include/linux/trace_seq.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_TRACE_SEQ_H
   3 #define _LINUX_TRACE_SEQ_H
   4
   5 #include <linux/seq_buf.h>
   6
   7 #include <asm/page.h>
   8
   9 /*
  10  * Trace sequences are used to allow a function to call several other functions
  11  * to create a string of data to use (up to a max of PAGE_SIZE).
  12  */
  13
  14 struct trace_seq {
  15         unsigned char           buffer[PAGE_SIZE];
  16         struct seq_buf          seq;
  17         int                     full;
  18 };
  19
  20 static inline void
  21 trace_seq_init(struct trace_seq *s)
  22 {
  23         seq_buf_init(&s->seq, s->buffer, PAGE_SIZE);
  24         s->full = 0;
  25 }
  26
  27 /**
  28  * trace_seq_used - amount of actual data written to buffer
  29  * @s: trace sequence descriptor
  30  *
  31  * Returns the amount of data written to the buffer.
  32  *
  33  * IMPORTANT!
  34  *
  35  * Use this instead of @s->seq.len if you need to pass the amount
  36  * of data from the buffer to another buffer (userspace, or what not).
  37  * The @s->seq.len on overflow is bigger than the buffer size and
  38  * using it can cause access to undefined memory.
  39  */
  40 static inline int trace_seq_used(struct trace_seq *s)
  41 {
  42         return seq_buf_used(&s->seq);
  43 }
  44
  45 /**
  46  * trace_seq_buffer_ptr - return pointer to next location in buffer
  47  * @s: trace sequence descriptor
  48  *
  49  * Returns the pointer to the buffer where the next write to
  50  * the buffer will happen. This is useful to save the location
  51  * that is about to be written to and then return the result
  52  * of that write.
  53  */
  54 static inline unsigned char *
  55 trace_seq_buffer_ptr(struct trace_seq *s)
  56 {
  57         return s->buffer + seq_buf_used(&s->seq);
  58 }
  59
  60 /**
  61  * trace_seq_has_overflowed - return true if the trace_seq took too much
  62  * @s: trace sequence descriptor
  63  *
  64  * Returns true if too much data was added to the trace_seq and it is
  65  * now full and will not take anymore.
  66  */
  67 static inline bool trace_seq_has_overflowed(struct trace_seq *s)
  68 {
  69         return s->full || seq_buf_has_overflowed(&s->seq);
  70 }
  71
  72 /*
  73  * Currently only defined when tracing is enabled.
  74  */
  75 #ifdef CONFIG_TRACING
  76 extern __printf(2, 3)
  77 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
  78 extern __printf(2, 0)
  79 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
  80 extern void
  81 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
  82 extern int trace_print_seq(struct seq_file *m, struct trace_seq *s);
  83 extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
  84                              int cnt);
  85 extern void trace_seq_puts(struct trace_seq *s, const char *str);
  86 extern void trace_seq_putc(struct trace_seq *s, unsigned char c);
  87 extern void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len);
  88 extern void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
  89                                 unsigned int len);
  90 extern int trace_seq_path(struct trace_seq *s, const struct path *path);
  91
  92 extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
  93                              int nmaskbits);
  94
  95 #else /* CONFIG_TRACING */
  96 static inline void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
  97 {
  98 }
  99 static inline void
 100 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 101 {
 102 }
 103
 104 static inline void
 105 trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
 106                   int nmaskbits)
 107 {
 108 }
 109
 110 static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s)
 111 {
 112         return 0;
 113 }
 114 static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
 115                                     int cnt)
 116 {
 117         return 0;
 118 }
 119 static inline void trace_seq_puts(struct trace_seq *s, const char *str)
 120 {
 121 }
 122 static inline void trace_seq_putc(struct trace_seq *s, unsigned char c)
 123 {
 124 }
 125 static inline void
 126 trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
 127 {
 128 }
 129 static inline void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
 130                                        unsigned int len)
 131 {
 132 }
 133 static inline int trace_seq_path(struct trace_seq *s, const struct path *path)
 134 {
 135         return 0;
 136 }
 137 #endif /* CONFIG_TRACING */
 138
 139 #endif /* _LINUX_TRACE_SEQ_H */