Branch data Line data Source code
1 : : /* Linux kernel image support for libdwfl.
2 : : Copyright (C) 2009-2011 Red Hat, Inc.
3 : : This file is part of elfutils.
4 : :
5 : : This file is free software; you can redistribute it and/or modify
6 : : it under the terms of either
7 : :
8 : : * the GNU Lesser General Public License as published by the Free
9 : : Software Foundation; either version 3 of the License, or (at
10 : : your option) any later version
11 : :
12 : : or
13 : :
14 : : * the GNU General Public License as published by the Free
15 : : Software Foundation; either version 2 of the License, or (at
16 : : your option) any later version
17 : :
18 : : or both in parallel, as here.
19 : :
20 : : elfutils is distributed in the hope that it will be useful, but
21 : : WITHOUT ANY WARRANTY; without even the implied warranty of
22 : : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 : : General Public License for more details.
24 : :
25 : : You should have received copies of the GNU General Public License and
26 : : the GNU Lesser General Public License along with this program. If
27 : : not, see <http://www.gnu.org/licenses/>. */
28 : :
29 : : #include "libdwflP.h"
30 : : #include "system.h"
31 : :
32 : : #include <unistd.h>
33 : : #include <endian.h>
34 : :
35 : : #if BYTE_ORDER == LITTLE_ENDIAN
36 : : # define LE16(x) (x)
37 : : #else
38 : : # define LE16(x) bswap_16 (x)
39 : : #endif
40 : :
41 : : /* See Documentation/x86/boot.txt in Linux kernel sources
42 : : for an explanation of these format details. */
43 : :
44 : : #define MAGIC1 0xaa55
45 : : #define MAGIC2 0x53726448 /* "HdrS" little-endian */
46 : : #define MIN_VERSION 0x0208
47 : :
48 : : #define H_START (H_SETUP_SECTS & -4)
49 : : #define H_SETUP_SECTS 0x1f1
50 : : #define H_MAGIC1 0x1fe
51 : : #define H_MAGIC2 0x202
52 : : #define H_VERSION 0x206
53 : : #define H_PAYLOAD_OFFSET 0x248
54 : : #define H_PAYLOAD_LENGTH 0x24c
55 : : #define H_END 0x250
56 : : #define H_READ_SIZE (H_END - H_START)
57 : :
58 : : Dwfl_Error
59 : : internal_function
60 : 0 : __libdw_image_header (int fd, off64_t *start_offset,
61 : : void *mapped, size_t mapped_size)
62 : : {
63 [ # # ]: 0 : if (likely (mapped_size > H_END))
64 : : {
65 : 0 : const void *header = mapped;
66 : : char header_buffer[H_READ_SIZE];
67 [ # # ]: 0 : if (header == NULL)
68 : : {
69 : 0 : ssize_t n = pread_retry (fd, header_buffer, H_READ_SIZE,
70 : 0 : *start_offset + H_START);
71 [ # # ]: 0 : if (n < 0)
72 : : return DWFL_E_ERRNO;
73 [ # # ]: 0 : if (n < H_READ_SIZE)
74 : : return DWFL_E_BADELF;
75 : :
76 : : header = header_buffer - H_START;
77 : : }
78 : :
79 [ # # ]: 0 : if (*(uint16_t *) (header + H_MAGIC1) == LE16 (MAGIC1)
80 [ # # ]: 0 : && *(uint32_t *) (header + H_MAGIC2) == LE32 (MAGIC2)
81 [ # # ]: 0 : && LE16 (*(uint16_t *) (header + H_VERSION)) >= MIN_VERSION)
82 : : {
83 : : /* The magic numbers match and the version field is sufficient.
84 : : Extract the payload bounds. */
85 : :
86 : 0 : uint32_t offset = LE32 (*(uint32_t *) (header + H_PAYLOAD_OFFSET));
87 : 0 : uint32_t length = LE32 (*(uint32_t *) (header + H_PAYLOAD_LENGTH));
88 : :
89 [ # # ]: 0 : offset += ((*(uint8_t *) (header + H_SETUP_SECTS) ?: 4) + 1) * 512;
90 : :
91 [ # # ][ # # ]: 0 : if (offset > H_END && offset < mapped_size
92 [ # # ]: 0 : && mapped_size - offset >= length)
93 : : {
94 : : /* It looks kosher. Use it! */
95 : 0 : *start_offset += offset;
96 : : return DWFL_E_NOERROR;
97 : : }
98 : : }
99 : : }
100 : : return DWFL_E_BADELF;
101 : : }
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