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[PATCH 5/5] Gold: Don't fail on R_X86_64_[REX_]GOTPCRELX relocations

From: "H.J. Lu" <hjl dot tools at gmail dot com>
To: binutils at sourceware dot org
Date: Thu, 22 Oct 2015 04:41:39 -0700
Subject: [PATCH 5/5] Gold: Don't fail on R_X86_64_[REX_]GOTPCRELX relocations
Authentication-results: sourceware.org; auth=none
References: <1445514099-20925-1-git-send-email-hjl dot tools at gmail dot com>

This patch updates gold to treat the R_X86_64_GOTPCRELX and
R_X86_64_REX_GOTPCRELX relocations proposed in

https://groups.google.com/forum/#!topic/x86-64-abi/n9AWHogmVY0

the same as R_X86_64_GOTPCREL.  FIXME: Gold should perform the
transformations as suggested.

elfcpp/

	* x86_64.h (R_X86_64_GOTPCRELX): New.
	(R_X86_64_REX_GOTPCRELX): Likewise.

gold/

	* x86_64.cc (Target_x86_64<size>::Scan::get_reference_flags):
	Treat R_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX the same
	as R_X86_64_GOTPCREL.
	(Target_x86_64<size>::Scan::local): Likewise.
	(Target_x86_64<size>::Scan::possible_function_pointer_reloc):
	Likewise.
	(Target_x86_64<size>::Scan::global): Likewise.
	(Target_x86_64<size>::Relocate::relocate): Likewise.
	(Target_x86_64<size>::Relocatable_size_for_reloc::get_size_for_reloc):
	Likewise.
---
 elfcpp/x86_64.h |  4 ++++
 gold/x86_64.cc  | 20 ++++++++++++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/elfcpp/x86_64.h b/elfcpp/x86_64.h
index e97ff52..52cb9ae 100644
--- a/elfcpp/x86_64.h
+++ b/elfcpp/x86_64.h
@@ -94,6 +94,10 @@ enum
   R_X86_64_RELATIVE64 = 38,      // 64-bit adjust by program base
   R_X86_64_PC32_BND = 39,  // PC relative 32 bit signed with BND prefix
   R_X86_64_PLT32_BND = 40, // 32 bit PLT address with BND prefix
+  R_X86_64_GOTPCRELX = 41, // 32 bit signed PC relative offset to GOT
+			   // without REX prefix, relaxable.
+  R_X86_64_REX_GOTPCRELX = 42, // 32 bit signed PC relative offset to GOT
+			       // with REX prefix, relaxable.
   // GNU vtable garbage collection extensions.
   R_X86_64_GNU_VTINHERIT = 250,
   R_X86_64_GNU_VTENTRY = 251
diff --git a/gold/x86_64.cc b/gold/x86_64.cc
index 007af1d..c728a00 100644
--- a/gold/x86_64.cc
+++ b/gold/x86_64.cc
@@ -2191,6 +2191,8 @@ Target_x86_64<size>::Scan::get_reference_flags(unsigned int r_type)
     case elfcpp::R_X86_64_GOT32:
     case elfcpp::R_X86_64_GOTPCREL64:
     case elfcpp::R_X86_64_GOTPCREL:
+    case elfcpp::R_X86_64_GOTPCRELX:
+    case elfcpp::R_X86_64_REX_GOTPCRELX:
     case elfcpp::R_X86_64_GOTPLT64:
       // Absolute in GOT.
       return Symbol::ABSOLUTE_REF;
@@ -2475,6 +2477,8 @@ Target_x86_64<size>::Scan::local(Symbol_table* symtab,
     case elfcpp::R_X86_64_GOT32:
     case elfcpp::R_X86_64_GOTPCREL64:
     case elfcpp::R_X86_64_GOTPCREL:
+    case elfcpp::R_X86_64_GOTPCRELX:
+    case elfcpp::R_X86_64_REX_GOTPCRELX:
     case elfcpp::R_X86_64_GOTPLT64:
       {
 	// The symbol requires a GOT section.
@@ -2485,7 +2489,9 @@ Target_x86_64<size>::Scan::local(Symbol_table* symtab,
 	// mov foo@GOTPCREL(%rip), %reg
 	// to lea foo(%rip), %reg.
 	// in Relocate::relocate.
-	if (r_type == elfcpp::R_X86_64_GOTPCREL
+	if ((r_type == elfcpp::R_X86_64_GOTPCREL
+	     || r_type == elfcpp::R_X86_64_GOTPCRELX
+	     || r_type == elfcpp::R_X86_64_REX_GOTPCRELX)
 	    && reloc.get_r_offset() >= 2
 	    && !is_ifunc)
 	  {
@@ -2713,6 +2719,8 @@ Target_x86_64<size>::Scan::possible_function_pointer_reloc(unsigned int r_type)
     case elfcpp::R_X86_64_GOT32:
     case elfcpp::R_X86_64_GOTPCREL64:
     case elfcpp::R_X86_64_GOTPCREL:
+    case elfcpp::R_X86_64_GOTPCRELX:
+    case elfcpp::R_X86_64_REX_GOTPCRELX:
     case elfcpp::R_X86_64_GOTPLT64:
       {
 	return true;
@@ -2901,6 +2909,8 @@ Target_x86_64<size>::Scan::global(Symbol_table* symtab,
     case elfcpp::R_X86_64_GOT32:
     case elfcpp::R_X86_64_GOTPCREL64:
     case elfcpp::R_X86_64_GOTPCREL:
+    case elfcpp::R_X86_64_GOTPCRELX:
+    case elfcpp::R_X86_64_REX_GOTPCRELX:
     case elfcpp::R_X86_64_GOTPLT64:
       {
 	// The symbol requires a GOT entry.
@@ -2910,7 +2920,9 @@ Target_x86_64<size>::Scan::global(Symbol_table* symtab,
 	// mov foo@GOTPCREL(%rip), %reg
 	// to lea foo(%rip), %reg.
 	// in Relocate::relocate, then there is nothing to do here.
-	if (r_type == elfcpp::R_X86_64_GOTPCREL
+	if ((r_type == elfcpp::R_X86_64_GOTPCREL
+	     || r_type == elfcpp::R_X86_64_GOTPCRELX
+	     || r_type == elfcpp::R_X86_64_REX_GOTPCRELX)
 	    && reloc.get_r_offset() >= 2
 	    && Target_x86_64<size>::can_convert_mov_to_lea(gsym))
 	  {
@@ -3538,6 +3550,8 @@ Target_x86_64<size>::Relocate::relocate(
       break;
 
     case elfcpp::R_X86_64_GOTPCREL:
+    case elfcpp::R_X86_64_GOTPCRELX:
+    case elfcpp::R_X86_64_REX_GOTPCRELX:
       {
       // Convert
       // mov foo@GOTPCREL(%rip), %reg
@@ -4320,6 +4334,8 @@ Target_x86_64<size>::Relocatable_size_for_reloc::get_size_for_reloc(
     case elfcpp::R_X86_64_GOT64:
     case elfcpp::R_X86_64_GOTPCREL64:
     case elfcpp::R_X86_64_GOTPCREL:
+    case elfcpp::R_X86_64_GOTPCRELX:
+    case elfcpp::R_X86_64_REX_GOTPCRELX:
     case elfcpp::R_X86_64_GOTPLT64:
       return 8;
 
-- 
2.4.3

Follow-Ups:
- Re: [PATCH 5/5] Gold: Don't fail on R_X86_64_[REX_]GOTPCRELX relocations
  - From: Cary Coutant

References:
- [PATCH 0/5] Add support for R_386_GOT32X/R_X86_64_[REX_]GOTPCRELX
  - From: H.J. Lu

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