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Diffstat (limited to 'elfutils/libdwfl/image-header.c')
| -rw-r--r-- | elfutils/libdwfl/image-header.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/elfutils/libdwfl/image-header.c b/elfutils/libdwfl/image-header.c new file mode 100644 index 00000000..6341fc8c --- /dev/null +++ b/elfutils/libdwfl/image-header.c @@ -0,0 +1,124 @@ +/* Linux kernel image support for libdwfl. + Copyright (C) 2009 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 + <http://www.openinventionnetwork.com>. */ + +#include "libdwflP.h" +#include "system.h" + +#include <unistd.h> +#include <endian.h> + +#if BYTE_ORDER == LITTLE_ENDIAN +# define LE16(x) (x) +# define LE32(x) (x) +#else +# define LE16(x) bswap_16 (x) +# define LE32(x) bswap_32 (x) +#endif + +/* See Documentation/x86/boot.txt in Linux kernel sources + for an explanation of these format details. */ + +#define MAGIC1 0xaa55 +#define MAGIC2 0x53726448 /* "HdrS" little-endian */ +#define MIN_VERSION 0x0208 + +#define H_START (H_SETUP_SECTS & -4) +#define H_SETUP_SECTS 0x1f1 +#define H_MAGIC1 0x1fe +#define H_MAGIC2 0x202 +#define H_VERSION 0x206 +#define H_PAYLOAD_OFFSET 0x248 +#define H_PAYLOAD_LENGTH 0x24c +#define H_END 0x250 +#define H_READ_SIZE (H_END - H_START) + +Dwfl_Error +internal_function +__libdw_image_header (int fd, off64_t *start_offset, + void *mapped, size_t mapped_size) +{ + if (likely (mapped_size > H_END)) + { + const void *header = mapped; + char header_buffer[H_READ_SIZE]; + if (header == NULL) + { + ssize_t n = pread_retry (fd, header_buffer, H_READ_SIZE, + *start_offset + H_START); + if (n < 0) + return DWFL_E_ERRNO; + if (n < H_READ_SIZE) + return DWFL_E_BADELF; + + header = header_buffer - H_START; + } + + if (*(uint16_t *) (header + H_MAGIC1) == LE16 (MAGIC1) + && *(uint32_t *) (header + H_MAGIC2) == LE32 (MAGIC2) + && LE16 (*(uint16_t *) (header + H_VERSION)) >= MIN_VERSION) + { + /* The magic numbers match and the version field is sufficient. + Extract the payload bounds. */ + + uint32_t offset = LE32 (*(uint32_t *) (header + H_PAYLOAD_OFFSET)); + uint32_t length = LE32 (*(uint32_t *) (header + H_PAYLOAD_LENGTH)); + + offset += ((*(uint8_t *) (header + H_SETUP_SECTS) ?: 4) + 1) * 512; + + if (offset > H_END && offset < mapped_size + && mapped_size - offset >= length) + { + /* It looks kosher. Use it! */ + *start_offset += offset; + return DWFL_E_NOERROR; + } + } + } + return DWFL_E_BADELF; +} |