powerpc TLS in PIEs
This patch removes unnecessary GOT IE TLS relocations in PIEs. Useful with --no-tls-optimize, or with an enormous TLS segment. With the default --tls-optimize in effect IE code sequences will be edited to LE under the same circumstances we can remove the GOT reloc. * elf32-ppc.c (got_entries_needed, got_relocs_needed): New functions. (allocate_dynrelocs, ppc_elf_size_dynamic_sections): Use them here. (ppc_elf_relocate_section): Don't output a dynamic relocation for IE GOT entries in an executable. * elf64-ppc.c (allocate_got): Trim unnecessary TPREL relocs. (ppc64_elf_size_dynamic_sections): Likewise. (ppc64_elf_relocate_section): Likewise.
This commit is contained in:
Alan Modra
parent
98bbb1b861
commit
f15d0b545b
3 changed files with 91 additions and 45 deletions
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@ -1,3 +1,13 @@
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2017-11-04 Alan Modra <amodra@gmail.com>
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* elf32-ppc.c (got_entries_needed, got_relocs_needed): New functions.
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(allocate_dynrelocs, ppc_elf_size_dynamic_sections): Use them here.
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(ppc_elf_relocate_section): Don't output a dynamic relocation
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for IE GOT entries in an executable.
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* elf64-ppc.c (allocate_got): Trim unnecessary TPREL relocs.
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(ppc64_elf_size_dynamic_sections): Likewise.
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(ppc64_elf_relocate_section): Likewise.
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2017-11-04 Alan Modra <amodra@gmail.com>
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* elf32-ppc.c (readonly_dynrelocs): Delete info param. Update all
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112
bfd/elf32-ppc.c
112
bfd/elf32-ppc.c
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@ -5751,6 +5751,45 @@ allocate_got (struct ppc_elf_link_hash_table *htab, unsigned int need)
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return where;
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}
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/* Calculate size of GOT entries for symbol given its TLS_MASK.
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TLS_LD is excluded because those go in a special GOT slot. */
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static inline unsigned int
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got_entries_needed (int tls_mask)
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{
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unsigned int need;
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if ((tls_mask & TLS_TLS) == 0)
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need = 4;
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else
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{
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need = 0;
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if ((tls_mask & TLS_GD) != 0)
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need += 8;
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if ((tls_mask & (TLS_TPREL | TLS_TPRELGD)) != 0)
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need += 4;
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if ((tls_mask & TLS_DTPREL) != 0)
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need += 4;
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}
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return need;
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}
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/* Calculate size of relocs needed for symbol given its TLS_MASK and
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NEEDed GOT entries. KNOWN says a TPREL offset can be calculated at
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link time. */
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static inline unsigned int
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got_relocs_needed (int tls_mask, unsigned int need, bfd_boolean known)
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{
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/* All the entries we allocated need relocs.
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Except IE in executable with a local symbol. We could also omit
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the DTPREL reloc on the second word of a GD entry under the same
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condition as that for IE, but ld.so needs to differentiate
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LD and GD entries. */
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if ((tls_mask & (TLS_TPREL | TLS_TPRELGD)) != 0 && known)
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need -= 4;
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return need * sizeof (Elf32_External_Rela) / 4;
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}
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/* If H is undefined, make it dynamic if that makes sense. */
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static bfd_boolean
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@ -5801,27 +5840,17 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
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return FALSE;
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need = 0;
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if ((eh->tls_mask & TLS_TLS) != 0)
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if ((eh->tls_mask & TLS_LD) != 0)
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{
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if ((eh->tls_mask & TLS_LD) != 0)
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{
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if (!eh->elf.def_dynamic)
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/* We'll just use htab->tlsld_got.offset. This should
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always be the case. It's a little odd if we have
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a local dynamic reloc against a non-local symbol. */
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htab->tlsld_got.refcount += 1;
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else
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need += 8;
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}
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if ((eh->tls_mask & TLS_GD) != 0)
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if (!eh->elf.def_dynamic)
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/* We'll just use htab->tlsld_got.offset. This should
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always be the case. It's a little odd if we have
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a local dynamic reloc against a non-local symbol. */
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htab->tlsld_got.refcount += 1;
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else
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need += 8;
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if ((eh->tls_mask & (TLS_TPREL | TLS_TPRELGD)) != 0)
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need += 4;
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if ((eh->tls_mask & TLS_DTPREL) != 0)
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need += 4;
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}
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else
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need += 4;
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need += got_entries_needed (eh->tls_mask);
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if (need == 0)
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eh->elf.got.offset = (bfd_vma) -1;
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else
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@ -5833,16 +5862,18 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
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&& !SYMBOL_REFERENCES_LOCAL (info, &eh->elf)))
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&& !UNDEFWEAK_NO_DYNAMIC_RELOC (info, &eh->elf))
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{
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asection *rsec = htab->elf.srelgot;
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asection *rsec;
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bfd_boolean tprel_known = (bfd_link_executable (info)
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&& SYMBOL_REFERENCES_LOCAL (info,
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&eh->elf));
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need = got_relocs_needed (eh->tls_mask, need, tprel_known);
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if ((eh->tls_mask & TLS_LD) != 0 && eh->elf.def_dynamic)
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need -= sizeof (Elf32_External_Rela);
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rsec = htab->elf.srelgot;
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if (eh->elf.type == STT_GNU_IFUNC)
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rsec = htab->elf.irelplt;
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/* All the entries we allocated need relocs.
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Except LD only needs one. */
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if ((eh->tls_mask & TLS_LD) != 0
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&& eh->elf.def_dynamic)
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need -= 4;
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rsec->size += need * (sizeof (Elf32_External_Rela) / 4);
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rsec->size += need;
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}
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}
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}
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@ -6244,20 +6275,10 @@ ppc_elf_size_dynamic_sections (bfd *output_bfd,
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for (; local_got < end_local_got; ++local_got, ++lgot_masks)
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if (*local_got > 0)
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{
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unsigned int need = 0;
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if ((*lgot_masks & TLS_TLS) != 0)
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{
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if ((*lgot_masks & TLS_GD) != 0)
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need += 8;
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if ((*lgot_masks & TLS_LD) != 0)
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htab->tlsld_got.refcount += 1;
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if ((*lgot_masks & (TLS_TPREL | TLS_TPRELGD)) != 0)
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need += 4;
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if ((*lgot_masks & TLS_DTPREL) != 0)
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need += 4;
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}
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else
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need += 4;
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unsigned int need;
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if ((*lgot_masks & TLS_LD) != 0)
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htab->tlsld_got.refcount += 1;
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need = got_entries_needed (*lgot_masks);
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if (need == 0)
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*local_got = (bfd_vma) -1;
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else
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@ -6265,10 +6286,14 @@ ppc_elf_size_dynamic_sections (bfd *output_bfd,
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*local_got = allocate_got (htab, need);
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if (bfd_link_pic (info))
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{
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asection *srel = htab->elf.srelgot;
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asection *srel;
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bfd_boolean tprel_known = bfd_link_executable (info);
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need = got_relocs_needed (*lgot_masks, need, tprel_known);
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srel = htab->elf.srelgot;
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if ((*lgot_masks & PLT_IFUNC) != 0)
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srel = htab->elf.irelplt;
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srel->size += need * (sizeof (Elf32_External_Rela) / 4);
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srel->size += need;
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}
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}
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}
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@ -8428,7 +8453,10 @@ ppc_elf_relocate_section (bfd *output_bfd,
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|| (bfd_link_pic (info)
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&& (h == NULL
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|| !UNDEFWEAK_NO_DYNAMIC_RELOC (info, h)
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|| offp == &htab->tlsld_got.offset)))
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|| offp == &htab->tlsld_got.offset)
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&& !(tls_ty == (TLS_TLS | TLS_TPREL)
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&& bfd_link_executable (info)
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&& SYMBOL_REFERENCES_LOCAL (info, h))))
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{
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asection *rsec = htab->elf.srelgot;
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bfd_byte * loc;
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@ -9584,7 +9584,10 @@ allocate_got (struct elf_link_hash_entry *h,
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htab->elf.irelplt->size += rentsize;
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htab->got_reli_size += rentsize;
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}
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else if ((bfd_link_pic (info)
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else if (((bfd_link_pic (info)
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&& !((gent->tls_type & TLS_TPREL) != 0
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&& bfd_link_executable (info)
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&& SYMBOL_REFERENCES_LOCAL (info, h)))
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|| (htab->elf.dynamic_sections_created
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&& h->dynindx != -1
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&& !SYMBOL_REFERENCES_LOCAL (info, h)))
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@ -10072,7 +10075,9 @@ ppc64_elf_size_dynamic_sections (bfd *output_bfd,
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htab->elf.irelplt->size += rel_size;
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htab->got_reli_size += rel_size;
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}
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else if (bfd_link_pic (info))
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else if (bfd_link_pic (info)
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&& !((ent->tls_type & TLS_TPREL) != 0
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&& bfd_link_executable (info)))
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{
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asection *srel = ppc64_elf_tdata (ibfd)->relgot;
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srel->size += rel_size;
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@ -14514,7 +14519,10 @@ ppc64_elf_relocate_section (bfd *output_bfd,
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&& (h == NULL
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|| !UNDEFWEAK_NO_DYNAMIC_RELOC (info, &h->elf)
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|| (tls_type == (TLS_TLS | TLS_LD)
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&& !h->elf.def_dynamic))))
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&& !h->elf.def_dynamic))
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&& !(tls_type == (TLS_TLS | TLS_TPREL)
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&& bfd_link_executable (info)
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&& SYMBOL_REFERENCES_LOCAL (info, &h->elf))))
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relgot = ppc64_elf_tdata (ent->owner)->relgot;
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if (relgot != NULL)
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{
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