include/linux/marker.h

   1 #ifndef _LINUX_MARKER_H
   2 #define _LINUX_MARKER_H
   3
   4 /*
   5  * Code markup for dynamic and static tracing.
   6  *
   7  * See Documentation/marker.txt.
   8  *
   9  * (C) Copyright 2006 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  10  *
  11  * This file is released under the GPLv2.
  12  * See the file COPYING for more details.
  13  */
  14
  15 #include <linux/types.h>
  16
  17 struct module;
  18 struct marker;
  19
  20 /**
  21  * marker_probe_func - Type of a marker probe function
  22  * @mdata: pointer of type struct marker
  23  * @private_data: caller site private data
  24  * @fmt: format string
  25  * @...: variable argument list
  26  *
  27  * Type of marker probe functions. They receive the mdata and need to parse the
  28  * format string to recover the variable argument list.
  29  */
  30 typedef void marker_probe_func(const struct marker *mdata,
  31         void *private_data, const char *fmt, ...);
  32
  33 struct marker {
  34         const char *name;       /* Marker name */
  35         const char *format;     /* Marker format string, describing the
  36                                  * variable argument list.
  37                                  */
  38         char state;             /* Marker state. */
  39         marker_probe_func *call;/* Probe handler function pointer */
  40         void *private;          /* Private probe data */
  41 } __attribute__((aligned(8)));
  42
  43 #ifdef CONFIG_MARKERS
  44
  45 /*
  46  * Note : the empty asm volatile with read constraint is used here instead of a
  47  * "used" attribute to fix a gcc 4.1.x bug.
  48  * Make sure the alignment of the structure in the __markers section will
  49  * not add unwanted padding between the beginning of the section and the
  50  * structure. Force alignment to the same alignment as the section start.
  51  */
  52 #define __trace_mark(name, call_data, format, args...)                  \
  53         do {                                                            \
  54                 static const char __mstrtab_name_##name[]               \
  55                 __attribute__((section("__markers_strings")))           \
  56                 = #name;                                                \
  57                 static const char __mstrtab_format_##name[]             \
  58                 __attribute__((section("__markers_strings")))           \
  59                 = format;                                               \
  60                 static struct marker __mark_##name                      \
  61                 __attribute__((section("__markers"), aligned(8))) =     \
  62                 { __mstrtab_name_##name, __mstrtab_format_##name,       \
  63                 0, __mark_empty_function, NULL };                       \
  64                 __mark_check_format(format, ## args);                   \
  65                 if (unlikely(__mark_##name.state)) {                    \
  66                         preempt_disable();                              \
  67                         (*__mark_##name.call)                           \
  68                                 (&__mark_##name, call_data,             \
  69                                 format, ## args);                       \
  70                         preempt_enable();                               \
  71                 }                                                       \
  72         } while (0)
  73
  74 extern void marker_update_probe_range(struct marker *begin,
  75         struct marker *end, struct module *probe_module, int *refcount);
  76 #else /* !CONFIG_MARKERS */
  77 #define __trace_mark(name, call_data, format, args...) \
  78                 __mark_check_format(format, ## args)
  79 static inline void marker_update_probe_range(struct marker *begin,
  80         struct marker *end, struct module *probe_module, int *refcount)
  81 { }
  82 #endif /* CONFIG_MARKERS */
  83
  84 /**
  85  * trace_mark - Marker
  86  * @name: marker name, not quoted.
  87  * @format: format string
  88  * @args...: variable argument list
  89  *
  90  * Places a marker.
  91  */
  92 #define trace_mark(name, format, args...) \
  93         __trace_mark(name, NULL, format, ## args)
  94
  95 #define MARK_MAX_FORMAT_LEN     1024
  96
  97 /**
  98  * MARK_NOARGS - Format string for a marker with no argument.
  99  */
 100 #define MARK_NOARGS " "
 101
 102 /* To be used for string format validity checking with gcc */
 103 static inline void __printf(1, 2) __mark_check_format(const char *fmt, ...)
 104 {
 105 }
 106
 107 extern marker_probe_func __mark_empty_function;
 108
 109 /*
 110  * Connect a probe to a marker.
 111  * private data pointer must be a valid allocated memory address, or NULL.
 112  */
 113 extern int marker_probe_register(const char *name, const char *format,
 114                                 marker_probe_func *probe, void *private);
 115
 116 /*
 117  * Returns the private data given to marker_probe_register.
 118  */
 119 extern void *marker_probe_unregister(const char *name);
 120 /*
 121  * Unregister a marker by providing the registered private data.
 122  */
 123 extern void *marker_probe_unregister_private_data(void *private);
 124
 125 extern int marker_arm(const char *name);
 126 extern int marker_disarm(const char *name);
 127 extern void *marker_get_private_data(const char *name);
 128
 129 #endif