Add support for .note.gnu.property sections.

elfcpp/
	PR gold/22914
	* elfcpp.h (NT_GNU_PROPERTY_TYPE_0): New note type.
	(GNU_PROPERTY_*): New Gnu property types.
	* x86_64.h (GNU_PROPERTY_X86_FEATURE_1_IBT)
	(GNU_PROPERTY_X86_FEATURE_1_SHSTK): New x86 feature bits.

gold/
	PR gold/22914
	* layout.cc (Layout::Layout): Initialize gnu_properties_.
	(read_sized_value, write_sized_value): New functions.
	(Layout::layout_gnu_property): New method.
	(Layout::create_notes): Call create_gnu_properties_note.
	(Layout::create_gnu_properties_note): New method.
	* layout.h (Layout::layout_gnu_property): New method.
	(Layout::create_gnu_properties_note): New method.
	(Layout::Gnu_property, Layout::Gnu_properties): New types.
	(Layout::gnu_properties_): New data member.
	* object.cc (Sized_relobj_file::layout_gnu_property_section): New
	method.
	(Sized_relobj_file::do_layout): Handle .note.gnu.property sections.
	* object.h (Sized_relobj_file::layout_gnu_property_section): New
	method.
	* target.h (Target::merge_gnu_property): New method.
	(Target::do_merge_gnu_property): New virtual method.
	* x86_64.cc (Target_x86_64::do_merge_gnu_property): New method.
	* testsuite/Makefile.am (gnu_property_test): New test case.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/gnu_property_a.S: New source file.
	* testsuite/gnu_property_b.S: New source file.
	* testsuite/gnu_property_c.S: New source file.
	* testsuite/gnu_property_main.c: New source file.
	* testsuite/gnu_property_test.sh: New test script.

1 files changed, 104 insertions, 0 deletions

diff --git a/gold/object.cc b/gold/object.cc
index 2b58f04..8c874fe 100644
--- a/gold/object.cc
+++ b/gold/object.cc
@@ -1282,6 +1282,102 @@ Sized_relobj_file<size, big_endian>::layout_eh_frame_section(
     this->set_relocs_must_follow_section_writes();
 }
 
+// Layout an input .note.gnu.property section.
+
+// This note section has an *extremely* non-standard layout.
+// The gABI spec says that ELF-64 files should have 8-byte fields and
+// 8-byte alignment in the note section, but the Gnu tools generally
+// use 4-byte fields and 4-byte alignment (see the comment for
+// Layout::create_note).  This section uses 4-byte fields (i.e.,
+// namesz, descsz, and type are always 4 bytes), the name field is
+// padded to a multiple of 4 bytes, but the desc field is padded
+// to a multiple of 4 or 8 bytes, depending on the ELF class.
+// The individual properties within the desc field always use
+// 4-byte pr_type and pr_datasz fields, but pr_data is padded to
+// a multiple of 4 or 8 bytes, depending on the ELF class.
+
+template<int size, bool big_endian>
+void
+Sized_relobj_file<size, big_endian>::layout_gnu_property_section(
+    Layout* layout,
+    unsigned int shndx)
+{
+  section_size_type contents_len;
+  const unsigned char* pcontents = this->section_contents(shndx,
+							  &contents_len,
+							  false);
+  const unsigned char* pcontents_end = pcontents + contents_len;
+
+  // Loop over all the notes in this section.
+  while (pcontents < pcontents_end)
+    {
+      if (pcontents + 16 > pcontents_end)
+	{
+	  gold_warning(_("%s: corrupt .note.gnu.property section "
+			 "(note too short)"),
+		       this->name().c_str());
+	  return;
+	}
+
+      size_t namesz = elfcpp::Swap<32, big_endian>::readval(pcontents);
+      size_t descsz = elfcpp::Swap<32, big_endian>::readval(pcontents + 4);
+      unsigned int ntype = elfcpp::Swap<32, big_endian>::readval(pcontents + 8);
+      const unsigned char* pname = pcontents + 12;
+
+      if (namesz != 4 || strcmp(reinterpret_cast<const char*>(pname), "GNU") != 0)
+	{
+	  gold_warning(_("%s: corrupt .note.gnu.property section "
+			 "(name is not 'GNU')"),
+		       this->name().c_str());
+	  return;
+	}
+
+      if (ntype != elfcpp::NT_GNU_PROPERTY_TYPE_0)
+	{
+	  gold_warning(_("%s: unsupported note type %d "
+			 "in .note.gnu.property section"),
+		       this->name().c_str(), ntype);
+	  return;
+	}
+
+      size_t aligned_namesz = align_address(namesz, 4);
+      const unsigned char* pdesc = pname + aligned_namesz;
+
+      if (pdesc + descsz > pcontents + contents_len)
+	{
+	  gold_warning(_("%s: corrupt .note.gnu.property section"),
+		       this->name().c_str());
+	  return;
+	}
+
+      const unsigned char* pprop = pdesc;
+
+      // Loop over the program properties in this note.
+      while (pprop < pdesc + descsz)
+	{
+	  if (pprop + 8 > pdesc + descsz)
+	    {
+	      gold_warning(_("%s: corrupt .note.gnu.property section"),
+			   this->name().c_str());
+	      return;
+	    }
+	  unsigned int pr_type = elfcpp::Swap<32, big_endian>::readval(pprop);
+	  size_t pr_datasz = elfcpp::Swap<32, big_endian>::readval(pprop + 4);
+	  pprop += 8;
+	  if (pprop + pr_datasz > pdesc + descsz)
+	    {
+	      gold_warning(_("%s: corrupt .note.gnu.property section"),
+			   this->name().c_str());
+	      return;
+	    }
+	  layout->layout_gnu_property(ntype, pr_type, pr_datasz, pprop, this);
+	  pprop += align_address(pr_datasz, size / 8);
+	}
+
+      pcontents = pdesc + align_address(descsz, size / 8);
+    }
+}
+
 // Lay out the input sections.  We walk through the sections and check
 // whether they should be included in the link.  If they should, we
 // pass them to the Layout object, which will return an output section
@@ -1538,6 +1634,14 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
 	      omit[i] = true;
 	    }
 
+	  // Handle .note.gnu.property sections.
+	  if (sh_type == elfcpp::SHT_NOTE
+	      && strcmp(name, ".note.gnu.property") == 0)
+	    {
+	      this->layout_gnu_property_section(layout, i);
+	      omit[i] = true;
+	    }
+
 	  bool discard = omit[i];
 	  if (!discard)
 	    {