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
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Stack tracing support
*
* Copyright (C) 2012 ARM Ltd.
*/
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/ftrace.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/stacktrace.h>
#include <asm/irq.h>
#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>
/*
* Start an unwind from a pt_regs.
*
* The unwind will begin at the PC within the regs.
*
* The regs must be on a stack currently owned by the calling task.
*/
static inline void unwind_init_from_regs(struct unwind_state *state,
struct pt_regs *regs)
{
unwind_init_common(state, current);
state->fp = regs->regs[29];
state->pc = regs->pc;
}
/*
* Start an unwind from a caller.
*
* The unwind will begin at the caller of whichever function this is inlined
* into.
*
* The function which invokes this must be noinline.
*/
static __always_inline void unwind_init_from_caller(struct unwind_state *state)
{
unwind_init_common(state, current);
state->fp = (unsigned long)__builtin_frame_address(1);
state->pc = (unsigned long)__builtin_return_address(0);
}
/*
* Start an unwind from a blocked task.
*
* The unwind will begin at the blocked tasks saved PC (i.e. the caller of
* cpu_switch_to()).
*
* The caller should ensure the task is blocked in cpu_switch_to() for the
* duration of the unwind, or the unwind will be bogus. It is never valid to
* call this for the current task.
*/
static inline void unwind_init_from_task(struct unwind_state *state,
struct task_struct *task)
{
unwind_init_common(state, task);
state->fp = thread_saved_fp(task);
state->pc = thread_saved_pc(task);
}
/*
* We can only safely access per-cpu stacks from current in a non-preemptible
* context.
*/
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;
if (on_task_stack(tsk, sp, size, info))
return true;
if (tsk != current || preemptible())
return false;
if (on_irq_stack(sp, size, info))
return true;
if (on_overflow_stack(sp, size, info))
return true;
if (on_sdei_stack(sp, size, info))
return true;
return false;
}
/*
* Unwind from one frame record (A) to the next frame record (B).
*
* We terminate early if the location of B indicates a malformed chain of frame
* records (e.g. a cycle), determined based on the location and fp value of A
* and the location (but not the fp value) of B.
*/
static int notrace unwind_next(struct unwind_state *state)
{
struct task_struct *tsk = state->task;
unsigned long fp = state->fp;
struct stack_info info;
int err;
/* Final frame; nothing to unwind */
if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)
return -ENOENT;
err = unwind_next_common(state, &info, on_accessible_stack, NULL);
if (err)
return err;
state->pc = ptrauth_strip_insn_pac(state->pc);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
if (tsk->ret_stack &&
(state->pc == (unsigned long)return_to_handler)) {
unsigned long orig_pc;
/*
* This is a case where function graph tracer has
* modified a return address (LR) in a stack frame
* to hook a function return.
* So replace it to an original value.
*/
orig_pc = ftrace_graph_ret_addr(tsk, NULL, state->pc,
(void *)state->fp);
if (WARN_ON_ONCE(state->pc == orig_pc))
return -EINVAL;
state->pc = orig_pc;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
#ifdef CONFIG_KRETPROBES
if (is_kretprobe_trampoline(state->pc))
state->pc = kretprobe_find_ret_addr(tsk, (void *)state->fp, &state->kr_cur);
#endif
return 0;
}
NOKPROBE_SYMBOL(unwind_next);
static void notrace 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;
}
}
NOKPROBE_SYMBOL(unwind);
static bool dump_backtrace_entry(void *arg, unsigned long where)
{
char *loglvl = arg;
printk("%s %pSb\n", loglvl, (void *)where);
return true;
}
void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
const char *loglvl)
{
pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
if (regs && user_mode(regs))
return;
if (!tsk)
tsk = current;
if (!try_get_task_stack(tsk))
return;
printk("%sCall trace:\n", loglvl);
arch_stack_walk(dump_backtrace_entry, (void *)loglvl, tsk, regs);
put_task_stack(tsk);
}
void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
{
dump_backtrace(NULL, tsk, loglvl);
barrier();
}
noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
void *cookie, struct task_struct *task,
struct pt_regs *regs)
{
struct unwind_state state;
if (regs) {
if (task != current)
return;
unwind_init_from_regs(&state, regs);
} else if (task == current) {
unwind_init_from_caller(&state);
} else {
unwind_init_from_task(&state, task);
}
unwind(&state, consume_entry, cookie);
}
|
