Fix for gold linking tlsdesc into an executable with -pie.

(Also included in this patch is a minor typo fix in gold/ChangeLog.)

When linking the following tlsdesc access sequence into an executable with -pie,

     adrp    x0, :tlsdesc:tls_gd
     ldr     x1, [x0, #:tlsdesc_lo12:tls_gd]
     add     x0, x0, :tlsdesc_lo12:tls_gd
     .tlsdesccall    tls_gd
     blr	     x1
     mrs	     x1, tpidr_el0
     add	     x0, x1, x0
     ldr	     w0, [x0]

current gold-aarch64 backend does tls-desc-gd-to-ie relaxation, into

       adrp    x0, 1000 <__FRAME_END__+0x720>
       ldr     x1, [x0,#4064]	  ;; <=== the target register should be x0
       nop
       nop
       mrs	x1, tpidr_el0
       add	x0, x1, x0
       ldr	w0, [x0]

This code is wrong. The fix changes ldr target register into x0.

diff --git a/gold/ChangeLog b/gold/ChangeLog
index 1a75a1e..3c9b75c 100644 (file)
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,8 @@
+2014-11-26  Jing Yu  <jingyu@google.com>
+
+       * aarch64.cc (Relocate::tls_desc_gd_to_ie): Set ldr target
+       register to be x0 when to relax TLSDESC_LD64_LO12.
+
 2014-11-26  Alan Modra  <amodra@gmail.com>
 
        * powerpc.cc (struct Stub_table_owner): New.
@@ -162,7 +167,7 @@
        * aarch64.cc (AArch64_relocate_functions::maybe_apply_stub):
        Add "typename" keyword.
 
-2014-09-22  Han Shen  <shenhan@google.com>
+2014-10-15  Han Shen  <shenhan@google.com>
             Jing Yu   <jingyu@google.com>
 
        Patch for gold aarch64 backend to support relaxation.

diff --git a/gold/aarch64.cc b/gold/aarch64.cc
index 125953a..d5a0a85 100644 (file)
--- a/gold/aarch64.cc
+++ b/gold/aarch64.cc
@@ -6536,6 +6536,11 @@ Target_aarch64<size, big_endian>::Relocate::tls_desc_gd_to_ie(
 
     case elfcpp::R_AARCH64_TLSDESC_LD64_LO12:
       {
+       // Set ldr target register to be x0.
+       Insntype insn = elfcpp::Swap<32, big_endian>::readval(ip);
+       insn &= 0xffffffe0;
+       elfcpp::Swap<32, big_endian>::writeval(ip, insn);
+       // Do relocation.
        const AArch64_reloc_property* reloc_property =
            aarch64_reloc_property_table->get_reloc_property(
              elfcpp::R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC);