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 #include <linux/llist.h>
13 
14 #include <asm/memory.h>
15 #include <asm/ptrace.h>
16 #include <asm/sdei.h>
17 
18 enum stack_type {
19 	STACK_TYPE_UNKNOWN,
20 	STACK_TYPE_TASK,
21 	STACK_TYPE_IRQ,
22 	STACK_TYPE_OVERFLOW,
23 	STACK_TYPE_SDEI_NORMAL,
24 	STACK_TYPE_SDEI_CRITICAL,
25 	__NR_STACK_TYPES
26 };
27 
28 struct stack_info {
29 	unsigned long low;
30 	unsigned long high;
31 	enum stack_type type;
32 };
33 
34 /*
35  * A snapshot of a frame record or fp/lr register values, along with some
36  * accounting information necessary for robust unwinding.
37  *
38  * @fp:          The fp value in the frame record (or the real fp)
39  * @pc:          The lr value in the frame record (or the real lr)
40  *
41  * @stacks_done: Stacks which have been entirely unwound, for which it is no
42  *               longer valid to unwind to.
43  *
44  * @prev_fp:     The fp that pointed to this frame record, or a synthetic value
45  *               of 0. This is used to ensure that within a stack, each
46  *               subsequent frame record is at an increasing address.
47  * @prev_type:   The type of stack this frame record was on, or a synthetic
48  *               value of STACK_TYPE_UNKNOWN. This is used to detect a
49  *               transition from one stack to another.
50  *
51  * @kr_cur:      When KRETPROBES is selected, holds the kretprobe instance
52  *               associated with the most recently encountered replacement lr
53  *               value.
54  */
55 struct stackframe {
56 	unsigned long fp;
57 	unsigned long pc;
58 	DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
59 	unsigned long prev_fp;
60 	enum stack_type prev_type;
61 #ifdef CONFIG_KRETPROBES
62 	struct llist_node *kr_cur;
63 #endif
64 };
65 
66 extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
67 			   const char *loglvl);
68 
69 DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
70 
71 static inline bool on_stack(unsigned long sp, unsigned long size,
72 			    unsigned long low, unsigned long high,
73 			    enum stack_type type, struct stack_info *info)
74 {
75 	if (!low)
76 		return false;
77 
78 	if (sp < low || sp + size < sp || sp + size > high)
79 		return false;
80 
81 	if (info) {
82 		info->low = low;
83 		info->high = high;
84 		info->type = type;
85 	}
86 	return true;
87 }
88 
89 static inline bool on_irq_stack(unsigned long sp, unsigned long size,
90 				struct stack_info *info)
91 {
92 	unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr);
93 	unsigned long high = low + IRQ_STACK_SIZE;
94 
95 	return on_stack(sp, size, low, high, STACK_TYPE_IRQ, info);
96 }
97 
98 static inline bool on_task_stack(const struct task_struct *tsk,
99 				 unsigned long sp, unsigned long size,
100 				 struct stack_info *info)
101 {
102 	unsigned long low = (unsigned long)task_stack_page(tsk);
103 	unsigned long high = low + THREAD_SIZE;
104 
105 	return on_stack(sp, size, low, high, STACK_TYPE_TASK, info);
106 }
107 
108 #ifdef CONFIG_VMAP_STACK
109 DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
110 
111 static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
112 				struct stack_info *info)
113 {
114 	unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack);
115 	unsigned long high = low + OVERFLOW_STACK_SIZE;
116 
117 	return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info);
118 }
119 #else
120 static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
121 			struct stack_info *info) { return false; }
122 #endif
123 
124 
125 /*
126  * We can only safely access per-cpu stacks from current in a non-preemptible
127  * context.
128  */
129 static inline bool on_accessible_stack(const struct task_struct *tsk,
130 				       unsigned long sp, unsigned long size,
131 				       struct stack_info *info)
132 {
133 	if (info)
134 		info->type = STACK_TYPE_UNKNOWN;
135 
136 	if (on_task_stack(tsk, sp, size, info))
137 		return true;
138 	if (tsk != current || preemptible())
139 		return false;
140 	if (on_irq_stack(sp, size, info))
141 		return true;
142 	if (on_overflow_stack(sp, size, info))
143 		return true;
144 	if (on_sdei_stack(sp, size, info))
145 		return true;
146 
147 	return false;
148 }
149 
150 #endif	/* __ASM_STACKTRACE_H */
151