1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Program to hack in a PT_NOTE program header entry in an ELF file.
4 * This is needed for OF on RS/6000s to load an image correctly.
5 * Note that OF needs a program header entry for the note, not an
6 * ELF section.
7 *
8 * Copyright 2000 Paul Mackerras.
9 *
10 * Adapted for 64 bit little endian images by Andrew Tauferner.
11 *
12 * Usage: addnote zImage
13 */
14#include <stdio.h>
15#include <stdlib.h>
16#include <fcntl.h>
17#include <unistd.h>
18#include <string.h>
19
20/* CHRP note section */
21static const char arch[] = "PowerPC";
22
23#define N_DESCR	6
24unsigned int descr[N_DESCR] = {
25	0xffffffff,		/* real-mode = true */
26	0x02000000,		/* real-base, i.e. where we expect OF to be */
27	0xffffffff,		/* real-size */
28	0xffffffff,		/* virt-base */
29	0xffffffff,		/* virt-size */
30	0x4000,			/* load-base */
31};
32
33/* RPA note section */
34static const char rpaname[] = "IBM,RPA-Client-Config";
35
36/*
37 * Note: setting ignore_my_client_config *should* mean that OF ignores
38 * all the other fields, but there is a firmware bug which means that
39 * it looks at the splpar field at least.  So these values need to be
40 * reasonable.
41 */
42#define N_RPA_DESCR	8
43unsigned int rpanote[N_RPA_DESCR] = {
44	0,			/* lparaffinity */
45	64,			/* min_rmo_size */
46	0,			/* min_rmo_percent */
47	40,			/* max_pft_size */
48	1,			/* splpar */
49	-1,			/* min_load */
50	0,			/* new_mem_def */
51	1,			/* ignore_my_client_config */
52};
53
54#define ROUNDUP(len)	(((len) + 3) & ~3)
55
56unsigned char buf[1024];
57#define ELFDATA2LSB     1
58#define ELFDATA2MSB     2
59static int e_data = ELFDATA2MSB;
60#define ELFCLASS32      1
61#define ELFCLASS64      2
62static int e_class = ELFCLASS32;
63
64#define GET_16BE(off)	((buf[off] << 8) + (buf[(off)+1]))
65#define GET_32BE(off)	((GET_16BE(off) << 16U) + GET_16BE((off)+2U))
66#define GET_64BE(off)	((((unsigned long long)GET_32BE(off)) << 32ULL) + \
67			((unsigned long long)GET_32BE((off)+4ULL)))
68#define PUT_16BE(off, v)(buf[off] = ((v) >> 8) & 0xff, \
69			 buf[(off) + 1] = (v) & 0xff)
70#define PUT_32BE(off, v)(PUT_16BE((off), (v) >> 16L), PUT_16BE((off) + 2, (v)))
71#define PUT_64BE(off, v)((PUT_32BE((off), (v) >> 32L), \
72			  PUT_32BE((off) + 4, (v))))
73
74#define GET_16LE(off)	((buf[off]) + (buf[(off)+1] << 8))
75#define GET_32LE(off)	(GET_16LE(off) + (GET_16LE((off)+2U) << 16U))
76#define GET_64LE(off)	((unsigned long long)GET_32LE(off) + \
77			(((unsigned long long)GET_32LE((off)+4ULL)) << 32ULL))
78#define PUT_16LE(off, v) (buf[off] = (v) & 0xff, \
79			  buf[(off) + 1] = ((v) >> 8) & 0xff)
80#define PUT_32LE(off, v) (PUT_16LE((off), (v)), PUT_16LE((off) + 2, (v) >> 16L))
81#define PUT_64LE(off, v) (PUT_32LE((off), (v)), PUT_32LE((off) + 4, (v) >> 32L))
82
83#define GET_16(off)	(e_data == ELFDATA2MSB ? GET_16BE(off) : GET_16LE(off))
84#define GET_32(off)	(e_data == ELFDATA2MSB ? GET_32BE(off) : GET_32LE(off))
85#define GET_64(off)	(e_data == ELFDATA2MSB ? GET_64BE(off) : GET_64LE(off))
86#define PUT_16(off, v)	(e_data == ELFDATA2MSB ? PUT_16BE(off, v) : \
87			 PUT_16LE(off, v))
88#define PUT_32(off, v)  (e_data == ELFDATA2MSB ? PUT_32BE(off, v) : \
89			 PUT_32LE(off, v))
90#define PUT_64(off, v)  (e_data == ELFDATA2MSB ? PUT_64BE(off, v) : \
91			 PUT_64LE(off, v))
92
93/* Structure of an ELF file */
94#define E_IDENT		0	/* ELF header */
95#define	E_PHOFF		(e_class == ELFCLASS32 ? 28 : 32)
96#define E_PHENTSIZE	(e_class == ELFCLASS32 ? 42 : 54)
97#define E_PHNUM		(e_class == ELFCLASS32 ? 44 : 56)
98#define E_HSIZE		(e_class == ELFCLASS32 ? 52 : 64)
99
100#define EI_MAGIC	0	/* offsets in E_IDENT area */
101#define EI_CLASS	4
102#define EI_DATA		5
103
104#define PH_TYPE		0	/* ELF program header */
105#define PH_OFFSET	(e_class == ELFCLASS32 ? 4 : 8)
106#define PH_FILESZ	(e_class == ELFCLASS32 ? 16 : 32)
107#define PH_HSIZE	(e_class == ELFCLASS32 ? 32 : 56)
108
109#define PT_NOTE		4	/* Program header type = note */
110
111
112unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };
113
114int
115main(int ac, char **av)
116{
117	int fd, n, i;
118	unsigned long ph, ps, np;
119	long nnote, nnote2, ns;
120
121	if (ac != 2) {
122		fprintf(stderr, "Usage: %s elf-file\n", av[0]);
123		exit(1);
124	}
125	fd = open(av[1], O_RDWR);
126	if (fd < 0) {
127		perror(av[1]);
128		exit(1);
129	}
130
131	nnote = 12 + ROUNDUP(strlen(arch) + 1) + sizeof(descr);
132	nnote2 = 12 + ROUNDUP(strlen(rpaname) + 1) + sizeof(rpanote);
133
134	n = read(fd, buf, sizeof(buf));
135	if (n < 0) {
136		perror("read");
137		exit(1);
138	}
139
140	if (memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0)
141		goto notelf;
142	e_class = buf[E_IDENT+EI_CLASS];
143	if (e_class != ELFCLASS32 && e_class != ELFCLASS64)
144		goto notelf;
145	e_data = buf[E_IDENT+EI_DATA];
146	if (e_data != ELFDATA2MSB && e_data != ELFDATA2LSB)
147		goto notelf;
148	if (n < E_HSIZE)
149		goto notelf;
150
151	ph = (e_class == ELFCLASS32 ? GET_32(E_PHOFF) : GET_64(E_PHOFF));
152	ps = GET_16(E_PHENTSIZE);
153	np = GET_16(E_PHNUM);
154	if (ph < E_HSIZE || ps < PH_HSIZE || np < 1)
155		goto notelf;
156	if (ph + (np + 2) * ps + nnote + nnote2 > n)
157		goto nospace;
158
159	for (i = 0; i < np; ++i) {
160		if (GET_32(ph + PH_TYPE) == PT_NOTE) {
161			fprintf(stderr, "%s already has a note entry\n",
162				av[1]);
163			exit(0);
164		}
165		ph += ps;
166	}
167
168	/* XXX check that the area we want to use is all zeroes */
169	for (i = 0; i < 2 * ps + nnote + nnote2; ++i)
170		if (buf[ph + i] != 0)
171			goto nospace;
172
173	/* fill in the program header entry */
174	ns = ph + 2 * ps;
175	PUT_32(ph + PH_TYPE, PT_NOTE);
176	if (e_class == ELFCLASS32)
177		PUT_32(ph + PH_OFFSET, ns);
178	else
179		PUT_64(ph + PH_OFFSET, ns);
180
181	if (e_class == ELFCLASS32)
182		PUT_32(ph + PH_FILESZ, nnote);
183	else
184		PUT_64(ph + PH_FILESZ, nnote);
185
186	/* fill in the note area we point to */
187	/* XXX we should probably make this a proper section */
188	PUT_32(ns, strlen(arch) + 1);
189	PUT_32(ns + 4, N_DESCR * 4);
190	PUT_32(ns + 8, 0x1275);
191	strcpy((char *) &buf[ns + 12], arch);
192	ns += 12 + strlen(arch) + 1;
193	for (i = 0; i < N_DESCR; ++i, ns += 4)
194		PUT_32BE(ns, descr[i]);
195
196	/* fill in the second program header entry and the RPA note area */
197	ph += ps;
198	PUT_32(ph + PH_TYPE, PT_NOTE);
199	if (e_class == ELFCLASS32)
200		PUT_32(ph + PH_OFFSET, ns);
201	else
202		PUT_64(ph + PH_OFFSET, ns);
203
204	if (e_class == ELFCLASS32)
205		PUT_32(ph + PH_FILESZ, nnote);
206	else
207		PUT_64(ph + PH_FILESZ, nnote2);
208
209	/* fill in the note area we point to */
210	PUT_32(ns, strlen(rpaname) + 1);
211	PUT_32(ns + 4, sizeof(rpanote));
212	PUT_32(ns + 8, 0x12759999);
213	strcpy((char *) &buf[ns + 12], rpaname);
214	ns += 12 + ROUNDUP(strlen(rpaname) + 1);
215	for (i = 0; i < N_RPA_DESCR; ++i, ns += 4)
216		PUT_32BE(ns, rpanote[i]);
217
218	/* Update the number of program headers */
219	PUT_16(E_PHNUM, np + 2);
220
221	/* write back */
222	i = lseek(fd, (long) 0, SEEK_SET);
223	if (i < 0) {
224		perror("lseek");
225		exit(1);
226	}
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