__tls_get_addr_opt GOT entries

My 2017-01-24 patch (commit f0158f44) wrongly applied an optimization
of GOT entries for the __tls_get_addr_opt stub, to shared libraries.

When the TLS segment layout is known, as it is for the executable and
shared libraries loaded at initial program start, powerpc supports a
__tls_get_addr optimization.  On the first call to __tls_get_addr for
a given __tls_index GOT entry, the DTPMOD word is set to zero and the
DTPREL word to the thread pointer offset to the thread variable.  This
allows the __tls_get_addr_opt stub to return that value immediately
without making a call into glibc for any subsequent __tls_get_addr
calls using that __tls_index GOT entry.

That's all fine, but I thought I'd be clever and when the thread
variable is local, set up the GOT entry as if __tls_get_addr had
already been called.  Which is good only for the executable, since ld
cannot know the TLS layout for shared libraries.

Of course, if this only applies to executables there isn't much point
to the optimization.  Normally, GD and LD code in an executable will
be converted to IE or LE, losing the __tls_get_addr call.  So the only
time it will trigger is with --no-tls-optimize.  Thus, revert all
support.

	* elf64-ppc.c (ppc64_elf_relocate_section): Don't optimize
	__tls_index GOT entries when using __tls_get_addr_opt stub.
	* elf32-ppc.c (ppc_elf_relocate_section): Likewise.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index a98c93ac7cea0829a735dca8c73d24bdc96887d4..fbd44a7adace036cf31f5eb634958f82e143b90d 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,9 @@
+2017-07-16  Alan Modra  <amodra@gmail.com>
+
+       * elf64-ppc.c (ppc64_elf_relocate_section): Don't optimize
+       __tls_index GOT entries when using __tls_get_addr_opt stub.
+       * elf32-ppc.c (ppc_elf_relocate_section): Likewise.
+
 2017-07-12  Alan Modra  <amodra@gmail.com>
 
        * po/es.po: Update from translationproject.org/latest/bfd/.

diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index 27d62ab00abd6fbbbd65d7c08b5a9727213c7f44..6d8b5020f54ff96e4854a724627dc4627b071644 100644 (file)
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -8639,10 +8639,6 @@ ppc_elf_relocate_section (bfd *output_bfd,
                    else
                      {
                        bfd_vma value = relocation;
-                       int tlsopt = (htab->plt_type == PLT_NEW
-                                     && !htab->params->no_tls_get_addr_opt
-                                     && htab->tls_get_addr != NULL
-                                     && htab->tls_get_addr->plt.plist != NULL);
 
                        if (tls_ty != 0)
                          {
@@ -8654,8 +8650,7 @@ ppc_elf_relocate_section (bfd *output_bfd,
                                  value = 0;
                                else
                                  value -= htab->elf.tls_sec->vma + DTP_OFFSET;
-                               if ((tls_ty & TLS_TPREL)
-                                   || (tlsopt && !(tls_ty & TLS_DTPREL)))
+                               if (tls_ty & TLS_TPREL)
                                  value += DTP_OFFSET - TP_OFFSET;
                              }
 
@@ -8663,7 +8658,7 @@ ppc_elf_relocate_section (bfd *output_bfd,
                              {
                                bfd_put_32 (input_bfd, value,
                                            htab->elf.sgot->contents + off + 4);
-                               value = !tlsopt;
+                               value = 1;
                              }
                          }
                        bfd_put_32 (input_bfd, value,
@@ -9008,34 +9003,6 @@ ppc_elf_relocate_section (bfd *output_bfd,
                  break;
                }
            }
-         else if (r_type == R_PPC_DTPMOD32
-                  && htab->plt_type == PLT_NEW
-                  && !htab->params->no_tls_get_addr_opt
-                  && htab->tls_get_addr != NULL
-                  && htab->tls_get_addr->plt.plist != NULL)
-           {
-             /* Set up for __tls_get_addr_opt stub when this entry
-                does not have dynamic relocs.  */
-             relocation = 0;
-             /* Set up the next word for local dynamic.  If it turns
-                out to be global dynamic, the reloc will overwrite
-                this value.  */
-             if (rel->r_offset + 8 <= input_section->size)
-               bfd_put_32 (input_bfd, DTP_OFFSET - TP_OFFSET,
-                           contents + rel->r_offset + 4);
-           }
-         else if (r_type == R_PPC_DTPREL32
-                  && htab->plt_type == PLT_NEW
-                  && !htab->params->no_tls_get_addr_opt
-                  && htab->tls_get_addr != NULL
-                  && htab->tls_get_addr->plt.plist != NULL
-                  && rel > relocs
-                  && rel[-1].r_info == ELF32_R_INFO (r_symndx, R_PPC_DTPMOD32)
-                  && rel[-1].r_offset + 4 == rel->r_offset)
-           {
-             /* __tls_get_addr_opt stub value.  */
-             addend += DTP_OFFSET - TP_OFFSET;
-           }
          break;
 
        case R_PPC_RELAX_PLT:

diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index 319d58f86a03cddcb23c465c70a2e22266c6a328..70ad6c5a69b1dc22ffffc38a0c315e21066b1dc7 100644 (file)
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -14647,11 +14647,6 @@ ppc64_elf_relocate_section (bfd *output_bfd,
                   emitting a reloc.  */
                else
                  {
-                   int tlsopt
-                     = (htab->params->tls_get_addr_opt
-                        && htab->tls_get_addr_fd != NULL
-                        && htab->tls_get_addr_fd->elf.plt.plist != NULL);
-
                    relocation += addend;
                    if (tls_type != 0)
                      {
@@ -14663,8 +14658,7 @@ ppc64_elf_relocate_section (bfd *output_bfd,
                              relocation = 0;
                            else
                              relocation -= htab->elf.tls_sec->vma + DTP_OFFSET;
-                           if ((tls_type & TLS_TPREL)
-                               || (tlsopt && !(tls_type & TLS_DTPREL)))
+                           if (tls_type & TLS_TPREL)
                              relocation += DTP_OFFSET - TP_OFFSET;
                          }
 
@@ -14672,7 +14666,7 @@ ppc64_elf_relocate_section (bfd *output_bfd,
                          {
                            bfd_put_64 (output_bfd, relocation,
                                        got->contents + off + 8);
-                           relocation = !tlsopt;
+                           relocation = 1;
                          }
                      }
                    bfd_put_64 (output_bfd, relocation,
@@ -15080,32 +15074,6 @@ ppc64_elf_relocate_section (bfd *output_bfd,
                    addend = outrel.r_offset;
                }
            }
-         else if (r_type == R_PPC64_DTPMOD64
-                  && htab->params->tls_get_addr_opt
-                  && htab->tls_get_addr_fd != NULL
-                  && htab->tls_get_addr_fd->elf.plt.plist != NULL)
-           {
-             /* Set up for __tls_get_addr_opt stub, when this entry
-                does not have dynamic relocs.  */
-             relocation = 0;
-             /* Set up the next word for local dynamic.  If it turns
-                out to be global dynamic, the reloc will overwrite
-                this value.  */
-             if (rel->r_offset + 16 <= input_section->size)
-               bfd_put_64 (input_bfd, DTP_OFFSET - TP_OFFSET,
-                           contents + rel->r_offset + 8);
-           }
-         else if (r_type == R_PPC64_DTPREL64
-                  && htab->params->tls_get_addr_opt
-                  && htab->tls_get_addr_fd != NULL
-                  && htab->tls_get_addr_fd->elf.plt.plist != NULL
-                  && rel > relocs
-                  && rel[-1].r_info == ELF64_R_INFO (r_symndx, R_PPC64_DTPMOD64)
-                  && rel[-1].r_offset + 8 == rel->r_offset)
-           {
-             /* __tls_get_addr_opt stub value.  */
-             addend += DTP_OFFSET - TP_OFFSET;
-           }
          break;
 
        case R_PPC64_COPY:
@@ -15899,4 +15867,3 @@ ppc64_elf_finish_dynamic_sections (bfd *output_bfd,
 #define elf64_bed      elf64_powerpc_fbsd_bed
 
 #include "elf64-target.h"
-