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
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(void *,unsigned long),void * arg)19 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
20 bool (*fn)(void *, unsigned long), void *arg)
21 {
22 unsigned long fp, sp, pc;
23 int level = 0;
24
25 if (regs) {
26 fp = frame_pointer(regs);
27 sp = user_stack_pointer(regs);
28 pc = instruction_pointer(regs);
29 } else if (task == NULL || task == current) {
30 fp = (unsigned long)__builtin_frame_address(0);
31 sp = current_stack_pointer;
32 pc = (unsigned long)walk_stackframe;
33 } else {
34 /* task blocked in __switch_to */
35 fp = task->thread.s[0];
36 sp = task->thread.sp;
37 pc = task->thread.ra;
38 }
39
40 for (;;) {
41 unsigned long low, high;
42 struct stackframe *frame;
43
44 if (unlikely(!__kernel_text_address(pc) || (level++ >= 1 && !fn(arg, pc))))
45 break;
46
47 /* Validate frame pointer */
48 low = sp + sizeof(struct stackframe);
49 high = ALIGN(sp, THREAD_SIZE);
50 if (unlikely(fp < low || fp > high || fp & 0x7))
51 break;
52 /* Unwind stack frame */
53 frame = (struct stackframe *)fp - 1;
54 sp = fp;
55 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
56 fp = frame->ra;
57 pc = regs->ra;
58 } else {
59 fp = frame->fp;
60 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
61 (unsigned long *)(fp - 8));
62 }
63
64 }
65 }
66
67 #else /* !CONFIG_FRAME_POINTER */
68
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(void *,unsigned long),void * arg)69 void notrace walk_stackframe(struct task_struct *task,
70 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
71 {
72 unsigned long sp, pc;
73 unsigned long *ksp;
74
75 if (regs) {
76 sp = user_stack_pointer(regs);
77 pc = instruction_pointer(regs);
78 } else if (task == NULL || task == current) {
79 sp = current_stack_pointer;
80 pc = (unsigned long)walk_stackframe;
81 } else {
82 /* task blocked in __switch_to */
83 sp = task->thread.sp;
84 pc = task->thread.ra;
85 }
86
87 if (unlikely(sp & 0x7))
88 return;
89
90 ksp = (unsigned long *)sp;
91 while (!kstack_end(ksp)) {
92 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
93 break;
94 pc = (*ksp++) - 0x4;
95 }
96 }
97
98 #endif /* CONFIG_FRAME_POINTER */
99
print_trace_address(void * arg,unsigned long pc)100 static bool print_trace_address(void *arg, unsigned long pc)
101 {
102 const char *loglvl = arg;
103
104 print_ip_sym(loglvl, pc);
105 return true;
106 }
107
dump_backtrace(struct pt_regs * regs,struct task_struct * task,const char * loglvl)108 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
109 const char *loglvl)
110 {
111 walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
112 }
113
show_stack(struct task_struct * task,unsigned long * sp,const char * loglvl)114 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
115 {
116 pr_cont("%sCall Trace:\n", loglvl);
117 dump_backtrace(NULL, task, loglvl);
118 }
119
save_wchan(void * arg,unsigned long pc)120 static bool save_wchan(void *arg, unsigned long pc)
121 {
122 if (!in_sched_functions(pc)) {
123 unsigned long *p = arg;
124 *p = pc;
125 return false;
126 }
127 return true;
128 }
129
__get_wchan(struct task_struct * task)130 unsigned long __get_wchan(struct task_struct *task)
131 {
132 unsigned long pc = 0;
133
134 if (!try_get_task_stack(task))
135 return 0;
136 walk_stackframe(task, NULL, save_wchan, &pc);
137 put_task_stack(task);
138 return pc;
139 }
140
arch_stack_walk(stack_trace_consume_fn consume_entry,void * cookie,struct task_struct * task,struct pt_regs * regs)141 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
142 struct task_struct *task, struct pt_regs *regs)
143 {
144 walk_stackframe(task, regs, consume_entry, cookie);
145 }
146
