include/ust/marker.h

   1 #ifndef _UST_MARKER_H
   2 #define _UST_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  * (C) Copyright 2009 Pierre-Marc Fournier <pierre-marc dot fournier at polymtl dot ca>
  11  * (C) Copyright 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  12  *
  13  * This library is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU Lesser General Public
  15  * License as published by the Free Software Foundation;
  16  * version 2.1 of the License.
  17  *
  18  * This library is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  21  * Lesser General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU Lesser General Public
  24  * License along with this library; if not, write to the Free Software
  25  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  26  */
  27
  28 #include <stdarg.h>
  29 #include <stdint.h>
  30 #include <stddef.h>
  31 #include <bits/wordsize.h>
  32 #include <urcu/list.h>
  33
  34 struct ust_marker;
  35 struct ust_marker_probe_array;
  36
  37 /**
  38  * ust_marker_probe_func - Type of a marker probe function
  39  * @mdata: marker data
  40  * @probe_private: probe private data
  41  * @call_private: call site private data
  42  * @fmt: format string
  43  * @args: variable argument list pointer. Use a pointer to overcome C's
  44  *        inability to pass this around as a pointer in a portable manner in
  45  *        the callee otherwise.
  46  *
  47  * Type of marker probe functions. They receive the mdata and need to parse the
  48  * format string to recover the variable argument list.
  49  */
  50 typedef void ust_marker_probe_func(const struct ust_marker *mdata,
  51                 void *probe_private, void *call_private,
  52                 const char *fmt, va_list *args);
  53
  54 struct ust_marker_probe_closure {
  55         ust_marker_probe_func *func;    /* Callback */
  56         void *probe_private;            /* Private probe data */
  57 };
  58
  59 struct ust_marker {
  60         const char *channel;    /* Name of channel where to send data */
  61         const char *name;       /* Marker name */
  62         const char *format;     /* Marker format string, describing the
  63                                  * variable argument list.
  64                                  */
  65         char state;             /* State. */
  66         char ptype;             /* probe type : 0 : single, 1 : multi */
  67                                 /* Probe wrapper */
  68         uint16_t channel_id;    /* Numeric channel identifier, dynamic */
  69         uint16_t event_id;      /* Numeric event identifier, dynamic */
  70         void (*call)(const struct ust_marker *mdata, void *call_private, ...);
  71         struct ust_marker_probe_closure single;
  72         struct ust_marker_probe_array *multi;
  73         const char *tp_name;    /* Optional tracepoint name */
  74         void *tp_cb;            /* Optional tracepoint callback */
  75 };
  76
  77 /*
  78  * We keep the "channel" as internal field for marker.c *only*. It will be
  79  * removed soon.
  80  */
  81
  82 /*
  83  * __ust_marker_ptrs section is not const (read-only) because it needs to be
  84  * read-write to let the linker apply relocations and keep the object PIC.
  85  */
  86 #define _DEFINE_UST_MARKER(channel, name, tp_name_str, tp_cb, format)   \
  87                 static const char __mstrtab_##channel##_##name[]        \
  88                 __attribute__((section("__ust_markers_strings")))       \
  89                 = #channel "\0" #name "\0" format;                      \
  90                 static struct ust_marker __ust_marker_def_##name        \
  91                 __attribute__((section("__ust_markers"))) =             \
  92                 { __mstrtab_##channel##_##name,                         \
  93                   &__mstrtab_##channel##_##name[sizeof(#channel)],      \
  94                   &__mstrtab_##channel##_##name[sizeof(#channel) +      \
  95                                                 sizeof(#name)],         \
  96                   0, 0, 0, 0, ust_marker_probe_cb,                      \
  97                   { __ust_marker_empty_function, NULL},                 \
  98                   NULL, tp_name_str, tp_cb };                           \
  99                 static struct ust_marker * __ust_marker_ptr_##name      \
 100                         __attribute__((used, section("__ust_marker_ptrs"))) = \
 101                         &__ust_marker_def_##name
 102
 103 /*
 104  * Make sure the alignment of the structure in the __ust_marker section will
 105  * not add unwanted padding between the beginning of the section and the
 106  * structure. Force alignment to the same alignment as the section start.
 107  */
 108
 109 #define __ust_marker(channel, name, call_private, format, args...)      \
 110         do {                                                            \
 111                 _DEFINE_UST_MARKER(channel, name, NULL, NULL, format);  \
 112                 __ust_marker_check_format(format, ## args);             \
 113                 if (__builtin_expect(!!(__ust_marker_def_##name.state), 0)) \
 114                         (__ust_marker_def_##name.call)                  \
 115                                 (&__ust_marker_def_##name, call_private,\
 116                                 ## args);                               \
 117         } while (0)
 118
 119 /**
 120  * ust_marker - Marker using code patching
 121  * @name: marker name, not quoted.
 122  * @format: format string
 123  * @args...: variable argument list
 124  *
 125  * Places a marker at caller site.
 126  */
 127 #define ust_marker(name, format, args...) \
 128         __ust_marker(ust, name, NULL, format, ## args)
 129
 130 /**
 131  * UST_MARKER_NOARGS - Format string for a marker with no argument.
 132  */
 133 #define UST_MARKER_NOARGS " "
 134
 135 /* To be used for string format validity checking with gcc */
 136 static inline
 137 void __attribute__((format(printf, 1, 2)))
 138  ___ust_marker_check_format(const char *fmt, ...)
 139 {
 140 }
 141
 142 #define __ust_marker_check_format(format, args...)                      \
 143         do {                                                            \
 144                 if (0)                                                  \
 145                         ___ust_marker_check_format(format, ## args);    \
 146         } while (0)
 147
 148 extern ust_marker_probe_func __ust_marker_empty_function;
 149
 150 extern void ust_marker_probe_cb(const struct ust_marker *mdata,
 151         void *call_private, ...);
 152
 153 struct ust_marker_lib {
 154         struct ust_marker * const *ust_marker_start;
 155         int ust_marker_count;
 156         struct cds_list_head list;
 157 };
 158
 159 #define UST_MARKER_LIB                                                  \
 160         extern struct ust_marker * const __start___ust_marker_ptrs[] __attribute__((weak, visibility("hidden"))); \
 161         extern struct ust_marker * const __stop___ust_marker_ptrs[] __attribute__((weak, visibility("hidden"))); \
 162         static struct ust_marker * __ust_marker_ptr_dummy               \
 163                 __attribute__((used, section("__ust_marker_ptrs")));    \
 164                                                                         \
 165         static void __attribute__((constructor)) __ust_marker__init(void) \
 166         {                                                               \
 167                 ust_marker_register_lib(__start___ust_marker_ptrs,      \
 168                                     __stop___ust_marker_ptrs            \
 169                                     - __start___ust_marker_ptrs);       \
 170         }                                                               \
 171                                                                         \
 172         static void __attribute__((destructor)) __ust_marker__destroy(void) \
 173         {                                                               \
 174                 ust_marker_unregister_lib(__start___ust_marker_ptrs);   \
 175         }
 176
 177 extern
 178 int ust_marker_register_lib(struct ust_marker * const *ust_marker_start,
 179                             int ust_marker_count);
 180 extern
 181 int ust_marker_unregister_lib(struct ust_marker * const *ust_marker_start);
 182
 183 /*
 184  * trace_mark() -- DEPRECATED
 185  * @channel: name prefix, not quoted. Ignored.
 186  * @name: marker name, not quoted.
 187  * @format: format string
 188  * @args...: variable argument list
 189  *
 190  * Kept as a compatibility API and is *DEPRECATED* in favor of
 191  * ust_marker().
 192  */
 193 #define trace_mark(channel, name, format, args...)      \
 194         ust_marker(name, format, ## args)
 195
 196 static inline __attribute__((deprecated))
 197 void __MARKER_LIB_IS_DEPRECATED()
 198 {
 199 }
 200
 201 /*
 202  * MARKER_LIB is kept for backward compatibility and is *DEPRECATED*.
 203  * Use UST_MARKER_LIB instead.
 204  */
 205 #define MARKER_LIB                      \
 206         __MARKER_LIB_IS_DEPRECATED();   \
 207         UST_MARKER_LIB
 208
 209 /**
 210  * MARKER_NOARGS - Compatibility API. *DEPRECATED*. Use
 211  * UST_MARKER_NOARGS instead.
 212  */
 213 #define MARK_NOARGS     UST_MARKER_NOARGS
 214
 215 #endif /* _UST_MARKER_H */