1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (C) 2005-2017 Andes Technology Corporation
3 
4 #include <linux/sched/debug.h>
5 #include <linux/sched/task_stack.h>
6 #include <linux/stacktrace.h>
7 #include <linux/ftrace.h>
8 
save_stack_trace(struct stack_trace * trace)9 void save_stack_trace(struct stack_trace *trace)
10 {
11 	save_stack_trace_tsk(current, trace);
12 }
13 EXPORT_SYMBOL_GPL(save_stack_trace);
14 
save_stack_trace_tsk(struct task_struct * tsk,struct stack_trace * trace)15 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
16 {
17 	unsigned long *fpn;
18 	int skip = trace->skip;
19 	int savesched;
20 	int graph_idx = 0;
21 
22 	if (tsk == current) {
23 		__asm__ __volatile__("\tori\t%0, $fp, #0\n":"=r"(fpn));
24 		savesched = 1;
25 	} else {
26 		fpn = (unsigned long *)thread_saved_fp(tsk);
27 		savesched = 0;
28 	}
29 
30 	while (!kstack_end(fpn) && !((unsigned long)fpn & 0x3)
31 	       && (fpn >= (unsigned long *)TASK_SIZE)) {
32 		unsigned long lpp, fpp;
33 
34 		lpp = fpn[LP_OFFSET];
35 		fpp = fpn[FP_OFFSET];
36 		if (!__kernel_text_address(lpp))
37 			break;
38 		else
39 			lpp = ftrace_graph_ret_addr(tsk, &graph_idx, lpp, NULL);
40 
41 		if (savesched || !in_sched_functions(lpp)) {
42 			if (skip) {
43 				skip--;
44 			} else {
45 				trace->entries[trace->nr_entries++] = lpp;
46 				if (trace->nr_entries >= trace->max_entries)
47 					break;
48 			}
49 		}
50 		fpn = (unsigned long *)fpp;
51 	}
52 }
53 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
54