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author | H.J. Lu <hjl.tools@gmail.com> | 2017-09-02 07:37:05 -0700 |
---|---|---|
committer | H.J. Lu <hjl.tools@gmail.com> | 2017-09-02 15:12:04 -0700 |
commit | 5e2ac45d561dffec63af4c83a545b46db032c70c (patch) | |
tree | e9a264c81105fc2f48427635a068e8f4c92aa448 /bfd/elfxx-x86.c | |
parent | 2926eb2c326c625f54db61796fbe034b31f0958f (diff) | |
download | gdb-5e2ac45d561dffec63af4c83a545b46db032c70c.zip gdb-5e2ac45d561dffec63af4c83a545b46db032c70c.tar.gz gdb-5e2ac45d561dffec63af4c83a545b46db032c70c.tar.bz2 |
x86: Add _bfd_x86_elf_size_dynamic_sections
elf_i386_size_dynamic_sections and elf_x86_64_size_dynamic_sections are
very similar, except for the followings:
1. elf_i386_size_dynamic_sections checks GOT_TLS_IE and GOT_TLS_IE_BOTH.
elf_x86_64_size_dynamic_sections checks only GOT_TLS_IE. Since
GOT_TLS_IE_BOTH is never true for x86-64, it is OK to check GOT_TLS_IE
for both i386 and x86-64.
2, x86-64 sets tlsdesc_plt, but i386 doesn't. We set tlsdesc_plt only
if target_id == X86_64_ELF_DATA.
3. x86-64 has
if (s != htab->elf.srelplt)
s->reloc_count = 0;
and i386 has
s->reloc_count = 0;
i386 did have
if (s != htab->srelplt)
s->reloc_count = 0;
in the original commit:
commit 67a4f2b710581acc83afecff55424af285ecbc28
Author: Alexandre Oliva <aoliva@redhat.com>
Date: Wed Jan 18 21:07:51 2006 +0000
But it was removed by
commit 5ae0bfb60a576344d7f701605346282c1144499e
Author: Richard Sandiford <rdsandiford@googlemail.com>
Date: Tue Feb 28 07:16:12 2006 +0000
bfd/
* elf32-i386.c (elf_i386_link_hash_table): Add next_tls_desc_index.
(elf_i386_link_hash_table_create): Initialize it.
(elf_i386_compute_jump_table_size): Use it instead of
srelplt->reloc_count.
(allocate_dynrelocs): Likewise.
(elf_i386_size_dynamic_sections): Likewise.
(elf_i386_relocate_section): Likewise.
A later commit:
commit e1f987424b7b3f5ac63a2a6ae044a202a44b8ff8
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Fri Oct 21 15:13:37 2011 +0000
Put IRELATIVE relocations after JUMP_SLOT.
bfd/
2011-10-21 H.J. Lu <hongjiu.lu@intel.com>
PR ld/13302
* elf32-i386.c (elf_i386_link_hash_table): Add next_jump_slot_index
and next_irelative_index.
(elf_i386_link_hash_table_create): Initialize next_jump_slot_index
and next_irelative_index.
(elf_i386_allocate_dynrelocs): Increment reloc_count instead of
next_tls_desc_index.
(elf_i386_size_dynamic_sections): Set next_tls_desc_index and
next_irelative_index from reloc_count.
(elf_i386_finish_dynamic_symbol): Put R_386_IRELATIVE after
R_386_JUMP_SLOT.
changed it back to use reloc_count again. So it is correct to use
if (s != htab->elf.srelplt)
s->reloc_count = 0;
for both i386 and x86-64 now.
4. i386 and x86-64 use different DT_XXXs. They are handled by adding
them to elf_x86_link_hash_table.
With these changes, we can share _bfd_x86_elf_size_dynamic_sections in
elf32-i386.c and elf64-x86-64.c.
* elf32-i386.c (elf_i386_convert_load): Renamed to ...
(_bfd_i386_elf_convert_load): This. Remove static.
(elf_i386_size_dynamic_sections): Removed.
(elf_backend_size_dynamic_sections): Likewise.
* elf64-x86-64.c (elf_x86_64_convert_load): Renamed to ...
(_bfd_x86_64_elf_convert_load): This. Remove static.
(elf_x86_64_size_dynamic_sections): Removed.
(elf_backend_size_dynamic_sections): Likewise.
* elfxx-x86.c (_bfd_x86_elf_allocate_dynrelocs): Renamed to ...
(elf_x86_allocate_dynrelocs): This. Make it static.
(_bfd_x86_elf_allocate_local_dynrelocs): Renamed to ...
(elf_x86_allocate_local_dynreloc): This. Make it static.
(elf_i386_is_reloc_section): New function.
(elf_x86_64_is_reloc_section): Likewise.
(_bfd_x86_elf_link_hash_table_create): Initialize convert_load,
is_reloc_section, dt_reloc, dt_reloc_sz and dt_reloc_ent.
Rearrange got_entry_size initialization.
(_bfd_x86_elf_size_dynamic_sections): New function.
* elfxx-x86.h (elf_x86_link_hash_table): Add convert_load,
is_reloc_section, dt_reloc, dt_reloc_sz and dt_reloc_ent.
(_bfd_i386_elf_convert_load): New.
(_bfd_x86_64_elf_convert_load): Likewise.
(_bfd_x86_elf_size_dynamic_sections): Likewise.
(elf_backend_size_dynamic_sections): Likewise.
(_bfd_x86_elf_allocate_dynrelocs): Removed.
(_bfd_x86_elf_allocate_local_dynrelocs): Likewise.
Diffstat (limited to 'bfd/elfxx-x86.c')
-rw-r--r-- | bfd/elfxx-x86.c | 467 |
1 files changed, 460 insertions, 7 deletions
diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c index 646b251..874799e 100644 --- a/bfd/elfxx-x86.c +++ b/bfd/elfxx-x86.c @@ -82,8 +82,8 @@ _bfd_x86_elf_dtpoff_base (struct bfd_link_info *info) /* Allocate space in .plt, .got and associated reloc sections for dynamic relocs. */ -bfd_boolean -_bfd_x86_elf_allocate_dynrelocs (struct elf_link_hash_entry *h, +static bfd_boolean +elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf) { struct bfd_link_info *info; @@ -573,8 +573,8 @@ _bfd_x86_elf_readonly_dynrelocs (struct elf_link_hash_entry *h, /* Allocate space in .plt, .got and associated reloc sections for local dynamic relocs. */ -bfd_boolean -_bfd_x86_elf_allocate_local_dynrelocs (void **slot, void *inf) +static bfd_boolean +elf_x86_allocate_local_dynreloc (void **slot, void *inf) { struct elf_link_hash_entry *h = (struct elf_link_hash_entry *) *slot; @@ -586,7 +586,7 @@ _bfd_x86_elf_allocate_local_dynrelocs (void **slot, void *inf) || h->root.type != bfd_link_hash_defined) abort (); - return _bfd_x86_elf_allocate_dynrelocs (h, inf); + return elf_x86_allocate_dynrelocs (h, inf); } /* Find and/or create a hash entry for local symbol. */ @@ -721,6 +721,20 @@ elf_x86_link_hash_table_free (bfd *obfd) _bfd_elf_link_hash_table_free (obfd); } +static bfd_boolean +elf_i386_is_reloc_section (const char *secname) +{ + return CONST_STRNEQ (secname, ".rel"); +} + +#ifdef BFD64 +static bfd_boolean +elf_x86_64_is_reloc_section (const char *secname) +{ + return CONST_STRNEQ (secname, ".rela"); +} +#endif + /* Create an x86 ELF linker hash table. */ struct bfd_link_hash_table * @@ -745,12 +759,21 @@ _bfd_x86_elf_link_hash_table_create (bfd *abfd) } #ifdef BFD64 + /* NB: If BFD64 isn't defined, only i386 will be supported. */ + if (bed->target_id == X86_64_ELF_DATA) + { + ret->convert_load = _bfd_x86_64_elf_convert_load; + ret->is_reloc_section = elf_x86_64_is_reloc_section; + ret->dt_reloc = DT_RELA; + ret->dt_reloc_sz = DT_RELASZ; + ret->dt_reloc_ent = DT_RELAENT; + ret->got_entry_size = 8; + } if (ABI_64_P (abfd)) { ret->r_info = elf64_r_info; ret->r_sym = elf64_r_sym; ret->sizeof_reloc = sizeof (Elf64_External_Rela); - ret->got_entry_size = 8; ret->pointer_r_type = R_X86_64_64; ret->dynamic_interpreter = ELF64_DYNAMIC_INTERPRETER; ret->dynamic_interpreter_size = sizeof ELF64_DYNAMIC_INTERPRETER; @@ -764,7 +787,6 @@ _bfd_x86_elf_link_hash_table_create (bfd *abfd) if (bed->target_id == X86_64_ELF_DATA) { ret->sizeof_reloc = sizeof (Elf32_External_Rela); - ret->got_entry_size = 8; ret->pointer_r_type = R_X86_64_32; ret->dynamic_interpreter = ELFX32_DYNAMIC_INTERPRETER; ret->dynamic_interpreter_size @@ -773,6 +795,11 @@ _bfd_x86_elf_link_hash_table_create (bfd *abfd) } else { + ret->convert_load = _bfd_i386_elf_convert_load; + ret->is_reloc_section = elf_i386_is_reloc_section; + ret->dt_reloc = DT_REL; + ret->dt_reloc_sz = DT_RELSZ; + ret->dt_reloc_ent = DT_RELENT; ret->sizeof_reloc = sizeof (Elf32_External_Rel); ret->got_entry_size = 4; ret->pointer_r_type = R_386_32; @@ -839,6 +866,432 @@ _bfd_x86_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info) return _bfd_elf_link_check_relocs (abfd, info); } +/* Set the sizes of the dynamic sections. */ + +bfd_boolean +_bfd_x86_elf_size_dynamic_sections (bfd *output_bfd, + struct bfd_link_info *info) +{ + struct elf_x86_link_hash_table *htab; + bfd *dynobj; + asection *s; + bfd_boolean relocs; + bfd *ibfd; + const struct elf_backend_data *bed + = get_elf_backend_data (output_bfd); + + htab = elf_x86_hash_table (info, bed->target_id); + if (htab == NULL) + return FALSE; + dynobj = htab->elf.dynobj; + if (dynobj == NULL) + abort (); + + /* Set up .got offsets for local syms, and space for local dynamic + relocs. */ + for (ibfd = info->input_bfds; ibfd != NULL; ibfd = ibfd->link.next) + { + bfd_signed_vma *local_got; + bfd_signed_vma *end_local_got; + char *local_tls_type; + bfd_vma *local_tlsdesc_gotent; + bfd_size_type locsymcount; + Elf_Internal_Shdr *symtab_hdr; + asection *srel; + + if (! is_x86_elf (ibfd, htab)) + continue; + + for (s = ibfd->sections; s != NULL; s = s->next) + { + struct elf_dyn_relocs *p; + + if (!htab->convert_load (ibfd, s, info)) + return FALSE; + + for (p = ((struct elf_dyn_relocs *) + elf_section_data (s)->local_dynrel); + p != NULL; + p = p->next) + { + if (!bfd_is_abs_section (p->sec) + && bfd_is_abs_section (p->sec->output_section)) + { + /* Input section has been discarded, either because + it is a copy of a linkonce section or due to + linker script /DISCARD/, so we'll be discarding + the relocs too. */ + } + else if (htab->is_vxworks + && strcmp (p->sec->output_section->name, + ".tls_vars") == 0) + { + /* Relocations in vxworks .tls_vars sections are + handled specially by the loader. */ + } + else if (p->count != 0) + { + srel = elf_section_data (p->sec)->sreloc; + srel->size += p->count * htab->sizeof_reloc; + if ((p->sec->output_section->flags & SEC_READONLY) != 0 + && (info->flags & DF_TEXTREL) == 0) + { + info->flags |= DF_TEXTREL; + if ((info->warn_shared_textrel && bfd_link_pic (info)) + || info->error_textrel) + /* xgettext:c-format */ + info->callbacks->einfo (_("%P: %B: warning: relocation in readonly section `%A'\n"), + p->sec->owner, p->sec); + } + } + } + } + + local_got = elf_local_got_refcounts (ibfd); + if (!local_got) + continue; + + symtab_hdr = &elf_symtab_hdr (ibfd); + locsymcount = symtab_hdr->sh_info; + end_local_got = local_got + locsymcount; + local_tls_type = elf_x86_local_got_tls_type (ibfd); + local_tlsdesc_gotent = elf_x86_local_tlsdesc_gotent (ibfd); + s = htab->elf.sgot; + srel = htab->elf.srelgot; + for (; local_got < end_local_got; + ++local_got, ++local_tls_type, ++local_tlsdesc_gotent) + { + *local_tlsdesc_gotent = (bfd_vma) -1; + if (*local_got > 0) + { + if (GOT_TLS_GDESC_P (*local_tls_type)) + { + *local_tlsdesc_gotent = htab->elf.sgotplt->size + - elf_x86_compute_jump_table_size (htab); + htab->elf.sgotplt->size += 2 * htab->got_entry_size; + *local_got = (bfd_vma) -2; + } + if (! GOT_TLS_GDESC_P (*local_tls_type) + || GOT_TLS_GD_P (*local_tls_type)) + { + *local_got = s->size; + s->size += htab->got_entry_size; + if (GOT_TLS_GD_P (*local_tls_type) + || *local_tls_type == GOT_TLS_IE_BOTH) + s->size += htab->got_entry_size; + } + if (bfd_link_pic (info) + || GOT_TLS_GD_ANY_P (*local_tls_type) + || (*local_tls_type & GOT_TLS_IE)) + { + if (*local_tls_type == GOT_TLS_IE_BOTH) + srel->size += 2 * htab->sizeof_reloc; + else if (GOT_TLS_GD_P (*local_tls_type) + || ! GOT_TLS_GDESC_P (*local_tls_type)) + srel->size += htab->sizeof_reloc; + if (GOT_TLS_GDESC_P (*local_tls_type)) + { + htab->elf.srelplt->size += htab->sizeof_reloc; + if (bed->target_id == X86_64_ELF_DATA) + htab->tlsdesc_plt = (bfd_vma) -1; + } + } + } + else + *local_got = (bfd_vma) -1; + } + } + + if (htab->tls_ld_or_ldm_got.refcount > 0) + { + /* Allocate 2 got entries and 1 dynamic reloc for R_386_TLS_LDM + or R_X86_64_TLSLD relocs. */ + htab->tls_ld_or_ldm_got.offset = htab->elf.sgot->size; + htab->elf.sgot->size += 2 * htab->got_entry_size; + htab->elf.srelgot->size += htab->sizeof_reloc; + } + else + htab->tls_ld_or_ldm_got.offset = -1; + + /* Allocate global sym .plt and .got entries, and space for global + sym dynamic relocs. */ + elf_link_hash_traverse (&htab->elf, elf_x86_allocate_dynrelocs, + info); + + /* Allocate .plt and .got entries, and space for local symbols. */ + htab_traverse (htab->loc_hash_table, elf_x86_allocate_local_dynreloc, + info); + + /* For every jump slot reserved in the sgotplt, reloc_count is + incremented. However, when we reserve space for TLS descriptors, + it's not incremented, so in order to compute the space reserved + for them, it suffices to multiply the reloc count by the jump + slot size. + + PR ld/13302: We start next_irelative_index at the end of .rela.plt + so that R_{386,X86_64}_IRELATIVE entries come last. */ + if (htab->elf.srelplt) + { + htab->next_tls_desc_index = htab->elf.srelplt->reloc_count; + htab->sgotplt_jump_table_size + = elf_x86_compute_jump_table_size (htab); + htab->next_irelative_index = htab->elf.srelplt->reloc_count - 1; + } + else if (htab->elf.irelplt) + htab->next_irelative_index = htab->elf.irelplt->reloc_count - 1; + + if (htab->tlsdesc_plt) + { + /* NB: tlsdesc_plt is set only for x86-64. If we're not using + lazy TLS relocations, don't generate the PLT and GOT entries + they require. */ + if ((info->flags & DF_BIND_NOW)) + htab->tlsdesc_plt = 0; + else + { + htab->tlsdesc_got = htab->elf.sgot->size; + htab->elf.sgot->size += htab->got_entry_size; + /* Reserve room for the initial entry. + FIXME: we could probably do away with it in this case. */ + if (htab->elf.splt->size == 0) + htab->elf.splt->size = htab->plt.plt_entry_size; + htab->tlsdesc_plt = htab->elf.splt->size; + htab->elf.splt->size += htab->plt.plt_entry_size; + } + } + + if (htab->elf.sgotplt) + { + /* Don't allocate .got.plt section if there are no GOT nor PLT + entries and there is no reference to _GLOBAL_OFFSET_TABLE_. */ + if ((htab->elf.hgot == NULL + || !htab->elf.hgot->ref_regular_nonweak) + && (htab->elf.sgotplt->size == bed->got_header_size) + && (htab->elf.splt == NULL + || htab->elf.splt->size == 0) + && (htab->elf.sgot == NULL + || htab->elf.sgot->size == 0) + && (htab->elf.iplt == NULL + || htab->elf.iplt->size == 0) + && (htab->elf.igotplt == NULL + || htab->elf.igotplt->size == 0)) + htab->elf.sgotplt->size = 0; + } + + if (_bfd_elf_eh_frame_present (info)) + { + if (htab->plt_eh_frame != NULL + && htab->elf.splt != NULL + && htab->elf.splt->size != 0 + && !bfd_is_abs_section (htab->elf.splt->output_section)) + htab->plt_eh_frame->size = htab->plt.eh_frame_plt_size; + + if (htab->plt_got_eh_frame != NULL + && htab->plt_got != NULL + && htab->plt_got->size != 0 + && !bfd_is_abs_section (htab->plt_got->output_section)) + htab->plt_got_eh_frame->size + = htab->non_lazy_plt->eh_frame_plt_size; + + /* Unwind info for the second PLT and .plt.got sections are + identical. */ + if (htab->plt_second_eh_frame != NULL + && htab->plt_second != NULL + && htab->plt_second->size != 0 + && !bfd_is_abs_section (htab->plt_second->output_section)) + htab->plt_second_eh_frame->size + = htab->non_lazy_plt->eh_frame_plt_size; + } + + /* We now have determined the sizes of the various dynamic sections. + Allocate memory for them. */ + relocs = FALSE; + for (s = dynobj->sections; s != NULL; s = s->next) + { + bfd_boolean strip_section = TRUE; + + if ((s->flags & SEC_LINKER_CREATED) == 0) + continue; + + if (s == htab->elf.splt + || s == htab->elf.sgot) + { + /* Strip this section if we don't need it; see the + comment below. */ + /* We'd like to strip these sections if they aren't needed, but if + we've exported dynamic symbols from them we must leave them. + It's too late to tell BFD to get rid of the symbols. */ + + if (htab->elf.hplt != NULL) + strip_section = FALSE; + } + else if (s == htab->elf.sgotplt + || s == htab->elf.iplt + || s == htab->elf.igotplt + || s == htab->plt_second + || s == htab->plt_got + || s == htab->plt_eh_frame + || s == htab->plt_got_eh_frame + || s == htab->plt_second_eh_frame + || s == htab->elf.sdynbss + || s == htab->elf.sdynrelro) + { + /* Strip these too. */ + } + else if (htab->is_reloc_section (bfd_get_section_name (dynobj, s))) + { + if (s->size != 0 + && s != htab->elf.srelplt + && s != htab->srelplt2) + relocs = TRUE; + + /* We use the reloc_count field as a counter if we need + to copy relocs into the output file. */ + if (s != htab->elf.srelplt) + s->reloc_count = 0; + } + else + { + /* It's not one of our sections, so don't allocate space. */ + continue; + } + + if (s->size == 0) + { + /* If we don't need this section, strip it from the + output file. This is mostly to handle .rel.bss and + .rel.plt. We must create both sections in + create_dynamic_sections, because they must be created + before the linker maps input sections to output + sections. The linker does that before + adjust_dynamic_symbol is called, and it is that + function which decides whether anything needs to go + into these sections. */ + if (strip_section) + s->flags |= SEC_EXCLUDE; + continue; + } + + if ((s->flags & SEC_HAS_CONTENTS) == 0) + continue; + + /* Allocate memory for the section contents. We use bfd_zalloc + here in case unused entries are not reclaimed before the + section's contents are written out. This should not happen, + but this way if it does, we get a R_386_NONE or R_X86_64_NONE + reloc instead of garbage. */ + s->contents = (unsigned char *) bfd_zalloc (dynobj, s->size); + if (s->contents == NULL) + return FALSE; + } + + if (htab->plt_eh_frame != NULL + && htab->plt_eh_frame->contents != NULL) + { + memcpy (htab->plt_eh_frame->contents, + htab->plt.eh_frame_plt, + htab->plt_eh_frame->size); + bfd_put_32 (dynobj, htab->elf.splt->size, + htab->plt_eh_frame->contents + PLT_FDE_LEN_OFFSET); + } + + if (htab->plt_got_eh_frame != NULL + && htab->plt_got_eh_frame->contents != NULL) + { + memcpy (htab->plt_got_eh_frame->contents, + htab->non_lazy_plt->eh_frame_plt, + htab->plt_got_eh_frame->size); + bfd_put_32 (dynobj, htab->plt_got->size, + (htab->plt_got_eh_frame->contents + + PLT_FDE_LEN_OFFSET)); + } + + if (htab->plt_second_eh_frame != NULL + && htab->plt_second_eh_frame->contents != NULL) + { + memcpy (htab->plt_second_eh_frame->contents, + htab->non_lazy_plt->eh_frame_plt, + htab->plt_second_eh_frame->size); + bfd_put_32 (dynobj, htab->plt_second->size, + (htab->plt_second_eh_frame->contents + + PLT_FDE_LEN_OFFSET)); + } + + if (htab->elf.dynamic_sections_created) + { + /* Add some entries to the .dynamic section. We fill in the + values later, in elf_{i386,x86_64}_finish_dynamic_sections, + but we must add the entries now so that we get the correct + size for the .dynamic section. The DT_DEBUG entry is filled + in by the dynamic linker and used by the debugger. */ +#define add_dynamic_entry(TAG, VAL) \ + _bfd_elf_add_dynamic_entry (info, TAG, VAL) + + if (bfd_link_executable (info)) + { + if (!add_dynamic_entry (DT_DEBUG, 0)) + return FALSE; + } + + if (htab->elf.splt->size != 0) + { + /* DT_PLTGOT is used by prelink even if there is no PLT + relocation. */ + if (!add_dynamic_entry (DT_PLTGOT, 0)) + return FALSE; + } + + if (htab->elf.srelplt->size != 0) + { + if (!add_dynamic_entry (DT_PLTRELSZ, 0) + || !add_dynamic_entry (DT_PLTREL, htab->dt_reloc) + || !add_dynamic_entry (DT_JMPREL, 0)) + return FALSE; + } + + if (htab->tlsdesc_plt + && (!add_dynamic_entry (DT_TLSDESC_PLT, 0) + || !add_dynamic_entry (DT_TLSDESC_GOT, 0))) + return FALSE; + + if (relocs) + { + if (!add_dynamic_entry (htab->dt_reloc, 0) + || !add_dynamic_entry (htab->dt_reloc_sz, 0) + || !add_dynamic_entry (htab->dt_reloc_ent, + htab->sizeof_reloc)) + return FALSE; + + /* If any dynamic relocs apply to a read-only section, + then we need a DT_TEXTREL entry. */ + if ((info->flags & DF_TEXTREL) == 0) + elf_link_hash_traverse (&htab->elf, + _bfd_x86_elf_readonly_dynrelocs, + info); + + if ((info->flags & DF_TEXTREL) != 0) + { + if (htab->readonly_dynrelocs_against_ifunc) + { + info->callbacks->einfo + (_("%P%X: read-only segment has dynamic IFUNC relocations; recompile with -fPIC\n")); + bfd_set_error (bfd_error_bad_value); + return FALSE; + } + + if (!add_dynamic_entry (DT_TEXTREL, 0)) + return FALSE; + } + } + if (htab->is_vxworks + && !elf_vxworks_add_dynamic_entries (output_bfd, info)) + return FALSE; + } +#undef add_dynamic_entry + + return TRUE; +} + bfd_boolean _bfd_x86_elf_always_size_sections (bfd *output_bfd, struct bfd_link_info *info) |