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
|
/*
* Copyright (C) 2016 Citrix Systems R&D Ltd.
*/
#include <xen/errno.h>
#include <xen/init.h>
#include <xen/lib.h>
#include <xen/livepatch_elf.h>
#include <xen/livepatch.h>
#include <xen/mm.h>
#include <xen/vmap.h>
#include <asm/cpufeature.h>
#include <asm/livepatch.h>
/* Override macros from asm/page.h to make them work with mfn_t */
#undef virt_to_mfn
#define virt_to_mfn(va) _mfn(__virt_to_mfn(va))
void *vmap_of_xen_text;
int arch_livepatch_safety_check(void)
{
return 0;
}
int arch_livepatch_quiesce(void)
{
mfn_t text_mfn;
unsigned int text_order;
if ( vmap_of_xen_text )
return -EINVAL;
text_mfn = virt_to_mfn(_start);
text_order = get_order_from_bytes(_end - _start);
/*
* The text section is read-only. So re-map Xen to be able to patch
* the code.
*/
vmap_of_xen_text = __vmap(&text_mfn, 1U << text_order, 1, 1, PAGE_HYPERVISOR,
VMAP_DEFAULT);
if ( !vmap_of_xen_text )
{
printk(XENLOG_ERR LIVEPATCH "Failed to setup vmap of hypervisor! (order=%u)\n",
text_order);
return -ENOMEM;
}
return 0;
}
void arch_livepatch_revive(void)
{
/*
* Nuke the instruction cache. Data cache has been cleaned before in
* arch_livepatch_[apply|revert].
*/
invalidate_icache();
if ( vmap_of_xen_text )
vunmap(vmap_of_xen_text);
vmap_of_xen_text = NULL;
}
int arch_livepatch_verify_func(const struct livepatch_func *func)
{
/* If NOPing only do up to maximum amount we can put in the ->opaque. */
if ( !func->new_addr && (func->new_size > sizeof(func->opaque) ||
func->new_size % ARCH_PATCH_INSN_SIZE) )
return -EOPNOTSUPP;
if ( func->old_size < ARCH_PATCH_INSN_SIZE )
return -EINVAL;
return 0;
}
void arch_livepatch_revert(const struct livepatch_func *func)
{
uint32_t *new_ptr;
unsigned int len;
new_ptr = func->old_addr - (void *)_start + vmap_of_xen_text;
len = livepatch_insn_len(func);
memcpy(new_ptr, func->opaque, len);
clean_and_invalidate_dcache_va_range(new_ptr, len);
}
void arch_livepatch_post_action(void)
{
/* Discard any stale instructions that may have been fetched. */
isb();
}
void arch_livepatch_mask(void)
{
/* Mask System Error (SError) */
local_abort_disable();
}
void arch_livepatch_unmask(void)
{
local_abort_enable();
}
bool arch_livepatch_symbol_ok(const struct livepatch_elf *elf,
const struct livepatch_elf_sym *sym)
{
/*
* - Mapping symbols - denote the "start of a sequence of bytes of the
* appropriate type" to mark certain features - such as start of region
* containing data ($d); ARM ($a), or A64 ($x) instructions.
* We ignore Thumb instructions ($t) as we shouldn't have them.
*
* The format is either short: '$x' or long: '$x.<any>'. We do not
* need this and more importantly - each payload will contain this
* resulting in symbol collisions.
*/
if ( sym->name[0] == '$' && sym->name[1] != '\0' )
{
char p = sym->name[1];
size_t len = strlen(sym->name);
if ( (len >= 3 && (sym->name[2] == '.' )) || (len == 2) )
{
if ( p == 'd' ||
#ifdef CONFIG_ARM_32
p == 'a'
#else
p == 'x'
#endif
)
return false;
}
}
return true;
}
int arch_livepatch_secure(const void *va, unsigned int pages, enum va_type type)
{
unsigned long start = (unsigned long)va;
unsigned int flags = 0;
ASSERT(va);
ASSERT(pages);
switch ( type )
{
case LIVEPATCH_VA_RX:
flags = PAGE_HYPERVISOR_RX;
break;
case LIVEPATCH_VA_RW:
flags = PAGE_HYPERVISOR_RW;
break;
case LIVEPATCH_VA_RO:
flags = PAGE_HYPERVISOR_RO;
break;
default:
return -EINVAL;
}
return modify_xen_mappings(start, start + pages * PAGE_SIZE, flags);
}
void __init arch_livepatch_init(void)
{
void *start, *end;
start = (void *)LIVEPATCH_VMAP_START;
end = (void *)LIVEPATCH_VMAP_END;
vm_init_type(VMAP_XEN, start, end);
cpus_set_cap(LIVEPATCH_FEATURE);
}
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/
|
