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
7 struct static_key opal_tracepoint_key = STATIC_KEY_INIT;
8
9 int opal_tracepoint_regfunc(void)
10 {
11 static_key_slow_inc(&opal_tracepoint_key);
12 return 0;
13 }
14
15 void opal_tracepoint_unregfunc(void)
16 {
17 static_key_slow_dec(&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 */
27 extern long opal_tracepoint_refcount;
28
29 int opal_tracepoint_regfunc(void)
30 {
31 opal_tracepoint_refcount++;
32 return 0;
33 }
34
35 void 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 */
45 static DEFINE_PER_CPU(unsigned int, opal_trace_depth);
46
47 void __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
64 out:
65 local_irq_restore(flags);
66 }
67
68 void __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
85 out:
86 local_irq_restore(flags);
87 }
88
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