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 <stdarg.h>
  16 #include <linux/types.h>
  17
  18 struct module;
  19 struct marker;
  20
  21 /**
  22  * marker_probe_func - Type of a marker probe function
  23  * @probe_private: probe private data
  24  * @call_private: call site private data
  25  * @fmt: format string
  26  * @args: variable argument list pointer. Use a pointer to overcome C's
  27  *        inability to pass this around as a pointer in a portable manner in
  28  *        the callee otherwise.
  29  *
  30  * Type of marker probe functions. They receive the mdata and need to parse the
  31  * format string to recover the variable argument list.
  32  */
  33 typedef void marker_probe_func(void *probe_private, void *call_private,
  34                 const char *fmt, va_list *args);
  35
  36 struct marker_probe_closure {
  37         marker_probe_func *func;        /* Callback */
  38         void *probe_private;            /* Private probe data */
  39 };
  40
  41 struct marker {
  42         const char *name;       /* Marker name */
  43         const char *format;     /* Marker format string, describing the
  44                                  * variable argument list.
  45                                  */
  46         char state;             /* Marker state. */
  47         char ptype;             /* probe type : 0 : single, 1 : multi */
  48                                 /* Probe wrapper */
  49         void (*call)(const struct marker *mdata, void *call_private, ...);
  50         struct marker_probe_closure single;
  51         struct marker_probe_closure *multi;
  52         const char *tp_name;    /* Optional tracepoint name */
  53         void *tp_cb;            /* Optional tracepoint callback */
  54 } __attribute__((aligned(8)));
  55
  56 #ifdef CONFIG_MARKERS
  57
  58 #define _DEFINE_MARKER(name, tp_name_str, tp_cb, format)                \
  59                 static const char __mstrtab_##name[]                    \
  60                 __attribute__((section("__markers_strings")))           \
  61                 = #name "\0" format;                                    \
  62                 static struct marker __mark_##name                      \
  63                 __attribute__((section("__markers"), aligned(8))) =     \
  64                 { __mstrtab_##name, &__mstrtab_##name[sizeof(#name)],   \
  65                   0, 0, marker_probe_cb, { __mark_empty_function, NULL},\
  66                   NULL, tp_name_str, tp_cb }
  67
  68 #define DEFINE_MARKER(name, format)                                     \
  69                 _DEFINE_MARKER(name, NULL, NULL, format)
  70
  71 #define DEFINE_MARKER_TP(name, tp_name, tp_cb, format)                  \
  72                 _DEFINE_MARKER(name, #tp_name, tp_cb, format)
  73
  74 /*
  75  * Note : the empty asm volatile with read constraint is used here instead of a
  76  * "used" attribute to fix a gcc 4.1.x bug.
  77  * Make sure the alignment of the structure in the __markers section will
  78  * not add unwanted padding between the beginning of the section and the
  79  * structure. Force alignment to the same alignment as the section start.
  80  *
  81  * The "generic" argument controls which marker enabling mechanism must be used.
  82  * If generic is true, a variable read is used.
  83  * If generic is false, immediate values are used.
  84  */
  85 #define __trace_mark(generic, name, call_private, format, args...)      \
  86         do {                                                            \
  87                 DEFINE_MARKER(name, format);                            \
  88                 __mark_check_format(format, ## args);                   \
  89                 if (unlikely(__mark_##name.state)) {                    \
  90                         (*__mark_##name.call)                           \
  91                                 (&__mark_##name, call_private, ## args);\
  92                 }                                                       \
  93         } while (0)
  94
  95 #define __trace_mark_tp(name, call_private, tp_name, tp_cb, format, args...) \
  96         do {                                                            \
  97                 void __check_tp_type(void)                              \
  98                 {                                                       \
  99                         register_trace_##tp_name(tp_cb);                \
 100                 }                                                       \
 101                 DEFINE_MARKER_TP(name, tp_name, tp_cb, format);         \
 102                 __mark_check_format(format, ## args);                   \
 103                 (*__mark_##name.call)(&__mark_##name, call_private,     \
 104                                         ## args);                       \
 105         } while (0)
 106
 107 extern void marker_update_probe_range(struct marker *begin,
 108         struct marker *end);
 109
 110 #define GET_MARKER(name)        (__mark_##name)
 111
 112 #else /* !CONFIG_MARKERS */
 113 #define DEFINE_MARKER(name, tp_name, tp_cb, format)
 114 #define __trace_mark(generic, name, call_private, format, args...) \
 115                 __mark_check_format(format, ## args)
 116 #define __trace_mark_tp(name, call_private, tp_name, tp_cb, format, args...) \
 117         do {                                                            \
 118                 void __check_tp_type(void)                              \
 119                 {                                                       \
 120                         register_trace_##tp_name(tp_cb);                \
 121                 }                                                       \
 122                 __mark_check_format(format, ## args);                   \
 123         } while (0)
 124 static inline void marker_update_probe_range(struct marker *begin,
 125         struct marker *end)
 126 { }
 127 #define GET_MARKER(name)
 128 #endif /* CONFIG_MARKERS */
 129
 130 /**
 131  * trace_mark - Marker using code patching
 132  * @name: marker name, not quoted.
 133  * @format: format string
 134  * @args...: variable argument list
 135  *
 136  * Places a marker using optimized code patching technique (imv_read())
 137  * to be enabled when immediate values are present.
 138  */
 139 #define trace_mark(name, format, args...) \
 140         __trace_mark(0, name, NULL, format, ## args)
 141
 142 /**
 143  * _trace_mark - Marker using variable read
 144  * @name: marker name, not quoted.
 145  * @format: format string
 146  * @args...: variable argument list
 147  *
 148  * Places a marker using a standard memory read (_imv_read()) to be
 149  * enabled. Should be used for markers in code paths where instruction
 150  * modification based enabling is not welcome. (__init and __exit functions,
 151  * lockdep, some traps, printk).
 152  */
 153 #define _trace_mark(name, format, args...) \
 154         __trace_mark(1, name, NULL, format, ## args)
 155
 156 /**
 157  * trace_mark_tp - Marker in a tracepoint callback
 158  * @name: marker name, not quoted.
 159  * @tp_name: tracepoint name, not quoted.
 160  * @tp_cb: tracepoint callback. Should have an associated global symbol so it
 161  *         is not optimized away by the compiler (should not be static).
 162  * @format: format string
 163  * @args...: variable argument list
 164  *
 165  * Places a marker in a tracepoint callback.
 166  */
 167 #define trace_mark_tp(name, tp_name, tp_cb, format, args...)    \
 168         __trace_mark_tp(name, NULL, tp_name, tp_cb, format, ## args)
 169
 170 /**
 171  * MARK_NOARGS - Format string for a marker with no argument.
 172  */
 173 #define MARK_NOARGS " "
 174
 175 /* To be used for string format validity checking with gcc */
 176 static inline void __printf(1, 2) ___mark_check_format(const char *fmt, ...)
 177 {
 178 }
 179
 180 #define __mark_check_format(format, args...)                            \
 181         do {                                                            \
 182                 if (0)                                                  \
 183                         ___mark_check_format(format, ## args);          \
 184         } while (0)
 185
 186 extern marker_probe_func __mark_empty_function;
 187
 188 extern void marker_probe_cb(const struct marker *mdata,
 189         void *call_private, ...);
 190
 191 /*
 192  * Connect a probe to a marker.
 193  * private data pointer must be a valid allocated memory address, or NULL.
 194  */
 195 extern int marker_probe_register(const char *name, const char *format,
 196                                 marker_probe_func *probe, void *probe_private);
 197
 198 /*
 199  * Returns the private data given to marker_probe_register.
 200  */
 201 extern int marker_probe_unregister(const char *name,
 202         marker_probe_func *probe, void *probe_private);
 203 /*
 204  * Unregister a marker by providing the registered private data.
 205  */
 206 extern int marker_probe_unregister_private_data(marker_probe_func *probe,
 207         void *probe_private);
 208
 209 extern void *marker_get_private_data(const char *name, marker_probe_func *probe,
 210         int num);
 211
 212 /*
 213  * marker_synchronize_unregister must be called between the last marker probe
 214  * unregistration and the first one of
 215  * - the end of module exit function
 216  * - the free of any resource used by the probes
 217  * to ensure the code and data are valid for any possibly running probes.
 218  */
 219 #define marker_synchronize_unregister() synchronize_sched()
 220
 221 #endif