mboot_extra.c revision 12947:f5f96e09bf49 
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
23 */
24
25#include <stdio.h>
26#include <errno.h>
27#include <assert.h>
28#include <unistd.h>
29#include <libintl.h>
30#include <sys/multiboot.h>
31#include <sys/sysmacros.h>
32
33#include "bblk_einfo.h"
34#include "boot_utils.h"
35#include "mboot_extra.h"
36
37/*
38 * Common functions to deal with the fake-multiboot encapsulation of the
39 * bootblock and the location of the extra information area.
40 */
41
42/* mboot checksum routine. */
43uint32_t
44compute_checksum(char *data, uint32_t size)
45{
46	uint32_t	*ck_ptr;
47	uint32_t	cksum = 0;
48	int		i;
49
50	ck_ptr = (uint32_t *)data;
51	for (i = 0; i < size; i += sizeof (uint32_t))
52		cksum += *ck_ptr++;
53
54	return (-cksum);
55}
56
57/* Given a buffer, look for a multiboot header within it. */
58int
59find_multiboot(char *buffer, uint32_t buf_size, uint32_t *mboot_off)
60{
61	multiboot_header_t	*mboot;
62	uint32_t		*iter;
63	uint32_t		cksum;
64	uint32_t		boundary;
65	int			i = 0;
66
67	iter = (uint32_t *)buffer;
68	*mboot_off = 0;
69	/* multiboot header has to be within the first 32K. */
70	boundary = MBOOT_SCAN_SIZE;
71	if (boundary > buf_size)
72		boundary = buf_size;
73
74	boundary = boundary - sizeof (multiboot_header_t);
75
76	for (i = 0; i < boundary; i += 4, iter++) {
77
78		mboot = (multiboot_header_t *)iter;
79		if (mboot->magic != MB_HEADER_MAGIC)
80			continue;
81
82		/* Found magic signature -- check checksum. */
83		cksum = -(mboot->flags + mboot->magic);
84		if (mboot->checksum != cksum) {
85			BOOT_DEBUG("multiboot magic found at %p, but checksum "
86			    "mismatches (is %x, should be %x)\n", mboot,
87			    mboot->checksum, cksum);
88			continue;
89		} else {
90			if (!(mboot->flags & BB_MBOOT_AOUT_FLAG)) {
91				BOOT_DEBUG("multiboot structure found, but no "
92				    "AOUT kludge specified, skipping.\n");
93				continue;
94			} else {
95				/* proper multiboot structure found. */
96				*mboot_off = i;
97				return (BC_SUCCESS);
98			}
99		}
100	}
101
102	return (BC_ERROR);
103}
104
105/*
106 * Given a pointer to the extra information area (a sequence of bb_header_ext_t
107 * + payload chunks), find the extended information structure.
108 */
109bblk_einfo_t *
110find_einfo(char *extra)
111{
112	bb_header_ext_t		*ext_header;
113	bblk_einfo_t		*einfo;
114	uint32_t		cksum;
115
116	assert(extra != NULL);
117
118	ext_header = (bb_header_ext_t *)extra;
119	cksum = compute_checksum(extra + sizeof (bb_header_ext_t),
120	    ext_header->size);
121	BOOT_DEBUG("Extended information header checksum is %x\n", cksum);
122
123	if (cksum != ext_header->checksum) {
124		BOOT_DEBUG("Unable to find extended versioning information, "
125		    "data looks corrupted\n");
126		return (NULL);
127	}
128
129	/*
130	 * Currently we only have one extra header so it must be encapsulating
131	 * the extended information structure.
132	 */
133	einfo = (bblk_einfo_t *)(extra + sizeof (bb_header_ext_t));
134	if (memcmp(einfo->magic, EINFO_MAGIC, EINFO_MAGIC_SIZE) != 0) {
135		BOOT_DEBUG("Unable to read stage2 extended versioning "
136		    "information, wrong magic identifier\n");
137		BOOT_DEBUG("Found %s, expected %s\n", einfo->magic,
138		    EINFO_MAGIC);
139		return (NULL);
140	}
141
142	return (einfo);
143}
144
145/*
146 * Given a pointer to the extra area, add the extended information structure
147 * encapsulated by a bb_header_ext_t structure.
148 */
149void
150add_einfo(char *extra, char *updt_str, bblk_hs_t *hs, uint32_t avail_space)
151{
152	bb_header_ext_t	*ext_hdr;
153	uint32_t	used_space;
154	unsigned char	*dest;
155	int		ret;
156
157	assert(extra != NULL);
158
159	if (updt_str == NULL) {
160		BOOT_DEBUG("WARNING: no update string passed to "
161		    "add_stage2_einfo()\n");
162		return;
163	}
164
165	/* Reserve space for the extra header. */
166	ext_hdr = (bb_header_ext_t *)extra;
167	dest = (unsigned char *)extra + sizeof (*ext_hdr);
168	/* Place the extended information structure. */
169	ret = prepare_and_write_einfo(dest, updt_str, hs, avail_space,
170	    &used_space);
171	if (ret != 0) {
172		(void) fprintf(stderr, gettext("Unable to write the extended "
173		    "versioning information\n"));
174		return;
175	}
176
177	/* Fill the extended information associated header. */
178	ext_hdr->size = P2ROUNDUP(used_space, 8);
179	ext_hdr->checksum = compute_checksum((char *)dest, ext_hdr->size);
180}
181