arch/powerpc/platforms/powernv/opal-tracepoints.c

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