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

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