| /* Emulation code used by all ELF targets. |
| Copyright (C) 1991-2024 Free Software Foundation, Inc. |
| |
| This file is part of the GNU Binutils. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| MA 02110-1301, USA. */ |
| |
| #include "sysdep.h" |
| #include "libiberty.h" |
| #include "bfd.h" |
| #include "bfdlink.h" |
| #include "ctf-api.h" |
| #include "ld.h" |
| #include "ldmain.h" |
| #include "ldmisc.h" |
| #include "ldexp.h" |
| #include "ldlang.h" |
| #include "ldctor.h" |
| #include "elf-bfd.h" |
| #include "elf/internal.h" |
| #include "ldelfgen.h" |
| |
| /* Info attached to an output_section_statement about input sections, |
| used when sorting SHF_LINK_ORDER sections. */ |
| |
| struct os_sections |
| { |
| /* Size allocated for isec. */ |
| unsigned int alloc; |
| /* Used entries in isec. */ |
| unsigned int count; |
| /* How many are SHF_LINK_ORDER. */ |
| unsigned int ordered; |
| /* Input sections attached to this output section. */ |
| struct os_sections_input { |
| lang_input_section_type *is; |
| unsigned int idx; |
| } isec[1]; |
| }; |
| |
| /* Add IS to data kept for OS. */ |
| |
| static bool |
| add_link_order_input_section (lang_input_section_type *is, |
| lang_output_section_statement_type *os) |
| { |
| struct os_sections *os_info = os->data; |
| asection *s; |
| |
| if (os_info == NULL) |
| { |
| os_info = xmalloc (sizeof (*os_info) + 63 * sizeof (*os_info->isec)); |
| os_info->alloc = 64; |
| os_info->count = 0; |
| os_info->ordered = 0; |
| os->data = os_info; |
| } |
| if (os_info->count == os_info->alloc) |
| { |
| size_t want; |
| os_info->alloc *= 2; |
| want = sizeof (*os_info) + (os_info->alloc - 1) * sizeof (*os_info->isec); |
| os_info = xrealloc (os_info, want); |
| os->data = os_info; |
| } |
| os_info->isec[os_info->count].is = is; |
| os_info->isec[os_info->count].idx = os_info->count; |
| os_info->count++; |
| s = is->section; |
| if (bfd_get_flavour (s->owner) == bfd_target_elf_flavour |
| && (s->flags & SEC_LINKER_CREATED) == 0 |
| && elf_linked_to_section (s) != NULL) |
| os_info->ordered++; |
| return false; |
| } |
| |
| /* Run over the linker's statement list, extracting info about input |
| sections attached to each output section. */ |
| |
| static bool |
| link_order_scan (lang_statement_union_type *u, |
| lang_output_section_statement_type *os) |
| { |
| asection *s; |
| bool ret = false; |
| |
| for (; u != NULL; u = u->header.next) |
| { |
| switch (u->header.type) |
| { |
| case lang_wild_statement_enum: |
| if (link_order_scan (u->wild_statement.children.head, os)) |
| ret = true; |
| break; |
| case lang_constructors_statement_enum: |
| if (link_order_scan (constructor_list.head, os)) |
| ret = true; |
| break; |
| case lang_output_section_statement_enum: |
| if (u->output_section_statement.constraint != -1 |
| && link_order_scan (u->output_section_statement.children.head, |
| &u->output_section_statement)) |
| ret = true; |
| break; |
| case lang_group_statement_enum: |
| if (link_order_scan (u->group_statement.children.head, os)) |
| ret = true; |
| break; |
| case lang_input_section_enum: |
| s = u->input_section.section; |
| if (s->output_section != NULL |
| && s->output_section->owner == link_info.output_bfd |
| && (s->output_section->flags & SEC_EXCLUDE) == 0 |
| && ((s->output_section->flags & SEC_HAS_CONTENTS) != 0 |
| || ((s->output_section->flags & (SEC_LOAD | SEC_THREAD_LOCAL)) |
| == (SEC_LOAD | SEC_THREAD_LOCAL)))) |
| if (add_link_order_input_section (&u->input_section, os)) |
| ret = true; |
| break; |
| default: |
| break; |
| } |
| } |
| return ret; |
| } |
| |
| /* Compare two sections based on the locations of the sections they are |
| linked to. Used by fixup_link_order. */ |
| |
| static int |
| compare_link_order (const void *a, const void *b) |
| { |
| const struct os_sections_input *ai = a; |
| const struct os_sections_input *bi = b; |
| asection *asec = NULL; |
| asection *bsec = NULL; |
| bfd_vma apos, bpos; |
| |
| if (bfd_get_flavour (ai->is->section->owner) == bfd_target_elf_flavour) |
| asec = elf_linked_to_section (ai->is->section); |
| if (bfd_get_flavour (bi->is->section->owner) == bfd_target_elf_flavour) |
| bsec = elf_linked_to_section (bi->is->section); |
| |
| /* Place unordered sections before ordered sections. */ |
| if (asec == NULL || bsec == NULL) |
| { |
| if (bsec != NULL) |
| return -1; |
| else if (asec != NULL) |
| return 1; |
| return ai->idx - bi->idx; |
| } |
| |
| apos = asec->output_section->lma + asec->output_offset; |
| bpos = bsec->output_section->lma + bsec->output_offset; |
| |
| if (apos < bpos) |
| return -1; |
| else if (apos > bpos) |
| return 1; |
| |
| if (! bfd_link_relocatable (&link_info)) |
| { |
| /* The only way we should get matching LMAs is when the first of |
| the two sections has zero size, or asec and bsec are the |
| same section. */ |
| if (asec->size < bsec->size) |
| return -1; |
| else if (asec->size > bsec->size) |
| return 1; |
| } |
| |
| /* If they are both zero size then they almost certainly have the same |
| VMA and thus are not ordered with respect to each other. Test VMA |
| anyway, and fall back to idx to make the result reproducible across |
| qsort implementations. */ |
| apos = asec->output_section->vma + asec->output_offset; |
| bpos = bsec->output_section->vma + bsec->output_offset; |
| if (apos < bpos) |
| return -1; |
| else if (apos > bpos) |
| return 1; |
| else |
| return ai->idx - bi->idx; |
| } |
| |
| /* Rearrange sections with SHF_LINK_ORDER into the same order as their |
| linked sections. */ |
| |
| static bool |
| fixup_link_order (lang_output_section_statement_type *os) |
| { |
| struct os_sections *os_info = os->data; |
| unsigned int i, j; |
| lang_input_section_type **orig_is; |
| asection **save_s; |
| |
| for (i = 0; i < os_info->count; i = j) |
| { |
| /* Normally a linker script will select SHF_LINK_ORDER sections |
| with an input section wildcard something like the following: |
| *(.IA_64.unwind* .gnu.linkonce.ia64unw.*) |
| However if some other random sections are smashed into an |
| output section, or if SHF_LINK_ORDER are split up by the |
| linker script, then we only want to sort sections matching a |
| given wildcard. That's the purpose of the pattern test. */ |
| for (j = i + 1; j < os_info->count; j++) |
| if (os_info->isec[j].is->pattern != os_info->isec[i].is->pattern) |
| break; |
| if (j - i > 1) |
| qsort (&os_info->isec[i], j - i, sizeof (*os_info->isec), |
| compare_link_order); |
| } |
| for (i = 0; i < os_info->count; i++) |
| if (os_info->isec[i].idx != i) |
| break; |
| if (i == os_info->count) |
| return false; |
| |
| /* Now reorder the linker input section statements to reflect the |
| proper sorting. The is done by rewriting the existing statements |
| rather than fiddling with lists, since the only thing we need to |
| change is the bfd section pointer. */ |
| orig_is = xmalloc (os_info->count * sizeof (*orig_is)); |
| save_s = xmalloc (os_info->count * sizeof (*save_s)); |
| for (i = 0; i < os_info->count; i++) |
| { |
| orig_is[os_info->isec[i].idx] = os_info->isec[i].is; |
| save_s[i] = os_info->isec[i].is->section; |
| } |
| for (i = 0; i < os_info->count; i++) |
| if (os_info->isec[i].idx != i) |
| { |
| orig_is[i]->section = save_s[i]; |
| /* Restore os_info to pristine state before the qsort, for the |
| next pass over sections. */ |
| os_info->isec[i].is = orig_is[i]; |
| os_info->isec[i].idx = i; |
| } |
| free (save_s); |
| free (orig_is); |
| return true; |
| } |
| |
| void |
| ldelf_map_segments (bool need_layout) |
| { |
| int tries = 10; |
| static bool done_link_order_scan = false; |
| |
| do |
| { |
| lang_relax_sections (need_layout); |
| need_layout = false; |
| |
| if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour) |
| { |
| lang_output_section_statement_type *os; |
| if (!done_link_order_scan) |
| { |
| link_order_scan (statement_list.head, NULL); |
| done_link_order_scan = true; |
| } |
| for (os = (void *) lang_os_list.head; os != NULL; os = os->next) |
| { |
| struct os_sections *os_info = os->data; |
| if (os_info != NULL && os_info->ordered != 0) |
| { |
| if (os_info->ordered != os_info->count |
| && bfd_link_relocatable (&link_info)) |
| { |
| einfo (_("%F%P: " |
| "%pA has both ordered and unordered sections\n"), |
| os->bfd_section); |
| return; |
| } |
| if (os_info->count > 1 |
| && fixup_link_order (os)) |
| need_layout = true; |
| } |
| } |
| } |
| |
| if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour |
| && !bfd_link_relocatable (&link_info)) |
| { |
| bfd_size_type phdr_size; |
| |
| phdr_size = elf_program_header_size (link_info.output_bfd); |
| /* If we don't have user supplied phdrs, throw away any |
| previous linker generated program headers. */ |
| if (lang_phdr_list == NULL) |
| elf_seg_map (link_info.output_bfd) = NULL; |
| if (!_bfd_elf_map_sections_to_segments (link_info.output_bfd, |
| &link_info, |
| &need_layout)) |
| einfo (_("%F%P: map sections to segments failed: %E\n")); |
| |
| if (phdr_size != elf_program_header_size (link_info.output_bfd)) |
| { |
| if (tries > 6) |
| /* The first few times we allow any change to |
| phdr_size . */ |
| need_layout = true; |
| else if (phdr_size |
| < elf_program_header_size (link_info.output_bfd)) |
| /* After that we only allow the size to grow. */ |
| need_layout = true; |
| else |
| elf_program_header_size (link_info.output_bfd) = phdr_size; |
| } |
| } |
| } |
| while (need_layout && --tries); |
| |
| if (tries == 0) |
| einfo (_("%F%P: looping in map_segments\n")); |
| |
| if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour |
| && lang_phdr_list == NULL) |
| { |
| /* If we don't have user supplied phdrs, strip zero-sized dynamic |
| sections and regenerate program headers. */ |
| const struct elf_backend_data *bed |
| = get_elf_backend_data (link_info.output_bfd); |
| if (bed->elf_backend_strip_zero_sized_dynamic_sections |
| && !bed->elf_backend_strip_zero_sized_dynamic_sections |
| (&link_info)) |
| einfo (_("%F%P: failed to strip zero-sized dynamic sections\n")); |
| } |
| } |
| |
| #ifdef ENABLE_LIBCTF |
| /* We want to emit CTF early if and only if we are not targetting ELF with this |
| invocation. */ |
| |
| int |
| ldelf_emit_ctf_early (void) |
| { |
| if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour) |
| return 0; |
| return 1; |
| } |
| |
| /* Callbacks used to map from bfd types to libctf types, under libctf's |
| control. */ |
| |
| struct ctf_strtab_iter_cb_arg |
| { |
| struct elf_strtab_hash *strtab; |
| size_t next_i; |
| size_t next_idx; |
| }; |
| |
| /* Return strings from the strtab to libctf, one by one. Returns NULL when |
| iteration is complete. */ |
| |
| static const char * |
| ldelf_ctf_strtab_iter_cb (uint32_t *offset, void *arg_) |
| { |
| bfd_size_type off; |
| const char *ret; |
| |
| struct ctf_strtab_iter_cb_arg *arg = |
| (struct ctf_strtab_iter_cb_arg *) arg_; |
| |
| /* There is no zeroth string. */ |
| if (arg->next_i == 0) |
| arg->next_i = 1; |
| |
| /* Hunt through strings until we fall off the end or find one with |
| a nonzero refcount. */ |
| do |
| { |
| if (arg->next_i >= _bfd_elf_strtab_len (arg->strtab)) |
| { |
| arg->next_i = 0; |
| return NULL; |
| } |
| |
| ret = _bfd_elf_strtab_str (arg->strtab, arg->next_i++, &off); |
| } |
| while (ret == NULL); |
| |
| *offset = off; |
| |
| /* If we've overflowed, we cannot share any further strings: the CTF |
| format cannot encode strings with such high offsets. */ |
| if (*offset != off) |
| return NULL; |
| |
| return ret; |
| } |
| |
| void |
| ldelf_acquire_strings_for_ctf |
| (struct ctf_dict *ctf_output, struct elf_strtab_hash *strtab) |
| { |
| struct ctf_strtab_iter_cb_arg args = { strtab, 0, 0 }; |
| if (!ctf_output) |
| return; |
| |
| if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour) |
| { |
| if (ctf_link_add_strtab (ctf_output, ldelf_ctf_strtab_iter_cb, |
| &args) < 0) |
| einfo (_("%F%P: warning: CTF strtab association failed; strings will " |
| "not be shared: %s\n"), |
| ctf_errmsg (ctf_errno (ctf_output))); |
| } |
| } |
| |
| void |
| ldelf_new_dynsym_for_ctf (struct ctf_dict *ctf_output, int symidx, |
| struct elf_internal_sym *sym) |
| { |
| ctf_link_sym_t lsym; |
| |
| if (!ctf_output) |
| return; |
| |
| /* New symbol. */ |
| if (sym != NULL) |
| { |
| lsym.st_name = NULL; |
| lsym.st_nameidx = sym->st_name; |
| lsym.st_nameidx_set = 1; |
| lsym.st_symidx = symidx; |
| lsym.st_shndx = sym->st_shndx; |
| lsym.st_type = ELF_ST_TYPE (sym->st_info); |
| lsym.st_value = sym->st_value; |
| if (ctf_link_add_linker_symbol (ctf_output, &lsym) < 0) |
| { |
| einfo (_("%F%P: warning: CTF symbol addition failed; CTF will " |
| "not be tied to symbols: %s\n"), |
| ctf_errmsg (ctf_errno (ctf_output))); |
| } |
| } |
| else |
| { |
| /* Shuffle all the symbols. */ |
| |
| if (ctf_link_shuffle_syms (ctf_output) < 0) |
| einfo (_("%F%P: warning: CTF symbol shuffling failed; CTF will " |
| "not be tied to symbols: %s\n"), |
| ctf_errmsg (ctf_errno (ctf_output))); |
| } |
| } |
| #else |
| int |
| ldelf_emit_ctf_early (void) |
| { |
| return 0; |
| } |
| |
| void |
| ldelf_acquire_strings_for_ctf (struct ctf_dict *ctf_output ATTRIBUTE_UNUSED, |
| struct elf_strtab_hash *strtab ATTRIBUTE_UNUSED) |
| {} |
| void |
| ldelf_new_dynsym_for_ctf (struct ctf_dict *ctf_output ATTRIBUTE_UNUSED, |
| int symidx ATTRIBUTE_UNUSED, |
| struct elf_internal_sym *sym ATTRIBUTE_UNUSED) |
| {} |
| #endif |