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 register unsigned long sp_in_global __asm__("sp");
16
17 #ifdef CONFIG_FRAME_POINTER
18
19 struct stackframe {
20 unsigned long fp;
21 unsigned long ra;
22 };
23
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(unsigned long,void *),void * arg)24 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
25 bool (*fn)(unsigned long, void *), void *arg)
26 {
27 unsigned long fp, sp, pc;
28
29 if (regs) {
30 fp = frame_pointer(regs);
31 sp = user_stack_pointer(regs);
32 pc = instruction_pointer(regs);
33 } else if (task == NULL || task == current) {
34 const register unsigned long current_sp = sp_in_global;
35 fp = (unsigned long)__builtin_frame_address(0);
36 sp = current_sp;
37 pc = (unsigned long)walk_stackframe;
38 } else {
39 /* task blocked in __switch_to */
40 fp = task->thread.s[0];
41 sp = task->thread.sp;
42 pc = task->thread.ra;
43 }
44
45 for (;;) {
46 unsigned long low, high;
47 struct stackframe *frame;
48
49 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
50 break;
51
52 /* Validate frame pointer */
53 low = sp + sizeof(struct stackframe);
54 high = ALIGN(sp, THREAD_SIZE);
55 if (unlikely(fp < low || fp > high || fp & 0x7))
56 break;
57 /* Unwind stack frame */
58 frame = (struct stackframe *)fp - 1;
59 sp = fp;
60 fp = frame->fp;
61 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
62 (unsigned long *)(fp - 8));
63 }
64 }
65
66 #else /* !CONFIG_FRAME_POINTER */
67
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(unsigned long,void *),void * arg)68 void notrace walk_stackframe(struct task_struct *task,
69 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
70 {
71 unsigned long sp, pc;
72 unsigned long *ksp;
73
74 if (regs) {
75 sp = user_stack_pointer(regs);
76 pc = instruction_pointer(regs);
77 } else if (task == NULL || task == current) {
78 sp = sp_in_global;
79 pc = (unsigned long)walk_stackframe;
80 } else {
81 /* task blocked in __switch_to */
82 sp = task->thread.sp;
83 pc = task->thread.ra;
84 }
85
86 if (unlikely(sp & 0x7))
87 return;
88
89 ksp = (unsigned long *)sp;
90 while (!kstack_end(ksp)) {
91 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
92 break;
93 pc = (*ksp++) - 0x4;
94 }
95 }
96
97 #endif /* CONFIG_FRAME_POINTER */
98
99
print_trace_address(unsigned long pc,void * arg)100 static bool print_trace_address(unsigned long pc, void *arg)
101 {
102 const char *loglvl = arg;
103
104 print_ip_sym(loglvl, pc);
105 return false;
106 }
107
show_stack(struct task_struct * task,unsigned long * sp,const char * loglvl)108 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
109 {
110 pr_cont("Call Trace:\n");
111 walk_stackframe(task, NULL, print_trace_address, (void *)loglvl);
112 }
113
save_wchan(unsigned long pc,void * arg)114 static bool save_wchan(unsigned long pc, void *arg)
115 {
116 if (!in_sched_functions(pc)) {
117 unsigned long *p = arg;
118 *p = pc;
119 return true;
120 }
121 return false;
122 }
123
get_wchan(struct task_struct * task)124 unsigned long get_wchan(struct task_struct *task)
125 {
126 unsigned long pc = 0;
127
128 if (likely(task && task != current && task->state != TASK_RUNNING))
129 walk_stackframe(task, NULL, save_wchan, &pc);
130 return pc;
131 }
132
133
134 #ifdef CONFIG_STACKTRACE
135
__save_trace(unsigned long pc,void * arg,bool nosched)136 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
137 {
138 struct stack_trace *trace = arg;
139
140 if (unlikely(nosched && in_sched_functions(pc)))
141 return false;
142 if (unlikely(trace->skip > 0)) {
143 trace->skip--;
144 return false;
145 }
146
147 trace->entries[trace->nr_entries++] = pc;
148 return (trace->nr_entries >= trace->max_entries);
149 }
150
save_trace(unsigned long pc,void * arg)151 static bool save_trace(unsigned long pc, void *arg)
152 {
153 return __save_trace(pc, arg, false);
154 }
155
156 /*
157 * Save stack-backtrace addresses into a stack_trace buffer.
158 */
save_stack_trace_tsk(struct task_struct * tsk,struct stack_trace * trace)159 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
160 {
161 walk_stackframe(tsk, NULL, save_trace, trace);
162 }
163 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
164
save_stack_trace(struct stack_trace * trace)165 void save_stack_trace(struct stack_trace *trace)
166 {
167 save_stack_trace_tsk(NULL, trace);
168 }
169 EXPORT_SYMBOL_GPL(save_stack_trace);
170
171 #endif /* CONFIG_STACKTRACE */
172