106 lines
2.9 KiB
C
106 lines
2.9 KiB
C
/* Linux kernel image support for libdwfl.
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Copyright (C) 2009-2011 Red Hat, Inc.
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This file is part of elfutils.
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This file is free software; you can redistribute it and/or modify
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it under the terms of either
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at
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your option) any later version
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or
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* the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at
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your option) any later version
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or both in parallel, as here.
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elfutils is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received copies of the GNU General Public License and
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the GNU Lesser General Public License along with this program. If
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not, see <http://www.gnu.org/licenses/>. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "libdwflP.h"
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#include "system.h"
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#include <unistd.h>
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#include <endian.h>
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#if BYTE_ORDER == LITTLE_ENDIAN
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# define LE16(x) (x)
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#else
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# define LE16(x) bswap_16 (x)
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#endif
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/* See Documentation/x86/boot.txt in Linux kernel sources
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for an explanation of these format details. */
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#define MAGIC1 0xaa55
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#define MAGIC2 0x53726448 /* "HdrS" little-endian */
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#define MIN_VERSION 0x0208
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#define H_START (H_SETUP_SECTS & -4)
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#define H_SETUP_SECTS 0x1f1
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#define H_MAGIC1 0x1fe
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#define H_MAGIC2 0x202
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#define H_VERSION 0x206
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#define H_PAYLOAD_OFFSET 0x248
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#define H_PAYLOAD_LENGTH 0x24c
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#define H_END 0x250
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#define H_READ_SIZE (H_END - H_START)
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Dwfl_Error
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internal_function
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__libdw_image_header (int fd, off_t *start_offset,
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void *mapped, size_t mapped_size)
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{
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if (likely (mapped_size > H_END))
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{
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const void *header = mapped;
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char header_buffer[H_READ_SIZE];
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if (header == NULL)
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{
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ssize_t n = pread_retry (fd, header_buffer, H_READ_SIZE,
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*start_offset + H_START);
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if (n < 0)
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return DWFL_E_ERRNO;
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if (n < H_READ_SIZE)
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return DWFL_E_BADELF;
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header = header_buffer - H_START;
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}
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if (*(uint16_t *) (header + H_MAGIC1) == LE16 (MAGIC1)
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&& *(uint32_t *) (header + H_MAGIC2) == LE32 (MAGIC2)
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&& LE16 (*(uint16_t *) (header + H_VERSION)) >= MIN_VERSION)
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{
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/* The magic numbers match and the version field is sufficient.
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Extract the payload bounds. */
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uint32_t offset = LE32 (*(uint32_t *) (header + H_PAYLOAD_OFFSET));
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uint32_t length = LE32 (*(uint32_t *) (header + H_PAYLOAD_LENGTH));
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offset += ((*(uint8_t *) (header + H_SETUP_SECTS) ?: 4) + 1) * 512;
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if (offset > H_END && offset < mapped_size
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&& mapped_size - offset >= length)
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{
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/* It looks kosher. Use it! */
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*start_offset += offset;
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return DWFL_E_NOERROR;
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}
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}
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}
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return DWFL_E_BADELF;
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}
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