1 // arm.cc -- arm target support for gold.
3 // Copyright 2009 Free Software Foundation, Inc.
4 // Written by Doug Kwan <dougkwan@google.com> based on the i386 code
5 // by Ian Lance Taylor <iant@google.com>.
7 // This file is part of gold.
9 // This program is free software; you can redistribute it and/or modify
10 // it under the terms of the GNU General Public License as published by
11 // the Free Software Foundation; either version 3 of the License, or
12 // (at your option) any later version.
14 // This program is distributed in the hope that it will be useful,
15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 // GNU General Public License for more details.
19 // You should have received a copy of the GNU General Public License
20 // along with this program; if not, write to the Free Software
21 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
22 // MA 02110-1301, USA.
32 #include "parameters.h"
39 #include "copy-relocs.h"
41 #include "target-reloc.h"
42 #include "target-select.h"
51 template<bool big_endian>
52 class Output_data_plt_arm;
54 // The arm target class.
56 // This is a very simple port of gold for ARM-EABI. It is intended for
57 // supporting Android only for the time being. Only these relocation types
78 // - Generate various branch stubs.
79 // - Support interworking.
80 // - Define section symbols __exidx_start and __exidx_stop.
81 // - Support more relocation types as needed.
82 // - Make PLTs more flexible for different architecture features like
84 // There are probably a lot more.
86 // Utilities for manipulating integers of up to 32-bits
90 // Sign extend an n-bit unsigned integer stored in an uint32_t into
91 // an int32_t. NO_BITS must be between 1 to 32.
94 sign_extend(uint32_t bits)
96 gold_assert(no_bits >= 0 && no_bits <= 32);
98 return static_cast<int32_t>(bits);
99 uint32_t mask = (~((uint32_t) 0)) >> (32 - no_bits);
101 uint32_t top_bit = 1U << (no_bits - 1);
102 int32_t as_signed = static_cast<int32_t>(bits);
103 return (bits & top_bit) ? as_signed + (-top_bit * 2) : as_signed;
106 // Detects overflow of an NO_BITS integer stored in a uint32_t.
107 template<int no_bits>
109 has_overflow(uint32_t bits)
111 gold_assert(no_bits >= 0 && no_bits <= 32);
114 int32_t max = (1 << (no_bits - 1)) - 1;
115 int32_t min = -(1 << (no_bits - 1));
116 int32_t as_signed = static_cast<int32_t>(bits);
117 return as_signed > max || as_signed < min;
120 // Detects overflow of an NO_BITS integer stored in a uint32_t when it
121 // fits in the given number of bits as either a signed or unsigned value.
122 // For example, has_signed_unsigned_overflow<8> would check
123 // -128 <= bits <= 255
124 template<int no_bits>
126 has_signed_unsigned_overflow(uint32_t bits)
128 gold_assert(no_bits >= 2 && no_bits <= 32);
131 int32_t max = static_cast<int32_t>((1U << no_bits) - 1);
132 int32_t min = -(1 << (no_bits - 1));
133 int32_t as_signed = static_cast<int32_t>(bits);
134 return as_signed > max || as_signed < min;
137 // Select bits from A and B using bits in MASK. For each n in [0..31],
138 // the n-th bit in the result is chosen from the n-th bits of A and B.
139 // A zero selects A and a one selects B.
140 static inline uint32_t
141 bit_select(uint32_t a, uint32_t b, uint32_t mask)
142 { return (a & ~mask) | (b & mask); }
145 template<bool big_endian>
146 class Target_arm : public Sized_target<32, big_endian>
149 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, big_endian>
153 : Sized_target<32, big_endian>(&arm_info),
154 got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
155 copy_relocs_(elfcpp::R_ARM_COPY), dynbss_(NULL)
158 // Process the relocations to determine unreferenced sections for
159 // garbage collection.
161 gc_process_relocs(const General_options& options,
162 Symbol_table* symtab,
164 Sized_relobj<32, big_endian>* object,
165 unsigned int data_shndx,
166 unsigned int sh_type,
167 const unsigned char* prelocs,
169 Output_section* output_section,
170 bool needs_special_offset_handling,
171 size_t local_symbol_count,
172 const unsigned char* plocal_symbols);
174 // Scan the relocations to look for symbol adjustments.
176 scan_relocs(const General_options& options,
177 Symbol_table* symtab,
179 Sized_relobj<32, big_endian>* object,
180 unsigned int data_shndx,
181 unsigned int sh_type,
182 const unsigned char* prelocs,
184 Output_section* output_section,
185 bool needs_special_offset_handling,
186 size_t local_symbol_count,
187 const unsigned char* plocal_symbols);
189 // Finalize the sections.
191 do_finalize_sections(Layout*);
193 // Return the value to use for a dynamic symbol which requires special
196 do_dynsym_value(const Symbol*) const;
198 // Relocate a section.
200 relocate_section(const Relocate_info<32, big_endian>*,
201 unsigned int sh_type,
202 const unsigned char* prelocs,
204 Output_section* output_section,
205 bool needs_special_offset_handling,
207 elfcpp::Elf_types<32>::Elf_Addr view_address,
208 section_size_type view_size,
209 const Reloc_symbol_changes*);
211 // Scan the relocs during a relocatable link.
213 scan_relocatable_relocs(const General_options& options,
214 Symbol_table* symtab,
216 Sized_relobj<32, big_endian>* object,
217 unsigned int data_shndx,
218 unsigned int sh_type,
219 const unsigned char* prelocs,
221 Output_section* output_section,
222 bool needs_special_offset_handling,
223 size_t local_symbol_count,
224 const unsigned char* plocal_symbols,
225 Relocatable_relocs*);
227 // Relocate a section during a relocatable link.
229 relocate_for_relocatable(const Relocate_info<32, big_endian>*,
230 unsigned int sh_type,
231 const unsigned char* prelocs,
233 Output_section* output_section,
234 off_t offset_in_output_section,
235 const Relocatable_relocs*,
237 elfcpp::Elf_types<32>::Elf_Addr view_address,
238 section_size_type view_size,
239 unsigned char* reloc_view,
240 section_size_type reloc_view_size);
242 // Return whether SYM is defined by the ABI.
244 do_is_defined_by_abi(Symbol* sym) const
245 { return strcmp(sym->name(), "__tls_get_addr") == 0; }
247 // Return the size of the GOT section.
251 gold_assert(this->got_ != NULL);
252 return this->got_->data_size();
255 // Map platform-specific reloc types
257 get_real_reloc_type (unsigned int r_type);
260 // The class which scans relocations.
265 : issued_non_pic_error_(false)
269 local(const General_options& options, Symbol_table* symtab,
270 Layout* layout, Target_arm* target,
271 Sized_relobj<32, big_endian>* object,
272 unsigned int data_shndx,
273 Output_section* output_section,
274 const elfcpp::Rel<32, big_endian>& reloc, unsigned int r_type,
275 const elfcpp::Sym<32, big_endian>& lsym);
278 global(const General_options& options, Symbol_table* symtab,
279 Layout* layout, Target_arm* target,
280 Sized_relobj<32, big_endian>* object,
281 unsigned int data_shndx,
282 Output_section* output_section,
283 const elfcpp::Rel<32, big_endian>& reloc, unsigned int r_type,
288 unsupported_reloc_local(Sized_relobj<32, big_endian>*,
289 unsigned int r_type);
292 unsupported_reloc_global(Sized_relobj<32, big_endian>*,
293 unsigned int r_type, Symbol*);
296 check_non_pic(Relobj*, unsigned int r_type);
298 // Almost identical to Symbol::needs_plt_entry except that it also
299 // handles STT_ARM_TFUNC.
301 symbol_needs_plt_entry(const Symbol* sym)
303 // An undefined symbol from an executable does not need a PLT entry.
304 if (sym->is_undefined() && !parameters->options().shared())
307 return (!parameters->doing_static_link()
308 && (sym->type() == elfcpp::STT_FUNC
309 || sym->type() == elfcpp::STT_ARM_TFUNC)
310 && (sym->is_from_dynobj()
311 || sym->is_undefined()
312 || sym->is_preemptible()));
315 // Whether we have issued an error about a non-PIC compilation.
316 bool issued_non_pic_error_;
319 // The class which implements relocation.
329 // Return whether the static relocation needs to be applied.
331 should_apply_static_reloc(const Sized_symbol<32>* gsym,
334 Output_section* output_section);
336 // Do a relocation. Return false if the caller should not issue
337 // any warnings about this relocation.
339 relocate(const Relocate_info<32, big_endian>*, Target_arm*,
340 Output_section*, size_t relnum,
341 const elfcpp::Rel<32, big_endian>&,
342 unsigned int r_type, const Sized_symbol<32>*,
343 const Symbol_value<32>*,
344 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
347 // Return whether we want to pass flag NON_PIC_REF for this
350 reloc_is_non_pic (unsigned int r_type)
354 case elfcpp::R_ARM_REL32:
355 case elfcpp::R_ARM_THM_CALL:
356 case elfcpp::R_ARM_CALL:
357 case elfcpp::R_ARM_JUMP24:
358 case elfcpp::R_ARM_PREL31:
366 // A class which returns the size required for a relocation type,
367 // used while scanning relocs during a relocatable link.
368 class Relocatable_size_for_reloc
372 get_size_for_reloc(unsigned int, Relobj*);
375 // Get the GOT section, creating it if necessary.
376 Output_data_got<32, big_endian>*
377 got_section(Symbol_table*, Layout*);
379 // Get the GOT PLT section.
381 got_plt_section() const
383 gold_assert(this->got_plt_ != NULL);
384 return this->got_plt_;
387 // Create a PLT entry for a global symbol.
389 make_plt_entry(Symbol_table*, Layout*, Symbol*);
391 // Get the PLT section.
392 const Output_data_plt_arm<big_endian>*
395 gold_assert(this->plt_ != NULL);
399 // Get the dynamic reloc section, creating it if necessary.
401 rel_dyn_section(Layout*);
403 // Return true if the symbol may need a COPY relocation.
404 // References from an executable object to non-function symbols
405 // defined in a dynamic object may need a COPY relocation.
407 may_need_copy_reloc(Symbol* gsym)
409 return (gsym->type() != elfcpp::STT_ARM_TFUNC
410 && gsym->may_need_copy_reloc());
413 // Add a potential copy relocation.
415 copy_reloc(Symbol_table* symtab, Layout* layout,
416 Sized_relobj<32, big_endian>* object,
417 unsigned int shndx, Output_section* output_section,
418 Symbol* sym, const elfcpp::Rel<32, big_endian>& reloc)
420 this->copy_relocs_.copy_reloc(symtab, layout,
421 symtab->get_sized_symbol<32>(sym),
422 object, shndx, output_section, reloc,
423 this->rel_dyn_section(layout));
426 // Information about this specific target which we pass to the
427 // general Target structure.
428 static const Target::Target_info arm_info;
430 // The types of GOT entries needed for this platform.
433 GOT_TYPE_STANDARD = 0 // GOT entry for a regular symbol
437 Output_data_got<32, big_endian>* got_;
439 Output_data_plt_arm<big_endian>* plt_;
440 // The GOT PLT section.
441 Output_data_space* got_plt_;
442 // The dynamic reloc section.
443 Reloc_section* rel_dyn_;
444 // Relocs saved to avoid a COPY reloc.
445 Copy_relocs<elfcpp::SHT_REL, 32, big_endian> copy_relocs_;
446 // Space for variables copied with a COPY reloc.
447 Output_data_space* dynbss_;
450 template<bool big_endian>
451 const Target::Target_info Target_arm<big_endian>::arm_info =
454 big_endian, // is_big_endian
455 elfcpp::EM_ARM, // machine_code
456 false, // has_make_symbol
457 false, // has_resolve
458 false, // has_code_fill
459 true, // is_default_stack_executable
461 "/usr/lib/libc.so.1", // dynamic_linker
462 0x8000, // default_text_segment_address
463 0x1000, // abi_pagesize (overridable by -z max-page-size)
464 0x1000, // common_pagesize (overridable by -z common-page-size)
465 elfcpp::SHN_UNDEF, // small_common_shndx
466 elfcpp::SHN_UNDEF, // large_common_shndx
467 0, // small_common_section_flags
468 0 // large_common_section_flags
471 // Arm relocate functions class
474 template<bool big_endian>
475 class Arm_relocate_functions : public Relocate_functions<32, big_endian>
480 STATUS_OKAY, // No error during relocation.
481 STATUS_OVERFLOW, // Relocation oveflow.
482 STATUS_BAD_RELOC // Relocation cannot be applied.
486 typedef Relocate_functions<32, big_endian> Base;
487 typedef Arm_relocate_functions<big_endian> This;
489 // Get an symbol value of *PSYMVAL with an ADDEND. This is a wrapper
490 // to Symbol_value::value(). If HAS_THUMB_BIT is true, that LSB is used
491 // to distinguish ARM and THUMB functions and it is treated specially.
492 static inline Symbol_value<32>::Value
493 arm_symbol_value (const Sized_relobj<32, big_endian> *object,
494 const Symbol_value<32>* psymval,
495 Symbol_value<32>::Value addend,
498 typedef Symbol_value<32>::Value Valtype;
502 Valtype raw = psymval->value(object, 0);
503 Valtype thumb_bit = raw & 1;
504 return ((raw & ~((Valtype) 1)) + addend) | thumb_bit;
507 return psymval->value(object, addend);
510 // FIXME: This probably only works for Android on ARM v5te. We should
511 // following GNU ld for the general case.
512 template<unsigned r_type>
513 static inline typename This::Status
514 arm_branch_common(unsigned char *view,
515 const Sized_relobj<32, big_endian>* object,
516 const Symbol_value<32>* psymval,
517 elfcpp::Elf_types<32>::Elf_Addr address,
520 typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
521 Valtype* wv = reinterpret_cast<Valtype*>(view);
522 Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
524 bool insn_is_b = (((val >> 28) & 0xf) <= 0xe)
525 && ((val & 0x0f000000UL) == 0x0a000000UL);
526 bool insn_is_uncond_bl = (val & 0xff000000UL) == 0xeb000000UL;
527 bool insn_is_cond_bl = (((val >> 28) & 0xf) < 0xe)
528 && ((val & 0x0f000000UL) == 0x0b000000UL);
529 bool insn_is_blx = (val & 0xfe000000UL) == 0xfa000000UL;
530 bool insn_is_any_branch = (val & 0x0e000000UL) == 0x0a000000UL;
532 if (r_type == elfcpp::R_ARM_CALL)
534 if (!insn_is_uncond_bl && !insn_is_blx)
535 return This::STATUS_BAD_RELOC;
537 else if (r_type == elfcpp::R_ARM_JUMP24)
539 if (!insn_is_b && !insn_is_cond_bl)
540 return This::STATUS_BAD_RELOC;
542 else if (r_type == elfcpp::R_ARM_PLT32)
544 if (!insn_is_any_branch)
545 return This::STATUS_BAD_RELOC;
550 Valtype addend = utils::sign_extend<26>(val << 2);
551 Valtype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
554 // If target has thumb bit set, we need to either turn the BL
555 // into a BLX (for ARMv5 or above) or generate a stub.
559 if (insn_is_uncond_bl)
560 val = (val & 0xffffff) | 0xfa000000 | ((x & 2) << 23);
562 return This::STATUS_BAD_RELOC;
565 gold_assert(!insn_is_blx);
567 val = utils::bit_select(val, (x >> 2), 0xffffffUL);
568 elfcpp::Swap<32, big_endian>::writeval(wv, val);
569 return (utils::has_overflow<26>(x)
570 ? This::STATUS_OVERFLOW : This::STATUS_OKAY);
576 static inline typename This::Status
577 abs8(unsigned char *view,
578 const Sized_relobj<32, big_endian>* object,
579 const Symbol_value<32>* psymval, bool has_thumb_bit)
581 typedef typename elfcpp::Swap<8, big_endian>::Valtype Valtype;
582 typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
583 Valtype* wv = reinterpret_cast<Valtype*>(view);
584 Valtype val = elfcpp::Swap<8, big_endian>::readval(wv);
585 Reltype addend = utils::sign_extend<8>(val);
586 Reltype x = This::arm_symbol_value(object, psymval, addend, has_thumb_bit);
587 val = utils::bit_select(val, x, 0xffU);
588 elfcpp::Swap<8, big_endian>::writeval(wv, val);
589 return (utils::has_signed_unsigned_overflow<8>(x)
590 ? This::STATUS_OVERFLOW
591 : This::STATUS_OKAY);
594 // R_ARM_ABS32: (S + A) | T
595 static inline typename This::Status
596 abs32(unsigned char *view,
597 const Sized_relobj<32, big_endian>* object,
598 const Symbol_value<32>* psymval,
601 typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
602 Valtype* wv = reinterpret_cast<Valtype*>(view);
603 Valtype addend = elfcpp::Swap<32, big_endian>::readval(wv);
604 Valtype x = This::arm_symbol_value(object, psymval, addend, has_thumb_bit);
605 elfcpp::Swap<32, big_endian>::writeval(wv, x);
606 return This::STATUS_OKAY;
609 // R_ARM_REL32: (S + A) | T - P
610 static inline typename This::Status
611 rel32(unsigned char *view,
612 const Sized_relobj<32, big_endian>* object,
613 const Symbol_value<32>* psymval,
614 elfcpp::Elf_types<32>::Elf_Addr address,
617 typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
618 Valtype* wv = reinterpret_cast<Valtype*>(view);
619 Valtype addend = elfcpp::Swap<32, big_endian>::readval(wv);
620 Valtype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
622 elfcpp::Swap<32, big_endian>::writeval(wv, x);
623 return This::STATUS_OKAY;
626 // R_ARM_THM_CALL: (S + A) | T - P
627 static inline typename This::Status
628 thm_call(unsigned char *view,
629 const Sized_relobj<32, big_endian>* object,
630 const Symbol_value<32>* psymval,
631 elfcpp::Elf_types<32>::Elf_Addr address,
634 // A thumb call consists of two instructions.
635 typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
636 typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
637 Valtype* wv = reinterpret_cast<Valtype*>(view);
638 Valtype hi = elfcpp::Swap<16, big_endian>::readval(wv);
639 Valtype lo = elfcpp::Swap<16, big_endian>::readval(wv + 1);
640 // Must be a BL instruction. lo == 11111xxxxxxxxxxx.
641 gold_assert((lo & 0xf800) == 0xf800);
642 Reltype addend = utils::sign_extend<23>(((hi & 0x7ff) << 12)
643 | ((lo & 0x7ff) << 1));
644 Reltype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
647 // If target has no thumb bit set, we need to either turn the BL
648 // into a BLX (for ARMv5 or above) or generate a stub.
651 // This only works for ARMv5 and above with interworking enabled.
654 hi = utils::bit_select(hi, (x >> 12), 0x7ffU);
655 lo = utils::bit_select(lo, (x >> 1), 0x7ffU);
656 elfcpp::Swap<16, big_endian>::writeval(wv, hi);
657 elfcpp::Swap<16, big_endian>::writeval(wv + 1, lo);
658 return (utils::has_overflow<23>(x)
659 ? This::STATUS_OVERFLOW
660 : This::STATUS_OKAY);
663 // R_ARM_BASE_PREL: B(S) + A - P
664 static inline typename This::Status
665 base_prel(unsigned char* view,
666 elfcpp::Elf_types<32>::Elf_Addr origin,
667 elfcpp::Elf_types<32>::Elf_Addr address)
669 Base::rel32(view, origin - address);
673 // R_ARM_GOT_BREL: GOT(S) + A - GOT_ORG
674 static inline typename This::Status
675 got_brel(unsigned char* view,
676 typename elfcpp::Swap<32, big_endian>::Valtype got_offset)
678 Base::rel32(view, got_offset);
679 return This::STATUS_OKAY;
682 // R_ARM_PLT32: (S + A) | T - P
683 static inline typename This::Status
684 plt32(unsigned char *view,
685 const Sized_relobj<32, big_endian>* object,
686 const Symbol_value<32>* psymval,
687 elfcpp::Elf_types<32>::Elf_Addr address,
690 return arm_branch_common<elfcpp::R_ARM_PLT32>(view, object, psymval,
691 address, has_thumb_bit);
694 // R_ARM_CALL: (S + A) | T - P
695 static inline typename This::Status
696 call(unsigned char *view,
697 const Sized_relobj<32, big_endian>* object,
698 const Symbol_value<32>* psymval,
699 elfcpp::Elf_types<32>::Elf_Addr address,
702 return arm_branch_common<elfcpp::R_ARM_CALL>(view, object, psymval,
703 address, has_thumb_bit);
706 // R_ARM_JUMP24: (S + A) | T - P
707 static inline typename This::Status
708 jump24(unsigned char *view,
709 const Sized_relobj<32, big_endian>* object,
710 const Symbol_value<32>* psymval,
711 elfcpp::Elf_types<32>::Elf_Addr address,
714 return arm_branch_common<elfcpp::R_ARM_JUMP24>(view, object, psymval,
715 address, has_thumb_bit);
718 // R_ARM_PREL: (S + A) | T - P
719 static inline typename This::Status
720 prel31(unsigned char *view,
721 const Sized_relobj<32, big_endian>* object,
722 const Symbol_value<32>* psymval,
723 elfcpp::Elf_types<32>::Elf_Addr address,
726 typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
727 Valtype* wv = reinterpret_cast<Valtype*>(view);
728 Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
729 Valtype addend = utils::sign_extend<31>(val);
730 Valtype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
732 val = utils::bit_select(val, x, 0x7fffffffU);
733 elfcpp::Swap<32, big_endian>::writeval(wv, val);
734 return (utils::has_overflow<31>(x) ?
735 This::STATUS_OVERFLOW : This::STATUS_OKAY);
739 // Get the GOT section, creating it if necessary.
741 template<bool big_endian>
742 Output_data_got<32, big_endian>*
743 Target_arm<big_endian>::got_section(Symbol_table* symtab, Layout* layout)
745 if (this->got_ == NULL)
747 gold_assert(symtab != NULL && layout != NULL);
749 this->got_ = new Output_data_got<32, big_endian>();
752 os = layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
754 | elfcpp::SHF_WRITE),
758 // The old GNU linker creates a .got.plt section. We just
759 // create another set of data in the .got section. Note that we
760 // always create a PLT if we create a GOT, although the PLT
762 this->got_plt_ = new Output_data_space(4, "** GOT PLT");
763 os = layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
765 | elfcpp::SHF_WRITE),
769 // The first three entries are reserved.
770 this->got_plt_->set_current_data_size(3 * 4);
772 // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
773 symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL,
775 0, 0, elfcpp::STT_OBJECT,
777 elfcpp::STV_HIDDEN, 0,
783 // Get the dynamic reloc section, creating it if necessary.
785 template<bool big_endian>
786 typename Target_arm<big_endian>::Reloc_section*
787 Target_arm<big_endian>::rel_dyn_section(Layout* layout)
789 if (this->rel_dyn_ == NULL)
791 gold_assert(layout != NULL);
792 this->rel_dyn_ = new Reloc_section(parameters->options().combreloc());
793 layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
794 elfcpp::SHF_ALLOC, this->rel_dyn_);
796 return this->rel_dyn_;
799 // A class to handle the PLT data.
801 template<bool big_endian>
802 class Output_data_plt_arm : public Output_section_data
805 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, big_endian>
808 Output_data_plt_arm(Layout*, Output_data_space*);
810 // Add an entry to the PLT.
812 add_entry(Symbol* gsym);
814 // Return the .rel.plt section data.
817 { return this->rel_; }
821 do_adjust_output_section(Output_section* os);
823 // Write to a map file.
825 do_print_to_mapfile(Mapfile* mapfile) const
826 { mapfile->print_output_data(this, _("** PLT")); }
829 // Template for the first PLT entry.
830 static const uint32_t first_plt_entry[5];
832 // Template for subsequent PLT entries.
833 static const uint32_t plt_entry[3];
835 // Set the final size.
837 set_final_data_size()
839 this->set_data_size(sizeof(first_plt_entry)
840 + this->count_ * sizeof(plt_entry));
843 // Write out the PLT data.
845 do_write(Output_file*);
847 // The reloc section.
849 // The .got.plt section.
850 Output_data_space* got_plt_;
851 // The number of PLT entries.
855 // Create the PLT section. The ordinary .got section is an argument,
856 // since we need to refer to the start. We also create our own .got
857 // section just for PLT entries.
859 template<bool big_endian>
860 Output_data_plt_arm<big_endian>::Output_data_plt_arm(Layout* layout,
861 Output_data_space* got_plt)
862 : Output_section_data(4), got_plt_(got_plt), count_(0)
864 this->rel_ = new Reloc_section(false);
865 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
866 elfcpp::SHF_ALLOC, this->rel_);
869 template<bool big_endian>
871 Output_data_plt_arm<big_endian>::do_adjust_output_section(Output_section* os)
876 // Add an entry to the PLT.
878 template<bool big_endian>
880 Output_data_plt_arm<big_endian>::add_entry(Symbol* gsym)
882 gold_assert(!gsym->has_plt_offset());
884 // Note that when setting the PLT offset we skip the initial
885 // reserved PLT entry.
886 gsym->set_plt_offset((this->count_) * sizeof(plt_entry)
887 + sizeof(first_plt_entry));
891 section_offset_type got_offset = this->got_plt_->current_data_size();
893 // Every PLT entry needs a GOT entry which points back to the PLT
894 // entry (this will be changed by the dynamic linker, normally
895 // lazily when the function is called).
896 this->got_plt_->set_current_data_size(got_offset + 4);
898 // Every PLT entry needs a reloc.
899 gsym->set_needs_dynsym_entry();
900 this->rel_->add_global(gsym, elfcpp::R_ARM_JUMP_SLOT, this->got_plt_,
903 // Note that we don't need to save the symbol. The contents of the
904 // PLT are independent of which symbols are used. The symbols only
905 // appear in the relocations.
909 // FIXME: This is not very flexible. Right now this has only been tested
910 // on armv5te. If we are to support additional architecture features like
911 // Thumb-2 or BE8, we need to make this more flexible like GNU ld.
913 // The first entry in the PLT.
914 template<bool big_endian>
915 const uint32_t Output_data_plt_arm<big_endian>::first_plt_entry[5] =
917 0xe52de004, // str lr, [sp, #-4]!
918 0xe59fe004, // ldr lr, [pc, #4]
919 0xe08fe00e, // add lr, pc, lr
920 0xe5bef008, // ldr pc, [lr, #8]!
921 0x00000000, // &GOT[0] - .
924 // Subsequent entries in the PLT.
926 template<bool big_endian>
927 const uint32_t Output_data_plt_arm<big_endian>::plt_entry[3] =
929 0xe28fc600, // add ip, pc, #0xNN00000
930 0xe28cca00, // add ip, ip, #0xNN000
931 0xe5bcf000, // ldr pc, [ip, #0xNNN]!
934 // Write out the PLT. This uses the hand-coded instructions above,
935 // and adjusts them as needed. This is all specified by the arm ELF
936 // Processor Supplement.
938 template<bool big_endian>
940 Output_data_plt_arm<big_endian>::do_write(Output_file* of)
942 const off_t offset = this->offset();
943 const section_size_type oview_size =
944 convert_to_section_size_type(this->data_size());
945 unsigned char* const oview = of->get_output_view(offset, oview_size);
947 const off_t got_file_offset = this->got_plt_->offset();
948 const section_size_type got_size =
949 convert_to_section_size_type(this->got_plt_->data_size());
950 unsigned char* const got_view = of->get_output_view(got_file_offset,
952 unsigned char* pov = oview;
954 elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
955 elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
957 // Write first PLT entry. All but the last word are constants.
958 const size_t num_first_plt_words = (sizeof(first_plt_entry)
959 / sizeof(plt_entry[0]));
960 for (size_t i = 0; i < num_first_plt_words - 1; i++)
961 elfcpp::Swap<32, big_endian>::writeval(pov + i * 4, first_plt_entry[i]);
962 // Last word in first PLT entry is &GOT[0] - .
963 elfcpp::Swap<32, big_endian>::writeval(pov + 16,
964 got_address - (plt_address + 16));
965 pov += sizeof(first_plt_entry);
967 unsigned char* got_pov = got_view;
969 memset(got_pov, 0, 12);
972 const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
973 unsigned int plt_offset = sizeof(first_plt_entry);
974 unsigned int plt_rel_offset = 0;
975 unsigned int got_offset = 12;
976 const unsigned int count = this->count_;
977 for (unsigned int i = 0;
980 pov += sizeof(plt_entry),
982 plt_offset += sizeof(plt_entry),
983 plt_rel_offset += rel_size,
986 // Set and adjust the PLT entry itself.
987 int32_t offset = ((got_address + got_offset)
988 - (plt_address + plt_offset + 8));
990 gold_assert(offset >= 0 && offset < 0x0fffffff);
991 uint32_t plt_insn0 = plt_entry[0] | ((offset >> 20) & 0xff);
992 elfcpp::Swap<32, big_endian>::writeval(pov, plt_insn0);
993 uint32_t plt_insn1 = plt_entry[1] | ((offset >> 12) & 0xff);
994 elfcpp::Swap<32, big_endian>::writeval(pov + 4, plt_insn1);
995 uint32_t plt_insn2 = plt_entry[2] | (offset & 0xfff);
996 elfcpp::Swap<32, big_endian>::writeval(pov + 8, plt_insn2);
998 // Set the entry in the GOT.
999 elfcpp::Swap<32, big_endian>::writeval(got_pov, plt_address);
1002 gold_assert(static_cast<section_size_type>(pov - oview) == oview_size);
1003 gold_assert(static_cast<section_size_type>(got_pov - got_view) == got_size);
1005 of->write_output_view(offset, oview_size, oview);
1006 of->write_output_view(got_file_offset, got_size, got_view);
1009 // Create a PLT entry for a global symbol.
1011 template<bool big_endian>
1013 Target_arm<big_endian>::make_plt_entry(Symbol_table* symtab, Layout* layout,
1016 if (gsym->has_plt_offset())
1019 if (this->plt_ == NULL)
1021 // Create the GOT sections first.
1022 this->got_section(symtab, layout);
1024 this->plt_ = new Output_data_plt_arm<big_endian>(layout, this->got_plt_);
1025 layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
1027 | elfcpp::SHF_EXECINSTR),
1030 this->plt_->add_entry(gsym);
1033 // Report an unsupported relocation against a local symbol.
1035 template<bool big_endian>
1037 Target_arm<big_endian>::Scan::unsupported_reloc_local(
1038 Sized_relobj<32, big_endian>* object,
1039 unsigned int r_type)
1041 gold_error(_("%s: unsupported reloc %u against local symbol"),
1042 object->name().c_str(), r_type);
1045 // We are about to emit a dynamic relocation of type R_TYPE. If the
1046 // dynamic linker does not support it, issue an error. The GNU linker
1047 // only issues a non-PIC error for an allocated read-only section.
1048 // Here we know the section is allocated, but we don't know that it is
1049 // read-only. But we check for all the relocation types which the
1050 // glibc dynamic linker supports, so it seems appropriate to issue an
1051 // error even if the section is not read-only.
1053 template<bool big_endian>
1055 Target_arm<big_endian>::Scan::check_non_pic(Relobj* object,
1056 unsigned int r_type)
1060 // These are the relocation types supported by glibc for ARM.
1061 case elfcpp::R_ARM_RELATIVE:
1062 case elfcpp::R_ARM_COPY:
1063 case elfcpp::R_ARM_GLOB_DAT:
1064 case elfcpp::R_ARM_JUMP_SLOT:
1065 case elfcpp::R_ARM_ABS32:
1066 case elfcpp::R_ARM_PC24:
1067 // FIXME: The following 3 types are not supported by Android's dynamic
1069 case elfcpp::R_ARM_TLS_DTPMOD32:
1070 case elfcpp::R_ARM_TLS_DTPOFF32:
1071 case elfcpp::R_ARM_TLS_TPOFF32:
1075 // This prevents us from issuing more than one error per reloc
1076 // section. But we can still wind up issuing more than one
1077 // error per object file.
1078 if (this->issued_non_pic_error_)
1080 object->error(_("requires unsupported dynamic reloc; "
1081 "recompile with -fPIC"));
1082 this->issued_non_pic_error_ = true;
1085 case elfcpp::R_ARM_NONE:
1090 // Scan a relocation for a local symbol.
1091 // FIXME: This only handles a subset of relocation types used by Android
1092 // on ARM v5te devices.
1094 template<bool big_endian>
1096 Target_arm<big_endian>::Scan::local(const General_options&,
1097 Symbol_table* symtab,
1100 Sized_relobj<32, big_endian>* object,
1101 unsigned int data_shndx,
1102 Output_section* output_section,
1103 const elfcpp::Rel<32, big_endian>& reloc,
1104 unsigned int r_type,
1105 const elfcpp::Sym<32, big_endian>&)
1107 r_type = get_real_reloc_type(r_type);
1110 case elfcpp::R_ARM_NONE:
1113 case elfcpp::R_ARM_ABS8:
1114 if (parameters->options().output_is_position_independent())
1116 // FIXME: Create a dynamic relocation for this location.
1117 gold_error(_("%s: gold bug: need dynamic ABS8 reloc"),
1118 object->name().c_str());
1122 case elfcpp::R_ARM_ABS32:
1123 // If building a shared library (or a position-independent
1124 // executable), we need to create a dynamic relocation for
1125 // this location. The relocation applied at link time will
1126 // apply the link-time value, so we flag the location with
1127 // an R_ARM_RELATIVE relocation so the dynamic loader can
1128 // relocate it easily.
1129 if (parameters->options().output_is_position_independent())
1131 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1132 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1133 // If we are to add more other reloc types than R_ARM_ABS32,
1134 // we need to add check_non_pic(object, r_type) here.
1135 rel_dyn->add_local_relative(object, r_sym, elfcpp::R_ARM_RELATIVE,
1136 output_section, data_shndx,
1137 reloc.get_r_offset());
1141 case elfcpp::R_ARM_REL32:
1142 case elfcpp::R_ARM_THM_CALL:
1143 case elfcpp::R_ARM_CALL:
1144 case elfcpp::R_ARM_PREL31:
1145 case elfcpp::R_ARM_JUMP24:
1146 case elfcpp::R_ARM_PLT32:
1149 case elfcpp::R_ARM_GOTOFF32:
1150 // We need a GOT section:
1151 target->got_section(symtab, layout);
1154 case elfcpp::R_ARM_BASE_PREL:
1155 // FIXME: What about this?
1158 case elfcpp::R_ARM_GOT_BREL:
1160 // The symbol requires a GOT entry.
1161 Output_data_got<32, big_endian>* got =
1162 target->got_section(symtab, layout);
1163 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1164 if (got->add_local(object, r_sym, GOT_TYPE_STANDARD))
1166 // If we are generating a shared object, we need to add a
1167 // dynamic RELATIVE relocation for this symbol's GOT entry.
1168 if (parameters->options().output_is_position_independent())
1170 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1171 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1172 rel_dyn->add_local_relative(
1173 object, r_sym, elfcpp::R_ARM_RELATIVE, got,
1174 object->local_got_offset(r_sym, GOT_TYPE_STANDARD));
1180 case elfcpp::R_ARM_TARGET1:
1181 // This should have been mapped to another type already.
1183 case elfcpp::R_ARM_COPY:
1184 case elfcpp::R_ARM_GLOB_DAT:
1185 case elfcpp::R_ARM_JUMP_SLOT:
1186 case elfcpp::R_ARM_RELATIVE:
1187 // These are relocations which should only be seen by the
1188 // dynamic linker, and should never be seen here.
1189 gold_error(_("%s: unexpected reloc %u in object file"),
1190 object->name().c_str(), r_type);
1194 unsupported_reloc_local(object, r_type);
1199 // Report an unsupported relocation against a global symbol.
1201 template<bool big_endian>
1203 Target_arm<big_endian>::Scan::unsupported_reloc_global(
1204 Sized_relobj<32, big_endian>* object,
1205 unsigned int r_type,
1208 gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1209 object->name().c_str(), r_type, gsym->demangled_name().c_str());
1212 // Scan a relocation for a global symbol.
1213 // FIXME: This only handles a subset of relocation types used by Android
1214 // on ARM v5te devices.
1216 template<bool big_endian>
1218 Target_arm<big_endian>::Scan::global(const General_options&,
1219 Symbol_table* symtab,
1222 Sized_relobj<32, big_endian>* object,
1223 unsigned int data_shndx,
1224 Output_section* output_section,
1225 const elfcpp::Rel<32, big_endian>& reloc,
1226 unsigned int r_type,
1229 r_type = get_real_reloc_type(r_type);
1232 case elfcpp::R_ARM_NONE:
1235 case elfcpp::R_ARM_ABS8:
1236 // Make a dynamic relocation if necessary.
1237 if (gsym->needs_dynamic_reloc(Symbol::ABSOLUTE_REF))
1239 // FIXME: Create a dynamic relocation for this location.
1240 gold_error(_("%s: gold bug: need dynamic ABS8 reloc for %s"),
1241 object->name().c_str(), gsym->demangled_name().c_str());
1245 case elfcpp::R_ARM_ABS32:
1247 // Make a dynamic relocation if necessary.
1248 if (gsym->needs_dynamic_reloc(Symbol::ABSOLUTE_REF))
1250 if (target->may_need_copy_reloc(gsym))
1252 target->copy_reloc(symtab, layout, object,
1253 data_shndx, output_section, gsym, reloc);
1255 else if (gsym->can_use_relative_reloc(false))
1257 // If we are to add more other reloc types than R_ARM_ABS32,
1258 // we need to add check_non_pic(object, r_type) here.
1259 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1260 rel_dyn->add_global_relative(gsym, elfcpp::R_ARM_RELATIVE,
1261 output_section, object,
1262 data_shndx, reloc.get_r_offset());
1266 // If we are to add more other reloc types than R_ARM_ABS32,
1267 // we need to add check_non_pic(object, r_type) here.
1268 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1269 rel_dyn->add_global(gsym, r_type, output_section, object,
1270 data_shndx, reloc.get_r_offset());
1276 case elfcpp::R_ARM_REL32:
1277 case elfcpp::R_ARM_PREL31:
1279 // Make a dynamic relocation if necessary.
1280 int flags = Symbol::NON_PIC_REF;
1281 if (gsym->needs_dynamic_reloc(flags))
1283 if (target->may_need_copy_reloc(gsym))
1285 target->copy_reloc(symtab, layout, object,
1286 data_shndx, output_section, gsym, reloc);
1290 check_non_pic(object, r_type);
1291 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1292 rel_dyn->add_global(gsym, r_type, output_section, object,
1293 data_shndx, reloc.get_r_offset());
1299 case elfcpp::R_ARM_JUMP24:
1300 case elfcpp::R_ARM_THM_CALL:
1301 case elfcpp::R_ARM_CALL:
1303 if (Target_arm<big_endian>::Scan::symbol_needs_plt_entry(gsym))
1304 target->make_plt_entry(symtab, layout, gsym);
1305 // Make a dynamic relocation if necessary.
1306 int flags = Symbol::NON_PIC_REF;
1307 if (gsym->type() == elfcpp::STT_FUNC
1308 || gsym->type() == elfcpp::STT_ARM_TFUNC)
1309 flags |= Symbol::FUNCTION_CALL;
1310 if (gsym->needs_dynamic_reloc(flags))
1312 if (target->may_need_copy_reloc(gsym))
1314 target->copy_reloc(symtab, layout, object,
1315 data_shndx, output_section, gsym,
1320 check_non_pic(object, r_type);
1321 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1322 rel_dyn->add_global(gsym, r_type, output_section, object,
1323 data_shndx, reloc.get_r_offset());
1329 case elfcpp::R_ARM_PLT32:
1330 // If the symbol is fully resolved, this is just a relative
1331 // local reloc. Otherwise we need a PLT entry.
1332 if (gsym->final_value_is_known())
1334 // If building a shared library, we can also skip the PLT entry
1335 // if the symbol is defined in the output file and is protected
1337 if (gsym->is_defined()
1338 && !gsym->is_from_dynobj()
1339 && !gsym->is_preemptible())
1341 target->make_plt_entry(symtab, layout, gsym);
1344 case elfcpp::R_ARM_GOTOFF32:
1345 // We need a GOT section.
1346 target->got_section(symtab, layout);
1349 case elfcpp::R_ARM_BASE_PREL:
1350 // FIXME: What about this?
1353 case elfcpp::R_ARM_GOT_BREL:
1355 // The symbol requires a GOT entry.
1356 Output_data_got<32, big_endian>* got =
1357 target->got_section(symtab, layout);
1358 if (gsym->final_value_is_known())
1359 got->add_global(gsym, GOT_TYPE_STANDARD);
1362 // If this symbol is not fully resolved, we need to add a
1363 // GOT entry with a dynamic relocation.
1364 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1365 if (gsym->is_from_dynobj()
1366 || gsym->is_undefined()
1367 || gsym->is_preemptible())
1368 got->add_global_with_rel(gsym, GOT_TYPE_STANDARD,
1369 rel_dyn, elfcpp::R_ARM_GLOB_DAT);
1372 if (got->add_global(gsym, GOT_TYPE_STANDARD))
1373 rel_dyn->add_global_relative(
1374 gsym, elfcpp::R_ARM_RELATIVE, got,
1375 gsym->got_offset(GOT_TYPE_STANDARD));
1381 case elfcpp::R_ARM_TARGET1:
1382 // This should have been mapped to another type already.
1384 case elfcpp::R_ARM_COPY:
1385 case elfcpp::R_ARM_GLOB_DAT:
1386 case elfcpp::R_ARM_JUMP_SLOT:
1387 case elfcpp::R_ARM_RELATIVE:
1388 // These are relocations which should only be seen by the
1389 // dynamic linker, and should never be seen here.
1390 gold_error(_("%s: unexpected reloc %u in object file"),
1391 object->name().c_str(), r_type);
1395 unsupported_reloc_global(object, r_type, gsym);
1400 // Process relocations for gc.
1402 template<bool big_endian>
1404 Target_arm<big_endian>::gc_process_relocs(const General_options& options,
1405 Symbol_table* symtab,
1407 Sized_relobj<32, big_endian>* object,
1408 unsigned int data_shndx,
1410 const unsigned char* prelocs,
1412 Output_section* output_section,
1413 bool needs_special_offset_handling,
1414 size_t local_symbol_count,
1415 const unsigned char* plocal_symbols)
1417 typedef Target_arm<big_endian> Arm;
1418 typedef typename Target_arm<big_endian>::Scan Scan;
1420 gold::gc_process_relocs<32, big_endian, Arm, elfcpp::SHT_REL, Scan>(
1430 needs_special_offset_handling,
1435 // Scan relocations for a section.
1437 template<bool big_endian>
1439 Target_arm<big_endian>::scan_relocs(const General_options& options,
1440 Symbol_table* symtab,
1442 Sized_relobj<32, big_endian>* object,
1443 unsigned int data_shndx,
1444 unsigned int sh_type,
1445 const unsigned char* prelocs,
1447 Output_section* output_section,
1448 bool needs_special_offset_handling,
1449 size_t local_symbol_count,
1450 const unsigned char* plocal_symbols)
1452 typedef typename Target_arm<big_endian>::Scan Scan;
1453 if (sh_type == elfcpp::SHT_RELA)
1455 gold_error(_("%s: unsupported RELA reloc section"),
1456 object->name().c_str());
1460 gold::scan_relocs<32, big_endian, Target_arm, elfcpp::SHT_REL, Scan>(
1470 needs_special_offset_handling,
1475 // Finalize the sections.
1477 template<bool big_endian>
1479 Target_arm<big_endian>::do_finalize_sections(Layout* layout)
1481 // Fill in some more dynamic tags.
1482 Output_data_dynamic* const odyn = layout->dynamic_data();
1485 if (this->got_plt_ != NULL)
1486 odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1488 if (this->plt_ != NULL)
1490 const Output_data* od = this->plt_->rel_plt();
1491 odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1492 odyn->add_section_address(elfcpp::DT_JMPREL, od);
1493 odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
1496 if (this->rel_dyn_ != NULL)
1498 const Output_data* od = this->rel_dyn_;
1499 odyn->add_section_address(elfcpp::DT_REL, od);
1500 odyn->add_section_size(elfcpp::DT_RELSZ, od);
1501 odyn->add_constant(elfcpp::DT_RELENT,
1502 elfcpp::Elf_sizes<32>::rel_size);
1505 if (!parameters->options().shared())
1507 // The value of the DT_DEBUG tag is filled in by the dynamic
1508 // linker at run time, and used by the debugger.
1509 odyn->add_constant(elfcpp::DT_DEBUG, 0);
1513 // Emit any relocs we saved in an attempt to avoid generating COPY
1515 if (this->copy_relocs_.any_saved_relocs())
1516 this->copy_relocs_.emit(this->rel_dyn_section(layout));
1518 // For the ARM target, we need to add a PT_ARM_EXIDX segment for
1519 // the .ARM.exidx section.
1520 if (!layout->script_options()->saw_phdrs_clause()
1521 && !parameters->options().relocatable())
1523 Output_section* exidx_section =
1524 layout->find_output_section(".ARM.exidx");
1526 if (exidx_section != NULL
1527 && exidx_section->type() == elfcpp::SHT_ARM_EXIDX)
1529 gold_assert(layout->find_output_segment(elfcpp::PT_ARM_EXIDX, 0, 0)
1531 Output_segment* exidx_segment =
1532 layout->make_output_segment(elfcpp::PT_ARM_EXIDX, elfcpp::PF_R);
1533 exidx_segment->add_output_section(exidx_section, elfcpp::PF_R);
1538 // Return whether a direct absolute static relocation needs to be applied.
1539 // In cases where Scan::local() or Scan::global() has created
1540 // a dynamic relocation other than R_ARM_RELATIVE, the addend
1541 // of the relocation is carried in the data, and we must not
1542 // apply the static relocation.
1544 template<bool big_endian>
1546 Target_arm<big_endian>::Relocate::should_apply_static_reloc(
1547 const Sized_symbol<32>* gsym,
1550 Output_section* output_section)
1552 // If the output section is not allocated, then we didn't call
1553 // scan_relocs, we didn't create a dynamic reloc, and we must apply
1555 if ((output_section->flags() & elfcpp::SHF_ALLOC) == 0)
1558 // For local symbols, we will have created a non-RELATIVE dynamic
1559 // relocation only if (a) the output is position independent,
1560 // (b) the relocation is absolute (not pc- or segment-relative), and
1561 // (c) the relocation is not 32 bits wide.
1563 return !(parameters->options().output_is_position_independent()
1564 && (ref_flags & Symbol::ABSOLUTE_REF)
1567 // For global symbols, we use the same helper routines used in the
1568 // scan pass. If we did not create a dynamic relocation, or if we
1569 // created a RELATIVE dynamic relocation, we should apply the static
1571 bool has_dyn = gsym->needs_dynamic_reloc(ref_flags);
1572 bool is_rel = (ref_flags & Symbol::ABSOLUTE_REF)
1573 && gsym->can_use_relative_reloc(ref_flags
1574 & Symbol::FUNCTION_CALL);
1575 return !has_dyn || is_rel;
1578 // Perform a relocation.
1580 template<bool big_endian>
1582 Target_arm<big_endian>::Relocate::relocate(
1583 const Relocate_info<32, big_endian>* relinfo,
1585 Output_section *output_section,
1587 const elfcpp::Rel<32, big_endian>& rel,
1588 unsigned int r_type,
1589 const Sized_symbol<32>* gsym,
1590 const Symbol_value<32>* psymval,
1591 unsigned char* view,
1592 elfcpp::Elf_types<32>::Elf_Addr address,
1593 section_size_type /* view_size */ )
1595 typedef Arm_relocate_functions<big_endian> Arm_relocate_functions;
1597 r_type = get_real_reloc_type(r_type);
1599 // If this the symbol may be a Thumb function, set thumb bit to 1.
1600 bool has_thumb_bit = ((gsym != NULL)
1601 && (gsym->type() == elfcpp::STT_FUNC
1602 || gsym->type() == elfcpp::STT_ARM_TFUNC));
1604 // Pick the value to use for symbols defined in shared objects.
1605 Symbol_value<32> symval;
1607 && gsym->use_plt_offset(reloc_is_non_pic(r_type)))
1609 symval.set_output_value(target->plt_section()->address()
1610 + gsym->plt_offset());
1615 const Sized_relobj<32, big_endian>* object = relinfo->object;
1617 // Get the GOT offset if needed.
1618 // The GOT pointer points to the end of the GOT section.
1619 // We need to subtract the size of the GOT section to get
1620 // the actual offset to use in the relocation.
1621 bool have_got_offset = false;
1622 unsigned int got_offset = 0;
1625 case elfcpp::R_ARM_GOT_BREL:
1628 gold_assert(gsym->has_got_offset(GOT_TYPE_STANDARD));
1629 got_offset = (gsym->got_offset(GOT_TYPE_STANDARD)
1630 - target->got_size());
1634 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1635 gold_assert(object->local_has_got_offset(r_sym, GOT_TYPE_STANDARD));
1636 got_offset = (object->local_got_offset(r_sym, GOT_TYPE_STANDARD)
1637 - target->got_size());
1639 have_got_offset = true;
1646 typename Arm_relocate_functions::Status reloc_status =
1647 Arm_relocate_functions::STATUS_OKAY;
1650 case elfcpp::R_ARM_NONE:
1653 case elfcpp::R_ARM_ABS8:
1654 if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, false,
1656 reloc_status = Arm_relocate_functions::abs8(view, object, psymval,
1660 case elfcpp::R_ARM_ABS32:
1661 if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
1663 reloc_status = Arm_relocate_functions::abs32(view, object, psymval,
1667 case elfcpp::R_ARM_REL32:
1668 reloc_status = Arm_relocate_functions::rel32(view, object, psymval,
1669 address, has_thumb_bit);
1672 case elfcpp::R_ARM_THM_CALL:
1673 reloc_status = Arm_relocate_functions::thm_call(view, object, psymval,
1674 address, has_thumb_bit);
1677 case elfcpp::R_ARM_GOTOFF32:
1679 elfcpp::Elf_types<32>::Elf_Addr got_origin;
1680 got_origin = target->got_plt_section()->address();
1681 reloc_status = Arm_relocate_functions::rel32(view, object, psymval,
1682 got_origin, has_thumb_bit);
1686 case elfcpp::R_ARM_BASE_PREL:
1689 // Get the addressing origin of the output segment defining the
1690 // symbol gsym (AAELF 4.6.1.2 Relocation types)
1691 gold_assert(gsym != NULL);
1692 if (gsym->source() == Symbol::IN_OUTPUT_SEGMENT)
1693 origin = gsym->output_segment()->vaddr();
1694 else if (gsym->source () == Symbol::IN_OUTPUT_DATA)
1695 origin = gsym->output_data()->address();
1698 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1699 _("cannot find origin of R_ARM_BASE_PREL"));
1702 reloc_status = Arm_relocate_functions::base_prel(view, origin, address);
1706 case elfcpp::R_ARM_GOT_BREL:
1707 gold_assert(have_got_offset);
1708 reloc_status = Arm_relocate_functions::got_brel(view, got_offset);
1711 case elfcpp::R_ARM_PLT32:
1712 gold_assert(gsym == NULL
1713 || gsym->has_plt_offset()
1714 || gsym->final_value_is_known()
1715 || (gsym->is_defined()
1716 && !gsym->is_from_dynobj()
1717 && !gsym->is_preemptible()));
1718 reloc_status = Arm_relocate_functions::plt32(view, object, psymval,
1719 address, has_thumb_bit);
1722 case elfcpp::R_ARM_CALL:
1723 reloc_status = Arm_relocate_functions::call(view, object, psymval,
1724 address, has_thumb_bit);
1727 case elfcpp::R_ARM_JUMP24:
1728 reloc_status = Arm_relocate_functions::jump24(view, object, psymval,
1729 address, has_thumb_bit);
1732 case elfcpp::R_ARM_PREL31:
1733 reloc_status = Arm_relocate_functions::prel31(view, object, psymval,
1734 address, has_thumb_bit);
1737 case elfcpp::R_ARM_TARGET1:
1738 // This should have been mapped to another type already.
1740 case elfcpp::R_ARM_COPY:
1741 case elfcpp::R_ARM_GLOB_DAT:
1742 case elfcpp::R_ARM_JUMP_SLOT:
1743 case elfcpp::R_ARM_RELATIVE:
1744 // These are relocations which should only be seen by the
1745 // dynamic linker, and should never be seen here.
1746 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1747 _("unexpected reloc %u in object file"),
1752 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1753 _("unsupported reloc %u"),
1758 // Report any errors.
1759 switch (reloc_status)
1761 case Arm_relocate_functions::STATUS_OKAY:
1763 case Arm_relocate_functions::STATUS_OVERFLOW:
1764 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1765 _("relocation overflow in relocation %u"),
1768 case Arm_relocate_functions::STATUS_BAD_RELOC:
1769 gold_error_at_location(
1773 _("unexpected opcode while processing relocation %u"),
1783 // Relocate section data.
1785 template<bool big_endian>
1787 Target_arm<big_endian>::relocate_section(
1788 const Relocate_info<32, big_endian>* relinfo,
1789 unsigned int sh_type,
1790 const unsigned char* prelocs,
1792 Output_section* output_section,
1793 bool needs_special_offset_handling,
1794 unsigned char* view,
1795 elfcpp::Elf_types<32>::Elf_Addr address,
1796 section_size_type view_size,
1797 const Reloc_symbol_changes* reloc_symbol_changes)
1799 typedef typename Target_arm<big_endian>::Relocate Arm_relocate;
1800 gold_assert(sh_type == elfcpp::SHT_REL);
1802 gold::relocate_section<32, big_endian, Target_arm, elfcpp::SHT_REL,
1809 needs_special_offset_handling,
1813 reloc_symbol_changes);
1816 // Return the size of a relocation while scanning during a relocatable
1819 template<bool big_endian>
1821 Target_arm<big_endian>::Relocatable_size_for_reloc::get_size_for_reloc(
1822 unsigned int r_type,
1825 r_type = get_real_reloc_type(r_type);
1828 case elfcpp::R_ARM_NONE:
1831 case elfcpp::R_ARM_ABS8:
1834 case elfcpp::R_ARM_ABS32:
1835 case elfcpp::R_ARM_REL32:
1836 case elfcpp::R_ARM_THM_CALL:
1837 case elfcpp::R_ARM_GOTOFF32:
1838 case elfcpp::R_ARM_BASE_PREL:
1839 case elfcpp::R_ARM_GOT_BREL:
1840 case elfcpp::R_ARM_PLT32:
1841 case elfcpp::R_ARM_CALL:
1842 case elfcpp::R_ARM_JUMP24:
1843 case elfcpp::R_ARM_PREL31:
1846 case elfcpp::R_ARM_TARGET1:
1847 // This should have been mapped to another type already.
1849 case elfcpp::R_ARM_COPY:
1850 case elfcpp::R_ARM_GLOB_DAT:
1851 case elfcpp::R_ARM_JUMP_SLOT:
1852 case elfcpp::R_ARM_RELATIVE:
1853 // These are relocations which should only be seen by the
1854 // dynamic linker, and should never be seen here.
1855 gold_error(_("%s: unexpected reloc %u in object file"),
1856 object->name().c_str(), r_type);
1860 object->error(_("unsupported reloc %u in object file"), r_type);
1865 // Scan the relocs during a relocatable link.
1867 template<bool big_endian>
1869 Target_arm<big_endian>::scan_relocatable_relocs(
1870 const General_options& options,
1871 Symbol_table* symtab,
1873 Sized_relobj<32, big_endian>* object,
1874 unsigned int data_shndx,
1875 unsigned int sh_type,
1876 const unsigned char* prelocs,
1878 Output_section* output_section,
1879 bool needs_special_offset_handling,
1880 size_t local_symbol_count,
1881 const unsigned char* plocal_symbols,
1882 Relocatable_relocs* rr)
1884 gold_assert(sh_type == elfcpp::SHT_REL);
1886 typedef gold::Default_scan_relocatable_relocs<elfcpp::SHT_REL,
1887 Relocatable_size_for_reloc> Scan_relocatable_relocs;
1889 gold::scan_relocatable_relocs<32, big_endian, elfcpp::SHT_REL,
1890 Scan_relocatable_relocs>(
1899 needs_special_offset_handling,
1905 // Relocate a section during a relocatable link.
1907 template<bool big_endian>
1909 Target_arm<big_endian>::relocate_for_relocatable(
1910 const Relocate_info<32, big_endian>* relinfo,
1911 unsigned int sh_type,
1912 const unsigned char* prelocs,
1914 Output_section* output_section,
1915 off_t offset_in_output_section,
1916 const Relocatable_relocs* rr,
1917 unsigned char* view,
1918 elfcpp::Elf_types<32>::Elf_Addr view_address,
1919 section_size_type view_size,
1920 unsigned char* reloc_view,
1921 section_size_type reloc_view_size)
1923 gold_assert(sh_type == elfcpp::SHT_REL);
1925 gold::relocate_for_relocatable<32, big_endian, elfcpp::SHT_REL>(
1930 offset_in_output_section,
1939 // Return the value to use for a dynamic symbol which requires special
1940 // treatment. This is how we support equality comparisons of function
1941 // pointers across shared library boundaries, as described in the
1942 // processor specific ABI supplement.
1944 template<bool big_endian>
1946 Target_arm<big_endian>::do_dynsym_value(const Symbol* gsym) const
1948 gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1949 return this->plt_section()->address() + gsym->plt_offset();
1952 // Map platform-specific relocs to real relocs
1954 template<bool big_endian>
1956 Target_arm<big_endian>::get_real_reloc_type (unsigned int r_type)
1960 case elfcpp::R_ARM_TARGET1:
1961 // This is either R_ARM_ABS32 or R_ARM_REL32;
1962 return elfcpp::R_ARM_ABS32;
1964 case elfcpp::R_ARM_TARGET2:
1965 // This can be any reloc type but ususally is R_ARM_GOT_PREL
1966 return elfcpp::R_ARM_GOT_PREL;
1973 // The selector for arm object files.
1975 template<bool big_endian>
1976 class Target_selector_arm : public Target_selector
1979 Target_selector_arm()
1980 : Target_selector(elfcpp::EM_ARM, 32, big_endian,
1981 (big_endian ? "elf32-bigarm" : "elf32-littlearm"))
1985 do_instantiate_target()
1986 { return new Target_arm<big_endian>(); }
1989 Target_selector_arm<false> target_selector_arm;
1990 Target_selector_arm<true> target_selector_armbe;
1992 } // End anonymous namespace.