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
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
|
// SPDX-License-Identifier: GPL-2.0
/*
* Early cpufeature override framework
*
* Copyright (C) 2020 Google LLC
* Author: Marc Zyngier <maz@kernel.org>
*/
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/libfdt.h>
#include <asm/cacheflush.h>
#include <asm/cpufeature.h>
#include <asm/setup.h>
#define FTR_DESC_NAME_LEN 20
#define FTR_DESC_FIELD_LEN 10
#define FTR_ALIAS_NAME_LEN 30
#define FTR_ALIAS_OPTION_LEN 80
struct ftr_set_desc {
char name[FTR_DESC_NAME_LEN];
struct arm64_ftr_override *override;
struct {
char name[FTR_DESC_FIELD_LEN];
u8 shift;
bool (*filter)(u64 val);
} fields[];
};
static bool __init mmfr1_vh_filter(u64 val)
{
/*
* If we ever reach this point while running VHE, we're
* guaranteed to be on one of these funky, VHE-stuck CPUs. If
* the user was trying to force nVHE on us, proceed with
* attitude adjustment.
*/
return !(is_kernel_in_hyp_mode() && val == 0);
}
static const struct ftr_set_desc mmfr1 __initconst = {
.name = "id_aa64mmfr1",
.override = &id_aa64mmfr1_override,
.fields = {
{ "vh", ID_AA64MMFR1_VHE_SHIFT, mmfr1_vh_filter },
{}
},
};
static const struct ftr_set_desc pfr1 __initconst = {
.name = "id_aa64pfr1",
.override = &id_aa64pfr1_override,
.fields = {
{ "bt", ID_AA64PFR1_BT_SHIFT },
{}
},
};
static const struct ftr_set_desc isar1 __initconst = {
.name = "id_aa64isar1",
.override = &id_aa64isar1_override,
.fields = {
{ "gpi", ID_AA64ISAR1_GPI_SHIFT },
{ "gpa", ID_AA64ISAR1_GPA_SHIFT },
{ "api", ID_AA64ISAR1_API_SHIFT },
{ "apa", ID_AA64ISAR1_APA_SHIFT },
{}
},
};
extern struct arm64_ftr_override kaslr_feature_override;
static const struct ftr_set_desc kaslr __initconst = {
.name = "kaslr",
#ifdef CONFIG_RANDOMIZE_BASE
.override = &kaslr_feature_override,
#endif
.fields = {
{ "disabled", 0 },
{}
},
};
static const struct ftr_set_desc * const regs[] __initconst = {
&mmfr1,
&pfr1,
&isar1,
&kaslr,
};
static const struct {
char alias[FTR_ALIAS_NAME_LEN];
char feature[FTR_ALIAS_OPTION_LEN];
} aliases[] __initconst = {
{ "kvm-arm.mode=nvhe", "id_aa64mmfr1.vh=0" },
{ "kvm-arm.mode=protected", "id_aa64mmfr1.vh=0" },
{ "arm64.nobti", "id_aa64pfr1.bt=0" },
{ "arm64.nopauth",
"id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 "
"id_aa64isar1.api=0 id_aa64isar1.apa=0" },
{ "nokaslr", "kaslr.disabled=1" },
};
static int __init find_field(const char *cmdline,
const struct ftr_set_desc *reg, int f, u64 *v)
{
char opt[FTR_DESC_NAME_LEN + FTR_DESC_FIELD_LEN + 2];
int len;
len = snprintf(opt, ARRAY_SIZE(opt), "%s.%s=",
reg->name, reg->fields[f].name);
if (!parameqn(cmdline, opt, len))
return -1;
return kstrtou64(cmdline + len, 0, v);
}
static void __init match_options(const char *cmdline)
{
int i;
for (i = 0; i < ARRAY_SIZE(regs); i++) {
int f;
if (!regs[i]->override)
continue;
for (f = 0; strlen(regs[i]->fields[f].name); f++) {
u64 shift = regs[i]->fields[f].shift;
u64 mask = 0xfUL << shift;
u64 v;
if (find_field(cmdline, regs[i], f, &v))
continue;
/*
* If an override gets filtered out, advertise
* it by setting the value to 0xf, but
* clearing the mask... Yes, this is fragile.
*/
if (regs[i]->fields[f].filter &&
!regs[i]->fields[f].filter(v)) {
regs[i]->override->val |= mask;
regs[i]->override->mask &= ~mask;
continue;
}
regs[i]->override->val &= ~mask;
regs[i]->override->val |= (v << shift) & mask;
regs[i]->override->mask |= mask;
return;
}
}
}
static __init void __parse_cmdline(const char *cmdline, bool parse_aliases)
{
do {
char buf[256];
size_t len;
int i;
cmdline = skip_spaces(cmdline);
for (len = 0; cmdline[len] && !isspace(cmdline[len]); len++);
if (!len)
return;
len = min(len, ARRAY_SIZE(buf) - 1);
strncpy(buf, cmdline, len);
buf[len] = 0;
if (strcmp(buf, "--") == 0)
return;
cmdline += len;
match_options(buf);
for (i = 0; parse_aliases && i < ARRAY_SIZE(aliases); i++)
if (parameq(buf, aliases[i].alias))
__parse_cmdline(aliases[i].feature, false);
} while (1);
}
static __init const u8 *get_bootargs_cmdline(void)
{
const u8 *prop;
void *fdt;
int node;
fdt = get_early_fdt_ptr();
if (!fdt)
return NULL;
node = fdt_path_offset(fdt, "/chosen");
if (node < 0)
return NULL;
prop = fdt_getprop(fdt, node, "bootargs", NULL);
if (!prop)
return NULL;
return strlen(prop) ? prop : NULL;
}
static __init void parse_cmdline(void)
{
const u8 *prop = get_bootargs_cmdline();
if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || !prop)
__parse_cmdline(CONFIG_CMDLINE, true);
if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop)
__parse_cmdline(prop, true);
}
/* Keep checkers quiet */
void init_feature_override(void);
asmlinkage void __init init_feature_override(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(regs); i++) {
if (regs[i]->override) {
regs[i]->override->val = 0;
regs[i]->override->mask = 0;
}
}
parse_cmdline();
for (i = 0; i < ARRAY_SIZE(regs); i++) {
if (regs[i]->override)
__flush_dcache_area(regs[i]->override,
sizeof(*regs[i]->override));
}
}
|
