1/*
2   Simple utility to make a single-image install kernel with initial ramdisk
3   for Sparc tftpbooting without need to set up nfs.
4
5   Copyright (C) 1996,1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
6   Pete Zaitcev <zaitcev@yahoo.com> endian fixes for cross-compiles, 2000.
7   Copyright (C) 2011 Sam Ravnborg <sam@ravnborg.org>
8
9   This program is free software; you can redistribute it and/or modify
10   it under the terms of the GNU General Public License as published by
11   the Free Software Foundation; either version 2 of the License, or
12   (at your option) any later version.
13
14   This program is distributed in the hope that it will be useful,
15   but WITHOUT ANY WARRANTY; without even the implied warranty of
16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17   GNU General Public License for more details.
18
19   You should have received a copy of the GNU General Public License
20   along with this program; if not, write to the Free Software
21   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
22
23#include <dirent.h>
24#include <stdlib.h>
25#include <string.h>
26#include <unistd.h>
27#include <ctype.h>
28#include <errno.h>
29#include <fcntl.h>
30#include <stdio.h>
31
32#include <sys/types.h>
33#include <sys/stat.h>
34
35/*
36 * Note: run this on an a.out kernel (use elftoaout for it),
37 * as PROM looks for a.out image only.
38 */
39
40#define AOUT_TEXT_OFFSET   32
41
42static int is64bit = 0;
43
44/* align to power-of-two size */
45static int align(int n)
46{
47	if (is64bit)
48		return (n + 0x1fff) & ~0x1fff;
49	else
50		return (n + 0xfff) & ~0xfff;
51}
52
53/* read two bytes as big endian */
54static unsigned short ld2(char *p)
55{
56	return (p[0] << 8) | p[1];
57}
58
59/* save 4 bytes as big endian */
60static void st4(char *p, unsigned int x)
61{
62	p[0] = x >> 24;
63	p[1] = x >> 16;
64	p[2] = x >> 8;
65	p[3] = x;
66}
67
68static void die(const char *str)
69{
70	perror(str);
71	exit(1);
72}
73
74static void usage(void)
75{
76	/* fs_img.gz is an image of initial ramdisk. */
77	fprintf(stderr, "Usage: piggyback bits vmlinux.aout System.map fs_img.gz\n");
78	fprintf(stderr, "\tKernel image will be modified in place.\n");
79	exit(1);
80}
81
82static int start_line(const char *line)
83{
84	if (strcmp(line + 8, " T _start\n") == 0)
85		return 1;
86	else if (strcmp(line + 16, " T _start\n") == 0)
87		return 1;
88	return 0;
89}
90
91static int end_line(const char *line)
92{
93	if (strcmp(line + 8, " A _end\n") == 0)
94		return 1;
95	else if (strcmp (line + 16, " A _end\n") == 0)
96		return 1;
97	return 0;
98}
99
100/*
101 * Find address for start and end in System.map.
102 * The file looks like this:
103 * f0004000 T _start
104 * f0379f79 A _end
105 * 1234567890123456
106 * ^coloumn 1
107 * There is support for 64 bit addresses too.
108 *
109 * Return 0 if either start or end is not found
110 */
111static int get_start_end(const char *filename, unsigned int *start,
112                                               unsigned int *end)
113{
114	FILE *map;
115	char buffer[1024];
116
117	*start = 0;
118	*end = 0;
119	map = fopen(filename, "r");
120	if (!map)
121		die(filename);
122	while (fgets(buffer, 1024, map)) {
123		if (start_line(buffer))
124			*start = strtoul(buffer, NULL, 16);
125		else if (end_line(buffer))
126			*end = strtoul(buffer, NULL, 16);
127	}
128	fclose (map);
129
130	if (*start == 0 || *end == 0)
131		return 0;
132
133	return 1;
134}
135
136#define LOOKBACK (128 * 4)
137#define BUFSIZE 1024
138/*
139 * Find the HdrS entry from head_32/head_64.
140 * We check if it is at the beginning of the file (sparc64 case)
141 * and if not we search for it.
142 * When we search do so in steps of 4 as HdrS is on a 4-byte aligned
143 * address (it is on same alignment as sparc instructions)
144 * Return the offset to the HdrS entry (as off_t)
145 */
146static off_t get_hdrs_offset(int kernelfd, const char *filename)
147{
148	char buffer[BUFSIZE];
149	off_t offset;
150	int i;
151
152	if (lseek(kernelfd, 0, SEEK_SET) < 0)
153		die("lseek");
154	if (read(kernelfd, buffer, BUFSIZE) != BUFSIZE)
155		die(filename);
156
157	if (buffer[40] == 'H' && buffer[41] == 'd' &&
158	    buffer[42] == 'r' && buffer[43] == 'S') {
159		return 40;
160	} else {
161		/*  Find the gokernel label */
162		/* Decode offset from branch instruction */
163		offset = ld2(buffer + AOUT_TEXT_OFFSET + 2) << 2;
164		/* Go back 512 bytes so we do not miss HdrS */
165		offset -= LOOKBACK;
166		/* skip a.out header */
167		offset += AOUT_TEXT_OFFSET;
168		if (lseek(kernelfd, offset, SEEK_SET) < 0)
169			die("lseek");
170		if (read(kernelfd, buffer, BUFSIZE) != BUFSIZE)
171			die(filename);
172
173		for (i = 0; i < LOOKBACK; i += 4) {
174			if (buffer[i + 0] == 'H' && buffer[i + 1] == 'd' &&
175			    buffer[i + 2] == 'r' && buffer[i + 3] == 'S') {
176				return offset + i;
177			}
178		}
179	}
180	fprintf (stderr, "Couldn't find headers signature in %s\n", filename);
181	exit(1);
182}
183
184int main(int argc,char **argv)
185{
186	static char aout_magic[] = { 0x01, 0x03, 0x01, 0x07 };
187	char buffer[1024];
188	unsigned int i, start, end;
189	off_t offset;
190	struct stat s;
191	int image, tail;
192
193	if (argc != 5)
194		usage();
195	if (strcmp(argv[1], "64") == 0)
196		is64bit = 1;
197	if (stat (argv[4], &s) < 0)
198		die(argv[4]);
199
200	if (!get_start_end(argv[3], &start, &end)) {
201		fprintf(stderr, "Could not determine start and end from %s\n",
202		        argv[3]);
203		exit(1);
204	}
205	if ((image = open(argv[2], O_RDWR)) < 0)
206		die(argv[2]);
207	if (read(image, buffer, 512) != 512)
208		die(argv[2]);
209	if (memcmp(buffer, aout_magic, 4) != 0) {
210		fprintf (stderr, "Not a.out. Don't blame me.\n");
211		exit(1);
212	}
213	/*
214	 * We need to fill in values for
215	 * sparc_ramdisk_image + sparc_ramdisk_size
216	 * To locate these symbols search for the "HdrS" text which appear
217	 * in the image a little before the gokernel symbol.
218	 * See definition of these in init_32.S
219	 */
220
221	offset = get_hdrs_offset(image, argv[2]);
222	/* skip HdrS + LINUX_VERSION_CODE + HdrS version */
223	offset += 10;
224
225	if (lseek(image, offset, 0) < 0)
226		die("lseek");
227
228	/*
229	 * root_flags = 0
230	 * root_dev = 1 (RAMDISK_MAJOR)
231	 * ram_flags = 0
232	 * sparc_ramdisk_image = "PAGE aligned address after _end")
233	 * sparc_ramdisk_size = size of image
234	 */
235	st4(buffer, 0);
236	st4(buffer + 4, 0x01000000);
237	st4(buffer + 8, align(end + 32));
238	st4(buffer + 12, s.st_size);
239
240	if (write(image, buffer + 2, 14) != 14)
241		die(argv[2]);
242
243	/* For sparc64 update a_text and clear a_data + a_bss */
244	if (is64bit)
245	{
246		if (lseek(image, 4, 0) < 0)
247			die("lseek");
248		/* a_text */
249		st4(buffer, align(end + 32 + 8191) - (start & ~0x3fffffUL) +
250		            s.st_size);
251		/* a_data */
252		st4(buffer + 4, 0);
253		/* a_bss */
254		st4(buffer + 8, 0);
255		if (write(image, buffer, 12) != 12)
256			die(argv[2]);
257	}
258
259	/* seek page aligned boundary in the image file and add boot image */
260	if (lseek(image, AOUT_TEXT_OFFSET - start + align(end + 32), 0) < 0)
261		die("lseek");
262	if ((tail = open(argv[4], O_RDONLY)) < 0)
263		die(argv[4]);
264	while ((i = read(tail, buffer, 1024)) > 0)
265		if (write(image, buffer, i) != i)
266			die(argv[2]);
267	if (close(image) < 0)
268		die("close");
269	if (close(tail) < 0)
270		die("close");
271	return 0;
272}
273