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
26 if (regs) {
27 fp = frame_pointer(regs);
28 sp = user_stack_pointer(regs);
29 pc = instruction_pointer(regs);
30 } else if (task == NULL || task == current) {
31 fp = (unsigned long)__builtin_frame_address(1);
32 sp = (unsigned long)__builtin_frame_address(0);
33 pc = (unsigned long)__builtin_return_address(0);
34 } else {
35 /* task blocked in __switch_to */
36 fp = task->thread.s[0];
37 sp = task->thread.sp;
38 pc = task->thread.ra;
39 }
40
41 for (;;) {
42 unsigned long low, high;
43 struct stackframe *frame;
44
45 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
46 break;
47
48 /* Validate frame pointer */
49 low = sp + sizeof(struct stackframe);
50 high = ALIGN(sp, THREAD_SIZE);
51 if (unlikely(fp < low || fp > high || fp & 0x7))
52 break;
53 /* Unwind stack frame */
54 frame = (struct stackframe *)fp - 1;
55 sp = fp;
56 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
57 fp = frame->ra;
58 pc = regs->ra;
59 } else {
60 fp = frame->fp;
61 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
62 (unsigned long *)(fp - 8));
63 }
64
65 }
66 }
67
68 #else /* !CONFIG_FRAME_POINTER */
69
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(void *,unsigned long),void * arg)70 void notrace walk_stackframe(struct task_struct *task,
71 struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
72 {
73 unsigned long sp, pc;
74 unsigned long *ksp;
75
76 if (regs) {
77 sp = user_stack_pointer(regs);
78 pc = instruction_pointer(regs);
79 } else if (task == NULL || task == current) {
80 sp = sp_in_global;
81 pc = (unsigned long)walk_stackframe;
82 } else {
83 /* task blocked in __switch_to */
84 sp = task->thread.sp;
85 pc = task->thread.ra;
86 }
87
88 if (unlikely(sp & 0x7))
89 return;
90
91 ksp = (unsigned long *)sp;
92 while (!kstack_end(ksp)) {
93 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
94 break;
95 pc = (*ksp++) - 0x4;
96 }
97 }
98
99 #endif /* CONFIG_FRAME_POINTER */
100
print_trace_address(void * arg,unsigned long pc)101 static bool print_trace_address(void *arg, unsigned long pc)
102 {
103 const char *loglvl = arg;
104
105 print_ip_sym(loglvl, pc);
106 return true;
107 }
108
dump_backtrace(struct pt_regs * regs,struct task_struct * task,const char * loglvl)109 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
110 const char *loglvl)
111 {
112 walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
113 }
114
show_stack(struct task_struct * task,unsigned long * sp,const char * loglvl)115 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
116 {
117 pr_cont("%sCall Trace:\n", loglvl);
118 dump_backtrace(NULL, task, loglvl);
119 }
120
save_wchan(void * arg,unsigned long pc)121 static bool save_wchan(void *arg, unsigned long pc)
122 {
123 if (!in_sched_functions(pc)) {
124 unsigned long *p = arg;
125 *p = pc;
126 return false;
127 }
128 return true;
129 }
130
get_wchan(struct task_struct * task)131 unsigned long get_wchan(struct task_struct *task)
132 {
133 unsigned long pc = 0;
134
135 if (likely(task && task != current && !task_is_running(task))) {
136 if (!try_get_task_stack(task))
137 return 0;
138 walk_stackframe(task, NULL, save_wchan, &pc);
139 put_task_stack(task);
140 }
141 return pc;
142 }
143
144 #ifdef CONFIG_STACKTRACE
145
arch_stack_walk(stack_trace_consume_fn consume_entry,void * cookie,struct task_struct * task,struct pt_regs * regs)146 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
147 struct task_struct *task, struct pt_regs *regs)
148 {
149 walk_stackframe(task, regs, consume_entry, cookie);
150 }
151
152 #endif /* CONFIG_STACKTRACE */
153
