1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2020, Bachmann electronic GmbH
4 */
5
6 #define LOG_CATEGORY LOGC_BOOT
7
8 #include <common.h>
9 #include <smbios.h>
10
verify_checksum(const struct smbios_entry * e)11 static inline int verify_checksum(const struct smbios_entry *e)
12 {
13 /*
14 * Checksums for SMBIOS tables are calculated to have a value, so that
15 * the sum over all bytes yields zero (using unsigned 8 bit arithmetic).
16 */
17 u8 *byte = (u8 *)e;
18 u8 sum = 0;
19
20 for (int i = 0; i < e->length; i++)
21 sum += byte[i];
22
23 return sum;
24 }
25
smbios_entry(u64 address,u32 size)26 const struct smbios_entry *smbios_entry(u64 address, u32 size)
27 {
28 const struct smbios_entry *entry = (struct smbios_entry *)(uintptr_t)address;
29
30 if (!address | !size)
31 return NULL;
32
33 if (memcmp(entry->anchor, "_SM_", 4))
34 return NULL;
35
36 if (verify_checksum(entry))
37 return NULL;
38
39 return entry;
40 }
41
next_header(const struct smbios_header * curr)42 static const struct smbios_header *next_header(const struct smbios_header *curr)
43 {
44 u8 *pos = ((u8 *)curr) + curr->length;
45
46 /* search for _double_ NULL bytes */
47 while (!((*pos == 0) && (*(pos + 1) == 0)))
48 pos++;
49
50 /* step behind the double NULL bytes */
51 pos += 2;
52
53 return (struct smbios_header *)pos;
54 }
55
smbios_header(const struct smbios_entry * entry,int type)56 const struct smbios_header *smbios_header(const struct smbios_entry *entry, int type)
57 {
58 const unsigned int num_header = entry->struct_count;
59 const struct smbios_header *header = (struct smbios_header *)entry->struct_table_address;
60
61 for (unsigned int i = 0; i < num_header; i++) {
62 if (header->type == type)
63 return header;
64
65 header = next_header(header);
66 }
67
68 return NULL;
69 }
70
string_from_smbios_table(const struct smbios_header * header,int idx)71 static const char *string_from_smbios_table(const struct smbios_header *header,
72 int idx)
73 {
74 unsigned int i = 1;
75 u8 *pos;
76
77 if (!header)
78 return NULL;
79
80 pos = ((u8 *)header) + header->length;
81
82 while (i < idx) {
83 if (*pos == 0x0)
84 i++;
85
86 pos++;
87 }
88
89 return (const char *)pos;
90 }
91
smbios_string(const struct smbios_header * header,int index)92 const char *smbios_string(const struct smbios_header *header, int index)
93 {
94 if (!header)
95 return NULL;
96
97 return string_from_smbios_table(header, index);
98 }
99
smbios_update_version_full(void * smbios_tab,const char * version)100 int smbios_update_version_full(void *smbios_tab, const char *version)
101 {
102 const struct smbios_header *hdr;
103 struct smbios_type0 *bios;
104 uint old_len, len;
105 char *ptr;
106
107 log_info("Updating SMBIOS table at %p\n", smbios_tab);
108 hdr = smbios_header(smbios_tab, SMBIOS_BIOS_INFORMATION);
109 if (!hdr)
110 return log_msg_ret("tab", -ENOENT);
111 bios = (struct smbios_type0 *)hdr;
112 ptr = (char *)smbios_string(hdr, bios->bios_ver);
113 if (!ptr)
114 return log_msg_ret("str", -ENOMEDIUM);
115
116 /*
117 * This string is supposed to have at least enough bytes and is
118 * padded with spaces. Update it, taking care not to move the
119 * \0 terminator, so that other strings in the string table
120 * are not disturbed. See smbios_add_string()
121 */
122 old_len = strnlen(ptr, SMBIOS_STR_MAX);
123 len = strnlen(version, SMBIOS_STR_MAX);
124 if (len > old_len)
125 return log_ret(-ENOSPC);
126
127 log_debug("Replacing SMBIOS type 0 version string '%s'\n", ptr);
128 memcpy(ptr, version, len);
129 #ifdef LOG_DEBUG
130 print_buffer((ulong)ptr, ptr, 1, old_len + 1, 0);
131 #endif
132
133 return 0;
134 }
135