PowerPC ifunc with local symbols
Alan Modra
amodra@gmail.com
Mon Dec 7 03:23:00 GMT 2015
This fixes some cases where the linker would incorrectly error on plt
relocs to local ifunc symbols. I've also tidied plt and ifunc
handling for ppc64, where check_relocs was allowing for the
possibility of plt calls via addr14/addr24 relocs but relocate_section
was not.
* elf32-ppc.c (ppc_elf_check_relocs): Don't error on local ifunc
plt call. Wrap long lines.
(ppc_elf_relocate_section): Wrap long lines.
* elf64-ppc.c (ppc64_elf_check_relocs): Don't error on local ifunc
plt calls. Move __tls_get_addr checks later. Don't create plt
for addr14/addr24 relocs.
(ppc64_elf_gc_sweep_hook): Adjust to suit check_relocs changes.
(ppc64_elf_relocate_section): Correct local ifunc handling for
PLT64, PLT32 and PLT16 relocs.
diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index 017de65..ea03598 100644
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -3948,6 +3948,7 @@ ppc_elf_check_relocs (bfd *abfd,
enum elf_ppc_reloc_type r_type;
struct elf_link_hash_entry *h;
int tls_type;
+ struct plt_entry **ifunc;
r_symndx = ELF32_R_SYM (rel->r_info);
if (r_symndx < symtab_hdr->sh_info)
@@ -3980,6 +3981,7 @@ ppc_elf_check_relocs (bfd *abfd,
tls_type = 0;
r_type = ELF32_R_TYPE (rel->r_info);
+ ifunc = NULL;
if (h == NULL && !htab->is_vxworks)
{
Elf_Internal_Sym *isym = bfd_sym_from_r_symndx (&htab->sym_cache,
@@ -3989,8 +3991,6 @@ ppc_elf_check_relocs (bfd *abfd,
if (ELF_ST_TYPE (isym->st_info) == STT_GNU_IFUNC)
{
- struct plt_entry **ifunc;
-
/* Set PLT_IFUNC flag for this sym, no GOT entry yet. */
ifunc = update_local_sym_info (abfd, symtab_hdr, r_symndx,
PLT_IFUNC);
@@ -4224,21 +4224,20 @@ ppc_elf_check_relocs (bfd *abfd,
#ifdef DEBUG
fprintf (stderr, "Reloc requires a PLT entry\n");
#endif
- /* This symbol requires a procedure linkage table entry. We
- actually build the entry in finish_dynamic_symbol,
- because this might be a case of linking PIC code without
- linking in any dynamic objects, in which case we don't
- need to generate a procedure linkage table after all. */
-
+ /* This symbol requires a procedure linkage table entry. */
if (h == NULL)
{
- /* It does not make sense to have a procedure linkage
- table entry for a local symbol. */
- info->callbacks->einfo (_("%P: %H: %s reloc against local symbol\n"),
- abfd, sec, rel->r_offset,
- ppc_elf_howto_table[r_type]->name);
- bfd_set_error (bfd_error_bad_value);
- return FALSE;
+ if (ifunc == NULL)
+ {
+ /* It does not make sense to have a procedure linkage
+ table entry for a non-ifunc local symbol. */
+ info->callbacks->einfo
+ (_("%P: %H: %s reloc against local symbol\n"),
+ abfd, sec, rel->r_offset,
+ ppc_elf_howto_table[r_type]->name);
+ bfd_set_error (bfd_error_bad_value);
+ return FALSE;
+ }
}
else
{
@@ -4316,9 +4315,10 @@ ppc_elf_check_relocs (bfd *abfd,
{
if (bfd_link_pic (info))
{
- info->callbacks->einfo (_("%P: %H: @local call to ifunc %s\n"),
- abfd, sec, rel->r_offset,
- h->root.root.string);
+ info->callbacks->einfo
+ (_("%P: %H: @local call to ifunc %s\n"),
+ abfd, sec, rel->r_offset,
+ h->root.root.string);
bfd_set_error (bfd_error_bad_value);
return FALSE;
}
@@ -8968,8 +8968,10 @@ ppc_elf_relocate_section (bfd *output_bfd,
case R_PPC_PLTREL24:
if (h != NULL && ifunc == NULL)
{
- struct plt_entry *ent = find_plt_ent (&h->plt.plist, got2,
- bfd_link_pic (info) ? addend : 0);
+ struct plt_entry *ent;
+
+ ent = find_plt_ent (&h->plt.plist, got2,
+ bfd_link_pic (info) ? addend : 0);
if (ent == NULL
|| htab->plt == NULL)
{
diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index 303170b..94c0f23 100644
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -5340,7 +5340,7 @@ ppc64_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
enum elf_ppc64_reloc_type r_type;
int tls_type;
struct _ppc64_elf_section_data *ppc64_sec;
- struct plt_entry **ifunc;
+ struct plt_entry **ifunc, **plt_list;
r_symndx = ELF64_R_SYM (rel->r_info);
if (r_symndx < symtab_hdr->sh_info)
@@ -5383,28 +5383,8 @@ ppc64_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
return FALSE;
}
}
- r_type = ELF64_R_TYPE (rel->r_info);
- if (is_branch_reloc (r_type))
- {
- if (h != NULL && (h == tga || h == dottga))
- {
- if (rel != relocs
- && (ELF64_R_TYPE (rel[-1].r_info) == R_PPC64_TLSGD
- || ELF64_R_TYPE (rel[-1].r_info) == R_PPC64_TLSLD))
- /* We have a new-style __tls_get_addr call with a marker
- reloc. */
- ;
- else
- /* Mark this section as having an old-style call. */
- sec->has_tls_get_addr_call = 1;
- }
-
- /* STT_GNU_IFUNC symbols must have a PLT entry. */
- if (ifunc != NULL
- && !update_plt_info (abfd, ifunc, rel->r_addend))
- return FALSE;
- }
+ r_type = ELF64_R_TYPE (rel->r_info);
switch (r_type)
{
case R_PPC64_TLSGD:
@@ -5516,27 +5496,29 @@ ppc64_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
case R_PPC64_PLT16_LO:
case R_PPC64_PLT32:
case R_PPC64_PLT64:
- /* This symbol requires a procedure linkage table entry. We
- actually build the entry in adjust_dynamic_symbol,
- because this might be a case of linking PIC code without
- linking in any dynamic objects, in which case we don't
- need to generate a procedure linkage table after all. */
- if (h == NULL)
- {
- /* It does not make sense to have a procedure linkage
- table entry for a local symbol. */
- bfd_set_error (bfd_error_bad_value);
- return FALSE;
- }
- else
+ /* This symbol requires a procedure linkage table entry. */
+ plt_list = ifunc;
+ if (h != NULL)
{
- if (!update_plt_info (abfd, &h->plt.plist, rel->r_addend))
- return FALSE;
h->needs_plt = 1;
if (h->root.root.string[0] == '.'
&& h->root.root.string[1] != '\0')
((struct ppc_link_hash_entry *) h)->is_func = 1;
+ plt_list = &h->plt.plist;
+ }
+ if (plt_list == NULL)
+ {
+ /* It does not make sense to have a procedure linkage
+ table entry for a non-ifunc local symbol. */
+ info->callbacks->einfo
+ (_("%P: %H: %s reloc against local symbol\n"),
+ abfd, sec, rel->r_offset,
+ ppc64_elf_howto_table[r_type]->name);
+ bfd_set_error (bfd_error_bad_value);
+ return FALSE;
}
+ if (!update_plt_info (abfd, plt_list, rel->r_addend))
+ return FALSE;
break;
/* The following relocations don't need to propagate the
@@ -5649,21 +5631,43 @@ ppc64_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
/* Fall through. */
case R_PPC64_REL24:
- if (h != NULL && ifunc == NULL)
+ plt_list = ifunc;
+ if (h != NULL)
{
- /* We may need a .plt entry if the function this reloc
- refers to is in a shared lib. */
- if (!update_plt_info (abfd, &h->plt.plist, rel->r_addend))
- return FALSE;
h->needs_plt = 1;
if (h->root.root.string[0] == '.'
&& h->root.root.string[1] != '\0')
((struct ppc_link_hash_entry *) h)->is_func = 1;
+
if (h == tga || h == dottga)
- sec->has_tls_reloc = 1;
+ {
+ sec->has_tls_reloc = 1;
+ if (rel != relocs
+ && (ELF64_R_TYPE (rel[-1].r_info) == R_PPC64_TLSGD
+ || ELF64_R_TYPE (rel[-1].r_info) == R_PPC64_TLSLD))
+ /* We have a new-style __tls_get_addr call with
+ a marker reloc. */
+ ;
+ else
+ /* Mark this section as having an old-style call. */
+ sec->has_tls_get_addr_call = 1;
+ }
+ plt_list = &h->plt.plist;
}
+
+ /* We may need a .plt entry if the function this reloc
+ refers to is in a shared lib. */
+ if (plt_list
+ && !update_plt_info (abfd, plt_list, rel->r_addend))
+ return FALSE;
break;
+ case R_PPC64_ADDR14:
+ case R_PPC64_ADDR14_BRNTAKEN:
+ case R_PPC64_ADDR14_BRTAKEN:
+ case R_PPC64_ADDR24:
+ goto dodyn;
+
case R_PPC64_TPREL64:
tls_type = TLS_EXPLICIT | TLS_TLS | TLS_TPREL;
if (bfd_link_pic (info))
@@ -5806,10 +5810,6 @@ ppc64_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
case R_PPC64_REL30:
case R_PPC64_REL32:
case R_PPC64_REL64:
- case R_PPC64_ADDR14:
- case R_PPC64_ADDR14_BRNTAKEN:
- case R_PPC64_ADDR14_BRTAKEN:
- case R_PPC64_ADDR24:
case R_PPC64_ADDR32:
case R_PPC64_UADDR16:
case R_PPC64_UADDR32:
@@ -6505,6 +6505,7 @@ ppc64_elf_gc_sweep_hook (bfd *abfd, struct bfd_link_info *info,
unsigned long r_symndx;
enum elf_ppc64_reloc_type r_type;
struct elf_link_hash_entry *h = NULL;
+ struct plt_entry **plt_list;
unsigned char tls_type = 0;
r_symndx = ELF64_R_SYM (rel->r_info);
@@ -6528,38 +6529,6 @@ ppc64_elf_gc_sweep_hook (bfd *abfd, struct bfd_link_info *info,
}
}
- if (is_branch_reloc (r_type))
- {
- struct plt_entry **ifunc = NULL;
- if (h != NULL)
- {
- if (h->type == STT_GNU_IFUNC)
- ifunc = &h->plt.plist;
- }
- else if (local_got_ents != NULL)
- {
- struct plt_entry **local_plt = (struct plt_entry **)
- (local_got_ents + symtab_hdr->sh_info);
- unsigned char *local_got_tls_masks = (unsigned char *)
- (local_plt + symtab_hdr->sh_info);
- if ((local_got_tls_masks[r_symndx] & PLT_IFUNC) != 0)
- ifunc = local_plt + r_symndx;
- }
- if (ifunc != NULL)
- {
- struct plt_entry *ent;
-
- for (ent = *ifunc; ent != NULL; ent = ent->next)
- if (ent->addend == rel->r_addend)
- break;
- if (ent == NULL)
- abort ();
- if (ent->plt.refcount > 0)
- ent->plt.refcount -= 1;
- continue;
- }
- }
-
switch (r_type)
{
case R_PPC64_GOT_TLSLD16:
@@ -6626,11 +6595,23 @@ ppc64_elf_gc_sweep_hook (bfd *abfd, struct bfd_link_info *info,
case R_PPC64_REL14_BRNTAKEN:
case R_PPC64_REL14_BRTAKEN:
case R_PPC64_REL24:
+ plt_list = NULL;
if (h != NULL)
+ plt_list = &h->plt.plist;
+ else if (local_got_ents != NULL)
+ {
+ struct plt_entry **local_plt = (struct plt_entry **)
+ (local_got_ents + symtab_hdr->sh_info);
+ unsigned char *local_got_tls_masks = (unsigned char *)
+ (local_plt + symtab_hdr->sh_info);
+ if ((local_got_tls_masks[r_symndx] & PLT_IFUNC) != 0)
+ plt_list = local_plt + r_symndx;
+ }
+ if (plt_list)
{
struct plt_entry *ent;
- for (ent = h->plt.plist; ent != NULL; ent = ent->next)
+ for (ent = *plt_list; ent != NULL; ent = ent->next)
if (ent->addend == rel->r_addend)
break;
if (ent != NULL && ent->plt.refcount > 0)
@@ -14488,30 +14469,43 @@ ppc64_elf_relocate_section (bfd *output_bfd,
case R_PPC64_PLT64:
/* Relocation is to the entry for this symbol in the
procedure linkage table. */
+ {
+ struct plt_entry **plt_list = NULL;
+ if (h != NULL)
+ plt_list = &h->elf.plt.plist;
+ else if (local_got_ents != NULL)
+ {
+ struct plt_entry **local_plt = (struct plt_entry **)
+ (local_got_ents + symtab_hdr->sh_info);
+ unsigned char *local_got_tls_masks = (unsigned char *)
+ (local_plt + symtab_hdr->sh_info);
+ if ((local_got_tls_masks[r_symndx] & PLT_IFUNC) != 0)
+ plt_list = local_plt + r_symndx;
+ }
+ if (plt_list)
+ {
+ struct plt_entry *ent;
- /* Resolve a PLT reloc against a local symbol directly,
- without using the procedure linkage table. */
- if (h == NULL)
- break;
-
- /* It's possible that we didn't make a PLT entry for this
- symbol. This happens when statically linking PIC code,
- or when using -Bsymbolic. Go find a match if there is a
- PLT entry. */
- if (htab->elf.splt != NULL)
- {
- struct plt_entry *ent;
- for (ent = h->elf.plt.plist; ent != NULL; ent = ent->next)
- if (ent->plt.offset != (bfd_vma) -1
- && ent->addend == orig_rel.r_addend)
- {
- relocation = (htab->elf.splt->output_section->vma
- + htab->elf.splt->output_offset
- + ent->plt.offset);
- unresolved_reloc = FALSE;
- break;
- }
- }
+ for (ent = *plt_list; ent != NULL; ent = ent->next)
+ if (ent->plt.offset != (bfd_vma) -1
+ && ent->addend == orig_rel.r_addend)
+ {
+ asection *plt;
+
+ plt = htab->elf.splt;
+ if (!htab->elf.dynamic_sections_created
+ || h == NULL
+ || h->elf.dynindx == -1)
+ plt = htab->elf.iplt;
+ relocation = (plt->output_section->vma
+ + plt->output_offset
+ + ent->plt.offset);
+ addend = 0;
+ unresolved_reloc = FALSE;
+ break;
+ }
+ }
+ }
break;
case R_PPC64_TOC:
--
Alan Modra
Australia Development Lab, IBM
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