[binutils-gdb] x86: Add _bfd_x86_elf_hide_symbol

[H.J.Lu <hjl at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=9f8575350f980aa6da8c488c6aa30862620eaa1f

commit 9f8575350f980aa6da8c488c6aa30862620eaa1f
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Oct 12 02:12:47 2017 -0700

    x86: Add _bfd_x86_elf_hide_symbol
    
    When there is no dynamic interpreter in PIE, make the undefined weak
    symbol dynamic so that PC relative branch to the undefined weak symbol
    will land to address 0.
    
    	* elf32-i386.c (elf_backend_hide_symbol): New.
    	* elf64-x86-64.c (elf_backend_hide_symbol): Likewise.
    	* elfxx-x86.c (_bfd_x86_elf_hide_symbol): Likewise.
    	* elfxx-x86.h (_bfd_x86_elf_hide_symbol): Likewise.

Diff:
---
 bfd/ChangeLog      |  7 +++++++
 bfd/elf32-i386.c   |  1 +
 bfd/elf64-x86-64.c |  4 +++-
 bfd/elfxx-x86.c    | 21 +++++++++++++++++++++
 bfd/elfxx-x86.h    |  3 +++
 5 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index fbcb11a..5651316 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2017-10-12  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* elf32-i386.c (elf_backend_hide_symbol): New.
+	* elf64-x86-64.c (elf_backend_hide_symbol): Likewise.
+	* elfxx-x86.c (_bfd_x86_elf_hide_symbol): Likewise.
+	* elfxx-x86.h (_bfd_x86_elf_hide_symbol): Likewise.
+
 2017-10-12  Alan Modra  <amodra@gmail.com>
 
 	* elflink.c (_bfd_elf_adjust_dynamic_symbol): Call
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index bcb219e..cf2e43f 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -4586,6 +4586,7 @@ elf_i386_link_setup_gnu_properties (struct bfd_link_info *info)
 #define elf_backend_reloc_type_class	      elf_i386_reloc_type_class
 #define elf_backend_relocate_section	      elf_i386_relocate_section
 #define elf_backend_setup_gnu_properties      elf_i386_link_setup_gnu_properties
+#define elf_backend_hide_symbol		      _bfd_x86_elf_hide_symbol
 
 #define elf_backend_linux_prpsinfo32_ugid16	TRUE
 
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 7d65dca..b970146 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -5187,7 +5187,9 @@ elf_x86_64_special_sections[]=
 #define elf_backend_additional_program_headers \
   elf_x86_64_additional_program_headers
 #define elf_backend_setup_gnu_properties \
- elf_x86_64_link_setup_gnu_properties
+  elf_x86_64_link_setup_gnu_properties
+#define elf_backend_hide_symbol \
+  _bfd_x86_elf_hide_symbol
 
 #include "elf64-target.h"
 
diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index 4384430..dd139ca 100644
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -1668,6 +1668,27 @@ _bfd_x86_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
   return _bfd_elf_adjust_dynamic_copy (info, h, s);
 }
 
+void
+_bfd_x86_elf_hide_symbol (struct bfd_link_info *info,
+			  struct elf_link_hash_entry *h,
+			  bfd_boolean force_local)
+{
+  if (h->root.type == bfd_link_hash_undefweak
+      && info->nointerp
+      && bfd_link_pie (info))
+    {
+      /* When there is no dynamic interpreter in PIE, make the undefined
+	 weak symbol dynamic so that PC relative branch to the undefined
+	 weak symbol will land to address 0.  */
+      struct elf_x86_link_hash_entry *eh = elf_x86_hash_entry (h);
+      if (h->plt.refcount > eh->func_pointer_refcount
+	  || eh->plt_got.refcount > 0)
+	return;
+    }
+
+  _bfd_elf_link_hash_hide_symbol (info, h, force_local);
+}
+
 /* Return TRUE if a symbol is referenced locally.  It is similar to
    SYMBOL_REFERENCES_LOCAL, but it also checks version script.  It
    works in check_relocs.  */
diff --git a/bfd/elfxx-x86.h b/bfd/elfxx-x86.h
index a2f5fc2..542439c 100644
--- a/bfd/elfxx-x86.h
+++ b/bfd/elfxx-x86.h
@@ -621,6 +621,9 @@ extern bfd_boolean _bfd_x86_elf_hash_symbol
 extern bfd_boolean _bfd_x86_elf_adjust_dynamic_symbol
   (struct bfd_link_info *, struct elf_link_hash_entry *);
 
+extern void _bfd_x86_elf_hide_symbol
+  (struct bfd_link_info *, struct elf_link_hash_entry *, bfd_boolean);
+
 extern bfd_boolean _bfd_x86_elf_link_symbol_references_local
   (struct bfd_link_info *, struct elf_link_hash_entry *);