1// SPDX-License-Identifier: GPL-2.0
2#include <linux/percpu.h>
3#include <linux/jump_label.h>
4#include <asm/trace.h>
5#include <asm/asm-prototypes.h>
6
7#ifdef CONFIG_JUMP_LABEL
8struct static_key opal_tracepoint_key = STATIC_KEY_INIT;
9
10int opal_tracepoint_regfunc(void)
11{
12	static_key_slow_inc(&opal_tracepoint_key);
13	return 0;
14}
15
16void opal_tracepoint_unregfunc(void)
17{
18	static_key_slow_dec(&opal_tracepoint_key);
19}
20#else
21/*
22 * We optimise OPAL calls by placing opal_tracepoint_refcount
23 * directly in the TOC so we can check if the opal tracepoints are
24 * enabled via a single load.
25 */
26
27/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
28extern long opal_tracepoint_refcount;
29
30int opal_tracepoint_regfunc(void)
31{
32	opal_tracepoint_refcount++;
33	return 0;
34}
35
36void opal_tracepoint_unregfunc(void)
37{
38	opal_tracepoint_refcount--;
39}
40#endif
41
42/*
43 * Since the tracing code might execute OPAL calls we need to guard against
44 * recursion.
45 */
46static DEFINE_PER_CPU(unsigned int, opal_trace_depth);
47
48void __trace_opal_entry(unsigned long opcode, unsigned long *args)
49{
50	unsigned long flags;
51	unsigned int *depth;
52
53	local_irq_save(flags);
54
55	depth = this_cpu_ptr(&opal_trace_depth);
56
57	if (*depth)
58		goto out;
59
60	(*depth)++;
61	preempt_disable();
62	trace_opal_entry(opcode, args);
63	(*depth)--;
64
65out:
66	local_irq_restore(flags);
67}
68
69void __trace_opal_exit(long opcode, unsigned long retval)
70{
71	unsigned long flags;
72	unsigned int *depth;
73
74	local_irq_save(flags);
75
76	depth = this_cpu_ptr(&opal_trace_depth);
77
78	if (*depth)
79		goto out;
80
81	(*depth)++;
82	trace_opal_exit(opcode, retval);
83	preempt_enable();
84	(*depth)--;
85
86out:
87	local_irq_restore(flags);
88}
89