1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2012 ARM Ltd.
4 */
5 #ifndef __ASM_STACKTRACE_H
6 #define __ASM_STACKTRACE_H
7
8 #include <linux/percpu.h>
9 #include <linux/sched.h>
10 #include <linux/sched/task_stack.h>
11 #include <linux/types.h>
12
13 #include <asm/memory.h>
14 #include <asm/ptrace.h>
15 #include <asm/sdei.h>
16
17 enum stack_type {
18 STACK_TYPE_UNKNOWN,
19 STACK_TYPE_TASK,
20 STACK_TYPE_IRQ,
21 STACK_TYPE_OVERFLOW,
22 STACK_TYPE_SDEI_NORMAL,
23 STACK_TYPE_SDEI_CRITICAL,
24 __NR_STACK_TYPES
25 };
26
27 struct stack_info {
28 unsigned long low;
29 unsigned long high;
30 enum stack_type type;
31 };
32
33 /*
34 * A snapshot of a frame record or fp/lr register values, along with some
35 * accounting information necessary for robust unwinding.
36 *
37 * @fp: The fp value in the frame record (or the real fp)
38 * @pc: The fp value in the frame record (or the real lr)
39 *
40 * @stacks_done: Stacks which have been entirely unwound, for which it is no
41 * longer valid to unwind to.
42 *
43 * @prev_fp: The fp that pointed to this frame record, or a synthetic value
44 * of 0. This is used to ensure that within a stack, each
45 * subsequent frame record is at an increasing address.
46 * @prev_type: The type of stack this frame record was on, or a synthetic
47 * value of STACK_TYPE_UNKNOWN. This is used to detect a
48 * transition from one stack to another.
49 *
50 * @graph: When FUNCTION_GRAPH_TRACER is selected, holds the index of a
51 * replacement lr value in the ftrace graph stack.
52 */
53 struct stackframe {
54 unsigned long fp;
55 unsigned long pc;
56 DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
57 unsigned long prev_fp;
58 enum stack_type prev_type;
59 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
60 int graph;
61 #endif
62 };
63
64 extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame);
65 extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
66 bool (*fn)(void *, unsigned long), void *data);
67 extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
68 const char *loglvl);
69
70 DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
71
on_stack(unsigned long sp,unsigned long low,unsigned long high,enum stack_type type,struct stack_info * info)72 static inline bool on_stack(unsigned long sp, unsigned long low,
73 unsigned long high, enum stack_type type,
74 struct stack_info *info)
75 {
76 if (!low)
77 return false;
78
79 if (sp < low || sp >= high)
80 return false;
81
82 if (info) {
83 info->low = low;
84 info->high = high;
85 info->type = type;
86 }
87 return true;
88 }
89
on_irq_stack(unsigned long sp,struct stack_info * info)90 static inline bool on_irq_stack(unsigned long sp,
91 struct stack_info *info)
92 {
93 unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr);
94 unsigned long high = low + IRQ_STACK_SIZE;
95
96 return on_stack(sp, low, high, STACK_TYPE_IRQ, info);
97 }
98
on_task_stack(const struct task_struct * tsk,unsigned long sp,struct stack_info * info)99 static inline bool on_task_stack(const struct task_struct *tsk,
100 unsigned long sp,
101 struct stack_info *info)
102 {
103 unsigned long low = (unsigned long)task_stack_page(tsk);
104 unsigned long high = low + THREAD_SIZE;
105
106 return on_stack(sp, low, high, STACK_TYPE_TASK, info);
107 }
108
109 #ifdef CONFIG_VMAP_STACK
110 DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
111
on_overflow_stack(unsigned long sp,struct stack_info * info)112 static inline bool on_overflow_stack(unsigned long sp,
113 struct stack_info *info)
114 {
115 unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack);
116 unsigned long high = low + OVERFLOW_STACK_SIZE;
117
118 return on_stack(sp, low, high, STACK_TYPE_OVERFLOW, info);
119 }
120 #else
on_overflow_stack(unsigned long sp,struct stack_info * info)121 static inline bool on_overflow_stack(unsigned long sp,
122 struct stack_info *info) { return false; }
123 #endif
124
125
126 /*
127 * We can only safely access per-cpu stacks from current in a non-preemptible
128 * context.
129 */
on_accessible_stack(const struct task_struct * tsk,unsigned long sp,struct stack_info * info)130 static inline bool on_accessible_stack(const struct task_struct *tsk,
131 unsigned long sp,
132 struct stack_info *info)
133 {
134 if (info)
135 info->type = STACK_TYPE_UNKNOWN;
136
137 if (on_task_stack(tsk, sp, info))
138 return true;
139 if (tsk != current || preemptible())
140 return false;
141 if (on_irq_stack(sp, info))
142 return true;
143 if (on_overflow_stack(sp, info))
144 return true;
145 if (on_sdei_stack(sp, info))
146 return true;
147
148 return false;
149 }
150
start_backtrace(struct stackframe * frame,unsigned long fp,unsigned long pc)151 static inline void start_backtrace(struct stackframe *frame,
152 unsigned long fp, unsigned long pc)
153 {
154 frame->fp = fp;
155 frame->pc = pc;
156 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
157 frame->graph = 0;
158 #endif
159
160 /*
161 * Prime the first unwind.
162 *
163 * In unwind_frame() we'll check that the FP points to a valid stack,
164 * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
165 * treated as a transition to whichever stack that happens to be. The
166 * prev_fp value won't be used, but we set it to 0 such that it is
167 * definitely not an accessible stack address.
168 */
169 bitmap_zero(frame->stacks_done, __NR_STACK_TYPES);
170 frame->prev_fp = 0;
171 frame->prev_type = STACK_TYPE_UNKNOWN;
172 }
173
174 #endif /* __ASM_STACKTRACE_H */
175
