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  * @probe_private: probe private data
  23  * @call_private: call site private data
  24  * @fmt: format string
  25  * @args: variable argument list pointer. Use a pointer to overcome C's
  26  *        inability to pass this around as a pointer in a portable manner in
  27  *        the callee otherwise.
  28  *
  29  * Type of marker probe functions. They receive the mdata and need to parse the
  30  * format string to recover the variable argument list.
  31  */
  32 typedef void marker_probe_func(void *probe_private, void *call_private,
  33                 const char *fmt, va_list *args);
  34
  35 struct marker_probe_closure {
  36         marker_probe_func *func;        /* Callback */
  37         void *probe_private;            /* Private probe data */
  38 };
  39
  40 struct marker {
  41         const char *name;       /* Marker name */
  42         const char *format;     /* Marker format string, describing the
  43                                  * variable argument list.
  44                                  */
  45         char state;             /* Marker state. */
  46         char ptype;             /* probe type : 0 : single, 1 : multi */
  47                                 /* Probe wrapper */
  48         void (*call)(const struct marker *mdata, void *call_private, ...);
  49         struct marker_probe_closure single;
  50         struct marker_probe_closure *multi;
  51 } __attribute__((aligned(8)));
  52
  53 #ifdef CONFIG_MARKERS
  54
  55 /*
  56  * Note : the empty asm volatile with read constraint is used here instead of a
  57  * "used" attribute to fix a gcc 4.1.x bug.
  58  * Make sure the alignment of the structure in the __markers section will
  59  * not add unwanted padding between the beginning of the section and the
  60  * structure. Force alignment to the same alignment as the section start.
  61  *
  62  * The "generic" argument controls which marker enabling mechanism must be used.
  63  * If generic is true, a variable read is used.
  64  * If generic is false, immediate values are used.
  65  */
  66 #define __trace_mark(generic, name, call_private, format, args...)      \
  67         do {                                                            \
  68                 static const char __mstrtab_##name[]                    \
  69                 __attribute__((section("__markers_strings")))           \
  70                 = #name "\0" format;                                    \
  71                 static struct marker __mark_##name                      \
  72                 __attribute__((section("__markers"), aligned(8))) =     \
  73                 { __mstrtab_##name, &__mstrtab_##name[sizeof(#name)],   \
  74                 0, 0, marker_probe_cb,                                  \
  75                 { __mark_empty_function, NULL}, NULL };                 \
  76                 __mark_check_format(format, ## args);                   \
  77                 if (unlikely(__mark_##name.state)) {                    \
  78                         (*__mark_##name.call)                           \
  79                                 (&__mark_##name, call_private, ## args);\
  80                 }                                                       \
  81         } while (0)
  82
  83 extern void marker_update_probe_range(struct marker *begin,
  84         struct marker *end);
  85 #else /* !CONFIG_MARKERS */
  86 #define __trace_mark(generic, name, call_private, format, args...) \
  87                 __mark_check_format(format, ## args)
  88 static inline void marker_update_probe_range(struct marker *begin,
  89         struct marker *end)
  90 { }
  91 #endif /* CONFIG_MARKERS */
  92
  93 /**
  94  * trace_mark - Marker using code patching
  95  * @name: marker name, not quoted.
  96  * @format: format string
  97  * @args...: variable argument list
  98  *
  99  * Places a marker using optimized code patching technique (imv_read())
 100  * to be enabled when immediate values are present.
 101  */
 102 #define trace_mark(name, format, args...) \
 103         __trace_mark(0, name, NULL, format, ## args)
 104
 105 /**
 106  * _trace_mark - Marker using variable read
 107  * @name: marker name, not quoted.
 108  * @format: format string
 109  * @args...: variable argument list
 110  *
 111  * Places a marker using a standard memory read (_imv_read()) to be
 112  * enabled. Should be used for markers in code paths where instruction
 113  * modification based enabling is not welcome. (__init and __exit functions,
 114  * lockdep, some traps, printk).
 115  */
 116 #define _trace_mark(name, format, args...) \
 117         __trace_mark(1, name, NULL, format, ## args)
 118
 119 /**
 120  * MARK_NOARGS - Format string for a marker with no argument.
 121  */
 122 #define MARK_NOARGS " "
 123
 124 /* To be used for string format validity checking with gcc */
 125 static inline void __printf(1, 2) ___mark_check_format(const char *fmt, ...)
 126 {
 127 }
 128
 129 #define __mark_check_format(format, args...)                            \
 130         do {                                                            \
 131                 if (0)                                                  \
 132                         ___mark_check_format(format, ## args);          \
 133         } while (0)
 134
 135 extern marker_probe_func __mark_empty_function;
 136
 137 extern void marker_probe_cb(const struct marker *mdata,
 138         void *call_private, ...);
 139 extern void marker_probe_cb_noarg(const struct marker *mdata,
 140         void *call_private, ...);
 141
 142 /*
 143  * Connect a probe to a marker.
 144  * private data pointer must be a valid allocated memory address, or NULL.
 145  */
 146 extern int marker_probe_register(const char *name, const char *format,
 147                                 marker_probe_func *probe, void *probe_private);
 148
 149 /*
 150  * Returns the private data given to marker_probe_register.
 151  */
 152 extern int marker_probe_unregister(const char *name,
 153         marker_probe_func *probe, void *probe_private);
 154 /*
 155  * Unregister a marker by providing the registered private data.
 156  */
 157 extern int marker_probe_unregister_private_data(marker_probe_func *probe,
 158         void *probe_private);
 159
 160 extern void *marker_get_private_data(const char *name, marker_probe_func *probe,
 161         int num);
 162
 163 #endif