1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2008 ARM Limited
4 * Copyright (C) 2014 Regents of the University of California
5 */
6
7 #include <linux/export.h>
8 #include <linux/kallsyms.h>
9 #include <linux/sched.h>
10 #include <linux/sched/debug.h>
11 #include <linux/sched/task_stack.h>
12 #include <linux/stacktrace.h>
13 #include <linux/ftrace.h>
14
15 #include <asm/stacktrace.h>
16
17 #ifdef CONFIG_FRAME_POINTER
18
19 extern asmlinkage void ret_from_exception(void);
20
fp_is_valid(unsigned long fp,unsigned long sp)21 static inline int fp_is_valid(unsigned long fp, unsigned long sp)
22 {
23 unsigned long low, high;
24
25 low = sp + sizeof(struct stackframe);
26 high = ALIGN(sp, THREAD_SIZE);
27
28 return !(fp < low || fp > high || fp & 0x07);
29 }
30
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(void *,unsigned long),void * arg)31 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
32 bool (*fn)(void *, unsigned long), void *arg)
33 {
34 unsigned long fp, sp, pc;
35 int graph_idx = 0;
36 int level = 0;
37
38 if (regs) {
39 fp = frame_pointer(regs);
40 sp = user_stack_pointer(regs);
41 pc = instruction_pointer(regs);
42 } else if (task == NULL || task == current) {
43 fp = (unsigned long)__builtin_frame_address(0);
44 sp = current_stack_pointer;
45 pc = (unsigned long)walk_stackframe;
46 level = -1;
47 } else {
48 /* task blocked in __switch_to */
49 fp = task->thread.s[0];
50 sp = task->thread.sp;
51 pc = task->thread.ra;
52 }
53
54 for (;;) {
55 struct stackframe *frame;
56
57 if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
58 break;
59
60 if (unlikely(!fp_is_valid(fp, sp)))
61 break;
62
63 /* Unwind stack frame */
64 frame = (struct stackframe *)fp - 1;
65 sp = fp;
66 if (regs && (regs->epc == pc) && fp_is_valid(frame->ra, sp)) {
67 /* We hit function where ra is not saved on the stack */
68 fp = frame->ra;
69 pc = regs->ra;
70 } else {
71 fp = frame->fp;
72 pc = ftrace_graph_ret_addr(current, &graph_idx, frame->ra,
73 &frame->ra);
74 if (pc == (unsigned long)ret_from_exception) {
75 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
76 break;
77
78 pc = ((struct pt_regs *)sp)->epc;
79 fp = ((struct pt_regs *)sp)->s0;
80 }
81 }
82
83 }
84 }
85
86 #else /* !CONFIG_FRAME_POINTER */
87
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(void *,unsigned long),void * arg)88 void notrace walk_stackframe(struct task_struct *task,
89 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
90 {
91 unsigned long sp, pc;
92 unsigned long *ksp;
93
94 if (regs) {
95 sp = user_stack_pointer(regs);
96 pc = instruction_pointer(regs);
97 } else if (task == NULL || task == current) {
98 sp = current_stack_pointer;
99 pc = (unsigned long)walk_stackframe;
100 } else {
101 /* task blocked in __switch_to */
102 sp = task->thread.sp;
103 pc = task->thread.ra;
104 }
105
106 if (unlikely(sp & 0x7))
107 return;
108
109 ksp = (unsigned long *)sp;
110 while (!kstack_end(ksp)) {
111 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
112 break;
113 pc = READ_ONCE_NOCHECK(*ksp++) - 0x4;
114 }
115 }
116
117 #endif /* CONFIG_FRAME_POINTER */
118
print_trace_address(void * arg,unsigned long pc)119 static bool print_trace_address(void *arg, unsigned long pc)
120 {
121 const char *loglvl = arg;
122
123 print_ip_sym(loglvl, pc);
124 return true;
125 }
126
dump_backtrace(struct pt_regs * regs,struct task_struct * task,const char * loglvl)127 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
128 const char *loglvl)
129 {
130 walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
131 }
132
show_stack(struct task_struct * task,unsigned long * sp,const char * loglvl)133 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
134 {
135 pr_cont("%sCall Trace:\n", loglvl);
136 dump_backtrace(NULL, task, loglvl);
137 }
138
save_wchan(void * arg,unsigned long pc)139 static bool save_wchan(void *arg, unsigned long pc)
140 {
141 if (!in_sched_functions(pc)) {
142 unsigned long *p = arg;
143 *p = pc;
144 return false;
145 }
146 return true;
147 }
148
__get_wchan(struct task_struct * task)149 unsigned long __get_wchan(struct task_struct *task)
150 {
151 unsigned long pc = 0;
152
153 if (!try_get_task_stack(task))
154 return 0;
155 walk_stackframe(task, NULL, save_wchan, &pc);
156 put_task_stack(task);
157 return pc;
158 }
159
arch_stack_walk(stack_trace_consume_fn consume_entry,void * cookie,struct task_struct * task,struct pt_regs * regs)160 noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
161 struct task_struct *task, struct pt_regs *regs)
162 {
163 walk_stackframe(task, regs, consume_entry, cookie);
164 }
165