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* elf32-ppc.c (section_covers_vma): New function.
(ppc_elf_get_synthetic_symtab): New function. (bfd_elf32_get_synthetic_symtab): Define. * elf64-ppc.c (section_covers_vma): New function. (ppc64_elf_get_synthetic_symtab): Generate sym@plt on glink branch table entries, and __glink_PLTresolve on resolver stub. (ppc64_elf_build_stubs): Rename __glink sym to __glink_PLTresolve.
This commit is contained in:
Alan Modra
parent
b091ad0577
commit
468392fb66
@ -1,3 +1,14 @@
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2008-05-14 Ulrich Weigand <uweigand@de.ibm.com>
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Alan Modra <amodra@bigpond.net.au>
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* elf32-ppc.c (section_covers_vma): New function.
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(ppc_elf_get_synthetic_symtab): New function.
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(bfd_elf32_get_synthetic_symtab): Define.
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* elf64-ppc.c (section_covers_vma): New function.
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(ppc64_elf_get_synthetic_symtab): Generate sym@plt on glink branch
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table entries, and __glink_PLTresolve on resolver stub.
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(ppc64_elf_build_stubs): Rename __glink sym to __glink_PLTresolve.
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2008-05-12 Alan Modra <amodra@bigpond.net.au>
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PR 6443
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205
bfd/elf32-ppc.c
205
bfd/elf32-ppc.c
@ -2291,6 +2291,208 @@ ppc_elf_final_write_processing (bfd *abfd, bfd_boolean linker ATTRIBUTE_UNUSED)
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apuinfo_list_finish ();
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}
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static bfd_boolean
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section_covers_vma (bfd *abfd ATTRIBUTE_UNUSED, asection *section, void *ptr)
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{
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bfd_vma vma = *(bfd_vma *) ptr;
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return ((section->flags & SEC_ALLOC) != 0
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&& section->vma <= vma
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&& vma < section->vma + section->size);
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}
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static long
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ppc_elf_get_synthetic_symtab (bfd *abfd, long symcount, asymbol **syms,
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long dynsymcount, asymbol **dynsyms,
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asymbol **ret)
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{
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bfd_boolean (*slurp_relocs) (bfd *, asection *, asymbol **, bfd_boolean);
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asection *plt, *relplt, *dynamic, *glink;
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bfd_vma glink_vma = 0;
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bfd_vma resolv_vma = 0;
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bfd_vma stub_vma;
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asymbol *s;
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arelent *p;
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long count, i;
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size_t size;
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char *names;
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bfd_byte buf[4];
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*ret = NULL;
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if ((abfd->flags & (DYNAMIC | EXEC_P)) == 0)
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return 0;
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if (dynsymcount <= 0)
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return 0;
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relplt = bfd_get_section_by_name (abfd, ".rela.plt");
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if (relplt == NULL)
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return 0;
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plt = bfd_get_section_by_name (abfd, ".plt");
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if (plt == NULL)
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return 0;
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/* Call common code to handle old-style executable PLTs. */
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if (elf_section_flags (plt) & SHF_EXECINSTR)
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return _bfd_elf_get_synthetic_symtab (abfd, symcount, syms,
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dynsymcount, dynsyms, ret);
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/* If this object was prelinked, the prelinker stored the address
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of .glink at got[1]. If it wasn't prelinked, got[1] will be zero. */
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dynamic = bfd_get_section_by_name (abfd, ".dynamic");
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if (dynamic != NULL)
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{
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bfd_byte *dynbuf, *extdyn, *extdynend;
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size_t extdynsize;
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void (*swap_dyn_in) (bfd *, const void *, Elf_Internal_Dyn *);
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if (!bfd_malloc_and_get_section (abfd, dynamic, &dynbuf))
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return -1;
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extdynsize = get_elf_backend_data (abfd)->s->sizeof_dyn;
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swap_dyn_in = get_elf_backend_data (abfd)->s->swap_dyn_in;
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extdyn = dynbuf;
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extdynend = extdyn + dynamic->size;
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for (; extdyn < extdynend; extdyn += extdynsize)
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{
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Elf_Internal_Dyn dyn;
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(*swap_dyn_in) (abfd, extdyn, &dyn);
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if (dyn.d_tag == DT_NULL)
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break;
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if (dyn.d_tag == DT_PPC_GOT)
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{
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unsigned int g_o_t = dyn.d_un.d_val;
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asection *got = bfd_get_section_by_name (abfd, ".got");
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if (got != NULL
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&& bfd_get_section_contents (abfd, got, buf,
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g_o_t - got->vma + 4, 4))
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glink_vma = bfd_get_32 (abfd, buf);
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break;
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}
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}
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free (dynbuf);
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}
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/* Otherwise we read the first plt entry. */
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if (glink_vma == 0)
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{
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if (bfd_get_section_contents (abfd, plt, buf, 0, 4))
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glink_vma = bfd_get_32 (abfd, buf);
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}
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if (glink_vma == 0)
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return 0;
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/* The .glink section usually does not survive the final
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link; search for the section (usually .text) where the
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glink stubs now reside. */
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glink = bfd_sections_find_if (abfd, section_covers_vma, &glink_vma);
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if (glink == NULL)
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return 0;
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/* Determine glink PLT resolver by reading the relative branch
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from the first glink stub. */
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if (bfd_get_section_contents (abfd, glink, buf,
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glink_vma - glink->vma, 4))
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{
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unsigned int insn = bfd_get_32 (abfd, buf);
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/* The first glink stub may either branch to the resolver ... */
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insn ^= B;
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if ((insn & ~0x3fffffc) == 0)
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resolv_vma = glink_vma + (insn ^ 0x2000000) - 0x2000000;
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/* ... or fall through a bunch of NOPs. */
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else if ((insn ^ B ^ NOP) == 0)
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for (i = 4;
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bfd_get_section_contents (abfd, glink, buf,
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glink_vma - glink->vma + i, 4);
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i += 4)
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if (bfd_get_32 (abfd, buf) != NOP)
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{
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resolv_vma = glink_vma + i;
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break;
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}
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}
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slurp_relocs = get_elf_backend_data (abfd)->s->slurp_reloc_table;
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if (! (*slurp_relocs) (abfd, relplt, dynsyms, TRUE))
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return -1;
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count = relplt->size / sizeof (Elf32_External_Rela);
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stub_vma = glink_vma - (bfd_vma) count * 16;
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size = count * sizeof (asymbol);
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p = relplt->relocation;
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for (i = 0; i < count; i++, p++)
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size += strlen ((*p->sym_ptr_ptr)->name) + sizeof ("@plt");
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size += sizeof (asymbol) + sizeof ("__glink");
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if (resolv_vma)
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size += sizeof (asymbol) + sizeof ("__glink_PLTresolve");
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s = *ret = bfd_malloc (size);
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if (s == NULL)
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return -1;
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names = (char *) (s + count + 1 + (resolv_vma != 0));
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p = relplt->relocation;
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for (i = 0; i < count; i++, p++)
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{
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size_t len;
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*s = **p->sym_ptr_ptr;
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/* Undefined syms won't have BSF_LOCAL or BSF_GLOBAL set. Since
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we are defining a symbol, ensure one of them is set. */
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if ((s->flags & BSF_LOCAL) == 0)
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s->flags |= BSF_GLOBAL;
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s->section = glink;
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s->value = stub_vma - glink->vma;
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s->name = names;
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s->udata.p = NULL;
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len = strlen ((*p->sym_ptr_ptr)->name);
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memcpy (names, (*p->sym_ptr_ptr)->name, len);
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names += len;
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memcpy (names, "@plt", sizeof ("@plt"));
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names += sizeof ("@plt");
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++s;
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stub_vma += 16;
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}
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/* Add a symbol at the start of the glink branch table. */
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memset (s, sizeof *s, 0);
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s->the_bfd = abfd;
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s->flags = BSF_GLOBAL;
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s->section = glink;
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s->value = glink_vma - glink->vma;
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s->name = names;
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memcpy (names, "__glink", sizeof ("__glink"));
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names += sizeof ("__glink");
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s++;
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count++;
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if (resolv_vma)
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{
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/* Add a symbol for the glink PLT resolver. */
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memset (s, sizeof *s, 0);
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s->the_bfd = abfd;
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s->flags = BSF_GLOBAL;
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s->section = glink;
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s->value = resolv_vma - glink->vma;
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s->name = names;
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memcpy (names, "__glink_PLTresolve", sizeof ("__glink_PLTresolve"));
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names += sizeof ("__glink_PLTresolve");
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s++;
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count++;
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}
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return count;
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}
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/* The following functions are specific to the ELF linker, while
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functions above are used generally. They appear in this file more
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or less in the order in which they are called. eg.
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@ -7818,6 +8020,7 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
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#define bfd_elf32_bfd_reloc_name_lookup ppc_elf_reloc_name_lookup
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#define bfd_elf32_bfd_set_private_flags ppc_elf_set_private_flags
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#define bfd_elf32_bfd_link_hash_table_create ppc_elf_link_hash_table_create
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#define bfd_elf32_get_synthetic_symtab ppc_elf_get_synthetic_symtab
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#define elf_backend_object_p ppc_elf_object_p
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#define elf_backend_gc_mark_hook ppc_elf_gc_mark_hook
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@ -7932,6 +8135,8 @@ ppc_elf_vxworks_final_write_processing (bfd *abfd, bfd_boolean linker)
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#undef elf_backend_got_header_size
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#define elf_backend_got_header_size 12
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#undef bfd_elf32_get_synthetic_symtab
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#undef bfd_elf32_bfd_link_hash_table_create
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#define bfd_elf32_bfd_link_hash_table_create \
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ppc_elf_vxworks_link_hash_table_create
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160
bfd/elf64-ppc.c
160
bfd/elf64-ppc.c
@ -2771,8 +2771,17 @@ sym_exists_at (asymbol **syms, long lo, long hi, int id, bfd_vma value)
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return NULL;
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}
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static bfd_boolean
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section_covers_vma (bfd *abfd ATTRIBUTE_UNUSED, asection *section, void *ptr)
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{
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bfd_vma vma = *(bfd_vma *) ptr;
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return ((section->flags & SEC_ALLOC) != 0
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&& section->vma <= vma
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&& vma < section->vma + section->size);
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}
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/* Create synthetic symbols, effectively restoring "dot-symbol" function
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entry syms. */
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entry syms. Also generate @plt symbols for the glink branch table. */
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static long
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ppc64_elf_get_synthetic_symtab (bfd *abfd,
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@ -2862,8 +2871,6 @@ ppc64_elf_get_synthetic_symtab (bfd *abfd,
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symcount = i;
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count = 0;
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if (opdsymend == secsymend)
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goto done;
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if (relocatable)
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{
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@ -2872,6 +2879,9 @@ ppc64_elf_get_synthetic_symtab (bfd *abfd,
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size_t size;
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long relcount;
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if (opdsymend == secsymend)
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goto done;
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slurp_relocs = get_elf_backend_data (abfd)->s->slurp_reloc_table;
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relcount = (opd->flags & SEC_RELOC) ? opd->reloc_count : 0;
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if (relcount == 0)
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@ -2960,8 +2970,13 @@ ppc64_elf_get_synthetic_symtab (bfd *abfd,
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}
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else
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{
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bfd_boolean (*slurp_relocs) (bfd *, asection *, asymbol **, bfd_boolean);
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bfd_byte *contents;
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size_t size;
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long plt_count = 0;
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bfd_vma glink_vma = 0, resolv_vma = 0;
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asection *dynamic, *glink = NULL, *relplt = NULL;
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arelent *p;
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if (!bfd_malloc_and_get_section (abfd, opd, &contents))
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{
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@ -2988,11 +3003,85 @@ ppc64_elf_get_synthetic_symtab (bfd *abfd,
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}
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}
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/* Get start of .glink stubs from DT_PPC64_GLINK. */
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dynamic = bfd_get_section_by_name (abfd, ".dynamic");
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if (dynamic != NULL)
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{
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bfd_byte *dynbuf, *extdyn, *extdynend;
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size_t extdynsize;
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void (*swap_dyn_in) (bfd *, const void *, Elf_Internal_Dyn *);
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if (!bfd_malloc_and_get_section (abfd, dynamic, &dynbuf))
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goto free_contents_and_exit;
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extdynsize = get_elf_backend_data (abfd)->s->sizeof_dyn;
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swap_dyn_in = get_elf_backend_data (abfd)->s->swap_dyn_in;
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extdyn = dynbuf;
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extdynend = extdyn + dynamic->size;
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for (; extdyn < extdynend; extdyn += extdynsize)
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{
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Elf_Internal_Dyn dyn;
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(*swap_dyn_in) (abfd, extdyn, &dyn);
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if (dyn.d_tag == DT_NULL)
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break;
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if (dyn.d_tag == DT_PPC64_GLINK)
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{
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/* The first glink stub starts at offset 32; see comment in
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ppc64_elf_finish_dynamic_sections. */
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glink_vma = dyn.d_un.d_val + 32;
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/* The .glink section usually does not survive the final
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link; search for the section (usually .text) where the
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glink stubs now reside. */
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glink = bfd_sections_find_if (abfd, section_covers_vma,
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&glink_vma);
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break;
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}
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}
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free (dynbuf);
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}
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if (glink != NULL)
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{
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/* Determine __glink trampoline by reading the relative branch
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from the first glink stub. */
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bfd_byte buf[4];
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if (bfd_get_section_contents (abfd, glink, buf,
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glink_vma + 4 - glink->vma, 4))
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{
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unsigned int insn = bfd_get_32 (abfd, buf);
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insn ^= B_DOT;
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if ((insn & ~0x3fffffc) == 0)
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resolv_vma = glink_vma + 4 + (insn ^ 0x2000000) - 0x2000000;
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}
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if (resolv_vma)
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size += sizeof (asymbol) + sizeof ("__glink_PLTresolve");
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}
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relplt = bfd_get_section_by_name (abfd, ".rela.plt");
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if (glink != NULL && relplt != NULL)
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{
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slurp_relocs = get_elf_backend_data (abfd)->s->slurp_reloc_table;
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if (! (*slurp_relocs) (abfd, relplt, dyn_syms, TRUE))
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goto free_contents_and_exit;
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plt_count = relplt->size / sizeof (Elf64_External_Rela);
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size += plt_count * sizeof (asymbol);
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p = relplt->relocation;
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for (i = 0; i < plt_count; i++, p++)
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size += strlen ((*p->sym_ptr_ptr)->name) + sizeof ("@plt");
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}
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s = *ret = bfd_malloc (size);
|
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if (s == NULL)
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goto free_contents_and_exit;
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names = (char *) (s + count);
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names = (char *) (s + count + plt_count + (resolv_vma != 0));
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for (i = secsymend; i < opdsymend; ++i)
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{
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@ -3048,6 +3137,66 @@ ppc64_elf_get_synthetic_symtab (bfd *abfd,
|
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}
|
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}
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free (contents);
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if (glink != NULL && relplt != NULL)
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{
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if (resolv_vma)
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{
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/* Add a symbol for the main glink trampoline. */
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memset (s, sizeof *s, 0);
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s->the_bfd = abfd;
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s->flags = BSF_GLOBAL;
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s->section = glink;
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s->value = resolv_vma - glink->vma;
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s->name = names;
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memcpy (names, "__glink_PLTresolve", sizeof ("__glink_PLTresolve"));
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names += sizeof ("__glink_PLTresolve");
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s++;
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count++;
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}
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/* FIXME: It would be very much nicer to put sym@plt on the
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stub rather than on the glink branch table entry. The
|
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objdump disassembler would then use a sensible symbol
|
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name on plt calls. The difficulty in doing so is
|
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a) finding the stubs, and,
|
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b) matching stubs against plt entries, and,
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c) there can be multiple stubs for a given plt entry.
|
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|
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Solving (a) could be done by code scanning, but older
|
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ppc64 binaries used different stubs to current code.
|
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(b) is the tricky one since you need to known the toc
|
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pointer for at least one function that uses a pic stub to
|
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be able to calculate the plt address referenced.
|
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(c) means gdb would need to set multiple breakpoints (or
|
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find the glink branch itself) when setting breakpoints
|
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for pending shared library loads. */
|
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p = relplt->relocation;
|
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for (i = 0; i < plt_count; i++, p++)
|
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{
|
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size_t len;
|
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|
||||
*s = **p->sym_ptr_ptr;
|
||||
/* Undefined syms won't have BSF_LOCAL or BSF_GLOBAL set. Since
|
||||
we are defining a symbol, ensure one of them is set. */
|
||||
if ((s->flags & BSF_LOCAL) == 0)
|
||||
s->flags |= BSF_GLOBAL;
|
||||
s->section = glink;
|
||||
s->value = glink_vma - glink->vma;
|
||||
s->name = names;
|
||||
s->udata.p = NULL;
|
||||
len = strlen ((*p->sym_ptr_ptr)->name);
|
||||
memcpy (names, (*p->sym_ptr_ptr)->name, len);
|
||||
names += len;
|
||||
memcpy (names, "@plt", sizeof ("@plt"));
|
||||
names += sizeof ("@plt");
|
||||
s++;
|
||||
glink_vma += 8;
|
||||
if (i >= 0x8000)
|
||||
glink_vma += 4;
|
||||
}
|
||||
count += plt_count;
|
||||
}
|
||||
}
|
||||
|
||||
done:
|
||||
@ -9802,7 +9951,8 @@ ppc64_elf_build_stubs (bfd_boolean emit_stub_syms,
|
||||
if (htab->emit_stub_syms)
|
||||
{
|
||||
struct elf_link_hash_entry *h;
|
||||
h = elf_link_hash_lookup (&htab->elf, "__glink", TRUE, FALSE, FALSE);
|
||||
h = elf_link_hash_lookup (&htab->elf, "__glink_PLTresolve",
|
||||
TRUE, FALSE, FALSE);
|
||||
if (h == NULL)
|
||||
return FALSE;
|
||||
if (h->root.type == bfd_link_hash_new)
|
||||
|
||||
Loading…
Reference in New Issue
Block a user