| 1 | /* IBM S/390-specific support for ELF 32 and 64 bit functions |
| 2 | Copyright (C) 2000-2019 Free Software Foundation, Inc. |
| 3 | Contributed by Andreas Krebbel. |
| 4 | |
| 5 | This file is part of BFD, the Binary File Descriptor library. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA |
| 20 | 02110-1301, USA. */ |
| 21 | |
| 22 | |
| 23 | /* Return TRUE if H is an IFUNC symbol. Simply checking for the |
| 24 | symbol type might not be enough since it might get changed to |
| 25 | STT_FUNC for pointer equality reasons. */ |
| 26 | static inline bfd_boolean |
| 27 | s390_is_ifunc_symbol_p (struct elf_link_hash_entry *h) |
| 28 | { |
| 29 | struct elf_s390_link_hash_entry *eh = (struct elf_s390_link_hash_entry*)h; |
| 30 | return h->type == STT_GNU_IFUNC || eh->ifunc_resolver_address != 0; |
| 31 | } |
| 32 | |
| 33 | /* Return true if .got.plt is supposed to be emitted after .got. */ |
| 34 | |
| 35 | static inline bfd_boolean |
| 36 | s390_gotplt_after_got_p (struct bfd_link_info *info) |
| 37 | { |
| 38 | struct elf_s390_link_hash_table *htab = elf_s390_hash_table (info); |
| 39 | |
| 40 | if (!htab->elf.sgot || !htab->elf.sgotplt) |
| 41 | return TRUE; |
| 42 | |
| 43 | if (htab->elf.sgot->output_section == htab->elf.sgotplt->output_section) |
| 44 | { |
| 45 | if (htab->elf.sgot->output_offset < htab->elf.sgotplt->output_offset) |
| 46 | return TRUE; |
| 47 | } |
| 48 | else |
| 49 | { |
| 50 | if (htab->elf.sgot->output_section->vma |
| 51 | <= htab->elf.sgotplt->output_section->vma) |
| 52 | return TRUE; |
| 53 | } |
| 54 | return FALSE; |
| 55 | } |
| 56 | |
| 57 | /* Return the value of the _GLOBAL_OFFSET_TABLE_ symbol. */ |
| 58 | |
| 59 | static inline bfd_vma |
| 60 | s390_got_pointer (struct bfd_link_info *info) |
| 61 | { |
| 62 | struct elf_s390_link_hash_table *htab = elf_s390_hash_table (info); |
| 63 | bfd_vma got_pointer; |
| 64 | |
| 65 | BFD_ASSERT (htab && htab->elf.hgot); |
| 66 | |
| 67 | got_pointer = (htab->elf.hgot->root.u.def.section->output_section->vma |
| 68 | + htab->elf.hgot->root.u.def.section->output_offset); |
| 69 | /* Our ABI requires the GOT pointer to point at the very beginning |
| 70 | of the global offset table. */ |
| 71 | BFD_ASSERT (got_pointer |
| 72 | <= (htab->elf.sgot->output_section->vma |
| 73 | + htab->elf.sgot->output_offset)); |
| 74 | BFD_ASSERT (got_pointer |
| 75 | <= (htab->elf.sgotplt->output_section->vma |
| 76 | + htab->elf.sgotplt->output_offset)); |
| 77 | |
| 78 | return got_pointer; |
| 79 | } |
| 80 | |
| 81 | |
| 82 | /* Return the offset of the .got versus _GLOBAL_OFFSET_TABLE_. */ |
| 83 | |
| 84 | static inline bfd_vma |
| 85 | s390_got_offset (struct bfd_link_info *info) |
| 86 | { |
| 87 | struct elf_s390_link_hash_table *htab = elf_s390_hash_table (info); |
| 88 | |
| 89 | /* The absolute address of the .got in the target image. */ |
| 90 | bfd_vma got_address = (htab->elf.sgot->output_section->vma |
| 91 | + htab->elf.sgot->output_offset); |
| 92 | |
| 93 | /* GOT offset must not be negative. */ |
| 94 | BFD_ASSERT (s390_got_pointer (info) <= got_address); |
| 95 | return got_address - s390_got_pointer (info); |
| 96 | } |
| 97 | |
| 98 | /* Return the offset of the .got.plt versus _GLOBAL_OFFSET_TABLE_. */ |
| 99 | |
| 100 | static inline bfd_vma |
| 101 | s390_gotplt_offset (struct bfd_link_info *info) |
| 102 | { |
| 103 | struct elf_s390_link_hash_table *htab = elf_s390_hash_table (info); |
| 104 | |
| 105 | /* The absolute address of the .got.plt in the target image. */ |
| 106 | bfd_vma gotplt_address = (htab->elf.sgotplt->output_section->vma |
| 107 | + htab->elf.sgotplt->output_offset); |
| 108 | |
| 109 | /* GOT offset must not be negative. */ |
| 110 | BFD_ASSERT (s390_got_pointer (info) <= gotplt_address); |
| 111 | return gotplt_address - s390_got_pointer (info); |
| 112 | } |
| 113 | |
| 114 | /* Create sections needed by STT_GNU_IFUNC symbol. */ |
| 115 | |
| 116 | static bfd_boolean |
| 117 | s390_elf_create_ifunc_sections (bfd *abfd, struct bfd_link_info *info) |
| 118 | { |
| 119 | flagword flags; |
| 120 | asection *s; |
| 121 | const struct elf_backend_data *bed = get_elf_backend_data (abfd); |
| 122 | struct elf_link_hash_table *htab = elf_hash_table (info); |
| 123 | |
| 124 | if (htab->iplt != NULL) |
| 125 | return TRUE; |
| 126 | |
| 127 | flags = bed->dynamic_sec_flags; |
| 128 | |
| 129 | if (bfd_link_pic (info)) |
| 130 | { |
| 131 | s = bfd_make_section_with_flags (abfd, ".rela.ifunc", |
| 132 | flags | SEC_READONLY); |
| 133 | if (s == NULL |
| 134 | || !bfd_set_section_alignment (s, bed->s->log_file_align)) |
| 135 | return FALSE; |
| 136 | htab->irelifunc = s; |
| 137 | } |
| 138 | |
| 139 | /* Create .iplt, .rel[a].iplt, and .igot.plt. */ |
| 140 | s = bfd_make_section_with_flags (abfd, ".iplt", |
| 141 | flags | SEC_CODE | SEC_READONLY); |
| 142 | if (s == NULL |
| 143 | || !bfd_set_section_alignment (s, bed->plt_alignment)) |
| 144 | return FALSE; |
| 145 | htab->iplt = s; |
| 146 | |
| 147 | s = bfd_make_section_with_flags (abfd, ".rela.iplt", flags | SEC_READONLY); |
| 148 | if (s == NULL |
| 149 | || !bfd_set_section_alignment (s, bed->s->log_file_align)) |
| 150 | return FALSE; |
| 151 | htab->irelplt = s; |
| 152 | |
| 153 | s = bfd_make_section_with_flags (abfd, ".igot.plt", flags); |
| 154 | if (s == NULL |
| 155 | || !bfd_set_section_alignment (s, bed->s->log_file_align)) |
| 156 | return FALSE; |
| 157 | htab->igotplt = s; |
| 158 | |
| 159 | return TRUE; |
| 160 | } |
| 161 | |
| 162 | |
| 163 | /* Allocate space in .plt, .got and associated reloc sections for |
| 164 | dynamic relocs against a STT_GNU_IFUNC symbol definition. */ |
| 165 | |
| 166 | static bfd_boolean |
| 167 | s390_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info, |
| 168 | struct elf_link_hash_entry *h) |
| 169 | { |
| 170 | struct elf_dyn_relocs *p; |
| 171 | struct elf_link_hash_table *htab; |
| 172 | struct elf_s390_link_hash_entry *eh = (struct elf_s390_link_hash_entry*)h; |
| 173 | struct elf_dyn_relocs **head = &eh->dyn_relocs; |
| 174 | |
| 175 | htab = elf_hash_table (info); |
| 176 | eh->ifunc_resolver_address = h->root.u.def.value; |
| 177 | eh->ifunc_resolver_section = h->root.u.def.section; |
| 178 | |
| 179 | /* Support garbage collection against STT_GNU_IFUNC symbols. */ |
| 180 | if (h->plt.refcount <= 0 && h->got.refcount <= 0) |
| 181 | { |
| 182 | /* When building shared library, we need to handle the case |
| 183 | where it is marked with regular reference, but not non-GOT |
| 184 | reference. It may happen if we didn't see STT_GNU_IFUNC |
| 185 | symbol at the time when checking relocations. */ |
| 186 | if (bfd_link_pic (info) |
| 187 | && !h->non_got_ref |
| 188 | && h->ref_regular) |
| 189 | for (p = *head; p != NULL; p = p->next) |
| 190 | if (p->count) |
| 191 | { |
| 192 | h->non_got_ref = 1; |
| 193 | goto keep; |
| 194 | } |
| 195 | |
| 196 | h->got = htab->init_got_offset; |
| 197 | h->plt = htab->init_plt_offset; |
| 198 | *head = NULL; |
| 199 | return TRUE; |
| 200 | } |
| 201 | |
| 202 | /* Return and discard space for dynamic relocations against it if |
| 203 | it is never referenced in a non-shared object. */ |
| 204 | if (!h->ref_regular) |
| 205 | { |
| 206 | if (h->plt.refcount > 0 |
| 207 | || h->got.refcount > 0) |
| 208 | abort (); |
| 209 | h->got = htab->init_got_offset; |
| 210 | h->plt = htab->init_plt_offset; |
| 211 | *head = NULL; |
| 212 | return TRUE; |
| 213 | } |
| 214 | |
| 215 | keep: |
| 216 | /* Without checking h->plt.refcount here we allocate a PLT slot. |
| 217 | When setting plt.refcount in check_relocs it might not have been |
| 218 | known that this will be an IFUNC symol. */ |
| 219 | h->plt.offset = htab->iplt->size; |
| 220 | h->needs_plt = 1; |
| 221 | htab->iplt->size += PLT_ENTRY_SIZE; |
| 222 | htab->igotplt->size += GOT_ENTRY_SIZE; |
| 223 | htab->irelplt->size += RELA_ENTRY_SIZE; |
| 224 | htab->irelplt->reloc_count++; |
| 225 | |
| 226 | /* In order to make pointer equality work with IFUNC symbols defined |
| 227 | in a non-PIE executable and referenced in a shared lib, we turn |
| 228 | the symbol into a STT_FUNC symbol and make the symbol value to |
| 229 | point to the IPLT slot. That way the referencing shared lib will |
| 230 | always get the PLT slot address when resolving the respective |
| 231 | R_390_GLOB_DAT/R_390_64 relocs on that symbol. */ |
| 232 | if (bfd_link_pde (info) |
| 233 | && h->def_regular |
| 234 | && h->ref_dynamic) |
| 235 | { |
| 236 | h->root.u.def.section = htab->iplt; |
| 237 | h->root.u.def.value = h->plt.offset; |
| 238 | h->size = PLT_ENTRY_SIZE; |
| 239 | h->type = STT_FUNC; |
| 240 | } |
| 241 | |
| 242 | if (!bfd_link_pic (info)) |
| 243 | *head = NULL; |
| 244 | |
| 245 | /* Finally, allocate space. */ |
| 246 | p = *head; |
| 247 | if (p != NULL) |
| 248 | { |
| 249 | bfd_size_type count = 0; |
| 250 | do |
| 251 | { |
| 252 | count += p->count; |
| 253 | p = p->next; |
| 254 | } |
| 255 | while (p != NULL); |
| 256 | htab->irelifunc->size += count * RELA_ENTRY_SIZE; |
| 257 | } |
| 258 | |
| 259 | /* Decide whether the got.iplt slot can be used. This has to be |
| 260 | avoided if the values in the GOT slots could differ for pointer |
| 261 | equality reasons. */ |
| 262 | if (h->got.refcount <= 0 |
| 263 | || (bfd_link_pic (info) |
| 264 | && (h->dynindx == -1 || h->forced_local)) |
| 265 | || bfd_link_pie (info) |
| 266 | || htab->sgot == NULL) |
| 267 | { |
| 268 | /* Use .got.iplt. */ |
| 269 | h->got.offset = (bfd_vma) -1; |
| 270 | } |
| 271 | else |
| 272 | { |
| 273 | h->got.offset = htab->sgot->size; |
| 274 | htab->sgot->size += GOT_ENTRY_SIZE; |
| 275 | if (bfd_link_pic (info)) |
| 276 | htab->srelgot->size += RELA_ENTRY_SIZE; |
| 277 | } |
| 278 | |
| 279 | return TRUE; |
| 280 | } |
| 281 | |
| 282 | static bfd_boolean |
| 283 | elf_s390_allocate_local_syminfo (bfd *abfd, Elf_Internal_Shdr *symtab_hdr) |
| 284 | { |
| 285 | bfd_size_type size; |
| 286 | |
| 287 | size = symtab_hdr->sh_info; |
| 288 | size *= (sizeof (bfd_signed_vma) /* local got */ |
| 289 | + sizeof (struct plt_entry) /* local plt */ |
| 290 | + sizeof(char)); /* local tls type */ |
| 291 | elf_local_got_refcounts (abfd) = ((bfd_signed_vma *) |
| 292 | bfd_zalloc (abfd, size)); |
| 293 | if (elf_local_got_refcounts (abfd) == NULL) |
| 294 | return FALSE; |
| 295 | elf_s390_local_plt (abfd) |
| 296 | = (struct plt_entry*)(elf_local_got_refcounts (abfd) |
| 297 | + symtab_hdr->sh_info); |
| 298 | elf_s390_local_got_tls_type (abfd) |
| 299 | = (char *) (elf_s390_local_plt (abfd) + symtab_hdr->sh_info); |
| 300 | |
| 301 | return TRUE; |
| 302 | } |
| 303 | |
| 304 | /* Whether to sort relocs output by ld -r or ld --emit-relocs, by |
| 305 | r_offset. Don't do so for code sections. We want to keep ordering |
| 306 | of GDCALL / PLT32DBL for TLS optimizations as is. On the other |
| 307 | hand, elf-eh-frame.c processing requires .eh_frame relocs to be |
| 308 | sorted. */ |
| 309 | |
| 310 | static bfd_boolean |
| 311 | elf_s390_elf_sort_relocs_p (asection *sec) |
| 312 | { |
| 313 | return (sec->flags & SEC_CODE) == 0; |
| 314 | } |
| 315 | |
| 316 | /* Merge object attributes from IBFD into OBFD. Raise an error if |
| 317 | there are conflicting attributes. */ |
| 318 | static bfd_boolean |
| 319 | elf_s390_merge_obj_attributes (bfd *ibfd, struct bfd_link_info *info) |
| 320 | { |
| 321 | bfd *obfd = info->output_bfd; |
| 322 | obj_attribute *in_attr, *in_attrs; |
| 323 | obj_attribute *out_attr, *out_attrs; |
| 324 | |
| 325 | if (!elf_known_obj_attributes_proc (obfd)[0].i) |
| 326 | { |
| 327 | /* This is the first object. Copy the attributes. */ |
| 328 | _bfd_elf_copy_obj_attributes (ibfd, obfd); |
| 329 | |
| 330 | /* Use the Tag_null value to indicate the attributes have been |
| 331 | initialized. */ |
| 332 | elf_known_obj_attributes_proc (obfd)[0].i = 1; |
| 333 | |
| 334 | return TRUE; |
| 335 | } |
| 336 | |
| 337 | in_attrs = elf_known_obj_attributes (ibfd)[OBJ_ATTR_GNU]; |
| 338 | out_attrs = elf_known_obj_attributes (obfd)[OBJ_ATTR_GNU]; |
| 339 | |
| 340 | /* Check for conflicting Tag_GNU_S390_ABI_Vector attributes and |
| 341 | merge non-conflicting ones. */ |
| 342 | in_attr = &in_attrs[Tag_GNU_S390_ABI_Vector]; |
| 343 | out_attr = &out_attrs[Tag_GNU_S390_ABI_Vector]; |
| 344 | |
| 345 | if (in_attr->i > 2) |
| 346 | _bfd_error_handler |
| 347 | /* xgettext:c-format */ |
| 348 | (_("warning: %pB uses unknown vector ABI %d"), ibfd, |
| 349 | in_attr->i); |
| 350 | else if (out_attr->i > 2) |
| 351 | _bfd_error_handler |
| 352 | /* xgettext:c-format */ |
| 353 | (_("warning: %pB uses unknown vector ABI %d"), obfd, |
| 354 | out_attr->i); |
| 355 | else if (in_attr->i != out_attr->i) |
| 356 | { |
| 357 | out_attr->type = ATTR_TYPE_FLAG_INT_VAL; |
| 358 | |
| 359 | if (in_attr->i && out_attr->i) |
| 360 | { |
| 361 | const char abi_str[3][9] = { "none", "software", "hardware" }; |
| 362 | |
| 363 | _bfd_error_handler |
| 364 | /* xgettext:c-format */ |
| 365 | (_("warning: %pB uses vector %s ABI, %pB uses %s ABI"), |
| 366 | ibfd, abi_str[in_attr->i], obfd, abi_str[out_attr->i]); |
| 367 | } |
| 368 | if (in_attr->i > out_attr->i) |
| 369 | out_attr->i = in_attr->i; |
| 370 | } |
| 371 | |
| 372 | /* Merge Tag_compatibility attributes and any common GNU ones. */ |
| 373 | _bfd_elf_merge_object_attributes (ibfd, info); |
| 374 | |
| 375 | return TRUE; |
| 376 | } |