1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
// SPDX-License-Identifier: GPL-2.0
/*
* Helpers for early access to EFI configuration table.
*
* Originally derived from arch/x86/boot/compressed/acpi.c
*/
#include "misc.h"
#include <linux/efi.h>
#include <asm/efi.h>
/**
* efi_get_type - Given a pointer to boot_params, determine the type of EFI environment.
*
* @bp: pointer to boot_params
*
* Return: EFI_TYPE_{32,64} for valid EFI environments, EFI_TYPE_NONE otherwise.
*/
enum efi_type efi_get_type(struct boot_params *bp)
{
struct efi_info *ei;
enum efi_type et;
const char *sig;
ei = &bp->efi_info;
sig = (char *)&ei->efi_loader_signature;
if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
et = EFI_TYPE_64;
} else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4)) {
et = EFI_TYPE_32;
} else {
debug_putstr("No EFI environment detected.\n");
et = EFI_TYPE_NONE;
}
#ifndef CONFIG_X86_64
/*
* Existing callers like acpi.c treat this case as an indicator to
* fall-through to non-EFI, rather than an error, so maintain that
* functionality here as well.
*/
if (ei->efi_systab_hi || ei->efi_memmap_hi) {
debug_putstr("EFI system table is located above 4GB and cannot be accessed.\n");
et = EFI_TYPE_NONE;
}
#endif
return et;
}
/**
* efi_get_system_table - Given a pointer to boot_params, retrieve the physical address
* of the EFI system table.
*
* @bp: pointer to boot_params
*
* Return: EFI system table address on success. On error, return 0.
*/
unsigned long efi_get_system_table(struct boot_params *bp)
{
unsigned long sys_tbl_pa;
struct efi_info *ei;
enum efi_type et;
/* Get systab from boot params. */
ei = &bp->efi_info;
#ifdef CONFIG_X86_64
sys_tbl_pa = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);
#else
sys_tbl_pa = ei->efi_systab;
#endif
if (!sys_tbl_pa) {
debug_putstr("EFI system table not found.");
return 0;
}
return sys_tbl_pa;
}
/**
* efi_get_conf_table - Given a pointer to boot_params, locate and return the physical
* address of EFI configuration table.
*
* @bp: pointer to boot_params
* @cfg_tbl_pa: location to store physical address of config table
* @cfg_tbl_len: location to store number of config table entries
*
* Return: 0 on success. On error, return params are left unchanged.
*/
int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa,
unsigned int *cfg_tbl_len)
{
unsigned long sys_tbl_pa;
enum efi_type et;
int ret;
if (!cfg_tbl_pa || !cfg_tbl_len)
return -EINVAL;
sys_tbl_pa = efi_get_system_table(bp);
if (!sys_tbl_pa)
return -EINVAL;
/* Handle EFI bitness properly */
et = efi_get_type(bp);
if (et == EFI_TYPE_64) {
efi_system_table_64_t *stbl = (efi_system_table_64_t *)sys_tbl_pa;
*cfg_tbl_pa = stbl->tables;
*cfg_tbl_len = stbl->nr_tables;
} else if (et == EFI_TYPE_32) {
efi_system_table_32_t *stbl = (efi_system_table_32_t *)sys_tbl_pa;
*cfg_tbl_pa = stbl->tables;
*cfg_tbl_len = stbl->nr_tables;
} else {
return -EINVAL;
}
return 0;
}
/* Get vendor table address/guid from EFI config table at the given index */
static int get_vendor_table(void *cfg_tbl, unsigned int idx,
unsigned long *vendor_tbl_pa,
efi_guid_t *vendor_tbl_guid,
enum efi_type et)
{
if (et == EFI_TYPE_64) {
efi_config_table_64_t *tbl_entry = (efi_config_table_64_t *)cfg_tbl + idx;
if (!IS_ENABLED(CONFIG_X86_64) && tbl_entry->table >> 32) {
debug_putstr("Error: EFI config table entry located above 4GB.\n");
return -EINVAL;
}
*vendor_tbl_pa = tbl_entry->table;
*vendor_tbl_guid = tbl_entry->guid;
} else if (et == EFI_TYPE_32) {
efi_config_table_32_t *tbl_entry = (efi_config_table_32_t *)cfg_tbl + idx;
*vendor_tbl_pa = tbl_entry->table;
*vendor_tbl_guid = tbl_entry->guid;
} else {
return -EINVAL;
}
return 0;
}
/**
* efi_find_vendor_table - Given EFI config table, search it for the physical
* address of the vendor table associated with GUID.
*
* @bp: pointer to boot_params
* @cfg_tbl_pa: pointer to EFI configuration table
* @cfg_tbl_len: number of entries in EFI configuration table
* @guid: GUID of vendor table
*
* Return: vendor table address on success. On error, return 0.
*/
unsigned long efi_find_vendor_table(struct boot_params *bp,
unsigned long cfg_tbl_pa,
unsigned int cfg_tbl_len,
efi_guid_t guid)
{
enum efi_type et;
unsigned int i;
et = efi_get_type(bp);
if (et == EFI_TYPE_NONE)
return 0;
for (i = 0; i < cfg_tbl_len; i++) {
unsigned long vendor_tbl_pa;
efi_guid_t vendor_tbl_guid;
int ret;
ret = get_vendor_table((void *)cfg_tbl_pa, i,
&vendor_tbl_pa,
&vendor_tbl_guid, et);
if (ret)
return 0;
if (!efi_guidcmp(guid, vendor_tbl_guid))
return vendor_tbl_pa;
}
return 0;
}
|