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
 9void save_stack_trace(struct stack_trace *trace)
10{
11	save_stack_trace_tsk(current, trace);
12}
13EXPORT_SYMBOL_GPL(save_stack_trace);
14
15void 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}
53EXPORT_SYMBOL_GPL(save_stack_trace_tsk);