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
|
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* KVM nVHE hypervisor stack tracing support.
*
* The unwinder implementation depends on the nVHE mode:
*
* 1) Non-protected nVHE mode - the host can directly access the
* HYP stack pages and unwind the HYP stack in EL1. This saves having
* to allocate shared buffers for the host to read the unwinded
* stacktrace.
*
* 2) pKVM (protected nVHE) mode - the host cannot directly access
* the HYP memory. The stack is unwinded in EL2 and dumped to a shared
* buffer where the host can read and print the stacktrace.
*
* Copyright (C) 2022 Google LLC
*/
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <asm/stacktrace/nvhe.h>
static bool on_overflow_stack(unsigned long sp, unsigned long size,
struct stack_info *info)
{
struct kvm_nvhe_stacktrace_info *stacktrace_info
= this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
unsigned long low = (unsigned long)stacktrace_info->overflow_stack_base;
unsigned long high = low + OVERFLOW_STACK_SIZE;
return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info);
}
static bool on_hyp_stack(unsigned long sp, unsigned long size,
struct stack_info *info)
{
struct kvm_nvhe_stacktrace_info *stacktrace_info
= this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
unsigned long low = (unsigned long)stacktrace_info->stack_base;
unsigned long high = low + PAGE_SIZE;
return on_stack(sp, size, low, high, STACK_TYPE_HYP, info);
}
static bool on_accessible_stack(const struct task_struct *tsk,
unsigned long sp, unsigned long size,
struct stack_info *info)
{
if (info)
info->type = STACK_TYPE_UNKNOWN;
return (on_overflow_stack(sp, size, info) ||
on_hyp_stack(sp, size, info));
}
static int unwind_next(struct unwind_state *state)
{
struct stack_info info;
return unwind_next_common(state, &info, on_accessible_stack,
kvm_nvhe_stack_kern_va);
}
static void unwind(struct unwind_state *state,
stack_trace_consume_fn consume_entry, void *cookie)
{
while (1) {
int ret;
if (!consume_entry(cookie, state->pc))
break;
ret = unwind_next(state);
if (ret < 0)
break;
}
}
/*
* kvm_nvhe_dump_backtrace_entry - Symbolize and print an nVHE backtrace entry
*
* @arg : the hypervisor offset, used for address translation
* @where : the program counter corresponding to the stack frame
*/
static bool kvm_nvhe_dump_backtrace_entry(void *arg, unsigned long where)
{
unsigned long va_mask = GENMASK_ULL(vabits_actual - 1, 0);
unsigned long hyp_offset = (unsigned long)arg;
/* Mask tags and convert to kern addr */
where = (where & va_mask) + hyp_offset;
kvm_err(" [<%016lx>] %pB\n", where, (void *)(where + kaslr_offset()));
return true;
}
static void kvm_nvhe_dump_backtrace_start(void)
{
kvm_err("nVHE call trace:\n");
}
static void kvm_nvhe_dump_backtrace_end(void)
{
kvm_err("---[ end nVHE call trace ]---\n");
}
/*
* hyp_dump_backtrace - Dump the non-protected nVHE backtrace.
*
* @hyp_offset: hypervisor offset, used for address translation.
*
* The host can directly access HYP stack pages in non-protected
* mode, so the unwinding is done directly from EL1. This removes
* the need for shared buffers between host and hypervisor for
* the stacktrace.
*/
static void hyp_dump_backtrace(unsigned long hyp_offset)
{
struct kvm_nvhe_stacktrace_info *stacktrace_info;
struct unwind_state state;
stacktrace_info = this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
kvm_nvhe_unwind_init(&state, stacktrace_info->fp, stacktrace_info->pc);
kvm_nvhe_dump_backtrace_start();
unwind(&state, kvm_nvhe_dump_backtrace_entry, (void *)hyp_offset);
kvm_nvhe_dump_backtrace_end();
}
#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE
DECLARE_KVM_NVHE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)],
pkvm_stacktrace);
/*
* pkvm_dump_backtrace - Dump the protected nVHE HYP backtrace.
*
* @hyp_offset: hypervisor offset, used for address translation.
*
* Dumping of the pKVM HYP backtrace is done by reading the
* stack addresses from the shared stacktrace buffer, since the
* host cannot directly access hypervisor memory in protected
* mode.
*/
static void pkvm_dump_backtrace(unsigned long hyp_offset)
{
unsigned long *stacktrace
= (unsigned long *) this_cpu_ptr_nvhe_sym(pkvm_stacktrace);
int i, size = NVHE_STACKTRACE_SIZE / sizeof(long);
kvm_nvhe_dump_backtrace_start();
/* The saved stacktrace is terminated by a null entry */
for (i = 0; i < size && stacktrace[i]; i++)
kvm_nvhe_dump_backtrace_entry((void *)hyp_offset, stacktrace[i]);
kvm_nvhe_dump_backtrace_end();
}
#else /* !CONFIG_PROTECTED_NVHE_STACKTRACE */
static void pkvm_dump_backtrace(unsigned long hyp_offset)
{
kvm_err("Cannot dump pKVM nVHE stacktrace: !CONFIG_PROTECTED_NVHE_STACKTRACE\n");
}
#endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */
/*
* kvm_nvhe_dump_backtrace - Dump KVM nVHE hypervisor backtrace.
*
* @hyp_offset: hypervisor offset, used for address translation.
*/
void kvm_nvhe_dump_backtrace(unsigned long hyp_offset)
{
if (is_protected_kvm_enabled())
pkvm_dump_backtrace(hyp_offset);
else
hyp_dump_backtrace(hyp_offset);
}
|
