Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
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linux
1/*
2 * Program to hack in a PT_NOTE program header entry in an ELF file.
3 * This is needed for OF on RS/6000s to load an image correctly.
4 * Note that OF needs a program header entry for the note, not an
5 * ELF section.
6 *
7 * Copyright 2000 Paul Mackerras.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 *
14 * Usage: addnote zImage
15 */
16#include <stdio.h>
17#include <stdlib.h>
18#include <fcntl.h>
19#include <unistd.h>
20#include <string.h>
21
22char arch[] = "PowerPC";
23
24#define N_DESCR 6
25unsigned int descr[N_DESCR] = {
26#if 1
27 /* values for IBM RS/6000 machines */
28 0xffffffff, /* real-mode = true */
29 0x00c00000, /* real-base, i.e. where we expect OF to be */
30 0xffffffff, /* real-size */
31 0xffffffff, /* virt-base */
32 0xffffffff, /* virt-size */
33 0x4000, /* load-base */
34#else
35 /* values for longtrail CHRP */
36 0, /* real-mode = false */
37 0xffffffff, /* real-base */
38 0xffffffff, /* real-size */
39 0xffffffff, /* virt-base */
40 0xffffffff, /* virt-size */
41 0x00600000, /* load-base */
42#endif
43};
44
45unsigned char buf[512];
46
47#define GET_16BE(off) ((buf[off] << 8) + (buf[(off)+1]))
48#define GET_32BE(off) ((GET_16BE(off) << 16) + GET_16BE((off)+2))
49
50#define PUT_16BE(off, v) (buf[off] = ((v) >> 8) & 0xff, \
51 buf[(off) + 1] = (v) & 0xff)
52#define PUT_32BE(off, v) (PUT_16BE((off), (v) >> 16), \
53 PUT_16BE((off) + 2, (v)))
54
55/* Structure of an ELF file */
56#define E_IDENT 0 /* ELF header */
57#define E_PHOFF 28
58#define E_PHENTSIZE 42
59#define E_PHNUM 44
60#define E_HSIZE 52 /* size of ELF header */
61
62#define EI_MAGIC 0 /* offsets in E_IDENT area */
63#define EI_CLASS 4
64#define EI_DATA 5
65
66#define PH_TYPE 0 /* ELF program header */
67#define PH_OFFSET 4
68#define PH_FILESZ 16
69#define PH_HSIZE 32 /* size of program header */
70
71#define PT_NOTE 4 /* Program header type = note */
72
73#define ELFCLASS32 1
74#define ELFDATA2MSB 2
75
76unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };
77
78int main(int ac, char **av)
79{
80 int fd, n, i;
81 int ph, ps, np;
82 int nnote, ns;
83
84 if (ac != 2) {
85 fprintf(stderr, "Usage: %s elf-file\n", av[0]);
86 exit(1);
87 }
88 fd = open(av[1], O_RDWR);
89 if (fd < 0) {
90 perror(av[1]);
91 exit(1);
92 }
93
94 nnote = strlen(arch) + 1 + (N_DESCR + 3) * 4;
95
96 n = read(fd, buf, sizeof(buf));
97 if (n < 0) {
98 perror("read");
99 exit(1);
100 }
101
102 if (n < E_HSIZE || memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0)
103 goto notelf;
104
105 if (buf[E_IDENT+EI_CLASS] != ELFCLASS32
106 || buf[E_IDENT+EI_DATA] != ELFDATA2MSB) {
107 fprintf(stderr, "%s is not a big-endian 32-bit ELF image\n",
108 av[1]);
109 exit(1);
110 }
111
112 ph = GET_32BE(E_PHOFF);
113 ps = GET_16BE(E_PHENTSIZE);
114 np = GET_16BE(E_PHNUM);
115 if (ph < E_HSIZE || ps < PH_HSIZE || np < 1)
116 goto notelf;
117 if (ph + (np + 1) * ps + nnote > n)
118 goto nospace;
119
120 for (i = 0; i < np; ++i) {
121 if (GET_32BE(ph + PH_TYPE) == PT_NOTE) {
122 fprintf(stderr, "%s already has a note entry\n",
123 av[1]);
124 exit(0);
125 }
126 ph += ps;
127 }
128
129 /* XXX check that the area we want to use is all zeroes */
130 for (i = 0; i < ps + nnote; ++i)
131 if (buf[ph + i] != 0)
132 goto nospace;
133
134 /* fill in the program header entry */
135 ns = ph + ps;
136 PUT_32BE(ph + PH_TYPE, PT_NOTE);
137 PUT_32BE(ph + PH_OFFSET, ns);
138 PUT_32BE(ph + PH_FILESZ, nnote);
139
140 /* fill in the note area we point to */
141 /* XXX we should probably make this a proper section */
142 PUT_32BE(ns, strlen(arch) + 1);
143 PUT_32BE(ns + 4, N_DESCR * 4);
144 PUT_32BE(ns + 8, 0x1275);
145 strcpy(&buf[ns + 12], arch);
146 ns += 12 + strlen(arch) + 1;
147 for (i = 0; i < N_DESCR; ++i)
148 PUT_32BE(ns + i * 4, descr[i]);
149
150 /* Update the number of program headers */
151 PUT_16BE(E_PHNUM, np + 1);
152
153 /* write back */
154 lseek(fd, (long) 0, SEEK_SET);
155 i = write(fd, buf, n);
156 if (i < 0) {
157 perror("write");
158 exit(1);
159 }
160 if (i < n) {
161 fprintf(stderr, "%s: write truncated\n", av[1]);
162 exit(1);
163 }
164
165 exit(0);
166
167 notelf:
168 fprintf(stderr, "%s does not appear to be an ELF file\n", av[0]);
169 exit(1);
170
171 nospace:
172 fprintf(stderr, "sorry, I can't find space in %s to put the note\n",
173 av[0]);
174 exit(1);
175}