arch/sparc/boot/piggyback_32.c

/*
   Simple utility to make a single-image install kernel with initial ramdisk
   for Sparc tftpbooting without need to set up nfs.

   Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   Pete Zaitcev <zaitcev@yahoo.com> endian fixes for cross-compiles, 2000.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include <dirent.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>

#include <sys/types.h>
#include <sys/stat.h>

/*
 * Note: run this on an a.out kernel (use elftoaout for it),
 * as PROM looks for a.out image only.
 */

#define AOUT_TEXT_OFFSET   32

/* read two bytes as big endian */
static unsigned short ld2(char *p)
{
	return (p[0] << 8) | p[1];
}

/* read 4 bytes as big endian */
static unsigned int ld4(char *p)
{
	return (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
}

/* save 4 bytes as big endian */
static void st4(char *p, unsigned int x)
{
	p[0] = x >> 24;
	p[1] = x >> 16;
	p[2] = x >> 8;
	p[3] = x;
}

static void die(const char *str)
{
	perror(str);
	exit(1);
}

static void usage(void)
{
	/* fs_img.gz is an image of initial ramdisk. */
	fprintf(stderr, "Usage: piggyback vmlinux.aout System.map fs_img.gz\n");
	fprintf(stderr, "\tKernel image will be modified in place.\n");
	exit(1);
}

static int start_line(const char *line)
{
	if (strcmp(line + 8, " T _start\n") == 0)
		return 1;
	else if (strcmp(line + 16, " T _start\n") == 0)
		return 1;
	return 0;
}

static int end_line(const char *line)
{
	if (strcmp(line + 8, " A _end\n") == 0)
		return 1;
	else if (strcmp (line + 16, " A _end\n") == 0)
		return 1;
	return 0;
}

/*
 * Find address for start and end in System.map.
 * The file looks like this:
 * f0004000 T _start
 * f0379f79 A _end
 * 1234567890123456
 * ^coloumn 1
 * There is support for 64 bit addresses too.
 *
 * Return 0 if either start or end is not found
 */
static int get_start_end(const char *filename, unsigned int *start, unsigned int *end)
{
	FILE *map;
	char buffer[1024];

	*start = 0;
	*end = 0;
	map = fopen(filename, "r");
	if (!map)
		die(filename);
	while (fgets(buffer, 1024, map)) {
		if (start_line(buffer))
			*start = strtoul(buffer, NULL, 16);
		else if (end_line(buffer))
			*end = strtoul(buffer, NULL, 16);
	}
	fclose (map);

	if (*start == 0 || *end == 0)
		return 0;

	return 1;
}

int main(int argc,char **argv)
{
	static char aout_magic[] = { 0x01, 0x03, 0x01, 0x07 };
	char buffer[1024], *q, *r;
	unsigned int i, j, k, start, end, offset;
	struct stat s;
	int image, tail;

	if (argc != 4)
		usage();
	if (stat (argv[3], &s) < 0)
		die(argv[3]);

	if (!get_start_end(argv[2], &start, &end)) {
		fprintf (stderr, "Could not determine start and end from %s\n", argv[2]);
		exit(1);
	}
	if ((image = open(argv[1], O_RDWR)) < 0)
		die(argv[1]);
	if (read(image, buffer, 512) != 512)
		die(argv[1]);
	if (memcmp (buffer, "\177ELF", 4) == 0) {
		q = buffer + ld4(buffer + 28);
		i = ld4(q + 4) + ld4(buffer + 24) - ld4(q + 8);
		if (lseek(image, i, 0) < 0)
			die("lseek");
		if (read(image, buffer, 512) != 512)
			die(argv[1]);
		j = 0;
	} else if (memcmp(buffer, aout_magic, 4) == 0) {
		i = j = AOUT_TEXT_OFFSET;
	} else {
		fprintf (stderr, "Not ELF nor a.out. Don't blame me.\n");
		exit(1);
	}
	k = i;
	/*
	 * We need to fill in values for sparc_ramdisk_image + sparc_ramdisk_size
	 * To locate these symbols search for the "HdrS" text which appear
	 * in the image a little before the gokernel symbol.
	 * See definition of these in init_32.S
	 */

	/*  Find the gokernel label */
	i += (ld2(buffer + j + 2) << 2) - 512;
	if (lseek(image, i, 0) < 0)
		die("lseek");
	if (read(image, buffer, 1024) != 1024)
		die(argv[1]);
	for (q = buffer, r = q + 512; q < r; q += 4) {
		if (*q == 'H' && q[1] == 'd' && q[2] == 'r' && q[3] == 'S')
			break;
	}
	if (q == r) {
		fprintf (stderr, "Couldn't find headers signature in the kernel.\n");
		exit(1);
	}
	offset = i + (q - buffer) + 10;
	if (lseek(image, offset, 0) < 0)
		die("lseek");

	/*
	 * root_flags = 0
	 * root_dev = 1 (RAMDISK_MAJOR)
	 * ram_flags = 0
	 * sparc_ramdisk_image = "PAGE aligned address after _end")
	 * sparc_ramdisk_size = size of image
	 */
	st4(buffer, 0);
	st4(buffer + 4, 0x01000000);
	st4(buffer + 8, (end + 32 + 4095) & ~4095);
	st4(buffer + 12, s.st_size);

	if (write(image, buffer + 2, 14) != 14)
		die(argv[1]);

	/* seek page aligned boundary in the image file and add boot image */
	if (lseek(image, k - start + ((end + 32 + 4095) & ~4095), 0) < 0)
		die("lseek");
	if ((tail = open(argv[3],O_RDONLY)) < 0)
		die(argv[3]);
	while ((i = read(tail, buffer, 1024)) > 0)
		if (write(image, buffer, i) != i)
			die(argv[1]);
	if (close(image) < 0)
		die("close");
	if (close(tail) < 0)
		die("close");
	return 0;
}