include/linux/dynamic_debug.h

   1 #ifndef _DYNAMIC_DEBUG_H
   2 #define _DYNAMIC_DEBUG_H
   3
   4 /* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
   5  * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
   6  * use independent hash functions, to reduce the chance of false positives.
   7  */
   8 extern long long dynamic_debug_enabled;
   9 extern long long dynamic_debug_enabled2;
  10
  11 /*
  12  * An instance of this structure is created in a special
  13  * ELF section at every dynamic debug callsite.  At runtime,
  14  * the special section is treated as an array of these.
  15  */
  16 struct _ddebug {
  17         /*
  18          * These fields are used to drive the user interface
  19          * for selecting and displaying debug callsites.
  20          */
  21         const char *modname;
  22         const char *function;
  23         const char *filename;
  24         const char *format;
  25         char primary_hash;
  26         char secondary_hash;
  27         unsigned int lineno:24;
  28         /*
  29          * The flags field controls the behaviour at the callsite.
  30          * The bits here are changed dynamically when the user
  31          * writes commands to <debugfs>/dynamic_debug/control
  32          */
  33 #define _DPRINTK_FLAGS_PRINT   (1<<0)  /* printk() a message using the format */
  34 #define _DPRINTK_FLAGS_DEFAULT 0
  35         unsigned int flags:8;
  36 } __attribute__((aligned(8)));
  37
  38
  39 int ddebug_add_module(struct _ddebug *tab, unsigned int n,
  40                                 const char *modname);
  41
  42 #if defined(CONFIG_DYNAMIC_DEBUG)
  43 extern int ddebug_remove_module(const char *mod_name);
  44
  45 #define __dynamic_dbg_enabled(dd)  ({        \
  46         int __ret = 0;                                                       \
  47         if (unlikely((dynamic_debug_enabled & (1LL << DEBUG_HASH)) &&        \
  48                         (dynamic_debug_enabled2 & (1LL << DEBUG_HASH2))))   \
  49                                 if (unlikely(dd.flags))                      \
  50                                         __ret = 1;                           \
  51         __ret; })
  52
  53 #define dynamic_pr_debug(fmt, ...) do {                                 \
  54         static struct _ddebug descriptor                                \
  55         __used                                                          \
  56         __attribute__((section("__verbose"), aligned(8))) =             \
  57         { KBUILD_MODNAME, __func__, __FILE__, fmt, DEBUG_HASH,  \
  58                 DEBUG_HASH2, __LINE__, _DPRINTK_FLAGS_DEFAULT };        \
  59         if (__dynamic_dbg_enabled(descriptor))                          \
  60                 printk(KERN_DEBUG pr_fmt(fmt),  ##__VA_ARGS__);         \
  61         } while (0)
  62
  63
  64 #define dynamic_dev_dbg(dev, fmt, ...) do {                             \
  65         static struct _ddebug descriptor                                \
  66         __used                                                          \
  67         __attribute__((section("__verbose"), aligned(8))) =             \
  68         { KBUILD_MODNAME, __func__, __FILE__, fmt, DEBUG_HASH,  \
  69                 DEBUG_HASH2, __LINE__, _DPRINTK_FLAGS_DEFAULT };        \
  70         if (__dynamic_dbg_enabled(descriptor))                          \
  71                 dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__);        \
  72         } while (0)
  73
  74 #else
  75
  76 static inline int ddebug_remove_module(const char *mod)
  77 {
  78         return 0;
  79 }
  80
  81 #define dynamic_pr_debug(fmt, ...)                                      \
  82         do { if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); } while (0)
  83 #define dynamic_dev_dbg(dev, format, ...)                               \
  84         do { if (0) dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__); } while (0)
  85 #endif
  86
  87 #endif