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 register unsigned long sp_in_global __asm__("sp");
18
19 #ifdef CONFIG_FRAME_POINTER
20
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(void *,unsigned long),void * arg)21 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
22 bool (*fn)(void *, unsigned long), void *arg)
23 {
24 unsigned long fp, sp, pc;
25 int level = 0;
26
27 if (regs) {
28 fp = frame_pointer(regs);
29 sp = user_stack_pointer(regs);
30 pc = instruction_pointer(regs);
31 } else if (task == NULL || task == current) {
32 fp = (unsigned long)__builtin_frame_address(0);
33 sp = sp_in_global;
34 pc = (unsigned long)walk_stackframe;
35 level = -1;
36 } else {
37 /* task blocked in __switch_to */
38 fp = task->thread.s[0];
39 sp = task->thread.sp;
40 pc = task->thread.ra;
41 }
42
43 for (;;) {
44 unsigned long low, high;
45 struct stackframe *frame;
46
47 if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
48 break;
49
50 /* Validate frame pointer */
51 low = sp + sizeof(struct stackframe);
52 high = ALIGN(sp, THREAD_SIZE);
53 if (unlikely(fp < low || fp > high || fp & 0x7))
54 break;
55 /* Unwind stack frame */
56 frame = (struct stackframe *)fp - 1;
57 sp = fp;
58 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
59 fp = frame->ra;
60 pc = regs->ra;
61 } else {
62 fp = frame->fp;
63 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
64 &frame->ra);
65 }
66
67 }
68 }
69
70 #else /* !CONFIG_FRAME_POINTER */
71
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(void *,unsigned long),void * arg)72 void notrace walk_stackframe(struct task_struct *task,
73 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
74 {
75 unsigned long sp, pc;
76 unsigned long *ksp;
77
78 if (regs) {
79 sp = user_stack_pointer(regs);
80 pc = instruction_pointer(regs);
81 } else if (task == NULL || task == current) {
82 sp = sp_in_global;
83 pc = (unsigned long)walk_stackframe;
84 } else {
85 /* task blocked in __switch_to */
86 sp = task->thread.sp;
87 pc = task->thread.ra;
88 }
89
90 if (unlikely(sp & 0x7))
91 return;
92
93 ksp = (unsigned long *)sp;
94 while (!kstack_end(ksp)) {
95 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
96 break;
97 pc = READ_ONCE_NOCHECK(*ksp++) - 0x4;
98 }
99 }
100
101 #endif /* CONFIG_FRAME_POINTER */
102
print_trace_address(void * arg,unsigned long pc)103 static bool print_trace_address(void *arg, unsigned long pc)
104 {
105 const char *loglvl = arg;
106
107 print_ip_sym(loglvl, pc);
108 return true;
109 }
110
dump_backtrace(struct pt_regs * regs,struct task_struct * task,const char * loglvl)111 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
112 const char *loglvl)
113 {
114 walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
115 }
116
show_stack(struct task_struct * task,unsigned long * sp,const char * loglvl)117 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
118 {
119 pr_cont("%sCall Trace:\n", loglvl);
120 dump_backtrace(NULL, task, loglvl);
121 }
122
save_wchan(void * arg,unsigned long pc)123 static bool save_wchan(void *arg, unsigned long pc)
124 {
125 if (!in_sched_functions(pc)) {
126 unsigned long *p = arg;
127 *p = pc;
128 return false;
129 }
130 return true;
131 }
132
get_wchan(struct task_struct * task)133 unsigned long get_wchan(struct task_struct *task)
134 {
135 unsigned long pc = 0;
136
137 if (likely(task && task != current && !task_is_running(task))) {
138 if (!try_get_task_stack(task))
139 return 0;
140 walk_stackframe(task, NULL, save_wchan, &pc);
141 put_task_stack(task);
142 }
143 return pc;
144 }
145
146 #ifdef CONFIG_STACKTRACE
147
arch_stack_walk(stack_trace_consume_fn consume_entry,void * cookie,struct task_struct * task,struct pt_regs * regs)148 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
149 struct task_struct *task, struct pt_regs *regs)
150 {
151 walk_stackframe(task, regs, consume_entry, cookie);
152 }
153
154 #endif /* CONFIG_STACKTRACE */
155