2 * Copyright (C) 2008 ARM Limited
3 * Copyright (C) 2014 Regents of the University of California
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.
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.
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>
22 #ifdef CONFIG_FRAME_POINTER
29 static void notrace walk_stackframe(struct task_struct *task,
30 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
32 unsigned long fp, sp, pc;
38 } else if (task == NULL || task == current) {
39 const register unsigned long current_sp __asm__ ("sp");
40 fp = (unsigned long)__builtin_frame_address(0);
42 pc = (unsigned long)walk_stackframe;
44 /* task blocked in __switch_to */
45 fp = task->thread.s[0];
51 unsigned long low, high;
52 struct stackframe *frame;
54 if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
57 /* Validate frame pointer */
58 low = sp + sizeof(struct stackframe);
59 high = ALIGN(sp, THREAD_SIZE);
60 if (unlikely(fp < low || fp > high || fp & 0x7))
62 /* Unwind stack frame */
63 frame = (struct stackframe *)fp - 1;
70 #else /* !CONFIG_FRAME_POINTER */
72 static void notrace walk_stackframe(struct task_struct *task,
73 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
81 } else if (task == NULL || task == current) {
82 const register unsigned long current_sp __asm__ ("sp");
84 pc = (unsigned long)walk_stackframe;
86 /* task blocked in __switch_to */
91 if (unlikely(sp & 0x7))
94 ksp = (unsigned long *)sp;
95 while (!kstack_end(ksp)) {
96 if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
102 #endif /* CONFIG_FRAME_POINTER */
105 static bool print_trace_address(unsigned long pc, void *arg)
111 void show_stack(struct task_struct *task, unsigned long *sp)
113 pr_cont("Call Trace:\n");
114 walk_stackframe(task, NULL, print_trace_address, NULL);
118 static bool save_wchan(unsigned long pc, void *arg)
120 if (!in_sched_functions(pc)) {
121 unsigned long *p = arg;
128 unsigned long get_wchan(struct task_struct *task)
130 unsigned long pc = 0;
132 if (likely(task && task != current && task->state != TASK_RUNNING))
133 walk_stackframe(task, NULL, save_wchan, &pc);
138 #ifdef CONFIG_STACKTRACE
140 static bool __save_trace(unsigned long pc, void *arg, bool nosched)
142 struct stack_trace *trace = arg;
144 if (unlikely(nosched && in_sched_functions(pc)))
146 if (unlikely(trace->skip > 0)) {
151 trace->entries[trace->nr_entries++] = pc;
152 return (trace->nr_entries >= trace->max_entries);
155 static bool save_trace(unsigned long pc, void *arg)
157 return __save_trace(pc, arg, false);
161 * Save stack-backtrace addresses into a stack_trace buffer.
163 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
165 walk_stackframe(tsk, NULL, save_trace, trace);
166 if (trace->nr_entries < trace->max_entries)
167 trace->entries[trace->nr_entries++] = ULONG_MAX;
169 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
171 void save_stack_trace(struct stack_trace *trace)
173 save_stack_trace_tsk(NULL, trace);
175 EXPORT_SYMBOL_GPL(save_stack_trace);
177 #endif /* CONFIG_STACKTRACE */