LXR linux/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
   7struct static_key opal_tracepoint_key = STATIC_KEY_INIT;
   8
   9int opal_tracepoint_regfunc(void)
  10{
  11        static_key_slow_inc(&opal_tracepoint_key);
  12        return 0;
  13}
  14
  15void 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 */
  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