LXR linux/include/linux/tracepoint-defs.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef TRACEPOINT_DEFS_H
   3#define TRACEPOINT_DEFS_H 1
   4
   5/*
   6 * File can be included directly by headers who only want to access
   7 * tracepoint->key to guard out of line trace calls, or the definition of
   8 * trace_print_flags{_u64}. Otherwise linux/tracepoint.h should be used.
   9 */
  10
  11#include <linux/atomic.h>
  12#include <linux/static_key.h>
  13
  14struct static_call_key;
  15
  16struct trace_print_flags {
  17        unsigned long           mask;
  18        const char              *name;
  19};
  20
  21struct trace_print_flags_u64 {
  22        unsigned long long      mask;
  23        const char              *name;
  24};
  25
  26struct tracepoint_func {
  27        void *func;
  28        void *data;
  29        int prio;
  30};
  31
  32struct tracepoint {
  33        const char *name;               /* Tracepoint name */
  34        struct static_key key;
  35        struct static_call_key *static_call_key;
  36        void *static_call_tramp;
  37        void *iterator;
  38        int (*regfunc)(void);
  39        void (*unregfunc)(void);
  40        struct tracepoint_func __rcu *funcs;
  41};
  42
  43#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
  44typedef const int tracepoint_ptr_t;
  45#else
  46typedef struct tracepoint * const tracepoint_ptr_t;
  47#endif
  48
  49struct bpf_raw_event_map {
  50        struct tracepoint       *tp;
  51        void                    *bpf_func;
  52        u32                     num_args;
  53        u32                     writable_size;
  54} __aligned(32);
  55
  56/*
  57 * If a tracepoint needs to be called from a header file, it is not
  58 * recommended to call it directly, as tracepoints in header files
  59 * may cause side-effects and bloat the kernel. Instead, use
  60 * tracepoint_enabled() to test if the tracepoint is enabled, then if
  61 * it is, call a wrapper function defined in a C file that will then
  62 * call the tracepoint.
  63 *
  64 * For "trace_foo_bar()", you would need to create a wrapper function
  65 * in a C file to call trace_foo_bar():
  66 *   void do_trace_foo_bar(args) { trace_foo_bar(args); }
  67 * Then in the header file, declare the tracepoint:
  68 *   DECLARE_TRACEPOINT(foo_bar);
  69 * And call your wrapper:
  70 *   static inline void some_inlined_function() {
  71 *            [..]
  72 *            if (tracepoint_enabled(foo_bar))
  73 *                    do_trace_foo_bar(args);
  74 *            [..]
  75 *   }
  76 *
  77 * Note: tracepoint_enabled(foo_bar) is equivalent to trace_foo_bar_enabled()
  78 *   but is safe to have in headers, where trace_foo_bar_enabled() is not.
  79 */
  80#define DECLARE_TRACEPOINT(tp) \
  81        extern struct tracepoint __tracepoint_##tp
  82
  83#ifdef CONFIG_TRACEPOINTS
  84# define tracepoint_enabled(tp) \
  85        static_key_false(&(__tracepoint_##tp).key)
  86#else
  87# define tracepoint_enabled(tracepoint) false
  88#endif
  89
  90#endif
  91