LCOV - code coverage report
Current view: top level - include/linux - tracepoint.h (source / functions) Hit Total Coverage
Test: Real Lines: 0 3 0.0 %
Date: 2020-10-17 15:46:16 Functions: 0 0 -
Legend: Neither, QEMU, Real, Both Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : /* SPDX-License-Identifier: GPL-2.0-only */
       2                 :            : #ifndef _LINUX_TRACEPOINT_H
       3                 :            : #define _LINUX_TRACEPOINT_H
       4                 :            : 
       5                 :            : /*
       6                 :            :  * Kernel Tracepoint API.
       7                 :            :  *
       8                 :            :  * See Documentation/trace/tracepoints.rst.
       9                 :            :  *
      10                 :            :  * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
      11                 :            :  *
      12                 :            :  * Heavily inspired from the Linux Kernel Markers.
      13                 :            :  */
      14                 :            : 
      15                 :            : #include <linux/smp.h>
      16                 :            : #include <linux/srcu.h>
      17                 :            : #include <linux/errno.h>
      18                 :            : #include <linux/types.h>
      19                 :            : #include <linux/cpumask.h>
      20                 :            : #include <linux/rcupdate.h>
      21                 :            : #include <linux/tracepoint-defs.h>
      22                 :            : 
      23                 :            : struct module;
      24                 :            : struct tracepoint;
      25                 :            : struct notifier_block;
      26                 :            : 
      27                 :            : struct trace_eval_map {
      28                 :            :         const char              *system;
      29                 :            :         const char              *eval_string;
      30                 :            :         unsigned long           eval_value;
      31                 :            : };
      32                 :            : 
      33                 :            : #define TRACEPOINT_DEFAULT_PRIO 10
      34                 :            : 
      35                 :            : extern struct srcu_struct tracepoint_srcu;
      36                 :            : 
      37                 :            : extern int
      38                 :            : tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
      39                 :            : extern int
      40                 :            : tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
      41                 :            :                                int prio);
      42                 :            : extern int
      43                 :            : tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
      44                 :            : extern void
      45                 :            : for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
      46                 :            :                 void *priv);
      47                 :            : 
      48                 :            : #ifdef CONFIG_MODULES
      49                 :            : struct tp_module {
      50                 :            :         struct list_head list;
      51                 :            :         struct module *mod;
      52                 :            : };
      53                 :            : 
      54                 :            : bool trace_module_has_bad_taint(struct module *mod);
      55                 :            : extern int register_tracepoint_module_notifier(struct notifier_block *nb);
      56                 :            : extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
      57                 :            : #else
      58                 :            : static inline bool trace_module_has_bad_taint(struct module *mod)
      59                 :            : {
      60                 :            :         return false;
      61                 :            : }
      62                 :            : static inline
      63                 :            : int register_tracepoint_module_notifier(struct notifier_block *nb)
      64                 :            : {
      65                 :            :         return 0;
      66                 :            : }
      67                 :            : static inline
      68                 :            : int unregister_tracepoint_module_notifier(struct notifier_block *nb)
      69                 :            : {
      70                 :            :         return 0;
      71                 :            : }
      72                 :            : #endif /* CONFIG_MODULES */
      73                 :            : 
      74                 :            : /*
      75                 :            :  * tracepoint_synchronize_unregister must be called between the last tracepoint
      76                 :            :  * probe unregistration and the end of module exit to make sure there is no
      77                 :            :  * caller executing a probe when it is freed.
      78                 :            :  */
      79                 :            : #ifdef CONFIG_TRACEPOINTS
      80                 :            : static inline void tracepoint_synchronize_unregister(void)
      81                 :            : {
      82                 :          0 :         synchronize_srcu(&tracepoint_srcu);
      83                 :          0 :         synchronize_rcu();
      84                 :            : }
      85                 :            : #else
      86                 :            : static inline void tracepoint_synchronize_unregister(void)
      87                 :            : { }
      88                 :            : #endif
      89                 :            : 
      90                 :            : #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
      91                 :            : extern int syscall_regfunc(void);
      92                 :            : extern void syscall_unregfunc(void);
      93                 :            : #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
      94                 :            : 
      95                 :            : #define PARAMS(args...) args
      96                 :            : 
      97                 :            : #define TRACE_DEFINE_ENUM(x)
      98                 :            : #define TRACE_DEFINE_SIZEOF(x)
      99                 :            : 
     100                 :            : #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
     101                 :            : static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
     102                 :            : {
     103                 :            :         return offset_to_ptr(p);
     104                 :            : }
     105                 :            : 
     106                 :            : #define __TRACEPOINT_ENTRY(name)                                        \
     107                 :            :         asm("      .section \"__tracepoints_ptrs\", \"a\"              \n"        \
     108                 :            :             "      .balign 4                                       \n"        \
     109                 :            :             "      .long   __tracepoint_" #name " - .            \n"        \
     110                 :            :             "      .previous                                       \n")
     111                 :            : #else
     112                 :            : static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
     113                 :            : {
     114                 :          0 :         return *p;
     115                 :            : }
     116                 :            : 
     117                 :            : #define __TRACEPOINT_ENTRY(name)                                         \
     118                 :            :         static tracepoint_ptr_t __tracepoint_ptr_##name __used           \
     119                 :            :         __attribute__((section("__tracepoints_ptrs"))) =               \
     120                 :            :                 &__tracepoint_##name
     121                 :            : #endif
     122                 :            : 
     123                 :            : #endif /* _LINUX_TRACEPOINT_H */
     124                 :            : 
     125                 :            : /*
     126                 :            :  * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
     127                 :            :  *  file ifdef protection.
     128                 :            :  *  This is due to the way trace events work. If a file includes two
     129                 :            :  *  trace event headers under one "CREATE_TRACE_POINTS" the first include
     130                 :            :  *  will override the TRACE_EVENT and break the second include.
     131                 :            :  */
     132                 :            : 
     133                 :            : #ifndef DECLARE_TRACE
     134                 :            : 
     135                 :            : #define TP_PROTO(args...)       args
     136                 :            : #define TP_ARGS(args...)        args
     137                 :            : #define TP_CONDITION(args...)   args
     138                 :            : 
     139                 :            : /*
     140                 :            :  * Individual subsystem my have a separate configuration to
     141                 :            :  * enable their tracepoints. By default, this file will create
     142                 :            :  * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
     143                 :            :  * wants to be able to disable its tracepoints from being created
     144                 :            :  * it can define NOTRACE before including the tracepoint headers.
     145                 :            :  */
     146                 :            : #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
     147                 :            : #define TRACEPOINTS_ENABLED
     148                 :            : #endif
     149                 :            : 
     150                 :            : #ifdef TRACEPOINTS_ENABLED
     151                 :            : 
     152                 :            : /*
     153                 :            :  * it_func[0] is never NULL because there is at least one element in the array
     154                 :            :  * when the array itself is non NULL.
     155                 :            :  *
     156                 :            :  * Note, the proto and args passed in includes "__data" as the first parameter.
     157                 :            :  * The reason for this is to handle the "void" prototype. If a tracepoint
     158                 :            :  * has a "void" prototype, then it is invalid to declare a function
     159                 :            :  * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
     160                 :            :  * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
     161                 :            :  */
     162                 :            : #define __DO_TRACE(tp, proto, args, cond, rcuidle)                      \
     163                 :            :         do {                                                            \
     164                 :            :                 struct tracepoint_func *it_func_ptr;                    \
     165                 :            :                 void *it_func;                                          \
     166                 :            :                 void *__data;                                           \
     167                 :            :                 int __maybe_unused __idx = 0;                           \
     168                 :            :                                                                         \
     169                 :            :                 if (!(cond))                                            \
     170                 :            :                         return;                                         \
     171                 :            :                                                                         \
     172                 :            :                 /* srcu can't be used from NMI */                       \
     173                 :            :                 WARN_ON_ONCE(rcuidle && in_nmi());                      \
     174                 :            :                                                                         \
     175                 :            :                 /* keep srcu and sched-rcu usage consistent */          \
     176                 :            :                 preempt_disable_notrace();                              \
     177                 :            :                                                                         \
     178                 :            :                 /*                                                      \
     179                 :            :                  * For rcuidle callers, use srcu since sched-rcu        \
     180                 :            :                  * doesn't work from the idle path.                     \
     181                 :            :                  */                                                     \
     182                 :            :                 if (rcuidle) {                                          \
     183                 :            :                         __idx = srcu_read_lock_notrace(&tracepoint_srcu);\
     184                 :            :                         rcu_irq_enter_irqson();                         \
     185                 :            :                 }                                                       \
     186                 :            :                                                                         \
     187                 :            :                 it_func_ptr = rcu_dereference_raw((tp)->funcs);              \
     188                 :            :                                                                         \
     189                 :            :                 if (it_func_ptr) {                                      \
     190                 :            :                         do {                                            \
     191                 :            :                                 it_func = (it_func_ptr)->func;               \
     192                 :            :                                 __data = (it_func_ptr)->data;                \
     193                 :            :                                 ((void(*)(proto))(it_func))(args);      \
     194                 :            :                         } while ((++it_func_ptr)->func);             \
     195                 :            :                 }                                                       \
     196                 :            :                                                                         \
     197                 :            :                 if (rcuidle) {                                          \
     198                 :            :                         rcu_irq_exit_irqson();                          \
     199                 :            :                         srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
     200                 :            :                 }                                                       \
     201                 :            :                                                                         \
     202                 :            :                 preempt_enable_notrace();                               \
     203                 :            :         } while (0)
     204                 :            : 
     205                 :            : #ifndef MODULE
     206                 :            : #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
     207                 :            :         static inline void trace_##name##_rcuidle(proto)                \
     208                 :            :         {                                                               \
     209                 :            :                 if (static_key_false(&__tracepoint_##name.key))             \
     210                 :            :                         __DO_TRACE(&__tracepoint_##name,            \
     211                 :            :                                 TP_PROTO(data_proto),                   \
     212                 :            :                                 TP_ARGS(data_args),                     \
     213                 :            :                                 TP_CONDITION(cond), 1);                 \
     214                 :            :         }
     215                 :            : #else
     216                 :            : #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
     217                 :            : #endif
     218                 :            : 
     219                 :            : /*
     220                 :            :  * Make sure the alignment of the structure in the __tracepoints section will
     221                 :            :  * not add unwanted padding between the beginning of the section and the
     222                 :            :  * structure. Force alignment to the same alignment as the section start.
     223                 :            :  *
     224                 :            :  * When lockdep is enabled, we make sure to always do the RCU portions of
     225                 :            :  * the tracepoint code, regardless of whether tracing is on. However,
     226                 :            :  * don't check if the condition is false, due to interaction with idle
     227                 :            :  * instrumentation. This lets us find RCU issues triggered with tracepoints
     228                 :            :  * even when this tracepoint is off. This code has no purpose other than
     229                 :            :  * poking RCU a bit.
     230                 :            :  */
     231                 :            : #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
     232                 :            :         extern struct tracepoint __tracepoint_##name;                   \
     233                 :            :         static inline void trace_##name(proto)                          \
     234                 :            :         {                                                               \
     235                 :            :                 if (static_key_false(&__tracepoint_##name.key))             \
     236                 :            :                         __DO_TRACE(&__tracepoint_##name,            \
     237                 :            :                                 TP_PROTO(data_proto),                   \
     238                 :            :                                 TP_ARGS(data_args),                     \
     239                 :            :                                 TP_CONDITION(cond), 0);                 \
     240                 :            :                 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {             \
     241                 :            :                         rcu_read_lock_sched_notrace();                  \
     242                 :            :                         rcu_dereference_sched(__tracepoint_##name.funcs);\
     243                 :            :                         rcu_read_unlock_sched_notrace();                \
     244                 :            :                 }                                                       \
     245                 :            :         }                                                               \
     246                 :            :         __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),          \
     247                 :            :                 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args))    \
     248                 :            :         static inline int                                               \
     249                 :            :         register_trace_##name(void (*probe)(data_proto), void *data)    \
     250                 :            :         {                                                               \
     251                 :            :                 return tracepoint_probe_register(&__tracepoint_##name,      \
     252                 :            :                                                 (void *)probe, data);   \
     253                 :            :         }                                                               \
     254                 :            :         static inline int                                               \
     255                 :            :         register_trace_prio_##name(void (*probe)(data_proto), void *data,\
     256                 :            :                                    int prio)                            \
     257                 :            :         {                                                               \
     258                 :            :                 return tracepoint_probe_register_prio(&__tracepoint_##name, \
     259                 :            :                                               (void *)probe, data, prio); \
     260                 :            :         }                                                               \
     261                 :            :         static inline int                                               \
     262                 :            :         unregister_trace_##name(void (*probe)(data_proto), void *data)  \
     263                 :            :         {                                                               \
     264                 :            :                 return tracepoint_probe_unregister(&__tracepoint_##name,\
     265                 :            :                                                 (void *)probe, data);   \
     266                 :            :         }                                                               \
     267                 :            :         static inline void                                              \
     268                 :            :         check_trace_callback_type_##name(void (*cb)(data_proto))        \
     269                 :            :         {                                                               \
     270                 :            :         }                                                               \
     271                 :            :         static inline bool                                              \
     272                 :            :         trace_##name##_enabled(void)                                    \
     273                 :            :         {                                                               \
     274                 :            :                 return static_key_false(&__tracepoint_##name.key);  \
     275                 :            :         }
     276                 :            : 
     277                 :            : /*
     278                 :            :  * We have no guarantee that gcc and the linker won't up-align the tracepoint
     279                 :            :  * structures, so we create an array of pointers that will be used for iteration
     280                 :            :  * on the tracepoints.
     281                 :            :  */
     282                 :            : #define DEFINE_TRACE_FN(name, reg, unreg)                                \
     283                 :            :         static const char __tpstrtab_##name[]                            \
     284                 :            :         __attribute__((section("__tracepoints_strings"))) = #name;     \
     285                 :            :         struct tracepoint __tracepoint_##name                            \
     286                 :            :         __attribute__((section("__tracepoints"), used)) =              \
     287                 :            :                 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
     288                 :            :         __TRACEPOINT_ENTRY(name);
     289                 :            : 
     290                 :            : #define DEFINE_TRACE(name)                                              \
     291                 :            :         DEFINE_TRACE_FN(name, NULL, NULL);
     292                 :            : 
     293                 :            : #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                              \
     294                 :            :         EXPORT_SYMBOL_GPL(__tracepoint_##name)
     295                 :            : #define EXPORT_TRACEPOINT_SYMBOL(name)                                  \
     296                 :            :         EXPORT_SYMBOL(__tracepoint_##name)
     297                 :            : 
     298                 :            : #else /* !TRACEPOINTS_ENABLED */
     299                 :            : #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
     300                 :            :         static inline void trace_##name(proto)                          \
     301                 :            :         { }                                                             \
     302                 :            :         static inline void trace_##name##_rcuidle(proto)                \
     303                 :            :         { }                                                             \
     304                 :            :         static inline int                                               \
     305                 :            :         register_trace_##name(void (*probe)(data_proto),                \
     306                 :            :                               void *data)                               \
     307                 :            :         {                                                               \
     308                 :            :                 return -ENOSYS;                                         \
     309                 :            :         }                                                               \
     310                 :            :         static inline int                                               \
     311                 :            :         unregister_trace_##name(void (*probe)(data_proto),              \
     312                 :            :                                 void *data)                             \
     313                 :            :         {                                                               \
     314                 :            :                 return -ENOSYS;                                         \
     315                 :            :         }                                                               \
     316                 :            :         static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
     317                 :            :         {                                                               \
     318                 :            :         }                                                               \
     319                 :            :         static inline bool                                              \
     320                 :            :         trace_##name##_enabled(void)                                    \
     321                 :            :         {                                                               \
     322                 :            :                 return false;                                           \
     323                 :            :         }
     324                 :            : 
     325                 :            : #define DEFINE_TRACE_FN(name, reg, unreg)
     326                 :            : #define DEFINE_TRACE(name)
     327                 :            : #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
     328                 :            : #define EXPORT_TRACEPOINT_SYMBOL(name)
     329                 :            : 
     330                 :            : #endif /* TRACEPOINTS_ENABLED */
     331                 :            : 
     332                 :            : #ifdef CONFIG_TRACING
     333                 :            : /**
     334                 :            :  * tracepoint_string - register constant persistent string to trace system
     335                 :            :  * @str - a constant persistent string that will be referenced in tracepoints
     336                 :            :  *
     337                 :            :  * If constant strings are being used in tracepoints, it is faster and
     338                 :            :  * more efficient to just save the pointer to the string and reference
     339                 :            :  * that with a printf "%s" instead of saving the string in the ring buffer
     340                 :            :  * and wasting space and time.
     341                 :            :  *
     342                 :            :  * The problem with the above approach is that userspace tools that read
     343                 :            :  * the binary output of the trace buffers do not have access to the string.
     344                 :            :  * Instead they just show the address of the string which is not very
     345                 :            :  * useful to users.
     346                 :            :  *
     347                 :            :  * With tracepoint_string(), the string will be registered to the tracing
     348                 :            :  * system and exported to userspace via the debugfs/tracing/printk_formats
     349                 :            :  * file that maps the string address to the string text. This way userspace
     350                 :            :  * tools that read the binary buffers have a way to map the pointers to
     351                 :            :  * the ASCII strings they represent.
     352                 :            :  *
     353                 :            :  * The @str used must be a constant string and persistent as it would not
     354                 :            :  * make sense to show a string that no longer exists. But it is still fine
     355                 :            :  * to be used with modules, because when modules are unloaded, if they
     356                 :            :  * had tracepoints, the ring buffers are cleared too. As long as the string
     357                 :            :  * does not change during the life of the module, it is fine to use
     358                 :            :  * tracepoint_string() within a module.
     359                 :            :  */
     360                 :            : #define tracepoint_string(str)                                          \
     361                 :            :         ({                                                              \
     362                 :            :                 static const char *___tp_str __tracepoint_string = str; \
     363                 :            :                 ___tp_str;                                              \
     364                 :            :         })
     365                 :            : #define __tracepoint_string     __attribute__((section("__tracepoint_str"), used))
     366                 :            : #else
     367                 :            : /*
     368                 :            :  * tracepoint_string() is used to save the string address for userspace
     369                 :            :  * tracing tools. When tracing isn't configured, there's no need to save
     370                 :            :  * anything.
     371                 :            :  */
     372                 :            : # define tracepoint_string(str) str
     373                 :            : # define __tracepoint_string
     374                 :            : #endif
     375                 :            : 
     376                 :            : /*
     377                 :            :  * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
     378                 :            :  * (void). "void" is a special value in a function prototype and can
     379                 :            :  * not be combined with other arguments. Since the DECLARE_TRACE()
     380                 :            :  * macro adds a data element at the beginning of the prototype,
     381                 :            :  * we need a way to differentiate "(void *data, proto)" from
     382                 :            :  * "(void *data, void)". The second prototype is invalid.
     383                 :            :  *
     384                 :            :  * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
     385                 :            :  * and "void *__data" as the callback prototype.
     386                 :            :  *
     387                 :            :  * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
     388                 :            :  * "void *__data, proto" as the callback prototype.
     389                 :            :  */
     390                 :            : #define DECLARE_TRACE_NOARGS(name)                                      \
     391                 :            :         __DECLARE_TRACE(name, void, ,                                   \
     392                 :            :                         cpu_online(raw_smp_processor_id()),             \
     393                 :            :                         void *__data, __data)
     394                 :            : 
     395                 :            : #define DECLARE_TRACE(name, proto, args)                                \
     396                 :            :         __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),              \
     397                 :            :                         cpu_online(raw_smp_processor_id()),             \
     398                 :            :                         PARAMS(void *__data, proto),                    \
     399                 :            :                         PARAMS(__data, args))
     400                 :            : 
     401                 :            : #define DECLARE_TRACE_CONDITION(name, proto, args, cond)                \
     402                 :            :         __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),              \
     403                 :            :                         cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
     404                 :            :                         PARAMS(void *__data, proto),                    \
     405                 :            :                         PARAMS(__data, args))
     406                 :            : 
     407                 :            : #define TRACE_EVENT_FLAGS(event, flag)
     408                 :            : 
     409                 :            : #define TRACE_EVENT_PERF_PERM(event, expr...)
     410                 :            : 
     411                 :            : #endif /* DECLARE_TRACE */
     412                 :            : 
     413                 :            : #ifndef TRACE_EVENT
     414                 :            : /*
     415                 :            :  * For use with the TRACE_EVENT macro:
     416                 :            :  *
     417                 :            :  * We define a tracepoint, its arguments, its printk format
     418                 :            :  * and its 'fast binary record' layout.
     419                 :            :  *
     420                 :            :  * Firstly, name your tracepoint via TRACE_EVENT(name : the
     421                 :            :  * 'subsystem_event' notation is fine.
     422                 :            :  *
     423                 :            :  * Think about this whole construct as the
     424                 :            :  * 'trace_sched_switch() function' from now on.
     425                 :            :  *
     426                 :            :  *
     427                 :            :  *  TRACE_EVENT(sched_switch,
     428                 :            :  *
     429                 :            :  *      *
     430                 :            :  *      * A function has a regular function arguments
     431                 :            :  *      * prototype, declare it via TP_PROTO():
     432                 :            :  *      *
     433                 :            :  *
     434                 :            :  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
     435                 :            :  *               struct task_struct *next),
     436                 :            :  *
     437                 :            :  *      *
     438                 :            :  *      * Define the call signature of the 'function'.
     439                 :            :  *      * (Design sidenote: we use this instead of a
     440                 :            :  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
     441                 :            :  *      *
     442                 :            :  *
     443                 :            :  *      TP_ARGS(rq, prev, next),
     444                 :            :  *
     445                 :            :  *      *
     446                 :            :  *      * Fast binary tracing: define the trace record via
     447                 :            :  *      * TP_STRUCT__entry(). You can think about it like a
     448                 :            :  *      * regular C structure local variable definition.
     449                 :            :  *      *
     450                 :            :  *      * This is how the trace record is structured and will
     451                 :            :  *      * be saved into the ring buffer. These are the fields
     452                 :            :  *      * that will be exposed to user-space in
     453                 :            :  *      * /sys/kernel/debug/tracing/events/<*>/format.
     454                 :            :  *      *
     455                 :            :  *      * The declared 'local variable' is called '__entry'
     456                 :            :  *      *
     457                 :            :  *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
     458                 :            :  *      *
     459                 :            :  *      *       pid_t   prev_pid;
     460                 :            :  *      *
     461                 :            :  *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
     462                 :            :  *      *
     463                 :            :  *      *       char    prev_comm[TASK_COMM_LEN];
     464                 :            :  *      *
     465                 :            :  *
     466                 :            :  *      TP_STRUCT__entry(
     467                 :            :  *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
     468                 :            :  *              __field(        pid_t,  prev_pid                        )
     469                 :            :  *              __field(        int,    prev_prio                       )
     470                 :            :  *              __array(        char,   next_comm,      TASK_COMM_LEN   )
     471                 :            :  *              __field(        pid_t,  next_pid                        )
     472                 :            :  *              __field(        int,    next_prio                       )
     473                 :            :  *      ),
     474                 :            :  *
     475                 :            :  *      *
     476                 :            :  *      * Assign the entry into the trace record, by embedding
     477                 :            :  *      * a full C statement block into TP_fast_assign(). You
     478                 :            :  *      * can refer to the trace record as '__entry' -
     479                 :            :  *      * otherwise you can put arbitrary C code in here.
     480                 :            :  *      *
     481                 :            :  *      * Note: this C code will execute every time a trace event
     482                 :            :  *      * happens, on an active tracepoint.
     483                 :            :  *      *
     484                 :            :  *
     485                 :            :  *      TP_fast_assign(
     486                 :            :  *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
     487                 :            :  *              __entry->prev_pid    = prev->pid;
     488                 :            :  *              __entry->prev_prio   = prev->prio;
     489                 :            :  *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
     490                 :            :  *              __entry->next_pid    = next->pid;
     491                 :            :  *              __entry->next_prio   = next->prio;
     492                 :            :  *      ),
     493                 :            :  *
     494                 :            :  *      *
     495                 :            :  *      * Formatted output of a trace record via TP_printk().
     496                 :            :  *      * This is how the tracepoint will appear under ftrace
     497                 :            :  *      * plugins that make use of this tracepoint.
     498                 :            :  *      *
     499                 :            :  *      * (raw-binary tracing wont actually perform this step.)
     500                 :            :  *      *
     501                 :            :  *
     502                 :            :  *      TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
     503                 :            :  *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
     504                 :            :  *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
     505                 :            :  *
     506                 :            :  * );
     507                 :            :  *
     508                 :            :  * This macro construct is thus used for the regular printk format
     509                 :            :  * tracing setup, it is used to construct a function pointer based
     510                 :            :  * tracepoint callback (this is used by programmatic plugins and
     511                 :            :  * can also by used by generic instrumentation like SystemTap), and
     512                 :            :  * it is also used to expose a structured trace record in
     513                 :            :  * /sys/kernel/debug/tracing/events/.
     514                 :            :  *
     515                 :            :  * A set of (un)registration functions can be passed to the variant
     516                 :            :  * TRACE_EVENT_FN to perform any (un)registration work.
     517                 :            :  */
     518                 :            : 
     519                 :            : #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
     520                 :            : #define DEFINE_EVENT(template, name, proto, args)               \
     521                 :            :         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
     522                 :            : #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
     523                 :            :         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
     524                 :            : #define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
     525                 :            :         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
     526                 :            : #define DEFINE_EVENT_CONDITION(template, name, proto,           \
     527                 :            :                                args, cond)                      \
     528                 :            :         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
     529                 :            :                                 PARAMS(args), PARAMS(cond))
     530                 :            : 
     531                 :            : #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
     532                 :            :         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
     533                 :            : #define TRACE_EVENT_FN(name, proto, args, struct,               \
     534                 :            :                 assign, print, reg, unreg)                      \
     535                 :            :         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
     536                 :            : #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct,            \
     537                 :            :                 assign, print, reg, unreg)                      \
     538                 :            :         DECLARE_TRACE_CONDITION(name, PARAMS(proto),    \
     539                 :            :                         PARAMS(args), PARAMS(cond))
     540                 :            : #define TRACE_EVENT_CONDITION(name, proto, args, cond,          \
     541                 :            :                               struct, assign, print)            \
     542                 :            :         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
     543                 :            :                                 PARAMS(args), PARAMS(cond))
     544                 :            : 
     545                 :            : #define TRACE_EVENT_FLAGS(event, flag)
     546                 :            : 
     547                 :            : #define TRACE_EVENT_PERF_PERM(event, expr...)
     548                 :            : 
     549                 :            : #define DECLARE_EVENT_NOP(name, proto, args)                            \
     550                 :            :         static inline void trace_##name(proto)                          \
     551                 :            :         { }                                                             \
     552                 :            :         static inline bool trace_##name##_enabled(void)                 \
     553                 :            :         {                                                               \
     554                 :            :                 return false;                                           \
     555                 :            :         }
     556                 :            : 
     557                 :            : #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print)       \
     558                 :            :         DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
     559                 :            : 
     560                 :            : #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
     561                 :            : #define DEFINE_EVENT_NOP(template, name, proto, args)                   \
     562                 :            :         DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
     563                 :            : 
     564                 :            : #endif /* ifdef TRACE_EVENT (see note above) */
    

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