diff options
Diffstat (limited to 'bfd/elf32-arm.c')
| -rw-r--r-- | bfd/elf32-arm.c | 213 |
1 files changed, 177 insertions, 36 deletions
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c index 53b4ac1..65c0873 100644 --- a/bfd/elf32-arm.c +++ b/bfd/elf32-arm.c @@ -1063,6 +1063,14 @@ static const bfd_vma elf32_arm_plt_entry [] = #endif +/* An initial stub used if the PLT entry is referenced from Thumb code. */ +#define PLT_THUMB_STUB_SIZE 4 +static const bfd_vma elf32_arm_plt_thumb_stub [] = + { + 0x4778, /* bx pc */ + 0x46c0 /* nop */ + }; + /* The entries in a PLT when using a DLL-based target with multiple address spaces. */ static const bfd_vma elf32_arm_symbian_plt_entry [] = @@ -1116,13 +1124,22 @@ struct elf32_arm_link_hash_entry /* Number of PC relative relocs copied for this symbol. */ struct elf32_arm_relocs_copied * relocs_copied; + + /* We reference count Thumb references to a PLT entry separately, + so that we can emit the Thumb trampoline only if needed. */ + bfd_signed_vma plt_thumb_refcount; + + /* Since PLT entries have variable size if the Thumb prologue is + used, we need to record the index into .got.plt instead of + recomputing it from the PLT offset. */ + bfd_signed_vma plt_got_offset; }; /* Traverse an arm ELF linker hash table. */ #define elf32_arm_link_hash_traverse(table, func, info) \ (elf_link_hash_traverse \ (&(table)->root, \ - (bfd_boolean (*) (struct elf_link_hash_entry *, void *))) (func), \ + (bfd_boolean (*) (struct elf_link_hash_entry *, void *)) (func), \ (info))) /* Get the ARM elf linker hash table from a link_info structure. */ @@ -1178,6 +1195,9 @@ struct elf32_arm_link_hash_table /* Small local sym to section mapping cache. */ struct sym_sec_cache sym_sec; + + /* For convenience in allocate_dynrelocs. */ + bfd * obfd; }; /* Create an entry in an ARM ELF linker hash table. */ @@ -1202,7 +1222,11 @@ elf32_arm_link_hash_newfunc (struct bfd_hash_entry * entry, _bfd_elf_link_hash_newfunc ((struct bfd_hash_entry *) ret, table, string)); if (ret != NULL) - ret->relocs_copied = NULL; + { + ret->relocs_copied = NULL; + ret->plt_thumb_refcount = 0; + ret->plt_got_offset = -1; + } return (struct bfd_hash_entry *) ret; } @@ -1315,6 +1339,17 @@ elf32_arm_copy_indirect_symbol (const struct elf_backend_data *bed, eind->relocs_copied = NULL; } + /* If the direct symbol already has an associated PLT entry, the + indirect symbol should not. If it doesn't, swap refcount information + from the indirect symbol. */ + if (edir->plt_thumb_refcount == 0) + { + edir->plt_thumb_refcount = eind->plt_thumb_refcount; + eind->plt_thumb_refcount = 0; + } + else + BFD_ASSERT (eind->plt_thumb_refcount == 0); + _bfd_elf_link_hash_copy_indirect (bed, dir, ind); } @@ -1360,6 +1395,7 @@ elf32_arm_link_hash_table_create (bfd *abfd) #endif ret->symbian_p = 0; ret->sym_sec.abfd = NULL; + ret->obfd = abfd; return &ret->root.root; } @@ -1559,6 +1595,10 @@ record_arm_to_thumb_glue (struct bfd_link_info * link_info, tmp_name, BSF_GLOBAL, s, val, NULL, TRUE, FALSE, &bh); + myh = (struct elf_link_hash_entry *) bh; + myh->type = ELF_ST_INFO (STB_LOCAL, STT_FUNC); + myh->forced_local = 1; + free (tmp_name); globals->arm_glue_size += ARM2THUMB_GLUE_SIZE; @@ -1576,7 +1616,6 @@ record_thumb_to_arm_glue (struct bfd_link_info *link_info, struct elf_link_hash_entry *myh; struct bfd_link_hash_entry *bh; struct elf32_arm_link_hash_table *hash_table; - char bind; bfd_vma val; hash_table = elf32_arm_hash_table (link_info); @@ -1614,8 +1653,8 @@ record_thumb_to_arm_glue (struct bfd_link_info *link_info, /* If we mark it 'Thumb', the disassembler will do a better job. */ myh = (struct elf_link_hash_entry *) bh; - bind = ELF_ST_BIND (myh->type); - myh->type = ELF_ST_INFO (bind, STT_ARM_TFUNC); + myh->type = ELF_ST_INFO (STB_LOCAL, STT_ARM_TFUNC); + myh->forced_local = 1; free (tmp_name); @@ -1713,6 +1752,9 @@ bfd_elf32_arm_get_bfd_for_interworking (bfd *abfd, struct bfd_link_info *info) if (info->relocatable) return TRUE; + /* Make sure we don't attach the glue sections to a dynamic object. */ + BFD_ASSERT (!(abfd->flags & DYNAMIC)); + globals = elf32_arm_hash_table (info); BFD_ASSERT (globals != NULL); @@ -1796,6 +1838,7 @@ bfd_elf32_arm_process_before_allocation (bfd *abfd, /* These are the only relocation types we care about. */ if ( r_type != R_ARM_PC24 + && r_type != R_ARM_PLT32 #ifndef OLD_ARM_ABI && r_type != R_ARM_CALL && r_type != R_ARM_JUMP24 @@ -1834,6 +1877,11 @@ bfd_elf32_arm_process_before_allocation (bfd *abfd, if (h == NULL) continue; + /* If the call will go through a PLT entry then we do not need + glue. */ + if (globals->splt != NULL && h->plt.offset != (bfd_vma) -1) + continue; + switch (r_type) { case R_ARM_PC24: @@ -2374,6 +2422,8 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, /* This symbol is local, or marked to become local. */ relocate = TRUE; + if (sym_flags == STT_ARM_TFUNC) + value |= 1; if (globals->symbian_p) { /* On Symbian OS, the data segment and text segement @@ -2652,8 +2702,11 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, { /* If it is not a call to Thumb, assume call to Arm. If it is a call relative to a section name, then it is not a - function call at all, but rather a long jump. */ - if (sym_flags != STT_ARM_TFUNC && sym_flags != STT_SECTION) + function call at all, but rather a long jump. Calls through + the PLT do not require stubs. */ + if (sym_flags != STT_ARM_TFUNC && sym_flags != STT_SECTION + && (h == NULL || splt == NULL + || h->plt.offset == (bfd_vma) -1)) { if (elf32_thumb_to_arm_stub (info, sym_name, input_bfd, output_bfd, input_section, @@ -2664,6 +2717,16 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, } } + /* Handle calls via the PLT. */ + if (h != NULL && splt != NULL && h->plt.offset != (bfd_vma) -1) + { + value = (splt->output_section->vma + + splt->output_offset + + h->plt.offset); + /* Target the Thumb stub before the ARM PLT entry. */ + value -= 4; + } + relocation = value + signed_addend; relocation -= (input_section->output_section->vma @@ -2911,6 +2974,13 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, off &= ~1; else { + /* If we are addressing a Thumb function, we need to + adjust the address by one, so that attempts to + call the function pointer will correctly + interpret it as Thumb code. */ + if (sym_flags == STT_ARM_TFUNC) + value |= 1; + bfd_put_32 (output_bfd, value, sgot->contents + off); if (info->shared) @@ -3876,6 +3946,9 @@ elf32_arm_gc_sweep_hook (bfd * abfd ATTRIBUTE_UNUSED, case R_ARM_JUMP24: case R_ARM_PREL31: #endif + case R_ARM_THM_PC22: + /* Should the interworking branches be here also? */ + r_symndx = ELF32_R_SYM (rel->r_info); if (r_symndx >= symtab_hdr->sh_info) { @@ -3884,15 +3957,18 @@ elf32_arm_gc_sweep_hook (bfd * abfd ATTRIBUTE_UNUSED, struct elf32_arm_relocs_copied *p; h = sym_hashes[r_symndx - symtab_hdr->sh_info]; + eh = (struct elf32_arm_link_hash_entry *) h; if (h->plt.refcount > 0) - h->plt.refcount -= 1; + { + h->plt.refcount -= 1; + if (ELF32_R_TYPE (rel->r_info) == R_ARM_THM_PC22) + eh->plt_thumb_refcount--; + } if (r_type == R_ARM_ABS32 || r_type == R_ARM_REL32) { - eh = (struct elf32_arm_link_hash_entry *) h; - for (pp = &eh->relocs_copied; (p = *pp) != NULL; pp = &p->next) if (p->section == sec) @@ -3951,6 +4027,7 @@ elf32_arm_check_relocs (bfd *abfd, struct bfd_link_info *info, for (rel = relocs; rel < rel_end; rel++) { struct elf_link_hash_entry *h; + struct elf32_arm_link_hash_entry *eh; unsigned long r_symndx; int r_type; @@ -3964,6 +4041,8 @@ elf32_arm_check_relocs (bfd *abfd, struct bfd_link_info *info, else h = sym_hashes[r_symndx - symtab_hdr->sh_info]; + eh = (struct elf32_arm_link_hash_entry *) h; + switch (r_type) { case R_ARM_GOT32: @@ -4018,6 +4097,8 @@ elf32_arm_check_relocs (bfd *abfd, struct bfd_link_info *info, case R_ARM_JUMP24: case R_ARM_PREL31: #endif + case R_ARM_THM_PC22: + /* Should the interworking branches be listed here? */ if (h != NULL) { /* If this reloc is in a read-only section, we might @@ -4039,12 +4120,16 @@ elf32_arm_check_relocs (bfd *abfd, struct bfd_link_info *info, || r_type == R_ARM_JUMP24 || r_type == R_ARM_PREL31 #endif - || r_type == R_ARM_PLT32) + || r_type == R_ARM_PLT32 + || r_type == R_ARM_THM_PC22) h->needs_plt = 1; /* If we create a PLT entry, this relocation will reference it, even if it's an ABS32 relocation. */ h->plt.refcount += 1; + + if (r_type == R_ARM_THM_PC22) + eh->plt_thumb_refcount += 1; } /* If we are creating a shared library, and this is a reloc @@ -4068,7 +4153,8 @@ elf32_arm_check_relocs (bfd *abfd, struct bfd_link_info *info, && r_type != R_ARM_JUMP24 && r_type != R_ARM_PREL31 #endif - && r_type != R_ARM_REL32) + && r_type != R_ARM_REL32 + && r_type != R_ARM_THM_PC22) || (h != NULL && (! info->symbolic || !h->def_regular)))) @@ -4317,6 +4403,7 @@ elf32_arm_adjust_dynamic_symbol (struct bfd_link_info * info, bfd * dynobj; asection * s; unsigned int power_of_two; + struct elf32_arm_link_hash_entry * eh; dynobj = elf_hash_table (info)->dynobj; @@ -4328,10 +4415,12 @@ elf32_arm_adjust_dynamic_symbol (struct bfd_link_info * info, && h->ref_regular && !h->def_regular))); + eh = (struct elf32_arm_link_hash_entry *) h; + /* If this is a function, put it in the procedure linkage table. We will fill in the contents of the procedure linkage table later, when we know the address of the .got section. */ - if (h->type == STT_FUNC + if (h->type == STT_FUNC || h->type == STT_ARM_TFUNC || h->needs_plt) { if (h->plt.refcount <= 0 @@ -4345,18 +4434,22 @@ elf32_arm_adjust_dynamic_symbol (struct bfd_link_info * info, such a case, we don't actually need to build a procedure linkage table, and we can just do a PC24 reloc instead. */ h->plt.offset = (bfd_vma) -1; + eh->plt_thumb_refcount = 0; h->needs_plt = 0; } return TRUE; } else - /* It's possible that we incorrectly decided a .plt reloc was - needed for an R_ARM_PC24 or similar reloc to a non-function sym - in check_relocs. We can't decide accurately between function - and non-function syms in check-relocs; Objects loaded later in - the link may change h->type. So fix it now. */ - h->plt.offset = (bfd_vma) -1; + { + /* It's possible that we incorrectly decided a .plt reloc was + needed for an R_ARM_PC24 or similar reloc to a non-function sym + in check_relocs. We can't decide accurately between function + and non-function syms in check-relocs; Objects loaded later in + the link may change h->type. So fix it now. */ + h->plt.offset = (bfd_vma) -1; + eh->plt_thumb_refcount = 0; + } /* If this is a weak symbol, and there is a real definition, the processor independent code will have arranged for us to see the @@ -4441,6 +4534,8 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf) struct elf32_arm_link_hash_entry *eh; struct elf32_arm_relocs_copied *p; + eh = (struct elf32_arm_link_hash_entry *) h; + if (h->root.type == bfd_link_hash_indirect) return TRUE; @@ -4477,6 +4572,14 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf) h->plt.offset = s->size; + /* If we will insert a Thumb trampoline before this PLT, leave room + for it. */ + if (!htab->symbian_p && eh->plt_thumb_refcount > 0) + { + h->plt.offset += PLT_THUMB_STUB_SIZE; + s->size += PLT_THUMB_STUB_SIZE; + } + /* If this symbol is not defined in a regular file, and we are not generating a shared library, then set the symbol to this location in the .plt. This is required to make function @@ -4487,15 +4590,24 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf) { h->root.u.def.section = s; h->root.u.def.value = h->plt.offset; + + /* Make sure the function is not marked as Thumb, in case + it is the target of an ABS32 relocation, which will + point to the PLT entry. */ + if (ELF_ST_TYPE (h->type) == STT_ARM_TFUNC) + h->type = ELF_ST_INFO (ELF_ST_BIND (h->type), STT_FUNC); } /* Make room for this entry. */ s->size += htab->plt_entry_size; if (!htab->symbian_p) - /* We also need to make an entry in the .got.plt section, which - will be placed in the .got section by the linker script. */ - htab->sgotplt->size += 4; + { + /* We also need to make an entry in the .got.plt section, which + will be placed in the .got section by the linker script. */ + eh->plt_got_offset = htab->sgotplt->size; + htab->sgotplt->size += 4; + } /* We also need to make an entry in the .rel.plt section. */ htab->srelplt->size += sizeof (Elf32_External_Rel); @@ -4542,7 +4654,6 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf) else h->got.offset = (bfd_vma) -1; - eh = (struct elf32_arm_link_hash_entry *) h; if (eh->relocs_copied == NULL) return TRUE; @@ -4867,9 +4978,11 @@ elf32_arm_finish_dynamic_symbol (bfd * output_bfd, struct bfd_link_info * info, { bfd * dynobj; struct elf32_arm_link_hash_table *htab; + struct elf32_arm_link_hash_entry *eh; dynobj = elf_hash_table (info)->dynobj; htab = elf32_arm_hash_table (info); + eh = (struct elf32_arm_link_hash_entry *) h; if (h->plt.offset != (bfd_vma) -1) { @@ -4888,13 +5001,6 @@ elf32_arm_finish_dynamic_symbol (bfd * output_bfd, struct bfd_link_info * info, srel = bfd_get_section_by_name (dynobj, ".rel.plt"); BFD_ASSERT (splt != NULL && srel != NULL); - /* Get the index in the procedure linkage table which - corresponds to this symbol. This is the index of this symbol - in all the symbols for which we are making plt entries. The - first entry in the procedure linkage table is reserved. */ - plt_index = ((h->plt.offset - htab->plt_header_size) - / htab->plt_entry_size); - /* Fill in the entry in the procedure linkage table. */ if (htab->symbian_p) { @@ -4909,6 +5015,13 @@ elf32_arm_finish_dynamic_symbol (bfd * output_bfd, struct bfd_link_info * info, + splt->output_offset + h->plt.offset + 4 * (i - 1)); rel.r_info = ELF32_R_INFO (h->dynindx, R_ARM_GLOB_DAT); + + /* Get the index in the procedure linkage table which + corresponds to this symbol. This is the index of this symbol + in all the symbols for which we are making plt entries. The + first entry in the procedure linkage table is reserved. */ + plt_index = ((h->plt.offset - htab->plt_header_size) + / htab->plt_entry_size); } else { @@ -4919,13 +5032,21 @@ elf32_arm_finish_dynamic_symbol (bfd * output_bfd, struct bfd_link_info * info, sgot = bfd_get_section_by_name (dynobj, ".got.plt"); BFD_ASSERT (sgot != NULL); - /* Get the offset into the .got table of the entry that - corresponds to this function. Each .got entry is 4 bytes. - The first three are reserved. */ - got_offset = (plt_index + 3) * 4; + /* Get the offset into the .got.plt table of the entry that + corresponds to this function. */ + got_offset = eh->plt_got_offset; + + /* Get the index in the procedure linkage table which + corresponds to this symbol. This is the index of this symbol + in all the symbols for which we are making plt entries. The + first three entries in .got.plt are reserved; after that + symbols appear in the same order as in .plt. */ + plt_index = (got_offset - 12) / 4; /* Calculate the displacement between the PLT slot and the - entry in the GOT. */ + entry in the GOT. The eight-byte offset accounts for the + value produced by adding to pc in the first instruction + of the PLT stub. */ got_displacement = (sgot->output_section->vma + sgot->output_offset + got_offset @@ -4936,6 +5057,14 @@ elf32_arm_finish_dynamic_symbol (bfd * output_bfd, struct bfd_link_info * info, BFD_ASSERT ((got_displacement & 0xf0000000) == 0); + if (eh->plt_thumb_refcount > 0) + { + bfd_put_16 (output_bfd, elf32_arm_plt_thumb_stub[0], + splt->contents + h->plt.offset - 4); + bfd_put_16 (output_bfd, elf32_arm_plt_thumb_stub[1], + splt->contents + h->plt.offset - 2); + } + bfd_put_32 (output_bfd, elf32_arm_plt_entry[0] | ((got_displacement & 0x0ff00000) >> 20), splt->contents + h->plt.offset + 0); bfd_put_32 (output_bfd, elf32_arm_plt_entry[1] | ((got_displacement & 0x000ff000) >> 12), @@ -5521,6 +5650,18 @@ elf32_arm_write_section (bfd *output_bfd ATTRIBUTE_UNUSED, asection *sec, return FALSE; } +/* Display STT_ARM_TFUNC symbols as functions. */ + +static void +elf32_arm_symbol_processing (bfd *abfd ATTRIBUTE_UNUSED, + asymbol *asym) +{ + elf_symbol_type *elfsym = (elf_symbol_type *) asym; + + if (ELF_ST_TYPE (elfsym->internal_elf_sym.st_info) == STT_ARM_TFUNC) + elfsym->symbol.flags |= BSF_FUNCTION; +} + #define ELF_ARCH bfd_arch_arm #define ELF_MACHINE_CODE EM_ARM #ifdef __QNXTARGET__ @@ -5559,6 +5700,7 @@ elf32_arm_write_section (bfd *output_bfd ATTRIBUTE_UNUSED, asection *sec, #define elf_backend_section_from_shdr elf32_arm_section_from_shdr #define elf_backend_final_write_processing elf32_arm_final_write_processing #define elf_backend_copy_indirect_symbol elf32_arm_copy_indirect_symbol +#define elf_backend_symbol_processing elf32_arm_symbol_processing #define elf_backend_can_refcount 1 #define elf_backend_can_gc_sections 1 @@ -5691,4 +5833,3 @@ elf32_arm_symbian_modify_segment_map (bfd *abfd, #define elf_backend_want_got_plt 0 #include "elf32-target.h" - |