LXR linux/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 CONFIG_JUMP_LABEL
   8struct static_key opal_tracepoint_key = STATIC_KEY_INIT;
   9
  10int opal_tracepoint_regfunc(void)
  11{
  12        static_key_slow_inc(&opal_tracepoint_key);
  13        return 0;
  14}
  15
  16void 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 */
  28extern long opal_tracepoint_refcount;
  29
  30int opal_tracepoint_regfunc(void)
  31{
  32        opal_tracepoint_refcount++;
  33        return 0;
  34}
  35
  36void 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 */
  46static DEFINE_PER_CPU(unsigned int, opal_trace_depth);
  47
  48void __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
  65out:
  66        local_irq_restore(flags);
  67}
  68
  69void __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
  86out:
  87        local_irq_restore(flags);
  88}
  89