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

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