1/*
2 * Stack trace utility for OpenRISC
3 *
4 * Copyright (C) 2017 Stafford Horne <shorne@gmail.com>
5 *
6 * This file is licensed under the terms of the GNU General Public License
7 * version 2.  This program is licensed "as is" without any warranty of any
8 * kind, whether express or implied.
9 *
10 * Losely based on work from sh and powerpc.
11 */
12
13#include <linux/export.h>
14#include <linux/sched.h>
15#include <linux/sched/debug.h>
16#include <linux/sched/task_stack.h>
17#include <linux/stacktrace.h>
18
19#include <asm/processor.h>
20#include <asm/unwinder.h>
21
22/*
23 * Save stack-backtrace addresses into a stack_trace buffer.
24 */
25static void
26save_stack_address(void *data, unsigned long addr, int reliable)
27{
28	struct stack_trace *trace = data;
29
30	if (!reliable)
31		return;
32
33	if (trace->skip > 0) {
34		trace->skip--;
35		return;
36	}
37
38	if (trace->nr_entries < trace->max_entries)
39		trace->entries[trace->nr_entries++] = addr;
40}
41
42void save_stack_trace(struct stack_trace *trace)
43{
44	unwind_stack(trace, (unsigned long *) &trace, save_stack_address);
45}
46EXPORT_SYMBOL_GPL(save_stack_trace);
47
48static void
49save_stack_address_nosched(void *data, unsigned long addr, int reliable)
50{
51	struct stack_trace *trace = (struct stack_trace *)data;
52
53	if (!reliable)
54		return;
55
56	if (in_sched_functions(addr))
57		return;
58
59	if (trace->skip > 0) {
60		trace->skip--;
61		return;
62	}
63
64	if (trace->nr_entries < trace->max_entries)
65		trace->entries[trace->nr_entries++] = addr;
66}
67
68void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
69{
70	unsigned long *sp = NULL;
71
72	if (!try_get_task_stack(tsk))
73		return;
74
75	if (tsk == current)
76		sp = (unsigned long *) &sp;
77	else {
78		unsigned long ksp;
79
80		/* Locate stack from kernel context */
81		ksp = task_thread_info(tsk)->ksp;
82		ksp += STACK_FRAME_OVERHEAD;	/* redzone */
83		ksp += sizeof(struct pt_regs);
84
85		sp = (unsigned long *) ksp;
86	}
87
88	unwind_stack(trace, sp, save_stack_address_nosched);
89
90	put_task_stack(tsk);
91}
92EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
93
94void
95save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
96{
97	unwind_stack(trace, (unsigned long *) regs->sp,
98		     save_stack_address_nosched);
99}
100EXPORT_SYMBOL_GPL(save_stack_trace_regs);
101