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Diffstat (limited to 'bfd/elf32-i386.c')
-rw-r--r--bfd/elf32-i386.c287
1 files changed, 221 insertions, 66 deletions
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index f6c9c65..2ae5e44 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -737,6 +737,20 @@ static const struct elf_i386_backend_data elf_i386_arch_bed =
#define elf_backend_arch_data &elf_i386_arch_bed
+/* Is a undefined weak symbol which is resolved to 0. Reference to an
+ undefined weak symbol is resolved to 0 when building executable if
+ it isn't dynamic and
+ 1. Has non-GOT/non-PLT relocations in text section. Or
+ 2. Has no GOT/PLT relocation.
+ */
+#define UNDEFINED_WEAK_RESOLVED_TO_ZERO(INFO, EH) \
+ ((EH)->elf.root.type == bfd_link_hash_undefweak \
+ && bfd_link_executable (INFO) \
+ && (elf_i386_hash_table (INFO)->interp == NULL \
+ || !(EH)->has_got_reloc \
+ || (EH)->has_non_got_reloc \
+ || !(INFO)->dynamic_undefined_weak))
+
/* i386 ELF linker hash entry. */
struct elf_i386_link_hash_entry
@@ -767,6 +781,12 @@ struct elf_i386_link_hash_entry
/* Symbol is referenced by R_386_GOTOFF relocation. */
unsigned int gotoff_ref : 1;
+ /* Symbol has GOT or PLT relocations. */
+ unsigned int has_got_reloc : 1;
+
+ /* Symbol has non-GOT/non-PLT relocations in text sections. */
+ unsigned int has_non_got_reloc : 1;
+
/* Reference count of C/C++ function pointer relocations in read-write
section which can be resolved at run-time. */
bfd_signed_vma func_pointer_refcount;
@@ -821,6 +841,7 @@ struct elf_i386_link_hash_table
struct elf_link_hash_table elf;
/* Short-cuts to get to dynamic linker sections. */
+ asection *interp;
asection *sdynbss;
asection *srelbss;
asection *plt_eh_frame;
@@ -895,6 +916,8 @@ elf_i386_link_hash_newfunc (struct bfd_hash_entry *entry,
eh->dyn_relocs = NULL;
eh->tls_type = GOT_UNKNOWN;
eh->gotoff_ref = 0;
+ eh->has_got_reloc = 0;
+ eh->has_non_got_reloc = 0;
eh->func_pointer_refcount = 0;
eh->plt_got.offset = (bfd_vma) -1;
eh->tlsdesc_got = (bfd_vma) -1;
@@ -1138,6 +1161,9 @@ elf_i386_copy_indirect_symbol (struct bfd_link_info *info,
generate a R_386_COPY reloc. */
edir->gotoff_ref |= eind->gotoff_ref;
+ edir->has_got_reloc |= eind->has_got_reloc;
+ edir->has_non_got_reloc |= eind->has_non_got_reloc;
+
if (ELIMINATE_COPY_RELOCS
&& ind->root.type != bfd_link_hash_indirect
&& dir->dynamic_adjusted)
@@ -1630,6 +1656,7 @@ elf_i386_check_relocs (bfd *abfd,
if (h == NULL)
continue;
+ eh->has_got_reloc = 1;
h->needs_plt = 1;
h->plt.refcount += 1;
break;
@@ -1760,18 +1787,27 @@ elf_i386_check_relocs (bfd *abfd,
return FALSE;
}
if (r_type != R_386_TLS_IE)
- break;
+ {
+ if (eh != NULL)
+ eh->has_got_reloc = 1;
+ break;
+ }
/* Fall through */
case R_386_TLS_LE_32:
case R_386_TLS_LE:
+ if (eh != NULL)
+ eh->has_got_reloc = 1;
if (bfd_link_executable (info))
break;
info->flags |= DF_STATIC_TLS;
- /* Fall through */
+ goto do_relocation;
case R_386_32:
case R_386_PC32:
+ if (eh != NULL && (sec->flags & SEC_CODE) != 0)
+ eh->has_non_got_reloc = 1;
+do_relocation:
if (h != NULL && bfd_link_executable (info))
{
/* If this reloc is in a read-only section, we might
@@ -2147,6 +2183,24 @@ elf_i386_gc_sweep_hook (bfd *abfd,
return TRUE;
}
+/* Remove undefined weak symbol from the dynamic symbol table if it
+ is resolved to 0. */
+
+static bfd_boolean
+elf_i386_fixup_symbol (struct bfd_link_info *info,
+ struct elf_link_hash_entry *h)
+{
+ if (h->dynindx != -1
+ && UNDEFINED_WEAK_RESOLVED_TO_ZERO (info,
+ elf_i386_hash_entry (h)))
+ {
+ h->dynindx = -1;
+ _bfd_elf_strtab_delref (elf_hash_table (info)->dynstr,
+ h->dynstr_index);
+ }
+ return TRUE;
+}
+
/* Adjust a symbol defined by a dynamic object and referenced by a
regular object. The current definition is in some section of the
dynamic object, but we're not including those sections. We have to
@@ -2335,6 +2389,7 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
struct elf_i386_link_hash_entry *eh;
struct elf_dyn_relocs *p;
unsigned plt_entry_size;
+ bfd_boolean resolved_to_zero;
if (h->root.type == bfd_link_hash_indirect)
return TRUE;
@@ -2348,6 +2403,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
plt_entry_size = GET_PLT_ENTRY_SIZE (info->output_bfd);
+ resolved_to_zero = UNDEFINED_WEAK_RESOLVED_TO_ZERO (info, eh);
+
/* Clear the reference count of function pointer relocations if
symbol isn't a normal function. */
if (h->type != STT_FUNC)
@@ -2405,7 +2462,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
/* Make sure this symbol is output as a dynamic symbol.
Undefined weak syms won't yet be marked as dynamic. */
if (h->dynindx == -1
- && !h->forced_local)
+ && !h->forced_local
+ && !resolved_to_zero)
{
if (! bfd_elf_link_record_dynamic_symbol (info, h))
return FALSE;
@@ -2462,9 +2520,15 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
script. */
htab->elf.sgotplt->size += 4;
- /* We also need to make an entry in the .rel.plt section. */
- htab->elf.srelplt->size += sizeof (Elf32_External_Rel);
- htab->elf.srelplt->reloc_count++;
+ /* There should be no PLT relocation against resolved
+ undefined weak symbol in executable. */
+ if (!resolved_to_zero)
+ {
+ /* We also need to make an entry in the .rel.plt
+ section. */
+ htab->elf.srelplt->size += sizeof (Elf32_External_Rel);
+ htab->elf.srelplt->reloc_count++;
+ }
}
if (get_elf_i386_backend_data (info->output_bfd)->is_vxworks
@@ -2520,7 +2584,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
/* Make sure this symbol is output as a dynamic symbol.
Undefined weak syms won't yet be marked as dynamic. */
if (h->dynindx == -1
- && !h->forced_local)
+ && !h->forced_local
+ && !resolved_to_zero)
{
if (! bfd_elf_link_record_dynamic_symbol (info, h))
return FALSE;
@@ -2548,7 +2613,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
R_386_TLS_IE resp. R_386_TLS_GOTIE needs one dynamic relocation,
(but if both R_386_TLS_IE_32 and R_386_TLS_IE is present, we
need two), R_386_TLS_GD needs one if local symbol and two if
- global. */
+ global. No dynamic relocation against resolved undefined weak
+ symbol in executable. */
if (tls_type == GOT_TLS_IE_BOTH)
htab->elf.srelgot->size += 2 * sizeof (Elf32_External_Rel);
else if ((GOT_TLS_GD_P (tls_type) && h->dynindx == -1)
@@ -2557,7 +2623,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
else if (GOT_TLS_GD_P (tls_type))
htab->elf.srelgot->size += 2 * sizeof (Elf32_External_Rel);
else if (! GOT_TLS_GDESC_P (tls_type)
- && (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
+ && ((ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
+ && !resolved_to_zero)
|| h->root.type != bfd_link_hash_undefweak)
&& (bfd_link_pic (info)
|| WILL_CALL_FINISH_DYNAMIC_SYMBOL (dyn, 0, h)))
@@ -2613,15 +2680,43 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
}
/* Also discard relocs on undefined weak syms with non-default
- visibility. */
+ visibility or in PIE. */
if (eh->dyn_relocs != NULL
&& h->root.type == bfd_link_hash_undefweak)
{
- if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
- eh->dyn_relocs = NULL;
+ /* Undefined weak symbol is never bound locally in shared
+ library. */
+ if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT
+ || resolved_to_zero)
+ {
+ if (h->non_got_ref)
+ {
+ /* Keep dynamic non-GOT/non-PLT relocation so that we
+ can branch to 0 without PLT. */
+ struct elf_dyn_relocs **pp;
+
+ for (pp = &eh->dyn_relocs; (p = *pp) != NULL; )
+ if (p->pc_count == 0)
+ *pp = p->next;
+ else
+ {
+ /* Remove non-R_386_PC32 relocation. */
+ p->count = p->pc_count;
+ pp = &p->next;
+ }
- /* Make sure undefined weak symbols are output as a dynamic
- symbol in PIEs. */
+ if (eh->dyn_relocs != NULL)
+ {
+ /* Make sure undefined weak symbols are output
+ as dynamic symbols in PIEs for dynamic non-GOT
+ non-PLT reloations. */
+ if (! bfd_elf_link_record_dynamic_symbol (info, h))
+ return FALSE;
+ }
+ }
+ else
+ eh->dyn_relocs = NULL;
+ }
else if (h->dynindx == -1
&& !h->forced_local)
{
@@ -2637,7 +2732,10 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
dynamic. Keep dynamic relocations for run-time function
pointer initialization. */
- if ((!h->non_got_ref || eh->func_pointer_refcount > 0)
+ if ((!h->non_got_ref
+ || eh->func_pointer_refcount > 0
+ || (h->root.type == bfd_link_hash_undefweak
+ && !resolved_to_zero))
&& ((h->def_dynamic
&& !h->def_regular)
|| (htab->elf.dynamic_sections_created
@@ -2647,7 +2745,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
/* Make sure this symbol is output as a dynamic symbol.
Undefined weak syms won't yet be marked as dynamic. */
if (h->dynindx == -1
- && !h->forced_local)
+ && !h->forced_local
+ && !resolved_to_zero)
{
if (! bfd_elf_link_record_dynamic_symbol (info, h))
return FALSE;
@@ -3110,6 +3209,7 @@ elf_i386_size_dynamic_sections (bfd *output_bfd, struct bfd_link_info *info)
abort ();
s->size = sizeof ELF_DYNAMIC_INTERPRETER;
s->contents = (unsigned char *) ELF_DYNAMIC_INTERPRETER;
+ htab->interp = s;
}
}
@@ -3640,6 +3740,7 @@ elf_i386_relocate_section (bfd *output_bfd,
int tls_type;
bfd_vma st_size;
asection *resolved_plt;
+ bfd_boolean resolved_to_zero;
r_type = ELF32_R_TYPE (rel->r_info);
if (r_type == R_386_GNU_VTINHERIT
@@ -3981,6 +4082,9 @@ elf_i386_relocate_section (bfd *output_bfd,
}
eh = (struct elf_i386_link_hash_entry *) h;
+ resolved_to_zero = (eh != NULL
+ && UNDEFINED_WEAK_RESOLVED_TO_ZERO (info, eh));
+
switch (r_type)
{
case R_386_GOT32X:
@@ -4246,18 +4350,25 @@ r_386_got32:
|| is_vxworks_tls)
break;
- /* Copy dynamic function pointer relocations. */
+ /* Copy dynamic function pointer relocations. Don't generate
+ dynamic relocations against resolved undefined weak symbols
+ in PIE, except for R_386_PC32. */
if ((bfd_link_pic (info)
&& (h == NULL
- || ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
- || h->root.type != bfd_link_hash_undefweak)
+ || ((ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
+ && (!resolved_to_zero
+ || r_type == R_386_PC32))
+ || h->root.type != bfd_link_hash_undefweak))
&& ((r_type != R_386_PC32 && r_type != R_386_SIZE32)
|| !SYMBOL_CALLS_LOCAL (info, h)))
|| (ELIMINATE_COPY_RELOCS
&& !bfd_link_pic (info)
&& h != NULL
&& h->dynindx != -1
- && (!h->non_got_ref || eh->func_pointer_refcount > 0)
+ && (!h->non_got_ref
+ || eh->func_pointer_refcount > 0
+ || (h->root.type == bfd_link_hash_undefweak
+ && !resolved_to_zero))
&& ((h->def_dynamic
&& !h->def_regular)
|| h->root.type == bfd_link_hash_undefweak
@@ -5011,6 +5122,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
unsigned plt_entry_size;
const struct elf_i386_backend_data *abed;
struct elf_i386_link_hash_entry *eh;
+ bfd_boolean local_undefweak;
htab = elf_i386_hash_table (info);
if (htab == NULL)
@@ -5021,6 +5133,11 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
eh = (struct elf_i386_link_hash_entry *) h;
+ /* We keep PLT/GOT entries without dynamic PLT/GOT relocations for
+ resolved undefined weak symbols in executable so that their
+ references have value 0 at run-time. */
+ local_undefweak = UNDEFINED_WEAK_RESOLVED_TO_ZERO (info, eh);
+
if (h->plt.offset != (bfd_vma) -1)
{
bfd_vma plt_index;
@@ -5048,6 +5165,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
it up. */
if ((h->dynindx == -1
+ && !local_undefweak
&& !((h->forced_local || bfd_link_executable (info))
&& h->def_regular
&& h->type == STT_GNU_IFUNC))
@@ -5136,54 +5254,61 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
+ abed->plt->plt_got_offset);
}
- /* Fill in the entry in the global offset table. */
- bfd_put_32 (output_bfd,
- (plt->output_section->vma
- + plt->output_offset
- + h->plt.offset
- + abed->plt->plt_lazy_offset),
- gotplt->contents + got_offset);
-
- /* Fill in the entry in the .rel.plt section. */
- rel.r_offset = (gotplt->output_section->vma
- + gotplt->output_offset
- + got_offset);
- if (h->dynindx == -1
- || ((bfd_link_executable (info)
- || ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
- && h->def_regular
- && h->type == STT_GNU_IFUNC))
+ /* Fill in the entry in the global offset table. Leave the entry
+ as zero for undefined weak symbol in PIE. No PLT relocation
+ against undefined weak symbol in PIE. */
+ if (!local_undefweak)
{
- /* If an STT_GNU_IFUNC symbol is locally defined, generate
- R_386_IRELATIVE instead of R_386_JUMP_SLOT. Store addend
- in the .got.plt section. */
bfd_put_32 (output_bfd,
- (h->root.u.def.value
- + h->root.u.def.section->output_section->vma
- + h->root.u.def.section->output_offset),
+ (plt->output_section->vma
+ + plt->output_offset
+ + h->plt.offset
+ + abed->plt->plt_lazy_offset),
gotplt->contents + got_offset);
- rel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
- /* R_386_IRELATIVE comes last. */
- plt_index = htab->next_irelative_index--;
- }
- else
- {
- rel.r_info = ELF32_R_INFO (h->dynindx, R_386_JUMP_SLOT);
- plt_index = htab->next_jump_slot_index++;
- }
- loc = relplt->contents + plt_index * sizeof (Elf32_External_Rel);
- bfd_elf32_swap_reloc_out (output_bfd, &rel, loc);
- /* Don't fill PLT entry for static executables. */
- if (plt == htab->elf.splt)
- {
- bfd_put_32 (output_bfd, plt_index * sizeof (Elf32_External_Rel),
- plt->contents + h->plt.offset
- + abed->plt->plt_reloc_offset);
- bfd_put_32 (output_bfd, - (h->plt.offset
- + abed->plt->plt_plt_offset + 4),
- plt->contents + h->plt.offset
- + abed->plt->plt_plt_offset);
+ /* Fill in the entry in the .rel.plt section. */
+ rel.r_offset = (gotplt->output_section->vma
+ + gotplt->output_offset
+ + got_offset);
+ if (h->dynindx == -1
+ || ((bfd_link_executable (info)
+ || ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
+ && h->def_regular
+ && h->type == STT_GNU_IFUNC))
+ {
+ /* If an STT_GNU_IFUNC symbol is locally defined, generate
+ R_386_IRELATIVE instead of R_386_JUMP_SLOT. Store addend
+ in the .got.plt section. */
+ bfd_put_32 (output_bfd,
+ (h->root.u.def.value
+ + h->root.u.def.section->output_section->vma
+ + h->root.u.def.section->output_offset),
+ gotplt->contents + got_offset);
+ rel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
+ /* R_386_IRELATIVE comes last. */
+ plt_index = htab->next_irelative_index--;
+ }
+ else
+ {
+ rel.r_info = ELF32_R_INFO (h->dynindx, R_386_JUMP_SLOT);
+ plt_index = htab->next_jump_slot_index++;
+ }
+
+ loc = relplt->contents + plt_index * sizeof (Elf32_External_Rel);
+ bfd_elf32_swap_reloc_out (output_bfd, &rel, loc);
+
+ /* Don't fill PLT entry for static executables. */
+ if (plt == htab->elf.splt)
+ {
+ bfd_put_32 (output_bfd,
+ plt_index * sizeof (Elf32_External_Rel),
+ plt->contents + h->plt.offset
+ + abed->plt->plt_reloc_offset);
+ bfd_put_32 (output_bfd, - (h->plt.offset
+ + abed->plt->plt_plt_offset + 4),
+ plt->contents + h->plt.offset
+ + abed->plt->plt_plt_offset);
+ }
}
}
else if (eh->plt_got.offset != (bfd_vma) -1)
@@ -5229,7 +5354,8 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
plt->contents + plt_offset + plt_got_offset);
}
- if (!h->def_regular
+ if (!local_undefweak
+ && !h->def_regular
&& (h->plt.offset != (bfd_vma) -1
|| eh->plt_got.offset != (bfd_vma) -1))
{
@@ -5246,9 +5372,12 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
sym->st_value = 0;
}
+ /* Don't generate dynamic GOT relocation against undefined weak
+ symbol in executable. */
if (h->got.offset != (bfd_vma) -1
&& ! GOT_TLS_GD_ANY_P (elf_i386_hash_entry(h)->tls_type)
- && (elf_i386_hash_entry(h)->tls_type & GOT_TLS_IE) == 0)
+ && (elf_i386_hash_entry(h)->tls_type & GOT_TLS_IE) == 0
+ && !local_undefweak)
{
Elf_Internal_Rela rel;
@@ -5348,6 +5477,25 @@ elf_i386_finish_local_dynamic_symbol (void **slot, void *inf)
h, NULL);
}
+/* Finish up undefined weak symbol handling in PIE. Fill its PLT entry
+ here since undefined weak symbol may not be dynamic and may not be
+ called for elf_i386_finish_dynamic_symbol. */
+
+static bfd_boolean
+elf_i386_pie_finish_undefweak_symbol (struct bfd_hash_entry *bh,
+ void *inf)
+{
+ struct elf_link_hash_entry *h = (struct elf_link_hash_entry *) bh;
+ struct bfd_link_info *info = (struct bfd_link_info *) inf;
+
+ if (h->root.type != bfd_link_hash_undefweak
+ || h->dynindx != -1)
+ return TRUE;
+
+ return elf_i386_finish_dynamic_symbol (info->output_bfd,
+ info, h, NULL);
+}
+
/* Used to decide how to sort relocs in an optimal manner for the
dynamic linker, before writing them out. */
@@ -5626,6 +5774,12 @@ elf_i386_finish_dynamic_sections (bfd *output_bfd,
elf_i386_finish_local_dynamic_symbol,
info);
+ /* Fill PLT entries for undefined weak symbols in PIE. */
+ if (bfd_link_pie (info))
+ bfd_hash_traverse (&info->hash->table,
+ elf_i386_pie_finish_undefweak_symbol,
+ info);
+
return TRUE;
}
@@ -5803,6 +5957,7 @@ elf_i386_add_symbol_hook (bfd * abfd,
((bfd_boolean (*) (bfd *, struct bfd_link_info *, asection *)) bfd_true)
#define elf_backend_hash_symbol elf_i386_hash_symbol
#define elf_backend_add_symbol_hook elf_i386_add_symbol_hook
+#define elf_backend_fixup_symbol elf_i386_fixup_symbol
#include "elf32-target.h"
generated by cgit v1.1 at 2025-01-02 17:24:46 +0000