diff options
Diffstat (limited to 'contrib/binutils/bfd/elf-eh-frame.c')
| -rw-r--r-- | contrib/binutils/bfd/elf-eh-frame.c | 1212 |
1 files changed, 1212 insertions, 0 deletions
diff --git a/contrib/binutils/bfd/elf-eh-frame.c b/contrib/binutils/bfd/elf-eh-frame.c new file mode 100644 index 0000000..b479c00 --- /dev/null +++ b/contrib/binutils/bfd/elf-eh-frame.c @@ -0,0 +1,1212 @@ +/* .eh_frame section optimization. + Copyright 2001, 2002 Free Software Foundation, Inc. + Written by Jakub Jelinek <jakub@redhat.com>. + +This file is part of BFD, the Binary File Descriptor library. + +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 2 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#include "bfd.h" +#include "sysdep.h" +#include "libbfd.h" +#include "elf-bfd.h" +#include "elf/dwarf2.h" + +#define EH_FRAME_HDR_SIZE 8 + +struct cie_header +{ + unsigned int length; + unsigned int id; +}; + +struct cie +{ + struct cie_header hdr; + unsigned char version; + unsigned char augmentation[20]; + unsigned int code_align; + int data_align; + unsigned int ra_column; + unsigned int augmentation_size; + struct elf_link_hash_entry *personality; + unsigned char per_encoding; + unsigned char lsda_encoding; + unsigned char fde_encoding; + unsigned char initial_insn_length; + unsigned char make_relative; + unsigned char make_lsda_relative; + unsigned char initial_instructions[50]; +}; + +struct eh_cie_fde +{ + unsigned int offset; + unsigned int size; + asection *sec; + unsigned int new_offset; + unsigned char fde_encoding; + unsigned char lsda_encoding; + unsigned char lsda_offset; + unsigned char cie : 1; + unsigned char removed : 1; + unsigned char make_relative : 1; + unsigned char make_lsda_relative : 1; +}; + +struct eh_frame_sec_info +{ + unsigned int count; + unsigned int alloced; + struct eh_cie_fde entry[1]; +}; + +struct eh_frame_array_ent +{ + bfd_vma initial_loc; + bfd_vma fde; +}; + +struct eh_frame_hdr_info +{ + struct cie last_cie; + asection *last_cie_sec; + unsigned int last_cie_offset; + unsigned int fde_count, array_count; + struct eh_frame_array_ent *array; + /* TRUE if .eh_frame_hdr should contain the sorted search table. + We build it if we successfully read all .eh_frame input sections + and recognize them. */ + boolean table; + boolean strip; +}; + +static bfd_vma read_unsigned_leb128 + PARAMS ((bfd *, char *, unsigned int *)); +static bfd_signed_vma read_signed_leb128 + PARAMS ((bfd *, char *, unsigned int *)); +static int get_DW_EH_PE_width + PARAMS ((int, int)); +static bfd_vma read_value + PARAMS ((bfd *, bfd_byte *, int)); +static void write_value + PARAMS ((bfd *, bfd_byte *, bfd_vma, int)); +static int cie_compare + PARAMS ((struct cie *, struct cie *)); +static int vma_compare + PARAMS ((const PTR a, const PTR b)); + +/* Helper function for reading uleb128 encoded data. */ + +static bfd_vma +read_unsigned_leb128 (abfd, buf, bytes_read_ptr) + bfd *abfd ATTRIBUTE_UNUSED; + char *buf; + unsigned int *bytes_read_ptr; +{ + bfd_vma result; + unsigned int num_read; + int shift; + unsigned char byte; + + result = 0; + shift = 0; + num_read = 0; + do + { + byte = bfd_get_8 (abfd, (bfd_byte *) buf); + buf ++; + num_read ++; + result |= (((bfd_vma) byte & 0x7f) << shift); + shift += 7; + } + while (byte & 0x80); + * bytes_read_ptr = num_read; + return result; +} + +/* Helper function for reading sleb128 encoded data. */ + +static bfd_signed_vma +read_signed_leb128 (abfd, buf, bytes_read_ptr) + bfd *abfd ATTRIBUTE_UNUSED; + char *buf; + unsigned int * bytes_read_ptr; +{ + bfd_vma result; + int shift; + int num_read; + unsigned char byte; + + result = 0; + shift = 0; + num_read = 0; + do + { + byte = bfd_get_8 (abfd, (bfd_byte *) buf); + buf ++; + num_read ++; + result |= (((bfd_vma) byte & 0x7f) << shift); + shift += 7; + } + while (byte & 0x80); + if (byte & 0x40) + result |= (((bfd_vma) -1) << (shift - 7)) << 7; + * bytes_read_ptr = num_read; + return result; +} + +#define read_uleb128(VAR, BUF) \ +do \ + { \ + (VAR) = read_unsigned_leb128 (abfd, buf, &leb128_tmp); \ + (BUF) += leb128_tmp; \ + } \ +while (0) + +#define read_sleb128(VAR, BUF) \ +do \ + { \ + (VAR) = read_signed_leb128 (abfd, buf, &leb128_tmp); \ + (BUF) += leb128_tmp; \ + } \ +while (0) + +/* Return 0 if either encoding is variable width, or not yet known to bfd. */ + +static +int get_DW_EH_PE_width (encoding, ptr_size) + int encoding, ptr_size; +{ + /* DW_EH_PE_ values of 0x60 and 0x70 weren't defined at the time .eh_frame + was added to bfd. */ + if ((encoding & 0x60) == 0x60) + return 0; + + switch (encoding & 7) + { + case DW_EH_PE_udata2: return 2; + case DW_EH_PE_udata4: return 4; + case DW_EH_PE_udata8: return 8; + case DW_EH_PE_absptr: return ptr_size; + default: + break; + } + + return 0; +} + +/* Read a width sized value from memory. */ + +static bfd_vma +read_value (abfd, buf, width) + bfd *abfd; + bfd_byte *buf; + int width; +{ + bfd_vma value; + + switch (width) + { + case 2: value = bfd_get_16 (abfd, buf); break; + case 4: value = bfd_get_32 (abfd, buf); break; + case 8: value = bfd_get_64 (abfd, buf); break; + default: BFD_FAIL (); return 0; + } + + return value; +} + +/* Store a width sized value to memory. */ + +static void +write_value (abfd, buf, value, width) + bfd *abfd; + bfd_byte *buf; + bfd_vma value; + int width; +{ + switch (width) + { + case 2: bfd_put_16 (abfd, value, buf); break; + case 4: bfd_put_32 (abfd, value, buf); break; + case 8: bfd_put_64 (abfd, value, buf); break; + default: BFD_FAIL (); + } +} + +/* Return zero if C1 and C2 CIEs can be merged. */ + +static +int cie_compare (c1, c2) + struct cie *c1, *c2; +{ + if (c1->hdr.length == c2->hdr.length + && c1->version == c2->version + && strcmp (c1->augmentation, c2->augmentation) == 0 + && strcmp (c1->augmentation, "eh") != 0 + && c1->code_align == c2->code_align + && c1->data_align == c2->data_align + && c1->ra_column == c2->ra_column + && c1->augmentation_size == c2->augmentation_size + && c1->personality == c2->personality + && c1->per_encoding == c2->per_encoding + && c1->lsda_encoding == c2->lsda_encoding + && c1->fde_encoding == c2->fde_encoding + && (c1->initial_insn_length + == c2->initial_insn_length) + && memcmp (c1->initial_instructions, + c2->initial_instructions, + c1->initial_insn_length) == 0) + return 0; + + return 1; +} + +/* This function is called for each input file before the .eh_frame + section is relocated. It discards duplicate CIEs and FDEs for discarded + functions. The function returns true iff any entries have been + deleted. */ + +boolean +_bfd_elf_discard_section_eh_frame (abfd, info, sec, ehdrsec, + reloc_symbol_deleted_p, cookie) + bfd *abfd; + struct bfd_link_info *info; + asection *sec, *ehdrsec; + boolean (*reloc_symbol_deleted_p) (bfd_vma, PTR); + struct elf_reloc_cookie *cookie; +{ + bfd_byte *ehbuf = NULL, *buf; + bfd_byte *last_cie, *last_fde; + struct cie_header hdr; + struct cie cie; + struct eh_frame_hdr_info *hdr_info; + struct eh_frame_sec_info *sec_info = NULL; + unsigned int leb128_tmp; + unsigned int cie_usage_count, last_cie_ndx, i, offset; + unsigned int make_relative, make_lsda_relative; + Elf_Internal_Rela *rel; + bfd_size_type new_size; + unsigned int ptr_size; + + if (sec->_raw_size == 0) + { + /* This file does not contain .eh_frame information. */ + return false; + } + + if ((sec->output_section != NULL + && bfd_is_abs_section (sec->output_section))) + { + /* At least one of the sections is being discarded from the + link, so we should just ignore them. */ + return false; + } + + BFD_ASSERT (elf_section_data (ehdrsec)->sec_info_type + == ELF_INFO_TYPE_EH_FRAME_HDR); + hdr_info = (struct eh_frame_hdr_info *) + elf_section_data (ehdrsec)->sec_info; + + /* Read the frame unwind information from abfd. */ + + ehbuf = (bfd_byte *) bfd_malloc (sec->_raw_size); + if (ehbuf == NULL) + goto free_no_table; + + if (! bfd_get_section_contents (abfd, sec, ehbuf, (bfd_vma) 0, + sec->_raw_size)) + goto free_no_table; + + if (sec->_raw_size >= 4 + && bfd_get_32 (abfd, ehbuf) == 0 + && cookie->rel == cookie->relend) + { + /* Empty .eh_frame section. */ + free (ehbuf); + return false; + } + + /* If .eh_frame section size doesn't fit into int, we cannot handle + it (it would need to use 64-bit .eh_frame format anyway). */ + if (sec->_raw_size != (unsigned int) sec->_raw_size) + goto free_no_table; + + ptr_size = (elf_elfheader (abfd)->e_ident[EI_CLASS] + == ELFCLASS64) ? 8 : 4; + buf = ehbuf; + last_cie = NULL; + last_cie_ndx = 0; + memset (&cie, 0, sizeof (cie)); + cie_usage_count = 0; + new_size = sec->_raw_size; + make_relative = hdr_info->last_cie.make_relative; + make_lsda_relative = hdr_info->last_cie.make_lsda_relative; + sec_info = bfd_zmalloc (sizeof (struct eh_frame_sec_info) + + 99 * sizeof (struct eh_cie_fde)); + if (sec_info == NULL) + goto free_no_table; + sec_info->alloced = 100; + +#define ENSURE_NO_RELOCS(buf) \ + if (cookie->rel < cookie->relend \ + && (cookie->rel->r_offset \ + < (bfd_size_type) ((buf) - ehbuf))) \ + goto free_no_table + +#define SKIP_RELOCS(buf) \ + while (cookie->rel < cookie->relend \ + && (cookie->rel->r_offset \ + < (bfd_size_type) ((buf) - ehbuf))) \ + cookie->rel++ + +#define GET_RELOC(buf) \ + ((cookie->rel < cookie->relend \ + && (cookie->rel->r_offset \ + == (bfd_size_type) ((buf) - ehbuf))) \ + ? cookie->rel : NULL) + + for (;;) + { + unsigned char *aug; + + if (sec_info->count == sec_info->alloced) + { + sec_info = bfd_realloc (sec_info, + sizeof (struct eh_frame_sec_info) + + (sec_info->alloced + 99) + * sizeof (struct eh_cie_fde)); + if (sec_info == NULL) + goto free_no_table; + + memset (&sec_info->entry[sec_info->alloced], 0, + 100 * sizeof (struct eh_cie_fde)); + sec_info->alloced += 100; + } + + last_fde = buf; + /* If we are at the end of the section, we still need to decide + on whether to output or discard last encountered CIE (if any). */ + if ((bfd_size_type) (buf - ehbuf) == sec->_raw_size) + hdr.id = (unsigned int) -1; + else + { + if ((bfd_size_type) (buf + 4 - ehbuf) > sec->_raw_size) + /* No space for CIE/FDE header length. */ + goto free_no_table; + + hdr.length = bfd_get_32 (abfd, buf); + if (hdr.length == 0xffffffff) + /* 64-bit .eh_frame is not supported. */ + goto free_no_table; + buf += 4; + if ((buf - ehbuf) + hdr.length > sec->_raw_size) + /* CIE/FDE not contained fully in this .eh_frame input section. */ + goto free_no_table; + + sec_info->entry[sec_info->count].offset = last_fde - ehbuf; + sec_info->entry[sec_info->count].size = 4 + hdr.length; + + if (hdr.length == 0) + { + /* CIE with length 0 must be only the last in the section. */ + if ((bfd_size_type) (buf - ehbuf) < sec->_raw_size) + goto free_no_table; + ENSURE_NO_RELOCS (buf); + sec_info->count++; + /* Now just finish last encountered CIE processing and break + the loop. */ + hdr.id = (unsigned int) -1; + } + else + { + hdr.id = bfd_get_32 (abfd, buf); + buf += 4; + if (hdr.id == (unsigned int) -1) + goto free_no_table; + } + } + + if (hdr.id == 0 || hdr.id == (unsigned int) -1) + { + unsigned int initial_insn_length; + + /* CIE */ + if (last_cie != NULL) + { + /* Now check if this CIE is identical to last CIE, in which case + we can remove it, provided we adjust all FDEs. + Also, it can be removed if we have removed all FDEs using + that. */ + if (cie_compare (&cie, &hdr_info->last_cie) == 0 + || cie_usage_count == 0) + { + new_size -= cie.hdr.length + 4; + sec_info->entry[last_cie_ndx].removed = 1; + sec_info->entry[last_cie_ndx].sec = hdr_info->last_cie_sec; + sec_info->entry[last_cie_ndx].new_offset + = hdr_info->last_cie_offset; + } + else + { + hdr_info->last_cie = cie; + hdr_info->last_cie_sec = sec; + hdr_info->last_cie_offset = last_cie - ehbuf; + sec_info->entry[last_cie_ndx].make_relative + = cie.make_relative; + sec_info->entry[last_cie_ndx].make_lsda_relative + = cie.make_lsda_relative; + } + } + + if (hdr.id == (unsigned int) -1) + break; + + last_cie_ndx = sec_info->count; + sec_info->entry[sec_info->count].cie = 1; + + cie_usage_count = 0; + memset (&cie, 0, sizeof (cie)); + cie.hdr = hdr; + cie.version = *buf++; + + /* Cannot handle unknown versions. */ + if (cie.version != 1) + goto free_no_table; + if (strlen (buf) > sizeof (cie.augmentation) - 1) + goto free_no_table; + + strcpy (cie.augmentation, buf); + buf = strchr (buf, '\0') + 1; + ENSURE_NO_RELOCS (buf); + if (buf[0] == 'e' && buf[1] == 'h') + { + /* GCC < 3.0 .eh_frame CIE */ + /* We cannot merge "eh" CIEs because __EXCEPTION_TABLE__ + is private to each CIE, so we don't need it for anything. + Just skip it. */ + buf += ptr_size; + SKIP_RELOCS (buf); + } + read_uleb128 (cie.code_align, buf); + read_sleb128 (cie.data_align, buf); + read_uleb128 (cie.ra_column, buf); + ENSURE_NO_RELOCS (buf); + cie.lsda_encoding = DW_EH_PE_omit; + cie.fde_encoding = DW_EH_PE_omit; + cie.per_encoding = DW_EH_PE_omit; + aug = cie.augmentation; + if (aug[0] != 'e' || aug[1] != 'h') + { + if (*aug == 'z') + { + aug++; + read_uleb128 (cie.augmentation_size, buf); + ENSURE_NO_RELOCS (buf); + } + + while (*aug != '\0') + switch (*aug++) + { + case 'L': + cie.lsda_encoding = *buf++; + ENSURE_NO_RELOCS (buf); + if (get_DW_EH_PE_width (cie.lsda_encoding, ptr_size) == 0) + goto free_no_table; + break; + case 'R': + cie.fde_encoding = *buf++; + ENSURE_NO_RELOCS (buf); + if (get_DW_EH_PE_width (cie.fde_encoding, ptr_size) == 0) + goto free_no_table; + break; + case 'P': + { + int per_width; + + cie.per_encoding = *buf++; + per_width = get_DW_EH_PE_width (cie.per_encoding, + ptr_size); + if (per_width == 0) + goto free_no_table; + if ((cie.per_encoding & 0xf0) == DW_EH_PE_aligned) + buf = (ehbuf + + ((buf - ehbuf + per_width - 1) + & ~((bfd_size_type) per_width - 1))); + ENSURE_NO_RELOCS (buf); + rel = GET_RELOC (buf); + /* Ensure we have a reloc here, against + a global symbol. */ + if (rel != NULL) + { + unsigned long r_symndx; + +#ifdef BFD64 + if (ptr_size == 8) + r_symndx = ELF64_R_SYM (cookie->rel->r_info); + else +#endif + r_symndx = ELF32_R_SYM (cookie->rel->r_info); + if (r_symndx >= cookie->locsymcount) + { + struct elf_link_hash_entry *h; + + r_symndx -= cookie->extsymoff; + h = cookie->sym_hashes[r_symndx]; + + while (h->root.type == bfd_link_hash_indirect + || h->root.type == bfd_link_hash_warning) + h = (struct elf_link_hash_entry *) + h->root.u.i.link; + + cie.personality = h; + } + cookie->rel++; + } + buf += per_width; + } + break; + default: + /* Unrecognized augmentation. Better bail out. */ + goto free_no_table; + } + } + + /* For shared libraries, try to get rid of as many RELATIVE relocs + as possible. + FIXME: For this to work, ELF backends need to perform the + relocation if omitting dynamic relocs, not skip it. */ + if (0 + && info->shared + && (cie.fde_encoding & 0xf0) == DW_EH_PE_absptr) + cie.make_relative = 1; + + if (0 + && info->shared + && (cie.lsda_encoding & 0xf0) == DW_EH_PE_absptr) + cie.make_lsda_relative = 1; + + /* If FDE encoding was not specified, it defaults to + DW_EH_absptr. */ + if (cie.fde_encoding == DW_EH_PE_omit) + cie.fde_encoding = DW_EH_PE_absptr; + + initial_insn_length = cie.hdr.length - (buf - last_fde - 4); + if (initial_insn_length <= 50) + { + cie.initial_insn_length = initial_insn_length; + memcpy (cie.initial_instructions, buf, initial_insn_length); + } + buf += initial_insn_length; + ENSURE_NO_RELOCS (buf); + last_cie = last_fde; + } + else + { + /* Ensure this FDE uses the last CIE encountered. */ + if (last_cie == NULL + || hdr.id != (unsigned int) (buf - 4 - last_cie)) + goto free_no_table; + + ENSURE_NO_RELOCS (buf); + rel = GET_RELOC (buf); + if (rel == NULL) + /* This should not happen. */ + goto free_no_table; + if ((*reloc_symbol_deleted_p) (buf - ehbuf, cookie)) + { + cookie->rel = rel; + /* This is a FDE against discarded section, it should + be deleted. */ + new_size -= hdr.length + 4; + sec_info->entry[sec_info->count].removed = 1; + } + else + { + cie_usage_count++; + hdr_info->fde_count++; + } + cookie->rel = rel; + if (cie.lsda_encoding != DW_EH_PE_omit) + { + unsigned int dummy; + + aug = buf; + buf += 2 * get_DW_EH_PE_width (cie.fde_encoding, ptr_size); + if (cie.augmentation[0] == 'z') + read_uleb128 (dummy, buf); + /* If some new augmentation data is added before LSDA + in FDE augmentation area, this need to be adjusted. */ + sec_info->entry[sec_info->count].lsda_offset = (buf - aug); + } + buf = last_fde + 4 + hdr.length; + SKIP_RELOCS (buf); + } + + sec_info->entry[sec_info->count].fde_encoding = cie.fde_encoding; + sec_info->entry[sec_info->count].lsda_encoding = cie.lsda_encoding; + sec_info->count++; + } + + elf_section_data (sec)->sec_info = sec_info; + elf_section_data (sec)->sec_info_type = ELF_INFO_TYPE_EH_FRAME; + + /* Ok, now we can assign new offsets. */ + offset = 0; + last_cie_ndx = 0; + for (i = 0; i < sec_info->count; i++) + { + if (! sec_info->entry[i].removed) + { + sec_info->entry[i].new_offset = offset; + offset += sec_info->entry[i].size; + if (sec_info->entry[i].cie) + { + last_cie_ndx = i; + make_relative = sec_info->entry[i].make_relative; + make_lsda_relative = sec_info->entry[i].make_lsda_relative; + } + else + { + sec_info->entry[i].make_relative = make_relative; + sec_info->entry[i].make_lsda_relative = make_lsda_relative; + } + } + else if (sec_info->entry[i].cie && sec_info->entry[i].sec == sec) + { + /* Need to adjust new_offset too. */ + BFD_ASSERT (sec_info->entry[last_cie_ndx].offset + == sec_info->entry[i].new_offset); + sec_info->entry[i].new_offset + = sec_info->entry[last_cie_ndx].new_offset; + } + } + if (hdr_info->last_cie_sec == sec) + { + BFD_ASSERT (sec_info->entry[last_cie_ndx].offset + == hdr_info->last_cie_offset); + hdr_info->last_cie_offset = sec_info->entry[last_cie_ndx].new_offset; + } + + /* FIXME: Currently it is not possible to shrink sections to zero size at + this point, so build a fake minimal CIE. */ + if (new_size == 0) + new_size = 16; + + /* Shrink the sec as needed. */ + sec->_cooked_size = new_size; + if (sec->_cooked_size == 0) + sec->flags |= SEC_EXCLUDE; + + free (ehbuf); + return new_size != sec->_raw_size; + +free_no_table: + if (ehbuf) + free (ehbuf); + if (sec_info) + free (sec_info); + hdr_info->table = false; + hdr_info->last_cie.hdr.length = 0; + return false; +} + +/* This function is called for .eh_frame_hdr section after + _bfd_elf_discard_section_eh_frame has been called on all .eh_frame + input sections. It finalizes the size of .eh_frame_hdr section. */ + +boolean +_bfd_elf_discard_section_eh_frame_hdr (abfd, info, sec) + bfd *abfd; + struct bfd_link_info *info; + asection *sec; +{ + struct eh_frame_hdr_info *hdr_info; + unsigned int ptr_size; + + ptr_size = (elf_elfheader (abfd)->e_ident[EI_CLASS] + == ELFCLASS64) ? 8 : 4; + + if ((elf_section_data (sec)->sec_info_type + != ELF_INFO_TYPE_EH_FRAME_HDR) + || ! info->eh_frame_hdr) + { + _bfd_strip_section_from_output (info, sec); + return false; + } + + hdr_info = (struct eh_frame_hdr_info *) + elf_section_data (sec)->sec_info; + if (hdr_info->strip) + return false; + sec->_cooked_size = EH_FRAME_HDR_SIZE; + if (hdr_info->table) + sec->_cooked_size += 4 + hdr_info->fde_count * 8; + + /* Request program headers to be recalculated. */ + elf_tdata (abfd)->program_header_size = 0; + elf_tdata (abfd)->eh_frame_hdr = true; + return true; +} + +/* This function is called from size_dynamic_sections. + It needs to decide whether .eh_frame_hdr should be output or not, + because later on it is too late for calling _bfd_strip_section_from_output, + since dynamic symbol table has been sized. */ + +boolean +_bfd_elf_maybe_strip_eh_frame_hdr (info) + struct bfd_link_info *info; +{ + asection *sec, *o; + bfd *abfd; + struct eh_frame_hdr_info *hdr_info; + + sec = bfd_get_section_by_name (elf_hash_table (info)->dynobj, ".eh_frame_hdr"); + if (sec == NULL) + return true; + + hdr_info + = bfd_zmalloc (sizeof (struct eh_frame_hdr_info)); + if (hdr_info == NULL) + return false; + + elf_section_data (sec)->sec_info = hdr_info; + elf_section_data (sec)->sec_info_type = ELF_INFO_TYPE_EH_FRAME_HDR; + + abfd = NULL; + if (info->eh_frame_hdr) + for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next) + { + /* Count only sections which have at least a single CIE or FDE. + There cannot be any CIE or FDE <= 8 bytes. */ + o = bfd_get_section_by_name (abfd, ".eh_frame"); + if (o && o->_raw_size > 8) + break; + } + + if (abfd == NULL) + { + _bfd_strip_section_from_output (info, sec); + hdr_info->strip = true; + } + else + hdr_info->table = true; + return true; +} + +/* Adjust an address in the .eh_frame section. Given OFFSET within + SEC, this returns the new offset in the adjusted .eh_frame section, + or -1 if the address refers to a CIE/FDE which has been removed + or to offset with dynamic relocation which is no longer needed. */ + +bfd_vma +_bfd_elf_eh_frame_section_offset (output_bfd, sec, offset) + bfd *output_bfd ATTRIBUTE_UNUSED; + asection *sec; + bfd_vma offset; +{ + struct eh_frame_sec_info *sec_info; + unsigned int lo, hi, mid; + + if (elf_section_data (sec)->sec_info_type != ELF_INFO_TYPE_EH_FRAME) + return offset; + sec_info = (struct eh_frame_sec_info *) + elf_section_data (sec)->sec_info; + + if (offset >= sec->_raw_size) + return offset - (sec->_cooked_size - sec->_raw_size); + + lo = 0; + hi = sec_info->count; + mid = 0; + while (lo < hi) + { + mid = (lo + hi) / 2; + if (offset < sec_info->entry[mid].offset) + hi = mid; + else if (offset + >= sec_info->entry[mid].offset + sec_info->entry[mid].size) + lo = mid + 1; + else + break; + } + + BFD_ASSERT (lo < hi); + + /* FDE or CIE was removed. */ + if (sec_info->entry[mid].removed) + return (bfd_vma) -1; + + /* If converting to DW_EH_PE_pcrel, there will be no need for run-time + relocation against FDE's initial_location field. */ + if (sec_info->entry[mid].make_relative + && ! sec_info->entry[mid].cie + && offset == sec_info->entry[mid].offset + 8) + return (bfd_vma) -1; + + /* If converting LSDA pointers to DW_EH_PE_pcrel, there will be no need + for run-time relocation against LSDA field. */ + if (sec_info->entry[mid].make_lsda_relative + && ! sec_info->entry[mid].cie + && (offset + == (sec_info->entry[mid].offset + 8 + + sec_info->entry[mid].lsda_offset))) + return (bfd_vma) -1; + + return (offset + sec_info->entry[mid].new_offset + - sec_info->entry[mid].offset); +} + +/* Write out .eh_frame section. This is called with the relocated + contents. */ + +boolean +_bfd_elf_write_section_eh_frame (abfd, sec, ehdrsec, contents) + bfd *abfd; + asection *sec, *ehdrsec; + bfd_byte *contents; +{ + struct eh_frame_sec_info *sec_info; + struct eh_frame_hdr_info *hdr_info; + unsigned int i; + bfd_byte *p, *buf; + unsigned int leb128_tmp; + unsigned int cie_offset = 0; + unsigned int ptr_size; + + ptr_size = (elf_elfheader (sec->owner)->e_ident[EI_CLASS] + == ELFCLASS64) ? 8 : 4; + + if (elf_section_data (sec)->sec_info_type != ELF_INFO_TYPE_EH_FRAME) + return bfd_set_section_contents (abfd, sec->output_section, + contents, + (file_ptr) sec->output_offset, + sec->_raw_size); + sec_info = (struct eh_frame_sec_info *) + elf_section_data (sec)->sec_info; + hdr_info = NULL; + if (ehdrsec + && (elf_section_data (ehdrsec)->sec_info_type + == ELF_INFO_TYPE_EH_FRAME_HDR)) + { + hdr_info = (struct eh_frame_hdr_info *) + elf_section_data (ehdrsec)->sec_info; + if (hdr_info->table && hdr_info->array == NULL) + hdr_info->array + = bfd_malloc (hdr_info->fde_count * sizeof(*hdr_info->array)); + if (hdr_info->array == NULL) + hdr_info = NULL; + } + + p = contents; + for (i = 0; i < sec_info->count; ++i) + { + if (sec_info->entry[i].removed) + { + if (sec_info->entry[i].cie) + { + /* If CIE is removed due to no remaining FDEs referencing it + and there were no CIEs kept before it, sec_info->entry[i].sec + will be zero. */ + if (sec_info->entry[i].sec == NULL) + cie_offset = 0; + else + { + cie_offset = sec_info->entry[i].new_offset; + cie_offset += (sec_info->entry[i].sec->output_section->vma + + sec_info->entry[i].sec->output_offset + - sec->output_section->vma + - sec->output_offset); + } + } + continue; + } + + if (sec_info->entry[i].cie) + { + /* CIE */ + cie_offset = sec_info->entry[i].new_offset; + if (sec_info->entry[i].make_relative + || sec_info->entry[i].make_lsda_relative) + { + unsigned char *aug; + unsigned int action; + unsigned int dummy, per_width, per_encoding; + + /* Need to find 'R' or 'L' augmentation's argument and modify + DW_EH_PE_* value. */ + action = (sec_info->entry[i].make_relative ? 1 : 0) + | (sec_info->entry[i].make_lsda_relative ? 2 : 0); + buf = contents + sec_info->entry[i].offset; + /* Skip length, id and version. */ + buf += 9; + aug = buf; + buf = strchr (buf, '\0') + 1; + read_uleb128 (dummy, buf); + read_sleb128 (dummy, buf); + read_uleb128 (dummy, buf); + if (*aug == 'z') + { + read_uleb128 (dummy, buf); + aug++; + } + + while (action) + switch (*aug++) + { + case 'L': + if (action & 2) + { + BFD_ASSERT (*buf == sec_info->entry[i].lsda_encoding); + *buf |= DW_EH_PE_pcrel; + action &= ~2; + } + buf++; + break; + case 'P': + per_encoding = *buf++; + per_width = get_DW_EH_PE_width (per_encoding, + ptr_size); + BFD_ASSERT (per_width != 0); + if ((per_encoding & 0xf0) == DW_EH_PE_aligned) + buf = (contents + + ((buf - contents + per_width - 1) + & ~((bfd_size_type) per_width - 1))); + buf += per_width; + break; + case 'R': + if (action & 1) + { + BFD_ASSERT (*buf == sec_info->entry[i].fde_encoding); + *buf |= DW_EH_PE_pcrel; + action &= ~1; + } + buf++; + break; + default: + BFD_FAIL (); + } + } + } + else + { + /* FDE */ + bfd_vma value = 0, address; + unsigned int width; + + buf = contents + sec_info->entry[i].offset; + /* Skip length. */ + buf += 4; + bfd_put_32 (abfd, + sec_info->entry[i].new_offset + 4 - cie_offset, buf); + buf += 4; + width = get_DW_EH_PE_width (sec_info->entry[i].fde_encoding, + ptr_size); + address = value = read_value (abfd, buf, width); + if (value) + { + switch (sec_info->entry[i].fde_encoding & 0xf0) + { + case DW_EH_PE_indirect: + case DW_EH_PE_textrel: + BFD_ASSERT (hdr_info == NULL); + break; + case DW_EH_PE_datarel: + { + asection *got = bfd_get_section_by_name (abfd, ".got"); + + BFD_ASSERT (got != NULL); + address += got->vma; + } + break; + case DW_EH_PE_pcrel: + value += (sec_info->entry[i].offset + - sec_info->entry[i].new_offset); + address += (sec->output_section->vma + sec->output_offset + + sec_info->entry[i].offset + 8); + break; + } + if (sec_info->entry[i].make_relative) + value -= (sec->output_section->vma + sec->output_offset + + sec_info->entry[i].new_offset + 8); + write_value (abfd, buf, value, width); + } + + if (hdr_info) + { + hdr_info->array[hdr_info->array_count].initial_loc = address; + hdr_info->array[hdr_info->array_count++].fde + = (sec->output_section->vma + sec->output_offset + + sec_info->entry[i].new_offset); + } + + if ((sec_info->entry[i].lsda_encoding & 0xf0) == DW_EH_PE_pcrel + || sec_info->entry[i].make_lsda_relative) + { + buf += sec_info->entry[i].lsda_offset; + width = get_DW_EH_PE_width (sec_info->entry[i].lsda_encoding, + ptr_size); + value = read_value (abfd, buf, width); + if (value) + { + if ((sec_info->entry[i].lsda_encoding & 0xf0) + == DW_EH_PE_pcrel) + value += (sec_info->entry[i].offset + - sec_info->entry[i].new_offset); + else if (sec_info->entry[i].make_lsda_relative) + value -= (sec->output_section->vma + sec->output_offset + + sec_info->entry[i].new_offset + 8 + + sec_info->entry[i].lsda_offset); + write_value (abfd, buf, value, width); + } + } + } + + BFD_ASSERT (p == contents + sec_info->entry[i].new_offset); + memmove (p, contents + sec_info->entry[i].offset, + sec_info->entry[i].size); + p += sec_info->entry[i].size; + } + + /* FIXME: Once _bfd_elf_discard_section_eh_frame will be able to + shrink sections to zero size, this won't be needed any more. */ + if (p == contents && sec->_cooked_size == 16) + { + bfd_put_32 (abfd, 12, p); /* Fake CIE length */ + bfd_put_32 (abfd, 0, p + 4); /* Fake CIE id */ + p[8] = 1; /* Fake CIE version */ + memset (p + 9, 0, 7); /* Fake CIE augmentation, 3xleb128 + and 3xDW_CFA_nop as pad */ + p += 16; + } + + BFD_ASSERT ((bfd_size_type) (p - contents) == sec->_cooked_size); + + return bfd_set_section_contents (abfd, sec->output_section, + contents, (file_ptr) sec->output_offset, + sec->_cooked_size); +} + +/* Helper function used to sort .eh_frame_hdr search table by increasing + VMA of FDE initial location. */ + +static int +vma_compare (a, b) + const PTR a; + const PTR b; +{ + struct eh_frame_array_ent *p = (struct eh_frame_array_ent *) a; + struct eh_frame_array_ent *q = (struct eh_frame_array_ent *) b; + if (p->initial_loc > q->initial_loc) + return 1; + if (p->initial_loc < q->initial_loc) + return -1; + return 0; +} + +/* Write out .eh_frame_hdr section. This must be called after + _bfd_elf_write_section_eh_frame has been called on all input + .eh_frame sections. + .eh_frame_hdr format: + ubyte version (currently 1) + ubyte eh_frame_ptr_enc (DW_EH_PE_* encoding of pointer to start of + .eh_frame section) + ubyte fde_count_enc (DW_EH_PE_* encoding of total FDE count + number (or DW_EH_PE_omit if there is no + binary search table computed)) + ubyte table_enc (DW_EH_PE_* encoding of binary search table, + or DW_EH_PE_omit if not present. + DW_EH_PE_datarel is using address of + .eh_frame_hdr section start as base) + [encoded] eh_frame_ptr (pointer to start of .eh_frame section) + optionally followed by: + [encoded] fde_count (total number of FDEs in .eh_frame section) + fde_count x [encoded] initial_loc, fde + (array of encoded pairs containing + FDE initial_location field and FDE address, + sorted by increasing initial_loc) */ + +boolean +_bfd_elf_write_section_eh_frame_hdr (abfd, sec) + bfd *abfd; + asection *sec; +{ + struct eh_frame_hdr_info *hdr_info; + unsigned int ptr_size; + bfd_byte *contents; + asection *eh_frame_sec; + bfd_size_type size; + + ptr_size = (elf_elfheader (sec->owner)->e_ident[EI_CLASS] + == ELFCLASS64) ? 8 : 4; + + BFD_ASSERT (elf_section_data (sec)->sec_info_type + == ELF_INFO_TYPE_EH_FRAME_HDR); + hdr_info = (struct eh_frame_hdr_info *) + elf_section_data (sec)->sec_info; + if (hdr_info->strip) + return true; + + size = EH_FRAME_HDR_SIZE; + if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count) + size += 4 + hdr_info->fde_count * 8; + contents = bfd_malloc (size); + if (contents == NULL) + return false; + + eh_frame_sec = bfd_get_section_by_name (abfd, ".eh_frame"); + if (eh_frame_sec == NULL) + return false; + + memset (contents, 0, EH_FRAME_HDR_SIZE); + contents[0] = 1; /* Version */ + contents[1] = DW_EH_PE_pcrel | DW_EH_PE_sdata4; /* .eh_frame offset */ + if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count) + { + contents[2] = DW_EH_PE_udata4; /* FDE count encoding */ + contents[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4; /* search table enc */ + } + else + { + contents[2] = DW_EH_PE_omit; + contents[3] = DW_EH_PE_omit; + } + bfd_put_32 (abfd, eh_frame_sec->vma - sec->output_section->vma - 4, + contents + 4); + if (contents[2] != DW_EH_PE_omit) + { + unsigned int i; + + bfd_put_32 (abfd, hdr_info->fde_count, contents + EH_FRAME_HDR_SIZE); + qsort (hdr_info->array, hdr_info->fde_count, sizeof (*hdr_info->array), + vma_compare); + for (i = 0; i < hdr_info->fde_count; i++) + { + bfd_put_32 (abfd, + hdr_info->array[i].initial_loc + - sec->output_section->vma, + contents + EH_FRAME_HDR_SIZE + i * 8 + 4); + bfd_put_32 (abfd, + hdr_info->array[i].fde - sec->output_section->vma, + contents + EH_FRAME_HDR_SIZE + i * 8 + 8); + } + } + + return bfd_set_section_contents (abfd, sec->output_section, + contents, (file_ptr) sec->output_offset, + sec->_cooked_size); +} |
