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. 12 * 13 * Have the trace seq to be 8K which is typically PAGE_SIZE * 2 on 14 * most architectures. The TRACE_SEQ_BUFFER_SIZE (which is 15 * TRACE_SEQ_SIZE minus the other fields of trace_seq), is the 16 * max size the output of a trace event may be. 17 */ 18 19 #define TRACE_SEQ_SIZE 8192 20 #define TRACE_SEQ_BUFFER_SIZE (TRACE_SEQ_SIZE - \ 21 (sizeof(struct seq_buf) + sizeof(size_t) + sizeof(int))) 22 23 struct trace_seq { 24 struct seq_buf seq; 25 size_t readpos; 26 int full; 27 char buffer[TRACE_SEQ_BUFFER_SIZE]; 28 }; 29 30 static inline void 31 trace_seq_init(struct trace_seq *s) 32 { 33 seq_buf_init(&s->seq, s->buffer, TRACE_SEQ_BUFFER_SIZE); 34 s->full = 0; 35 s->readpos = 0; 36 } 37 38 /** 39 * trace_seq_used - amount of actual data written to buffer 40 * @s: trace sequence descriptor 41 * 42 * Returns the amount of data written to the buffer. 43 * 44 * IMPORTANT! 45 * 46 * Use this instead of @s->seq.len if you need to pass the amount 47 * of data from the buffer to another buffer (userspace, or what not). 48 * The @s->seq.len on overflow is bigger than the buffer size and 49 * using it can cause access to undefined memory. 50 */ 51 static inline int trace_seq_used(struct trace_seq *s) 52 { 53 return seq_buf_used(&s->seq); 54 } 55 56 /** 57 * trace_seq_buffer_ptr - return pointer to next location in buffer 58 * @s: trace sequence descriptor 59 * 60 * Returns the pointer to the buffer where the next write to 61 * the buffer will happen. This is useful to save the location 62 * that is about to be written to and then return the result 63 * of that write. 64 */ 65 static inline char * 66 trace_seq_buffer_ptr(struct trace_seq *s) 67 { 68 return s->buffer + seq_buf_used(&s->seq); 69 } 70 71 /** 72 * trace_seq_has_overflowed - return true if the trace_seq took too much 73 * @s: trace sequence descriptor 74 * 75 * Returns true if too much data was added to the trace_seq and it is 76 * now full and will not take anymore. 77 */ 78 static inline bool trace_seq_has_overflowed(struct trace_seq *s) 79 { 80 return s->full || seq_buf_has_overflowed(&s->seq); 81 } 82 83 /** 84 * trace_seq_pop - pop off the last written character 85 * @s: trace sequence descriptor 86 * 87 * Removes the last written character to the trace_seq @s. 88 * 89 * Returns the last character or -1 if it is empty. 90 */ 91 static inline int trace_seq_pop(struct trace_seq *s) 92 { 93 return seq_buf_pop(&s->seq); 94 } 95 96 /* 97 * Currently only defined when tracing is enabled. 98 */ 99 #ifdef CONFIG_TRACING 100 extern __printf(2, 3) 101 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...); 102 extern __printf(2, 0) 103 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args); 104 extern __printf(2, 0) 105 void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary); 106 extern int trace_print_seq(struct seq_file *m, struct trace_seq *s); 107 extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, 108 int cnt); 109 extern void trace_seq_puts(struct trace_seq *s, const char *str); 110 extern void trace_seq_putc(struct trace_seq *s, unsigned char c); 111 extern void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len); 112 extern void trace_seq_putmem_hex(struct trace_seq *s, const void *mem, 113 unsigned int len); 114 extern int trace_seq_path(struct trace_seq *s, const struct path *path); 115 116 extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp, 117 int nmaskbits); 118 119 extern void trace_seq_bitmask_list(struct trace_seq *s, 120 const unsigned long *maskp, 121 int nmaskbits); 122 123 extern int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str, 124 int prefix_type, int rowsize, int groupsize, 125 const void *buf, size_t len, bool ascii); 126 char *trace_seq_acquire(struct trace_seq *s, unsigned int len); 127 128 #else /* CONFIG_TRACING */ 129 static inline __printf(2, 3) 130 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...) 131 { 132 } 133 static inline __printf(2, 0) 134 void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary) 135 { 136 } 137 138 static inline void 139 trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp, 140 int nmaskbits) 141 { 142 } 143 144 static inline void 145 trace_seq_bitmask_list(struct trace_seq *s, const unsigned long *maskp, 146 int nmaskbits) 147 { 148 } 149 150 static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s) 151 { 152 return 0; 153 } 154 static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, 155 int cnt) 156 { 157 return 0; 158 } 159 static inline void trace_seq_puts(struct trace_seq *s, const char *str) 160 { 161 } 162 static inline void trace_seq_putc(struct trace_seq *s, unsigned char c) 163 { 164 } 165 static inline void 166 trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len) 167 { 168 } 169 static inline void trace_seq_putmem_hex(struct trace_seq *s, const void *mem, 170 unsigned int len) 171 { 172 } 173 static inline int trace_seq_path(struct trace_seq *s, const struct path *path) 174 { 175 return 0; 176 } 177 static inline char *trace_seq_acquire(struct trace_seq *s, unsigned int len) 178 { 179 return NULL; 180 } 181 #endif /* CONFIG_TRACING */ 182 183 #endif /* _LINUX_TRACE_SEQ_H */ 184