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
|
// 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;
}
|
