From 6257e073193332dd18558686eda4c59ee93644de Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marcin=20Ko=C5=9Bcielnicki?= <koriakin@0x04.net>
Date: Fri, 3 Jun 2016 16:42:37 +0200
Subject: bfd/elf64-s390: Support partial got relro.

---
 bfd/elf64-s390.c            | 36 ++++++++++++++++++++++++++++++++++++
 ld/emulparams/elf64_s390.sh |  3 +++
 2 files changed, 39 insertions(+)

diff --git a/bfd/elf64-s390.c b/bfd/elf64-s390.c
index f3282d8..6e50381 100644
--- a/bfd/elf64-s390.c
+++ b/bfd/elf64-s390.c
@@ -653,6 +653,8 @@ struct elf_s390_link_hash_table
   asection *srelbss;
   asection *irelifunc;
 
+  bfd_boolean split_got;
+
   union {
     bfd_signed_vma refcount;
     bfd_vma offset;
@@ -736,6 +738,8 @@ create_got_section (bfd *dynobj,
 		    struct bfd_link_info *info)
 {
   struct elf_s390_link_hash_table *htab;
+  struct elf_link_hash_entry *h;
+  asection *got_section;
 
   if (! _bfd_elf_create_got_section (dynobj, info))
     return FALSE;
@@ -749,6 +753,28 @@ create_got_section (bfd *dynobj,
   htab->elf.srelgot = bfd_get_linker_section (dynobj, ".rela.got");
   if (!htab->elf.sgot || !htab->elf.sgotplt || !htab->elf.srelgot)
     abort ();
+
+  /* The condition here has to match linker script selection.  */
+  if (info->combreloc && info->relro && !(info->flags & DF_BIND_NOW))
+    {
+      htab->elf.sgot->size += GOT_ENTRY_SIZE;
+      got_section = htab->elf.sgot;
+      htab->split_got = TRUE;
+    }
+  else
+    {
+      got_section = htab->elf.sgotplt;
+      htab->split_got = FALSE;
+    }
+
+  /* Define the symbol _GLOBAL_OFFSET_TABLE_ at the start of the .got
+     or .got.plt section.  */
+  h = _bfd_elf_define_linkage_sym (dynobj, info, got_section,
+				   "_GLOBAL_OFFSET_TABLE_");
+  elf_hash_table (info)->hgot = h;
+  if (h == NULL)
+	return FALSE;
+
   return TRUE;
 }
 
@@ -3814,6 +3840,14 @@ elf_s390_finish_dynamic_sections (bfd *output_bfd,
 	->this_hdr.sh_entsize = 8;
     }
 
+  if (htab->elf.sgot && htab->split_got)
+    {
+      bfd_put_64 (output_bfd,
+		  (sdyn == NULL ? (bfd_vma) 0
+		   : sdyn->output_section->vma + sdyn->output_offset),
+		  htab->elf.sgot->contents);
+    }
+
   /* Finish dynamic symbol for local IFUNC symbols.  */
   for (ibfd = info->input_bfds; ibfd != NULL; ibfd = ibfd->link.next)
     {
@@ -3923,6 +3957,8 @@ const struct elf_size_info s390_elf64_size_info =
 #define elf_backend_want_got_plt	1
 #define elf_backend_plt_readonly	1
 #define elf_backend_want_plt_sym	0
+/* We create got symbol ourselves, since it may not be in .got.plt */
+#define elf_backend_want_got_sym	0
 #define elf_backend_got_header_size	24
 #define elf_backend_rela_normal		1
 
diff --git a/ld/emulparams/elf64_s390.sh b/ld/emulparams/elf64_s390.sh
index 98db3d3..9d58a3b 100644
--- a/ld/emulparams/elf64_s390.sh
+++ b/ld/emulparams/elf64_s390.sh
@@ -11,8 +11,11 @@ NOP=0x07070707
 TEMPLATE_NAME=elf32
 GENERATE_SHLIB_SCRIPT=yes
 GENERATE_PIE_SCRIPT=yes
+GENERATE_RELRO_SCRIPT=yes
 NO_SMALL_DATA=yes
 IREL_IN_PLT=
+SEPARATE_GOTPLT="SIZEOF (.got.plt) >= 24 ? 24 : 0"
+test -z "$RELRO" && unset SEPARATE_GOTPLT
 
 # Treat a host that matches the target with the possible exception of "x"
 # in the name as if it were native.
-- 
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