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 */
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/interrupt.h>
#include <asm/sections.h>
#include <asm/ptrace.h>
#include <asm/bitops.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>
unsigned long unwind_get_return_address(struct unwind_state *state)
{
if (unwind_done(state))
return 0;
return __kernel_text_address(state->ip) ? state->ip : 0;
}
EXPORT_SYMBOL_GPL(unwind_get_return_address);
static bool outside_of_stack(struct unwind_state *state, unsigned long sp)
{
return (sp <= state->sp) ||
(sp > state->stack_info.end - sizeof(struct stack_frame));
}
static bool update_stack_info(struct unwind_state *state, unsigned long sp)
{
struct stack_info *info = &state->stack_info;
unsigned long *mask = &state->stack_mask;
/* New stack pointer leaves the current stack */
if (get_stack_info(sp, state->task, info, mask) != 0 ||
!on_stack(info, sp, sizeof(struct stack_frame)))
/* 'sp' does not point to a valid stack */
return false;
return true;
}
static inline bool is_task_pt_regs(struct unwind_state *state,
struct pt_regs *regs)
{
return task_pt_regs(state->task) == regs;
}
bool unwind_next_frame(struct unwind_state *state)
{
struct stack_info *info = &state->stack_info;
struct stack_frame *sf;
struct pt_regs *regs;
unsigned long sp, ip;
bool reliable;
regs = state->regs;
if (unlikely(regs)) {
sp = state->sp;
sf = (struct stack_frame *) sp;
ip = READ_ONCE_NOCHECK(sf->gprs[8]);
reliable = false;
regs = NULL;
if (!__kernel_text_address(ip)) {
/* skip bogus %r14 */
state->regs = NULL;
return unwind_next_frame(state);
}
} else {
sf = (struct stack_frame *) state->sp;
sp = READ_ONCE_NOCHECK(sf->back_chain);
if (likely(sp)) {
/* Non-zero back-chain points to the previous frame */
if (unlikely(outside_of_stack(state, sp))) {
if (!update_stack_info(state, sp))
goto out_err;
}
sf = (struct stack_frame *) sp;
ip = READ_ONCE_NOCHECK(sf->gprs[8]);
reliable = true;
} else {
/* No back-chain, look for a pt_regs structure */
sp = state->sp + STACK_FRAME_OVERHEAD;
if (!on_stack(info, sp, sizeof(struct pt_regs)))
goto out_err;
regs = (struct pt_regs *) sp;
if (is_task_pt_regs(state, regs))
goto out_stop;
ip = READ_ONCE_NOCHECK(regs->psw.addr);
sp = READ_ONCE_NOCHECK(regs->gprs[15]);
if (unlikely(outside_of_stack(state, sp))) {
if (!update_stack_info(state, sp))
goto out_err;
}
reliable = true;
}
}
/* Sanity check: ABI requires SP to be aligned 8 bytes. */
if (sp & 0x7)
goto out_err;
ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *) sp);
/* Update unwind state */
state->sp = sp;
state->ip = ip;
state->regs = regs;
state->reliable = reliable;
return true;
out_err:
state->error = true;
out_stop:
state->stack_info.type = STACK_TYPE_UNKNOWN;
return false;
}
EXPORT_SYMBOL_GPL(unwind_next_frame);
void __unwind_start(struct unwind_state *state, struct task_struct *task,
struct pt_regs *regs, unsigned long first_frame)
{
struct stack_info *info = &state->stack_info;
struct stack_frame *sf;
unsigned long ip, sp;
memset(state, 0, sizeof(*state));
state->task = task;
state->regs = regs;
/* Don't even attempt to start from user mode regs: */
if (regs && user_mode(regs)) {
info->type = STACK_TYPE_UNKNOWN;
return;
}
/* Get the instruction pointer from pt_regs or the stack frame */
if (regs) {
ip = regs->psw.addr;
sp = regs->gprs[15];
} else if (task == current) {
sp = current_frame_address();
} else {
sp = task->thread.ksp;
}
/* Get current stack pointer and initialize stack info */
if (!update_stack_info(state, sp)) {
/* Something is wrong with the stack pointer */
info->type = STACK_TYPE_UNKNOWN;
state->error = true;
return;
}
if (!regs) {
/* Stack frame is within valid stack */
sf = (struct stack_frame *)sp;
ip = READ_ONCE_NOCHECK(sf->gprs[8]);
}
ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, NULL);
/* Update unwind state */
state->sp = sp;
state->ip = ip;
state->reliable = true;
if (!first_frame)
return;
/* Skip through the call chain to the specified starting frame */
while (!unwind_done(state)) {
if (on_stack(&state->stack_info, first_frame, sizeof(struct stack_frame))) {
if (state->sp >= first_frame)
break;
}
unwind_next_frame(state);
}
}
EXPORT_SYMBOL_GPL(__unwind_start);
|
