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 */
21 static const char arch[] = "PowerPC";
22 
23 #define N_DESCR	6
24 unsigned 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 */
34 static 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
43 unsigned 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 
56 unsigned char buf[1024];
57 #define ELFDATA2LSB     1
58 #define ELFDATA2MSB     2
59 static int e_data = ELFDATA2MSB;
60 #define ELFCLASS32      1
61 #define ELFCLASS64      2
62 static 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 
112 unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };
113 
114 int
main(int ac,char ** av)115 main(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