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

source code of linux/arch/powerpc/platforms/powernv/opal-tracepoints.c