kernel/trace/trace_preemptirq.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * preemptoff and irqoff tracepoints
   4  *
   5  * Copyright (C) Joel Fernandes (Google) <joel@joelfernandes.org>
   6  */
   7
   8 #include <linux/kallsyms.h>
   9 #include <linux/uaccess.h>
  10 #include <linux/module.h>
  11 #include <linux/ftrace.h>
  12 #include <linux/kprobes.h>
  13 #include <linux/hardirq.h>
  14 #include "trace.h"
  15
  16 #define CREATE_TRACE_POINTS
  17 #include <trace/events/preemptirq.h>
  18
  19 /*
  20  * Use regular trace points on architectures that implement noinstr
  21  * tooling: these calls will only happen with RCU enabled, which can
  22  * use a regular tracepoint.
  23  *
  24  * On older architectures, RCU may not be watching in idle. In that
  25  * case, wake up RCU to watch while calling the tracepoint. These
  26  * aren't NMI-safe - so exclude NMI contexts:
  27  */
  28 #ifdef CONFIG_ARCH_WANTS_NO_INSTR
  29 #define trace(point, args)      trace_##point(args)
  30 #else
  31 #define trace(point, args)                                      \
  32         do {                                                    \
  33                 if (trace_##point##_enabled()) {                \
  34                         bool exit_rcu = false;                  \
  35                         if (in_nmi())                           \
  36                                 break;                          \
  37                         if (!IS_ENABLED(CONFIG_TINY_RCU) &&     \
  38                             is_idle_task(current)) {            \
  39                                 ct_irq_enter();                 \
  40                                 exit_rcu = true;                \
  41                         }                                       \
  42                         trace_##point(args);                    \
  43                         if (exit_rcu)                           \
  44                                 ct_irq_exit();                  \
  45                 }                                               \
  46         } while (0)
  47 #endif
  48
  49 #ifdef CONFIG_TRACE_IRQFLAGS
  50 /* Per-cpu variable to prevent redundant calls when IRQs already off */
  51 static DEFINE_PER_CPU(int, tracing_irq_cpu);
  52
  53 /*
  54  * Like trace_hardirqs_on() but without the lockdep invocation. This is
  55  * used in the low level entry code where the ordering vs. RCU is important
  56  * and lockdep uses a staged approach which splits the lockdep hardirq
  57  * tracking into a RCU on and a RCU off section.
  58  */
  59 void trace_hardirqs_on_prepare(void)
  60 {
  61         if (this_cpu_read(tracing_irq_cpu)) {
  62                 trace(irq_enable, TP_ARGS(CALLER_ADDR0, CALLER_ADDR1));
  63                 tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1);
  64                 this_cpu_write(tracing_irq_cpu, 0);
  65         }
  66 }
  67 EXPORT_SYMBOL(trace_hardirqs_on_prepare);
  68 NOKPROBE_SYMBOL(trace_hardirqs_on_prepare);
  69
  70 void trace_hardirqs_on(void)
  71 {
  72         if (this_cpu_read(tracing_irq_cpu)) {
  73                 trace(irq_enable, TP_ARGS(CALLER_ADDR0, CALLER_ADDR1));
  74                 tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1);
  75                 this_cpu_write(tracing_irq_cpu, 0);
  76         }
  77
  78         lockdep_hardirqs_on_prepare();
  79         lockdep_hardirqs_on(CALLER_ADDR0);
  80 }
  81 EXPORT_SYMBOL(trace_hardirqs_on);
  82 NOKPROBE_SYMBOL(trace_hardirqs_on);
  83
  84 /*
  85  * Like trace_hardirqs_off() but without the lockdep invocation. This is
  86  * used in the low level entry code where the ordering vs. RCU is important
  87  * and lockdep uses a staged approach which splits the lockdep hardirq
  88  * tracking into a RCU on and a RCU off section.
  89  */
  90 void trace_hardirqs_off_finish(void)
  91 {
  92         if (!this_cpu_read(tracing_irq_cpu)) {
  93                 this_cpu_write(tracing_irq_cpu, 1);
  94                 tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1);
  95                 trace(irq_disable, TP_ARGS(CALLER_ADDR0, CALLER_ADDR1));
  96         }
  97
  98 }
  99 EXPORT_SYMBOL(trace_hardirqs_off_finish);
 100 NOKPROBE_SYMBOL(trace_hardirqs_off_finish);
 101
 102 void trace_hardirqs_off(void)
 103 {
 104         lockdep_hardirqs_off(CALLER_ADDR0);
 105
 106         if (!this_cpu_read(tracing_irq_cpu)) {
 107                 this_cpu_write(tracing_irq_cpu, 1);
 108                 tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1);
 109                 trace(irq_disable, TP_ARGS(CALLER_ADDR0, CALLER_ADDR1));
 110         }
 111 }
 112 EXPORT_SYMBOL(trace_hardirqs_off);
 113 NOKPROBE_SYMBOL(trace_hardirqs_off);
 114 #endif /* CONFIG_TRACE_IRQFLAGS */
 115
 116 #ifdef CONFIG_TRACE_PREEMPT_TOGGLE
 117
 118 void trace_preempt_on(unsigned long a0, unsigned long a1)
 119 {
 120         trace(preempt_enable, TP_ARGS(a0, a1));
 121         tracer_preempt_on(a0, a1);
 122 }
 123
 124 void trace_preempt_off(unsigned long a0, unsigned long a1)
 125 {
 126         trace(preempt_disable, TP_ARGS(a0, a1));
 127         tracer_preempt_off(a0, a1);
 128 }
 129 #endif