1/* IBM S/390-specific support for ELF 32 and 64 bit functions 2 Copyright (C) 2000-2020 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. */ 26static inline bfd_boolean 27s390_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 35static inline bfd_boolean 36s390_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 59static inline bfd_vma 60s390_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 84static inline bfd_vma 85s390_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 100static inline bfd_vma 101s390_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 116static bfd_boolean 117s390_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 166static bfd_boolean 167s390_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 215keep: 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 282static bfd_boolean 283elf_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 310static bfd_boolean 311elf_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. */ 318static bfd_boolean 319elf_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} 377