobj_file::Sized_relobj_file): Initialize osabi_.
	(Sized_relobj_file::do_layout): Keep SHF_GNU_RETAIN sections for
	GNU/FreBSD ELFOSABIs.
	* object.h (Osabi) New class.
	(Sized_relobj_file): Add osabi() and osabi_.
	* testsuite/Makefile.am (check_SCRIPTS): Add retain.sh.
	(check_DATA): Add retain_1.out retain_2.out.
	(MOSTLYCLEANFILES): Add retain_1 retain_2.
	(retain_1.out): New target.
	(retain_1): Likewise.
	(retain_1.o): Likewise.
	(retain_2.out): Likewise.
	(retain_2): Likewise.
	(retain_2.o): Likewise.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/retain.sh: New file.
	* testsuite/retain_1.s: Likewise.
	* testsuite/retain_2.s: Likewise.

1 files changed, 50 insertions, 0 deletions

diff --git a/gold/object.h b/gold/object.h
index b7bd38f..4afee99 100644
--- a/gold/object.h
+++ b/gold/object.h
@@ -384,6 +384,49 @@ build_compressed_section_map(const unsigned char* pshdrs, unsigned int shnum,
 			     const char* names, section_size_type names_size,
 			     Object* obj, bool decompress_if_needed);
 
+// Osabi represents the EI_OSABI field from the ELF header.
+
+template <int size, bool big_endian>
+class Osabi
+{
+ public:
+  Osabi(const elfcpp::Ehdr<size, big_endian>& ehdr)
+    : ei_osabi_(static_cast<elfcpp::ELFOSABI>(
+		    ehdr.get_e_ident()[elfcpp::EI_OSABI]))
+  { }
+
+  bool
+  has_shf_retain(elfcpp::Elf_Xword sh_flags) const
+  {
+    switch (this->ei_osabi_)
+      {
+      case elfcpp::ELFOSABI_GNU:
+      case elfcpp::ELFOSABI_FREEBSD:
+	return (sh_flags & elfcpp::SHF_GNU_RETAIN) != 0;
+      default:
+        break;
+      }
+    return false;
+  }
+
+  elfcpp::Elf_Xword
+  ignored_sh_flags() const
+  {
+    switch (this->ei_osabi_)
+      {
+      case elfcpp::ELFOSABI_GNU:
+      case elfcpp::ELFOSABI_FREEBSD:
+	return elfcpp::SHF_GNU_RETAIN;
+      default:
+        break;
+      }
+    return 0;
+  }
+
+ private:
+  elfcpp::ELFOSABI ei_osabi_;
+};
+
 // Object is an abstract base class which represents either a 32-bit
 // or a 64-bit input object.  This can be a regular object file
 // (ET_REL) or a shared object (ET_DYN).
@@ -2205,6 +2248,11 @@ class Sized_relobj_file : public Sized_relobj<size, big_endian>
   e_type() const
   { return this->e_type_; }
 
+  // Return the EI_OSABI.
+  const Osabi<size, big_endian>&
+  osabi() const
+  { return this->osabi_; }
+
   // Return the number of symbols.  This is only valid after
   // Object::add_symbols has been called.
   unsigned int
@@ -2845,6 +2893,8 @@ class Sized_relobj_file : public Sized_relobj<size, big_endian>
 
   // General access to the ELF file.
   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
+  // The EI_OSABI.
+  const Osabi<size, big_endian> osabi_;
   // Type of ELF file (ET_REL or ET_EXEC).  ET_EXEC files are allowed
   // as input files only for the --just-symbols option.
   int e_type_;