LXR linux/include/linux/trace

   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
  14struct trace_seq {
  15        unsigned char           buffer[PAGE_SIZE];
  16        struct seq_buf          seq;
  17        int                     full;
  18};
  19
  20static inline void
  21trace_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 */
  40static 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 */
  54static inline unsigned char *
  55trace_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 */
  67static 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
  76extern __printf(2, 3)
  77void trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
  78extern __printf(2, 0)
  79void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
  80extern void
  81trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
  82extern int trace_print_seq(struct seq_file *m, struct trace_seq *s);
  83extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
  84                             int cnt);
  85extern void trace_seq_puts(struct trace_seq *s, const char *str);
  86extern void trace_seq_putc(struct trace_seq *s, unsigned char c);
  87extern void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len);
  88extern void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
  89                                unsigned int len);
  90extern int trace_seq_path(struct trace_seq *s, const struct path *path);
  91
  92extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
  93                             int nmaskbits);
  94
  95#else /* CONFIG_TRACING */
  96static inline void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
  97{
  98}
  99static inline void
 100trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 101{
 102}
 103
 104static inline void
 105trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
 106                  int nmaskbits)
 107{
 108}
 109
 110static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s)
 111{
 112        return 0;
 113}
 114static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
 115                                    int cnt)
 116{
 117        return 0;
 118}
 119static inline void trace_seq_puts(struct trace_seq *s, const char *str)
 120{
 121}
 122static inline void trace_seq_putc(struct trace_seq *s, unsigned char c)
 123{
 124}
 125static inline void
 126trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
 127{
 128}
 129static inline void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
 130                                       unsigned int len)
 131{
 132}
 133static 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 */
 140