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1da177e4 LT |
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 | ||
22 | char arch[] = "PowerPC"; | |
23 | ||
24 | #define N_DESCR 6 | |
25 | unsigned int descr[N_DESCR] = { | |
26 | 0xffffffff, /* real-mode = true */ | |
27 | 0x00c00000, /* real-base, i.e. where we expect OF to be */ | |
28 | 0xffffffff, /* real-size */ | |
29 | 0xffffffff, /* virt-base */ | |
30 | 0xffffffff, /* virt-size */ | |
31 | 0x4000, /* load-base */ | |
32 | }; | |
33 | ||
34 | unsigned char buf[512]; | |
35 | ||
36 | #define GET_16BE(off) ((buf[off] << 8) + (buf[(off)+1])) | |
37 | #define GET_32BE(off) ((GET_16BE(off) << 16) + GET_16BE((off)+2)) | |
38 | ||
39 | #define PUT_16BE(off, v) (buf[off] = ((v) >> 8) & 0xff, \ | |
40 | buf[(off) + 1] = (v) & 0xff) | |
41 | #define PUT_32BE(off, v) (PUT_16BE((off), (v) >> 16), \ | |
42 | PUT_16BE((off) + 2, (v))) | |
43 | ||
44 | /* Structure of an ELF file */ | |
45 | #define E_IDENT 0 /* ELF header */ | |
46 | #define E_PHOFF 28 | |
47 | #define E_PHENTSIZE 42 | |
48 | #define E_PHNUM 44 | |
49 | #define E_HSIZE 52 /* size of ELF header */ | |
50 | ||
51 | #define EI_MAGIC 0 /* offsets in E_IDENT area */ | |
52 | #define EI_CLASS 4 | |
53 | #define EI_DATA 5 | |
54 | ||
55 | #define PH_TYPE 0 /* ELF program header */ | |
56 | #define PH_OFFSET 4 | |
57 | #define PH_FILESZ 16 | |
58 | #define PH_HSIZE 32 /* size of program header */ | |
59 | ||
60 | #define PT_NOTE 4 /* Program header type = note */ | |
61 | ||
62 | #define ELFCLASS32 1 | |
63 | #define ELFDATA2MSB 2 | |
64 | ||
65 | unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' }; | |
66 | ||
67 | int | |
68 | main(int ac, char **av) | |
69 | { | |
70 | int fd, n, i; | |
71 | int ph, ps, np; | |
72 | int nnote, ns; | |
73 | ||
74 | if (ac != 2) { | |
75 | fprintf(stderr, "Usage: %s elf-file\n", av[0]); | |
76 | exit(1); | |
77 | } | |
78 | fd = open(av[1], O_RDWR); | |
79 | if (fd < 0) { | |
80 | perror(av[1]); | |
81 | exit(1); | |
82 | } | |
83 | ||
84 | nnote = strlen(arch) + 1 + (N_DESCR + 3) * 4; | |
85 | ||
86 | n = read(fd, buf, sizeof(buf)); | |
87 | if (n < 0) { | |
88 | perror("read"); | |
89 | exit(1); | |
90 | } | |
91 | ||
92 | if (n < E_HSIZE || memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0) | |
93 | goto notelf; | |
94 | ||
95 | if (buf[E_IDENT+EI_CLASS] != ELFCLASS32 | |
96 | || buf[E_IDENT+EI_DATA] != ELFDATA2MSB) { | |
97 | fprintf(stderr, "%s is not a big-endian 32-bit ELF image\n", | |
98 | av[1]); | |
99 | exit(1); | |
100 | } | |
101 | ||
102 | ph = GET_32BE(E_PHOFF); | |
103 | ps = GET_16BE(E_PHENTSIZE); | |
104 | np = GET_16BE(E_PHNUM); | |
105 | if (ph < E_HSIZE || ps < PH_HSIZE || np < 1) | |
106 | goto notelf; | |
107 | if (ph + (np + 1) * ps + nnote > n) | |
108 | goto nospace; | |
109 | ||
110 | for (i = 0; i < np; ++i) { | |
111 | if (GET_32BE(ph + PH_TYPE) == PT_NOTE) { | |
112 | fprintf(stderr, "%s already has a note entry\n", | |
113 | av[1]); | |
114 | exit(0); | |
115 | } | |
116 | ph += ps; | |
117 | } | |
118 | ||
119 | /* XXX check that the area we want to use is all zeroes */ | |
120 | for (i = 0; i < ps + nnote; ++i) | |
121 | if (buf[ph + i] != 0) | |
122 | goto nospace; | |
123 | ||
124 | /* fill in the program header entry */ | |
125 | ns = ph + ps; | |
126 | PUT_32BE(ph + PH_TYPE, PT_NOTE); | |
127 | PUT_32BE(ph + PH_OFFSET, ns); | |
128 | PUT_32BE(ph + PH_FILESZ, nnote); | |
129 | ||
130 | /* fill in the note area we point to */ | |
131 | /* XXX we should probably make this a proper section */ | |
132 | PUT_32BE(ns, strlen(arch) + 1); | |
133 | PUT_32BE(ns + 4, N_DESCR * 4); | |
134 | PUT_32BE(ns + 8, 0x1275); | |
135 | strcpy(&buf[ns + 12], arch); | |
136 | ns += 12 + strlen(arch) + 1; | |
137 | for (i = 0; i < N_DESCR; ++i) | |
138 | PUT_32BE(ns + i * 4, descr[i]); | |
139 | ||
140 | /* Update the number of program headers */ | |
141 | PUT_16BE(E_PHNUM, np + 1); | |
142 | ||
143 | /* write back */ | |
144 | lseek(fd, (long) 0, SEEK_SET); | |
145 | i = write(fd, buf, n); | |
146 | if (i < 0) { | |
147 | perror("write"); | |
148 | exit(1); | |
149 | } | |
150 | if (i < n) { | |
151 | fprintf(stderr, "%s: write truncated\n", av[1]); | |
152 | exit(1); | |
153 | } | |
154 | ||
155 | exit(0); | |
156 | ||
157 | notelf: | |
158 | fprintf(stderr, "%s does not appear to be an ELF file\n", av[0]); | |
159 | exit(1); | |
160 | ||
161 | nospace: | |
162 | fprintf(stderr, "sorry, I can't find space in %s to put the note\n", | |
163 | av[0]); | |
164 | exit(1); | |
165 | } |