/* Advance to next CFI entry. Copyright (C) 2009-2010 Red Hat, Inc. This file is part of Red Hat elfutils. Red Hat elfutils 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; version 2 of the License. Red Hat elfutils 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 Red Hat elfutils; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. In addition, as a special exception, Red Hat, Inc. gives You the additional right to link the code of Red Hat elfutils with code licensed under any Open Source Initiative certified open source license (http://www.opensource.org/licenses/index.php) which requires the distribution of source code with any binary distribution and to distribute linked combinations of the two. Non-GPL Code permitted under this exception must only link to the code of Red Hat elfutils through those well defined interfaces identified in the file named EXCEPTION found in the source code files (the "Approved Interfaces"). The files of Non-GPL Code may instantiate templates or use macros or inline functions from the Approved Interfaces without causing the resulting work to be covered by the GNU General Public License. Only Red Hat, Inc. may make changes or additions to the list of Approved Interfaces. Red Hat's grant of this exception is conditioned upon your not adding any new exceptions. If you wish to add a new Approved Interface or exception, please contact Red Hat. You must obey the GNU General Public License in all respects for all of the Red Hat elfutils code and other code used in conjunction with Red Hat elfutils except the Non-GPL Code covered by this exception. If you modify this file, you may extend this exception to your version of the file, but you are not obligated to do so. If you do not wish to provide this exception without modification, you must delete this exception statement from your version and license this file solely under the GPL without exception. Red Hat elfutils is an included package of the Open Invention Network. An included package of the Open Invention Network is a package for which Open Invention Network licensees cross-license their patents. No patent license is granted, either expressly or impliedly, by designation as an included package. Should you wish to participate in the Open Invention Network licensing program, please visit www.openinventionnetwork.com . */ #ifdef HAVE_CONFIG_H # include #endif #include "cfi.h" #include "encoded-value.h" #include int dwarf_next_cfi (e_ident, data, eh_frame_p, off, next_off, entry) const unsigned char e_ident[]; Elf_Data *data; bool eh_frame_p; Dwarf_Off off; Dwarf_Off *next_off; Dwarf_CFI_Entry *entry; { /* Dummy struct for memory-access.h macros. */ BYTE_ORDER_DUMMY (dw, e_ident); /* If we reached the end before don't do anything. */ if (off == (Dwarf_Off) -1l /* Make sure there is enough space in the .debug_frame section for at least the initial word. We cannot test the rest since we don't know yet whether this is a 64-bit object or not. */ || unlikely (off + 4 >= data->d_size)) { *next_off = (Dwarf_Off) -1l; return 1; } /* This points into the .debug_frame section at the start of the entry. */ const uint8_t *bytes = data->d_buf + off; const uint8_t *limit = data->d_buf + data->d_size; /* The format of a CFI entry is described in DWARF3 6.4.1: */ uint64_t length = read_4ubyte_unaligned_inc (&dw, bytes); size_t offset_size = 4; if (length == DWARF3_LENGTH_64_BIT) { /* This is the 64-bit DWARF format. */ offset_size = 8; if (unlikely (limit - bytes < 8)) { invalid: __libdw_seterrno (DWARF_E_INVALID_DWARF); return -1; } length = read_8ubyte_unaligned_inc (&dw, bytes); } if (unlikely ((uint64_t) (limit - bytes) < length) || unlikely (length < offset_size + 1)) goto invalid; /* Now we know how large the entry is. Note the trick in the computation. If the offset_size is 4 the '- 4' term undoes the '2 *'. If offset_size is 8 this term computes the size of the escape value plus the 8 byte offset. */ *next_off = off + (2 * offset_size - 4) + length; limit = bytes + length; const uint8_t *const cie_pointer_start = bytes; if (offset_size == 8) entry->cie.CIE_id = read_8ubyte_unaligned_inc (&dw, bytes); else { entry->cie.CIE_id = read_4ubyte_unaligned_inc (&dw, bytes); /* Canonicalize the 32-bit CIE_ID value to 64 bits. */ if (!eh_frame_p && entry->cie.CIE_id == DW_CIE_ID_32) entry->cie.CIE_id = DW_CIE_ID_64; } if (eh_frame_p) { /* Canonicalize the .eh_frame CIE pointer to .debug_frame format. */ if (entry->cie.CIE_id == 0) entry->cie.CIE_id = DW_CIE_ID_64; else { /* In .eh_frame format, a CIE pointer is the distance from where it appears back to the beginning of the CIE. */ ptrdiff_t pos = cie_pointer_start - (const uint8_t *) data->d_buf; if (unlikely (entry->cie.CIE_id > (Dwarf_Off) pos) || unlikely (pos <= (ptrdiff_t) offset_size)) goto invalid; entry->cie.CIE_id = pos - entry->cie.CIE_id; } } if (entry->cie.CIE_id == DW_CIE_ID_64) { /* Read the version stamp. Always an 8-bit value. */ uint8_t version = *bytes++; if (version != 1 && (unlikely (version < 3) || unlikely (version > 4))) goto invalid; entry->cie.augmentation = (const char *) bytes; bytes = memchr (bytes, '\0', limit - bytes); if (unlikely (bytes == NULL)) goto invalid; ++bytes; /* The address size for CFI is implicit in the ELF class. */ uint_fast8_t address_size = e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8; uint_fast8_t segment_size = 0; if (version >= 4) { if (unlikely (limit - bytes < 5)) goto invalid; /* XXX We don't actually support address_size not matching the class. To do so, we'd have to return it here so that intern_new_cie could use it choose a specific fde_encoding. */ if (unlikely (*bytes != address_size)) { __libdw_seterrno (DWARF_E_VERSION); return -1; } address_size = *bytes++; segment_size = *bytes++; /* We don't actually support segment selectors. We'd have to roll this into the fde_encoding bits or something. */ if (unlikely (segment_size != 0)) { __libdw_seterrno (DWARF_E_VERSION); return -1; } } const char *ap = entry->cie.augmentation; /* g++ v2 "eh" has pointer immediately following augmentation string, so it must be handled first. */ if (unlikely (ap[0] == 'e' && ap[1] == 'h')) { ap += 2; bytes += address_size; } get_uleb128 (entry->cie.code_alignment_factor, bytes); get_sleb128 (entry->cie.data_alignment_factor, bytes); if (version >= 3) /* DWARF 3+ */ get_uleb128 (entry->cie.return_address_register, bytes); else /* DWARF 2 */ entry->cie.return_address_register = *bytes++; /* If we have sized augmentation data, we don't need to grok it all. */ entry->cie.fde_augmentation_data_size = 0; bool sized_augmentation = *ap == 'z'; if (sized_augmentation) { get_uleb128 (entry->cie.augmentation_data_size, bytes); if ((Dwarf_Word) (limit - bytes) < entry->cie.augmentation_data_size) goto invalid; entry->cie.augmentation_data = bytes; bytes += entry->cie.augmentation_data_size; } else { entry->cie.augmentation_data = bytes; for (; *ap != '\0'; ++ap) { uint8_t encoding; switch (*ap) { case 'L': /* Skip LSDA pointer encoding byte. */ case 'R': /* Skip FDE address encoding byte. */ encoding = *bytes++; entry->cie.fde_augmentation_data_size += encoded_value_size (data, e_ident, encoding, NULL); continue; case 'P': /* Skip encoded personality routine pointer. */ encoding = *bytes++; bytes += encoded_value_size (data, e_ident, encoding, bytes); continue; case 'S': /* Skip signal-frame flag. */ continue; default: /* Unknown augmentation string. initial_instructions might actually start with some augmentation data. */ break; } break; } entry->cie.augmentation_data_size = bytes - entry->cie.augmentation_data; } entry->cie.initial_instructions = bytes; entry->cie.initial_instructions_end = limit; } else { entry->fde.start = bytes; entry->fde.end = limit; } return 0; } INTDEF (dwarf_next_cfi)