1 /*
2 * Copyright (C) 2008 ARM Limited
3 * Copyright (C) 2014 Regents of the University of California
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 */
14
15 #include <linux/export.h>
16 #include <linux/kallsyms.h>
17 #include <linux/sched.h>
18 #include <linux/sched/debug.h>
19 #include <linux/sched/task_stack.h>
20 #include <linux/stacktrace.h>
21 #include <linux/ftrace.h>
22
23 #ifdef CONFIG_FRAME_POINTER
24
25 struct stackframe {
26 unsigned long fp;
27 unsigned long ra;
28 };
29
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(unsigned long,void *),void * arg)30 static void notrace walk_stackframe(struct task_struct *task,
31 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
32 {
33 unsigned long fp, sp, pc;
34
35 if (regs) {
36 fp = GET_FP(regs);
37 sp = GET_USP(regs);
38 pc = GET_IP(regs);
39 } else if (task == NULL || task == current) {
40 const register unsigned long current_sp __asm__ ("sp");
41 fp = (unsigned long)__builtin_frame_address(0);
42 sp = current_sp;
43 pc = (unsigned long)walk_stackframe;
44 } else {
45 /* task blocked in __switch_to */
46 fp = task->thread.s[0];
47 sp = task->thread.sp;
48 pc = task->thread.ra;
49 }
50
51 for (;;) {
52 unsigned long low, high;
53 struct stackframe *frame;
54
55 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
56 break;
57
58 /* Validate frame pointer */
59 low = sp + sizeof(struct stackframe);
60 high = ALIGN(sp, THREAD_SIZE);
61 if (unlikely(fp < low || fp > high || fp & 0x7))
62 break;
63 /* Unwind stack frame */
64 frame = (struct stackframe *)fp - 1;
65 sp = fp;
66 fp = frame->fp;
67 #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
68 pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
69 (unsigned long *)(fp - 8));
70 #else
71 pc = frame->ra - 0x4;
72 #endif
73 }
74 }
75
76 #else /* !CONFIG_FRAME_POINTER */
77
walk_stackframe(struct task_struct * task,struct pt_regs * regs,bool (* fn)(unsigned long,void *),void * arg)78 static void notrace walk_stackframe(struct task_struct *task,
79 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
80 {
81 unsigned long sp, pc;
82 unsigned long *ksp;
83
84 if (regs) {
85 sp = GET_USP(regs);
86 pc = GET_IP(regs);
87 } else if (task == NULL || task == current) {
88 const register unsigned long current_sp __asm__ ("sp");
89 sp = current_sp;
90 pc = (unsigned long)walk_stackframe;
91 } else {
92 /* task blocked in __switch_to */
93 sp = task->thread.sp;
94 pc = task->thread.ra;
95 }
96
97 if (unlikely(sp & 0x7))
98 return;
99
100 ksp = (unsigned long *)sp;
101 while (!kstack_end(ksp)) {
102 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
103 break;
104 pc = (*ksp++) - 0x4;
105 }
106 }
107
108 #endif /* CONFIG_FRAME_POINTER */
109
110
print_trace_address(unsigned long pc,void * arg)111 static bool print_trace_address(unsigned long pc, void *arg)
112 {
113 print_ip_sym(pc);
114 return false;
115 }
116
show_stack(struct task_struct * task,unsigned long * sp)117 void show_stack(struct task_struct *task, unsigned long *sp)
118 {
119 pr_cont("Call Trace:\n");
120 walk_stackframe(task, NULL, print_trace_address, NULL);
121 }
122
123
save_wchan(unsigned long pc,void * arg)124 static bool save_wchan(unsigned long pc, void *arg)
125 {
126 if (!in_sched_functions(pc)) {
127 unsigned long *p = arg;
128 *p = pc;
129 return true;
130 }
131 return false;
132 }
133
get_wchan(struct task_struct * task)134 unsigned long get_wchan(struct task_struct *task)
135 {
136 unsigned long pc = 0;
137
138 if (likely(task && task != current && task->state != TASK_RUNNING))
139 walk_stackframe(task, NULL, save_wchan, &pc);
140 return pc;
141 }
142
143
144 #ifdef CONFIG_STACKTRACE
145
__save_trace(unsigned long pc,void * arg,bool nosched)146 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
147 {
148 struct stack_trace *trace = arg;
149
150 if (unlikely(nosched && in_sched_functions(pc)))
151 return false;
152 if (unlikely(trace->skip > 0)) {
153 trace->skip--;
154 return false;
155 }
156
157 trace->entries[trace->nr_entries++] = pc;
158 return (trace->nr_entries >= trace->max_entries);
159 }
160
save_trace(unsigned long pc,void * arg)161 static bool save_trace(unsigned long pc, void *arg)
162 {
163 return __save_trace(pc, arg, false);
164 }
165
166 /*
167 * Save stack-backtrace addresses into a stack_trace buffer.
168 */
save_stack_trace_tsk(struct task_struct * tsk,struct stack_trace * trace)169 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
170 {
171 walk_stackframe(tsk, NULL, save_trace, trace);
172 if (trace->nr_entries < trace->max_entries)
173 trace->entries[trace->nr_entries++] = ULONG_MAX;
174 }
175 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
176
save_stack_trace(struct stack_trace * trace)177 void save_stack_trace(struct stack_trace *trace)
178 {
179 save_stack_trace_tsk(NULL, trace);
180 }
181 EXPORT_SYMBOL_GPL(save_stack_trace);
182
183 #endif /* CONFIG_STACKTRACE */
184
