include/linux/trace_seq.h

   1 #ifndef _LINUX_TRACE_SEQ_H
   2 #define _LINUX_TRACE_SEQ_H
   3
   4 #include <linux/seq_buf.h>
   5
   6 #include <asm/page.h>
   7
   8 /*
   9  * Trace sequences are used to allow a function to call several other functions
  10  * to create a string of data to use (up to a max of PAGE_SIZE).
  11  */
  12
  13 struct trace_seq {
  14         unsigned char           buffer[PAGE_SIZE];
  15         struct seq_buf          seq;
  16         int                     full;
  17 };
  18
  19 static inline void
  20 trace_seq_init(struct trace_seq *s)
  21 {
  22         seq_buf_init(&s->seq, s->buffer, PAGE_SIZE);
  23         s->full = 0;
  24 }
  25
  26 /**
  27  * trace_seq_used - amount of actual data written to buffer
  28  * @s: trace sequence descriptor
  29  *
  30  * Returns the amount of data written to the buffer.
  31  *
  32  * IMPORTANT!
  33  *
  34  * Use this instead of @s->seq.len if you need to pass the amount
  35  * of data from the buffer to another buffer (userspace, or what not).
  36  * The @s->seq.len on overflow is bigger than the buffer size and
  37  * using it can cause access to undefined memory.
  38  */
  39 static inline int trace_seq_used(struct trace_seq *s)
  40 {
  41         return seq_buf_used(&s->seq);
  42 }
  43
  44 /**
  45  * trace_seq_buffer_ptr - return pointer to next location in buffer
  46  * @s: trace sequence descriptor
  47  *
  48  * Returns the pointer to the buffer where the next write to
  49  * the buffer will happen. This is useful to save the location
  50  * that is about to be written to and then return the result
  51  * of that write.
  52  */
  53 static inline unsigned char *
  54 trace_seq_buffer_ptr(struct trace_seq *s)
  55 {
  56         return s->buffer + seq_buf_used(&s->seq);
  57 }
  58
  59 /**
  60  * trace_seq_has_overflowed - return true if the trace_seq took too much
  61  * @s: trace sequence descriptor
  62  *
  63  * Returns true if too much data was added to the trace_seq and it is
  64  * now full and will not take anymore.
  65  */
  66 static inline bool trace_seq_has_overflowed(struct trace_seq *s)
  67 {
  68         return s->full || seq_buf_has_overflowed(&s->seq);
  69 }
  70
  71 /*
  72  * Currently only defined when tracing is enabled.
  73  */
  74 #ifdef CONFIG_TRACING
  75 extern __printf(2, 3)
  76 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
  77 extern __printf(2, 0)
  78 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
  79 extern void
  80 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
  81 extern int trace_print_seq(struct seq_file *m, struct trace_seq *s);
  82 extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
  83                              int cnt);
  84 extern void trace_seq_puts(struct trace_seq *s, const char *str);
  85 extern void trace_seq_putc(struct trace_seq *s, unsigned char c);
  86 extern void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len);
  87 extern void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
  88                                 unsigned int len);
  89 extern int trace_seq_path(struct trace_seq *s, const struct path *path);
  90
  91 extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
  92                              int nmaskbits);
  93
  94 #else /* CONFIG_TRACING */
  95 static inline void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
  96 {
  97 }
  98 static inline void
  99 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 100 {
 101 }
 102
 103 static inline void
 104 trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
 105                   int nmaskbits)
 106 {
 107 }
 108
 109 static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s)
 110 {
 111         return 0;
 112 }
 113 static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
 114                                     int cnt)
 115 {
 116         return 0;
 117 }
 118 static inline void trace_seq_puts(struct trace_seq *s, const char *str)
 119 {
 120 }
 121 static inline void trace_seq_putc(struct trace_seq *s, unsigned char c)
 122 {
 123 }
 124 static inline void
 125 trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
 126 {
 127 }
 128 static inline void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
 129                                        unsigned int len)
 130 {
 131 }
 132 static inline int trace_seq_path(struct trace_seq *s, const struct path *path)
 133 {
 134         return 0;
 135 }
 136 #endif /* CONFIG_TRACING */
 137
 138 #endif /* _LINUX_TRACE_SEQ_H */