include/linux/dynamic_debug.h

   1 #ifndef _DYNAMIC_DEBUG_H
   2 #define _DYNAMIC_DEBUG_H
   3
   4 #include <linux/jump_label.h>
   5
   6 /* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
   7  * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
   8  * use independent hash functions, to reduce the chance of false positives.
   9  */
  10 extern long long dynamic_debug_enabled;
  11 extern long long dynamic_debug_enabled2;
  12
  13 /*
  14  * An instance of this structure is created in a special
  15  * ELF section at every dynamic debug callsite.  At runtime,
  16  * the special section is treated as an array of these.
  17  */
  18 struct _ddebug {
  19         /*
  20          * These fields are used to drive the user interface
  21          * for selecting and displaying debug callsites.
  22          */
  23         const char *modname;
  24         const char *function;
  25         const char *filename;
  26         const char *format;
  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         char enabled;
  37 } __attribute__((aligned(8)));
  38
  39
  40 int ddebug_add_module(struct _ddebug *tab, unsigned int n,
  41                                 const char *modname);
  42
  43 #if defined(CONFIG_DYNAMIC_DEBUG)
  44 extern int ddebug_remove_module(const char *mod_name);
  45
  46 #define dynamic_pr_debug(fmt, ...) do {                                 \
  47         __label__ do_printk;                                            \
  48         __label__ out;                                                  \
  49         static struct _ddebug descriptor                                \
  50         __used                                                          \
  51         __attribute__((section("__verbose"), aligned(8))) =             \
  52         { KBUILD_MODNAME, __func__, __FILE__, fmt, __LINE__,            \
  53                 _DPRINTK_FLAGS_DEFAULT };                               \
  54         JUMP_LABEL(&descriptor.enabled, do_printk);                     \
  55         goto out;                                                       \
  56 do_printk:                                                              \
  57         printk(KERN_DEBUG pr_fmt(fmt),  ##__VA_ARGS__);                 \
  58 out:    ;                                                               \
  59         } while (0)
  60
  61
  62 #define dynamic_dev_dbg(dev, fmt, ...) do {                             \
  63         __label__ do_printk;                                            \
  64         __label__ out;                                                  \
  65         static struct _ddebug descriptor                                \
  66         __used                                                          \
  67         __attribute__((section("__verbose"), aligned(8))) =             \
  68         { KBUILD_MODNAME, __func__, __FILE__, fmt, __LINE__,            \
  69                 _DPRINTK_FLAGS_DEFAULT };                               \
  70         JUMP_LABEL(&descriptor.enabled, do_printk);                     \
  71         goto out;                                                       \
  72 do_printk:                                                              \
  73         dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__);                \
  74 out:    ;                                                               \
  75         } while (0)
  76
  77 #else
  78
  79 static inline int ddebug_remove_module(const char *mod)
  80 {
  81         return 0;
  82 }
  83
  84 #define dynamic_pr_debug(fmt, ...)                                      \
  85         do { if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); } while (0)
  86 #define dynamic_dev_dbg(dev, fmt, ...)                                  \
  87         do { if (0) dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__); } while (0)
  88 #endif
  89
  90 #endif