static boolean ppc64_elf_gc_sweep_hook
PARAMS ((bfd *abfd, struct bfd_link_info *info, asection *sec,
const Elf_Internal_Rela *relocs));
+static boolean func_desc_adjust
+ PARAMS ((struct elf_link_hash_entry *, PTR));
+static boolean ppc64_elf_func_desc_adjust
+ PARAMS ((bfd *, struct bfd_link_info *));
static boolean ppc64_elf_adjust_dynamic_symbol
PARAMS ((struct bfd_link_info *, struct elf_link_hash_entry *));
+static void ppc64_elf_hide_symbol
+ PARAMS ((struct bfd_link_info *, struct elf_link_hash_entry *, boolean));
static boolean allocate_dynrelocs
PARAMS ((struct elf_link_hash_entry *, PTR));
static boolean readonly_dynrelocs
or less in the order in which they are called. eg.
ppc64_elf_check_relocs is called early in the link process,
ppc64_elf_finish_dynamic_sections is one of the last functions
- called. */
+ called.
+
+ PowerPC64-ELF uses a similar scheme to PowerPC64-XCOFF in that
+ functions have both a function code symbol and a function descriptor
+ symbol. A call to foo in a relocatable object file looks like:
+
+ . .text
+ . x:
+ . bl .foo
+ . nop
+
+ The function definition in another object file might be:
+
+ . .section .opd
+ . foo: .quad .foo
+ . .quad .TOC.@tocbase
+ . .quad 0
+ .
+ . .text
+ . .foo: blr
+
+ When the linker resolves the call during a static link, the branch
+ unsurprisingly just goes to .foo and the .opd information is unused.
+ If the function definition is in a shared library, things are a little
+ different: The call goes via a plt call stub, the opd information gets
+ copied to the plt, and the linker patches the nop.
+
+ . x:
+ . bl .foo_stub
+ . ld 2,40(1)
+ .
+ .
+ . .foo_stub:
+ . addis 12,2,Lfoo@toc@ha # in practice, the call stub
+ . addi 12,12,Lfoo@toc@l # is slightly optimised, but
+ . std 2,40(1) # this is the general idea
+ . ld 11,0(12)
+ . ld 2,8(12)
+ . mtctr 11
+ . ld 11,16(12)
+ . bctr
+ .
+ . .section .plt
+ . Lfoo: reloc (R_PPC64_JMP_SLOT, foo)
+
+ The "reloc ()" notation is supposed to indicate that the linker emits
+ an R_PPC64_JMP_SLOT reloc against foo. The dynamic linker does the opd
+ copying.
+
+ What are the difficulties here? Well, firstly, the relocations
+ examined by the linker in check_relocs are against the function code
+ sym .foo, while the dynamic relocation in the plt is emitted against
+ the function descriptor symbol, foo. Somewhere along the line, we need
+ to carefully copy dynamic link information from one symbol to the other.
+ Secondly, the generic part of the elf linker will make .foo a dynamic
+ symbol as is normal for most other backends. We need foo dynamic
+ instead, at least for an application final link. However, when
+ creating a shared library containing foo, we need to have both symbols
+ dynamic so that references to .foo are satisfied during the early
+ stages of linking. Otherwise the linker might decide to pull in a
+ definition from some other object, eg. a static library. Thirdly, we'd
+ like to use .foo as the stub symbol to avoid creating another symbol.
+ We need to make sure that when .foo labels a stub in a shared library,
+ it isn't exported. */
/* The linker needs to keep track of the number of relocs that it
decides to copy as dynamic relocs in check_relocs for each symbol.
/* Track dynamic relocs copied for this symbol. */
struct ppc_dyn_relocs *dyn_relocs;
+
+ /* Flag function code and descriptor symbols. */
+ unsigned int is_func:1;
+ unsigned int is_func_descriptor:1;
};
/* ppc64 ELF linker hash table. */
struct ppc_link_hash_entry *eh = (struct ppc_link_hash_entry *) entry;
eh->dyn_relocs = NULL;
+ eh->is_func = 0;
+ eh->is_func_descriptor = 0;
}
return entry;
eind->dyn_relocs = NULL;
}
+ edir->is_func |= eind->is_func;
+ edir->is_func_descriptor |= eind->is_func_descriptor;
+
_bfd_elf_link_hash_copy_indirect (dir, ind);
}
const Elf_Internal_Rela *rel;
const Elf_Internal_Rela *rel_end;
asection *sreloc;
+ boolean is_opd;
if (info->relocateable)
return true;
sym_hashes_end -= symtab_hdr->sh_info;
sreloc = NULL;
+ is_opd = strcmp (bfd_get_section_name (abfd, sec), ".opd") == 0;
rel_end = relocs + sec->reloc_count;
for (rel = relocs; rel < rel_end; rel++)
h->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_PLT;
h->plt.refcount += 1;
+ ((struct ppc_link_hash_entry *) h)->is_func = 1;
break;
/* The following relocations don't need to propagate the
break;
case R_PPC64_REL24:
- if (h != NULL)
+ if (h != NULL
+ && h->root.root.string[0] == '.'
+ && h->root.root.string[1] != 0)
{
/* We may need a .plt entry if the function this reloc
refers to is in a shared lib. */
h->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_PLT;
h->plt.refcount += 1;
+ ((struct ppc_link_hash_entry *) h)->is_func = 1;
}
break;
+ case R_PPC64_ADDR64:
+ if (is_opd
+ && h != NULL
+ && h->root.root.string[0] == '.'
+ && h->root.root.string[1] != 0)
+ {
+ struct elf_link_hash_entry *fdh;
+
+ fdh = elf_link_hash_lookup (&htab->elf, h->root.root.string + 1,
+ false, false, false);
+ if (fdh != NULL)
+ {
+ /* Ensure the function descriptor symbol string is
+ part of the code symbol string. We aren't
+ changing the name here, just allowing some tricks
+ in ppc64_elf_hide_symbol. */
+ fdh->root.root.string = h->root.root.string + 1;
+ ((struct ppc_link_hash_entry *) fdh)->is_func_descriptor = 1;
+ ((struct ppc_link_hash_entry *) h)->is_func = 1;
+ }
+ }
+ /* Fall through. */
+
case R_PPC64_REL64:
case R_PPC64_REL32:
case R_PPC64_REL14:
case R_PPC64_ADDR24:
case R_PPC64_ADDR30:
case R_PPC64_ADDR32:
- case R_PPC64_ADDR64:
case R_PPC64_UADDR16:
case R_PPC64_UADDR32:
case R_PPC64_UADDR64:
case R_PPC64_TOC:
+#if 0
+ /* Don't propagate .opd relocs. */
+ if (is_opd)
+ break;
+#endif
+
/* If we are creating a shared library, and this is a reloc
against a global symbol, or a non PC relative reloc
against a local symbol, then we need to copy the reloc
struct ppc_dyn_relocs *p;
struct ppc_dyn_relocs **head;
-#if 0
- /* Don't propagate .opd relocs. */
- if (strcmp (bfd_get_section_name (abfd, sec), ".opd") == 0)
- break;
-#endif
-
/* We must copy these reloc types into the output file.
Create a reloc section in dynobj and make room for
this reloc. */
if (h->plt.refcount > 0)
h->plt.refcount--;
}
- /* Fall thru. */
+ break;
case R_PPC64_REL14:
case R_PPC64_REL14_BRNTAKEN:
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
- change the definition to something the rest of the link can
- understand. */
-
+/* Called via elf_link_hash_traverse to transfer dynamic linking
+ information on function code symbol entries to their corresponding
+ function descriptor symbol entries. */
static boolean
-ppc64_elf_adjust_dynamic_symbol (info, h)
- struct bfd_link_info *info;
+func_desc_adjust (h, inf)
struct elf_link_hash_entry *h;
+ PTR inf;
{
+ struct bfd_link_info *info;
struct ppc_link_hash_table *htab;
- struct ppc_link_hash_entry * eh;
- struct ppc_dyn_relocs *p;
- asection *s;
- unsigned int power_of_two;
+ if (h->root.type == bfd_link_hash_indirect
+ || h->root.type == bfd_link_hash_warning)
+ return true;
+
+ info = (struct bfd_link_info *) inf;
htab = ppc_hash_table (info);
- /* If this is a function, put it in the procedure linkage table. We
- will fill in the contents of the procedure linkage table later. */
- if (h->type == STT_FUNC
- || (h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_PLT) != 0)
+ /* If this is a function code symbol, transfer dynamic linking
+ information to the function descriptor symbol. */
+ if (!((struct ppc_link_hash_entry *) h)->is_func)
+ return true;
+
+ if (h->plt.refcount > 0
+ && h->root.root.string[0] == '.'
+ && h->root.root.string[1] != '\0')
{
struct elf_link_hash_entry *fdh;
-
- /* If it's a function entry point, the name starts with a dot
- unless someone has written some poor assembly code. The ABI
- for .plt calls requires that there be a function descriptor
- sym which has the name of the function minus the dot. */
-
- if (h->plt.refcount <= 0
- || h->root.root.string[0] != '.'
- || h->root.root.string[1] == '\0')
- {
- h->plt.offset = (bfd_vma) -1;
- h->elf_link_hash_flags &= ~ELF_LINK_HASH_NEEDS_PLT;
- return true;
- }
+ boolean force_local;
/* Find the corresponding function descriptor symbol. Create it
- as undefined if necessary. ppc_elf64_finish_dynamic_symbol
- will look it up again and create a JMP_SLOT reloc for it. */
+ as undefined if necessary. */
- fdh = elf_link_hash_lookup (elf_hash_table (info),
- h->root.root.string + 1,
- false, false, false);
+ fdh = elf_link_hash_lookup (&htab->elf, h->root.root.string + 1,
+ false, false, true);
- if (fdh == NULL)
+ if (fdh == NULL && info->shared)
{
+ bfd *abfd;
asymbol *newsym;
/* Create it as undefined. */
- newsym = bfd_make_empty_symbol (htab->elf.dynobj);
+ if (h->root.type == bfd_link_hash_undefined
+ || h->root.type == bfd_link_hash_undefweak)
+ abfd = h->root.u.undef.abfd;
+ else if (h->root.type == bfd_link_hash_defined
+ || h->root.type == bfd_link_hash_defweak)
+ abfd = h->root.u.def.section->owner;
+ else
+ abort ();
+ newsym = bfd_make_empty_symbol (abfd);
newsym->name = h->root.root.string + 1;
newsym->section = bfd_und_section_ptr;
newsym->value = 0;
- newsym->flags = BSF_DYNAMIC | BSF_OBJECT;
+ newsym->flags = BSF_OBJECT;
+ if (h->root.type == bfd_link_hash_undefweak)
+ newsym->flags |= BSF_WEAK;
if ( !(_bfd_generic_link_add_one_symbol
- (info, htab->elf.dynobj, newsym->name, newsym->flags,
+ (info, abfd, newsym->name, newsym->flags,
newsym->section, newsym->value, NULL, false, false,
(struct bfd_link_hash_entry **) &fdh)))
{
}
}
- while (fdh->root.type == bfd_link_hash_indirect
- || fdh->root.type == bfd_link_hash_warning)
- fdh = (struct elf_link_hash_entry *) fdh->root.u.i.link;
+ if (fdh != NULL
+ && (fdh->elf_link_hash_flags & ELF_LINK_FORCED_LOCAL) == 0
+ && (info->shared
+ || (fdh->elf_link_hash_flags & ELF_LINK_HASH_DEF_DYNAMIC) != 0
+ || (fdh->elf_link_hash_flags & ELF_LINK_HASH_REF_DYNAMIC) != 0))
+ {
+ if (fdh->dynindx == -1)
+ if (! bfd_elf64_link_record_dynamic_symbol (info, fdh))
+ return false;
+ fdh->plt.refcount = h->plt.refcount;
+ fdh->elf_link_hash_flags |= (h->elf_link_hash_flags
+ & (ELF_LINK_HASH_REF_REGULAR
+ | ELF_LINK_HASH_REF_DYNAMIC
+ | ELF_LINK_HASH_REF_REGULAR_NONWEAK
+ | ELF_LINK_NON_GOT_REF));
+ fdh->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_PLT;
+ ((struct ppc_link_hash_entry *) fdh)->is_func_descriptor = 1;
+ fdh->root.root.string = h->root.root.string + 1;
+ }
+
+ /* Now that the info is on the function descriptor, clear the
+ function code sym info. Any function code syms for which we
+ don't have a definition in a regular file, we force local.
+ This prevents a shared library from exporting syms that have
+ been imported from another library. Function code syms that
+ are really in the library we must leave global to prevent the
+ linker dragging a definition in from a static library. */
+ force_local = (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) == 0;
+ _bfd_elf_link_hash_hide_symbol (info, h, force_local);
+ }
+
+ return true;
+}
- if (! info->shared
- && (fdh->elf_link_hash_flags & ELF_LINK_HASH_DEF_DYNAMIC) == 0
- && (fdh->elf_link_hash_flags & ELF_LINK_HASH_REF_DYNAMIC) == 0)
+/* Called near the start of bfd_elf_size_dynamic_sections. We use
+ this hook to transfer dynamic linking information gathered so far
+ on function code symbol entries, to their corresponding function
+ descriptor symbol entries. */
+static boolean
+ppc64_elf_func_desc_adjust (obfd, info)
+ bfd *obfd ATTRIBUTE_UNUSED;
+ struct bfd_link_info *info;
+{
+ struct ppc_link_hash_table *htab;
+
+ htab = ppc_hash_table (info);
+ elf_link_hash_traverse (&htab->elf, func_desc_adjust, (PTR) info);
+ 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
+ change the definition to something the rest of the link can
+ understand. */
+
+static boolean
+ppc64_elf_adjust_dynamic_symbol (info, h)
+ struct bfd_link_info *info;
+ struct elf_link_hash_entry *h;
+{
+ struct ppc_link_hash_table *htab;
+ struct ppc_link_hash_entry * eh;
+ struct ppc_dyn_relocs *p;
+ asection *s;
+ unsigned int power_of_two;
+
+ htab = ppc_hash_table (info);
+
+ /* Deal with function syms. */
+ if (h->type == STT_FUNC
+ || (h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_PLT) != 0)
+ {
+ /* Clear procedure linkage table information for any symbol that
+ won't need a .plt entry. */
+ if (!((struct ppc_link_hash_entry *) h)->is_func_descriptor
+ || h->plt.refcount <= 0
+ || (h->elf_link_hash_flags & ELF_LINK_FORCED_LOCAL) != 0
+ || (! info->shared
+ && (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_DYNAMIC) == 0
+ && (h->elf_link_hash_flags & ELF_LINK_HASH_REF_DYNAMIC) == 0))
{
- /* This case can occur if we saw a PLT reloc in an input
- file, but the symbol was never referred to by a dynamic
- object, or if all references were garbage collected. In
- such a case, we don't actually need to build a procedure
- linkage table entry. */
h->plt.offset = (bfd_vma) -1;
h->elf_link_hash_flags &= ~ELF_LINK_HASH_NEEDS_PLT;
- return true;
}
-
return true;
}
else
return true;
}
+/* If given a function descriptor symbol, hide both the function code
+ sym and the descriptor. */
+static void
+ppc64_elf_hide_symbol (info, h, force_local)
+ struct bfd_link_info *info;
+ struct elf_link_hash_entry *h;
+ boolean force_local;
+{
+ _bfd_elf_link_hash_hide_symbol (info, h, force_local);
+
+ if (((struct ppc_link_hash_entry *) h)->is_func_descriptor)
+ {
+ const char *name;
+ struct elf_link_hash_entry *fh;
+ struct ppc_link_hash_table *htab;
+
+ name = h->root.root.string - 1;
+ htab = ppc_hash_table (info);
+ fh = elf_link_hash_lookup (&htab->elf, name, false, false, false);
+ if (fh != NULL)
+ _bfd_elf_link_hash_hide_symbol (info, fh, force_local);
+ }
+}
+
/* This is the condition under which ppc64_elf_finish_dynamic_symbol
will be called from elflink.h. If elflink.h doesn't call our
finish_dynamic_symbol routine, we'll need to do something about
htab = ppc_hash_table (info);
if (htab->elf.dynamic_sections_created
- && h->plt.refcount > 0)
+ && h->plt.refcount > 0
+ && h->dynindx != -1)
{
- /* 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->elf_link_hash_flags & ELF_LINK_FORCED_LOCAL) == 0)
- {
- if (! bfd_elf64_link_record_dynamic_symbol (info, h))
- return false;
- }
-
- BFD_ASSERT (h->root.root.string[0] == '.'
- && h->root.root.string[1] != '\0');
+ BFD_ASSERT (((struct ppc_link_hash_entry *) h)->is_func_descriptor);
if (WILL_CALL_FINISH_DYNAMIC_SYMBOL (1, info, h))
{
- /* Make sure the corresponding function descriptor symbol is
- dynamic too. */
-
- if (h->dynindx != -1)
- {
- struct elf_link_hash_entry *fdh;
-
- fdh = elf_link_hash_lookup (elf_hash_table (info),
- h->root.root.string + 1,
- false, false, false);
-
- if (fdh == NULL)
- abort ();
-
- if (fdh->dynindx == -1
- && (fdh->elf_link_hash_flags & ELF_LINK_FORCED_LOCAL) == 0)
- {
- if (! bfd_elf64_link_record_dynamic_symbol (info, fdh))
- return false;
- }
- }
-
/* If this is the first .plt entry, make room for the special
first entry. */
s = htab->splt;
s->_raw_size += PLT_INITIAL_ENTRY_SIZE;
h->plt.offset = s->_raw_size;
- h->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_PLT;
/* Make room for this entry. */
s->_raw_size += PLT_ENTRY_SIZE;
return false;
}
- if (elf_hash_table (info)->dynamic_sections_created)
+ if (htab->elf.dynamic_sections_created)
{
/* Add some entries to the .dynamic section. We fill in the
values later, in ppc64_elf_finish_dynamic_sections, but we
if (htab->elf.dynamic_sections_created
&& h->plt.offset != (bfd_vma) -1)
{
+ struct elf_link_hash_entry *fh;
asection *s;
bfd_vma plt_r2;
bfd_byte *p;
unsigned int indx;
+ BFD_ASSERT (((struct ppc_link_hash_entry *) h)->is_func_descriptor);
+
+ fh = elf_link_hash_lookup (&htab->elf, h->root.root.string - 1,
+ false, false, true);
+
+ if (fh == NULL)
+ abort ();
+
+ BFD_ASSERT (((struct ppc_link_hash_entry *) fh)->is_func);
+
/* Point the function at the linkage stub. This works because
the only references to the function code sym are calls.
Function pointer comparisons use the function descriptor. */
s = htab->sstub;
- h->root.type = bfd_link_hash_defined;
- h->root.u.def.section = s;
- h->root.u.def.value = s->_cooked_size;
+ fh->root.type = bfd_link_hash_defined;
+ fh->root.u.def.section = s;
+ fh->root.u.def.value = s->_cooked_size;
/* Build the .plt call stub. */
plt_r2 = (htab->splt->output_section->vma
- elf_gp (htab->splt->output_section->owner)
- TOC_BASE_OFF);
- if (plt_r2 + 0x80000000 > 0xffffffff)
+ if (plt_r2 + 0x80000000 > 0xffffffff
+ || (plt_r2 & 3) != 0)
{
(*_bfd_error_handler)
- (_("linkage table overflow against `%s'"),
+ (_("linkage table error against `%s'"),
h->root.root.string);
bfd_set_error (bfd_error_bad_value);
htab->plt_overflow = true;
unsigned long r_symndx;
bfd_vma relocation;
boolean unresolved_reloc;
+ boolean has_nop;
long insn;
r_type = (enum elf_ppc_reloc_type) ELF64_R_TYPE (rel->r_info);
order to restore the TOC base pointer. Only calls to
shared objects need to alter the TOC base. These are
recognized by their need for a PLT entry. */
+ has_nop = 0;
if (h != NULL
&& (h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_PLT) != 0
/* Make sure that there really is an instruction after
bfd_put_32 (input_bfd,
(bfd_vma) 0xe8410028, /* ld r2,40(r1) */
pnext);
+ has_nop = 1;
}
}
+
+ if (h != NULL
+ && h->root.type == bfd_link_hash_undefweak
+ && r_type == R_PPC64_REL24
+ && addend == 0
+ && relocation == 0)
+ {
+ /* Tweak calls to undefined weak functions to behave as
+ if the "called" function immediately returns. We can
+ thus call to a weak function without first checking
+ whether the function is defined. */
+ relocation = 4;
+ if (has_nop)
+ relocation = 8;
+ }
break;
}
/* This symbol is local, or marked to become local. */
outrel.r_addend += relocation;
relocate = true;
- if (r_type == R_PPC64_ADDR64)
+ if (r_type == R_PPC64_ADDR64 || r_type == R_PPC64_TOC)
{
outrel.r_info = ELF64_R_INFO (0, R_PPC64_RELATIVE);
}
if (h->plt.offset != (bfd_vma) -1)
{
- struct elf_link_hash_entry *funcdesc_h;
Elf_Internal_Rela rela;
Elf64_External_Rela *loc;
if (htab->splt == NULL
|| htab->srelplt == NULL
- || htab->sglink == NULL
- || h->root.root.string[0] != '.'
- || h->root.root.string[1] == '\0')
+ || htab->sglink == NULL)
abort ();
- /* Find its corresponding function descriptor.
- ppc64_elf_adjust_dynamic_symbol has already set it up for us. */
-
- funcdesc_h = elf_link_hash_lookup (elf_hash_table (info),
- h->root.root.string + 1,
- false, false, false);
-
- if (funcdesc_h == NULL || funcdesc_h->dynindx == -1)
- abort ();
+ BFD_ASSERT (((struct ppc_link_hash_entry *) h)->is_func_descriptor);
/* Create a JMP_SLOT reloc to inform the dynamic linker to
fill in the PLT entry. */
rela.r_offset = (htab->splt->output_section->vma
+ htab->splt->output_offset
+ h->plt.offset);
- rela.r_info = ELF64_R_INFO (funcdesc_h->dynindx, R_PPC64_JMP_SLOT);
+ rela.r_info = ELF64_R_INFO (h->dynindx, R_PPC64_JMP_SLOT);
rela.r_addend = 0;
loc = (Elf64_External_Rela *) htab->srelplt->contents;
#define elf_backend_gc_mark_hook ppc64_elf_gc_mark_hook
#define elf_backend_gc_sweep_hook ppc64_elf_gc_sweep_hook
#define elf_backend_adjust_dynamic_symbol ppc64_elf_adjust_dynamic_symbol
+#define elf_backend_hide_symbol ppc64_elf_hide_symbol
+#define elf_backend_always_size_sections ppc64_elf_func_desc_adjust
#define elf_backend_size_dynamic_sections ppc64_elf_size_dynamic_sections
#define elf_backend_fake_sections ppc64_elf_fake_sections
#define elf_backend_relocate_section ppc64_elf_relocate_section
projects / binutils-gdb.git / commitdiff