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 * Adapted for 64 bit little endian images by Andrew Tauferner.
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 *
16 * Usage: addnote zImage
17 */
18#include <stdio.h>
19#include <stdlib.h>
20#include <fcntl.h>
21#include <unistd.h>
22#include <string.h>
23
24/* CHRP note section */
25static const char arch[] = "PowerPC";
26
27#define N_DESCR	6
28unsigned int descr[N_DESCR] = {
29	0xffffffff,		/* real-mode = true */
30	0x02000000,		/* real-base, i.e. where we expect OF to be */
31	0xffffffff,		/* real-size */
32	0xffffffff,		/* virt-base */
33	0xffffffff,		/* virt-size */
34	0x4000,			/* load-base */
35};
36
37/* RPA note section */
38static const char rpaname[] = "IBM,RPA-Client-Config";
39
40/*
41 * Note: setting ignore_my_client_config *should* mean that OF ignores
42 * all the other fields, but there is a firmware bug which means that
43 * it looks at the splpar field at least.  So these values need to be
44 * reasonable.
45 */
46#define N_RPA_DESCR	8
47unsigned int rpanote[N_RPA_DESCR] = {
48	0,			/* lparaffinity */
49	64,			/* min_rmo_size */
50	0,			/* min_rmo_percent */
51	40,			/* max_pft_size */
52	1,			/* splpar */
53	-1,			/* min_load */
54	0,			/* new_mem_def */
55	1,			/* ignore_my_client_config */
56};
57
58#define ROUNDUP(len)	(((len) + 3) & ~3)
59
60unsigned char buf[1024];
61#define ELFDATA2LSB     1
62#define ELFDATA2MSB     2
63static int e_data = ELFDATA2MSB;
64#define ELFCLASS32      1
65#define ELFCLASS64      2
66static int e_class = ELFCLASS32;
67
68#define GET_16BE(off)	((buf[off] << 8) + (buf[(off)+1]))
69#define GET_32BE(off)	((GET_16BE(off) << 16U) + GET_16BE((off)+2U))
70#define GET_64BE(off)	((((unsigned long long)GET_32BE(off)) << 32ULL) + \
71			((unsigned long long)GET_32BE((off)+4ULL)))
72#define PUT_16BE(off, v)(buf[off] = ((v) >> 8) & 0xff, \
73			 buf[(off) + 1] = (v) & 0xff)
74#define PUT_32BE(off, v)(PUT_16BE((off), (v) >> 16L), PUT_16BE((off) + 2, (v)))
75#define PUT_64BE(off, v)((PUT_32BE((off), (v) >> 32L), \
76			  PUT_32BE((off) + 4, (v))))
77
78#define GET_16LE(off)	((buf[off]) + (buf[(off)+1] << 8))
79#define GET_32LE(off)	(GET_16LE(off) + (GET_16LE((off)+2U) << 16U))
80#define GET_64LE(off)	((unsigned long long)GET_32LE(off) + \
81			(((unsigned long long)GET_32LE((off)+4ULL)) << 32ULL))
82#define PUT_16LE(off, v) (buf[off] = (v) & 0xff, \
83			  buf[(off) + 1] = ((v) >> 8) & 0xff)
84#define PUT_32LE(off, v) (PUT_16LE((off), (v)), PUT_16LE((off) + 2, (v) >> 16L))
85#define PUT_64LE(off, v) (PUT_32LE((off), (v)), PUT_32LE((off) + 4, (v) >> 32L))
86
87#define GET_16(off)	(e_data == ELFDATA2MSB ? GET_16BE(off) : GET_16LE(off))
88#define GET_32(off)	(e_data == ELFDATA2MSB ? GET_32BE(off) : GET_32LE(off))
89#define GET_64(off)	(e_data == ELFDATA2MSB ? GET_64BE(off) : GET_64LE(off))
90#define PUT_16(off, v)	(e_data == ELFDATA2MSB ? PUT_16BE(off, v) : \
91			 PUT_16LE(off, v))
92#define PUT_32(off, v)  (e_data == ELFDATA2MSB ? PUT_32BE(off, v) : \
93			 PUT_32LE(off, v))
94#define PUT_64(off, v)  (e_data == ELFDATA2MSB ? PUT_64BE(off, v) : \
95			 PUT_64LE(off, v))
96
97/* Structure of an ELF file */
98#define E_IDENT		0	/* ELF header */
99#define	E_PHOFF		(e_class == ELFCLASS32 ? 28 : 32)
100#define E_PHENTSIZE	(e_class == ELFCLASS32 ? 42 : 54)
101#define E_PHNUM		(e_class == ELFCLASS32 ? 44 : 56)
102#define E_HSIZE		(e_class == ELFCLASS32 ? 52 : 64)
103
104#define EI_MAGIC	0	/* offsets in E_IDENT area */
105#define EI_CLASS	4
106#define EI_DATA		5
107
108#define PH_TYPE		0	/* ELF program header */
109#define PH_OFFSET	(e_class == ELFCLASS32 ? 4 : 8)
110#define PH_FILESZ	(e_class == ELFCLASS32 ? 16 : 32)
111#define PH_HSIZE	(e_class == ELFCLASS32 ? 32 : 56)
112
113#define PT_NOTE		4	/* Program header type = note */
114
115
116unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };
117
118int
119main(int ac, char **av)
120{
121	int fd, n, i;
122	unsigned long ph, ps, np;
123	long nnote, nnote2, ns;
124
125	if (ac != 2) {
126		fprintf(stderr, "Usage: %s elf-file\n", av[0]);
127		exit(1);
128	}
129	fd = open(av[1], O_RDWR);
130	if (fd < 0) {
131		perror(av[1]);
132		exit(1);
133	}
134
135	nnote = 12 + ROUNDUP(strlen(arch) + 1) + sizeof(descr);
136	nnote2 = 12 + ROUNDUP(strlen(rpaname) + 1) + sizeof(rpanote);
137
138	n = read(fd, buf, sizeof(buf));
139	if (n < 0) {
140		perror("read");
141		exit(1);
142	}
143
144	if (memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0)
145		goto notelf;
146	e_class = buf[E_IDENT+EI_CLASS];
147	if (e_class != ELFCLASS32 && e_class != ELFCLASS64)
148		goto notelf;
149	e_data = buf[E_IDENT+EI_DATA];
150	if (e_data != ELFDATA2MSB && e_data != ELFDATA2LSB)
151		goto notelf;
152	if (n < E_HSIZE)
153		goto notelf;
154
155	ph = (e_class == ELFCLASS32 ? GET_32(E_PHOFF) : GET_64(E_PHOFF));
156	ps = GET_16(E_PHENTSIZE);
157	np = GET_16(E_PHNUM);
158	if (ph < E_HSIZE || ps < PH_HSIZE || np < 1)
159		goto notelf;
160	if (ph + (np + 2) * ps + nnote + nnote2 > n)
161		goto nospace;
162
163	for (i = 0; i < np; ++i) {
164		if (GET_32(ph + PH_TYPE) == PT_NOTE) {
165			fprintf(stderr, "%s already has a note entry\n",
166				av[1]);
167			exit(0);
168		}
169		ph += ps;
170	}
171
172	/* XXX check that the area we want to use is all zeroes */
173	for (i = 0; i < 2 * ps + nnote + nnote2; ++i)
174		if (buf[ph + i] != 0)
175			goto nospace;
176
177	/* fill in the program header entry */
178	ns = ph + 2 * ps;
179	PUT_32(ph + PH_TYPE, PT_NOTE);
180	if (e_class == ELFCLASS32)
181		PUT_32(ph + PH_OFFSET, ns);
182	else
183		PUT_64(ph + PH_OFFSET, ns);
184
185	if (e_class == ELFCLASS32)
186		PUT_32(ph + PH_FILESZ, nnote);
187	else
188		PUT_64(ph + PH_FILESZ, nnote);
189
190	/* fill in the note area we point to */
191	/* XXX we should probably make this a proper section */
192	PUT_32(ns, strlen(arch) + 1);
193	PUT_32(ns + 4, N_DESCR * 4);
194	PUT_32(ns + 8, 0x1275);
195	strcpy((char *) &buf[ns + 12], arch);
196	ns += 12 + strlen(arch) + 1;
197	for (i = 0; i < N_DESCR; ++i, ns += 4)
198		PUT_32BE(ns, descr[i]);
199
200	/* fill in the second program header entry and the RPA note area */
201	ph += ps;
202	PUT_32(ph + PH_TYPE, PT_NOTE);
203	if (e_class == ELFCLASS32)
204		PUT_32(ph + PH_OFFSET, ns);
205	else
206		PUT_64(ph + PH_OFFSET, ns);
207
208	if (e_class == ELFCLASS32)
209		PUT_32(ph + PH_FILESZ, nnote);
210	else
211		PUT_64(ph + PH_FILESZ, nnote2);
212
213	/* fill in the note area we point to */
214	PUT_32(ns, strlen(rpaname) + 1);
215	PUT_32(ns + 4, sizeof(rpanote));
216	PUT_32(ns + 8, 0x12759999);
217	strcpy((char *) &buf[ns + 12], rpaname);
218	ns += 12 + ROUNDUP(strlen(rpaname) + 1);
219	for (i = 0; i < N_RPA_DESCR; ++i, ns += 4)
220		PUT_32BE(ns, rpanote[i]);
221
222	/* Update the number of program headers */
223	PUT_16(E_PHNUM, np + 2);
224
225	/* write back */
226	lseek(fd, (long) 0, SEEK_SET);
227	i = write(fd, buf, n);
228	if (i < 0) {
229		perror("write");
230		exit(1);
231	}
232	if (i < n) {
233		fprintf(stderr, "%s: write truncated\n", av[1]);
234		exit(1);
235	}
236
237	exit(0);
238
239 notelf:
240	fprintf(stderr, "%s does not appear to be an ELF file\n", av[1]);
241	exit(1);
242
243 nospace:
244	fprintf(stderr, "sorry, I can't find space in %s to put the note\n",
245		av[1]);
246	exit(1);
247}
248