// SPDX-License-Identifier: GPL-2.0/* * trace_seq.c * * Copyright (C) 2008-2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com> * * The trace_seq is a handy tool that allows you to pass a descriptor around * to a buffer that other functions can write to. It is similar to the * seq_file functionality but has some differences. * * To use it, the trace_seq must be initialized with trace_seq_init(). * This will set up the counters within the descriptor. You can call * trace_seq_init() more than once to reset the trace_seq to start * from scratch. *  * A write to the buffer will either succeed or fail. That is, unlike * sprintf() there will not be a partial write (well it may write into * the buffer but it won't update the pointers). This allows users to * try to write something into the trace_seq buffer and if it fails * they can flush it and try again. * */#include <linux/uaccess.h>#include <linux/seq_file.h>#include <linux/trace_seq.h> /* How much buffer is left on the trace_seq? */#define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq) /* * trace_seq should work with being initialized with 0s. */static inline void __trace_seq_init(struct trace_seq *s){	if (unlikely(!s->seq.size))		trace_seq_init(s);} /** * trace_print_seq - move the contents of trace_seq into a seq_file * @m: the seq_file descriptor that is the destination * @s: the trace_seq descriptor that is the source. * * Returns 0 on success and non zero on error. If it succeeds to * write to the seq_file it will reset the trace_seq, otherwise * it does not modify the trace_seq to let the caller try again. */int trace_print_seq(struct seq_file *m, struct trace_seq *s){	int ret; 	__trace_seq_init(s); 	ret = seq_buf_print_seq(m, &s->seq); 	/*	 * Only reset this buffer if we successfully wrote to the	 * seq_file buffer. This lets the caller try again or	 * do something else with the contents.	 */	if (!ret)		trace_seq_init(s); 	return ret;} /** * trace_seq_printf - sequence printing of trace information * @s: trace sequence descriptor * @fmt: printf format string * * The tracer may use either sequence operations or its own * copy to user routines. To simplify formatting of a trace * trace_seq_printf() is used to store strings into a special * buffer (@s). Then the output may be either used by * the sequencer or pulled into another buffer. */void trace_seq_printf(struct trace_seq *s, const char *fmt, ...){	unsigned int save_len = s->seq.len;	va_list ap; 	if (s->full)		return; 	__trace_seq_init(s); 	va_start(ap, fmt);	seq_buf_vprintf(&s->seq, fmt, ap);	va_end(ap); 	/* If we can't write it all, don't bother writing anything */	if (unlikely(seq_buf_has_overflowed(&s->seq))) {		s->seq.len = save_len;		s->full = 1;	}}EXPORT_SYMBOL_GPL(trace_seq_printf); /** * trace_seq_bitmask - write a bitmask array in its ASCII representation * @s:		trace sequence descriptor * @maskp:	points to an array of unsigned longs that represent a bitmask * @nmaskbits:	The number of bits that are valid in @maskp * * Writes a ASCII representation of a bitmask string into @s. */void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,		      int nmaskbits){	unsigned int save_len = s->seq.len; 	if (s->full)		return; 	__trace_seq_init(s); 	seq_buf_printf(&s->seq, "%*pb", nmaskbits, maskp); 	if (unlikely(seq_buf_has_overflowed(&s->seq))) {		s->seq.len = save_len;		s->full = 1;	}}EXPORT_SYMBOL_GPL(trace_seq_bitmask); /** * trace_seq_vprintf - sequence printing of trace information * @s: trace sequence descriptor * @fmt: printf format string * @args: Arguments for the format string * * The tracer may use either sequence operations or its own * copy to user routines. To simplify formatting of a trace * trace_seq_printf is used to store strings into a special * buffer (@s). Then the output may be either used by * the sequencer or pulled into another buffer. */void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args){	unsigned int save_len = s->seq.len; 	if (s->full)		return; 	__trace_seq_init(s); 	seq_buf_vprintf(&s->seq, fmt, args); 	/* If we can't write it all, don't bother writing anything */	if (unlikely(seq_buf_has_overflowed(&s->seq))) {		s->seq.len = save_len;		s->full = 1;	}}EXPORT_SYMBOL_GPL(trace_seq_vprintf); /** * trace_seq_bprintf - Write the printf string from binary arguments * @s: trace sequence descriptor * @fmt: The format string for the @binary arguments * @binary: The binary arguments for @fmt. * * When recording in a fast path, a printf may be recorded with just * saving the format and the arguments as they were passed to the * function, instead of wasting cycles converting the arguments into * ASCII characters. Instead, the arguments are saved in a 32 bit * word array that is defined by the format string constraints. * * This function will take the format and the binary array and finish * the conversion into the ASCII string within the buffer. */void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary){	unsigned int save_len = s->seq.len; 	if (s->full)		return; 	__trace_seq_init(s); 	seq_buf_bprintf(&s->seq, fmt, binary); 	/* If we can't write it all, don't bother writing anything */	if (unlikely(seq_buf_has_overflowed(&s->seq))) {		s->seq.len = save_len;		s->full = 1;		return;	}}EXPORT_SYMBOL_GPL(trace_seq_bprintf); /** * trace_seq_puts - trace sequence printing of simple string * @s: trace sequence descriptor * @str: simple string to record * * The tracer may use either the sequence operations or its own * copy to user routines. This function records a simple string * into a special buffer (@s) for later retrieval by a sequencer * or other mechanism. */void trace_seq_puts(struct trace_seq *s, const char *str){	unsigned int len = strlen(str); 	if (s->full)		return; 	__trace_seq_init(s); 	if (len > TRACE_SEQ_BUF_LEFT(s)) {		s->full = 1;		return;	} 	seq_buf_putmem(&s->seq, str, len);}EXPORT_SYMBOL_GPL(trace_seq_puts); /** * trace_seq_putc - trace sequence printing of simple character * @s: trace sequence descriptor * @c: simple character to record * * The tracer may use either the sequence operations or its own * copy to user routines. This function records a simple character * into a special buffer (@s) for later retrieval by a sequencer * or other mechanism. */void trace_seq_putc(struct trace_seq *s, unsigned char c){	if (s->full)		return; 	__trace_seq_init(s); 	if (TRACE_SEQ_BUF_LEFT(s) < 1) {		s->full = 1;		return;	} 	seq_buf_putc(&s->seq, c);}EXPORT_SYMBOL_GPL(trace_seq_putc); /** * trace_seq_putmem - write raw data into the trace_seq buffer * @s: trace sequence descriptor * @mem: The raw memory to copy into the buffer * @len: The length of the raw memory to copy (in bytes) * * There may be cases where raw memory needs to be written into the * buffer and a strcpy() would not work. Using this function allows * for such cases. */void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len){	if (s->full)		return; 	__trace_seq_init(s); 	if (len > TRACE_SEQ_BUF_LEFT(s)) {		s->full = 1;		return;	} 	seq_buf_putmem(&s->seq, mem, len);}EXPORT_SYMBOL_GPL(trace_seq_putmem); /** * trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex * @s: trace sequence descriptor * @mem: The raw memory to write its hex ASCII representation of * @len: The length of the raw memory to copy (in bytes) * * This is similar to trace_seq_putmem() except instead of just copying the * raw memory into the buffer it writes its ASCII representation of it * in hex characters. */void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,			 unsigned int len){	unsigned int save_len = s->seq.len; 	if (s->full)		return; 	__trace_seq_init(s); 	/* Each byte is represented by two chars */	if (len * 2 > TRACE_SEQ_BUF_LEFT(s)) {		s->full = 1;		return;	} 	/* The added spaces can still cause an overflow */	seq_buf_putmem_hex(&s->seq, mem, len); 	if (unlikely(seq_buf_has_overflowed(&s->seq))) {		s->seq.len = save_len;		s->full = 1;		return;	}}EXPORT_SYMBOL_GPL(trace_seq_putmem_hex); /** * trace_seq_path - copy a path into the sequence buffer * @s: trace sequence descriptor * @path: path to write into the sequence buffer. * * Write a path name into the sequence buffer. * * Returns 1 if we successfully written all the contents to *   the buffer. * Returns 0 if we the length to write is bigger than the *   reserved buffer space. In this case, nothing gets written. */int trace_seq_path(struct trace_seq *s, const struct path *path){	unsigned int save_len = s->seq.len; 	if (s->full)		return 0; 	__trace_seq_init(s); 	if (TRACE_SEQ_BUF_LEFT(s) < 1) {		s->full = 1;		return 0;	} 	seq_buf_path(&s->seq, path, "\n"); 	if (unlikely(seq_buf_has_overflowed(&s->seq))) {		s->seq.len = save_len;		s->full = 1;		return 0;	} 	return 1;}EXPORT_SYMBOL_GPL(trace_seq_path); /** * trace_seq_to_user - copy the sequence buffer to user space * @s: trace sequence descriptor * @ubuf: The userspace memory location to copy to * @cnt: The amount to copy * * Copies the sequence buffer into the userspace memory pointed to * by @ubuf. It starts from the last read position (@s->readpos) * and writes up to @cnt characters or till it reaches the end of * the content in the buffer (@s->len), which ever comes first. * * On success, it returns a positive number of the number of bytes * it copied. * * On failure it returns -EBUSY if all of the content in the * sequence has been already read, which includes nothing in the * sequence (@s->len == @s->readpos). * * Returns -EFAULT if the copy to userspace fails. */int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt){	int ret;	__trace_seq_init(s);	ret = seq_buf_to_user(&s->seq, ubuf, s->readpos, cnt);	if (ret > 0)		s->readpos += ret;	return ret;}EXPORT_SYMBOL_GPL(trace_seq_to_user); int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str,		       int prefix_type, int rowsize, int groupsize,		       const void *buf, size_t len, bool ascii){	unsigned int save_len = s->seq.len; 	if (s->full)		return 0; 	__trace_seq_init(s); 	if (TRACE_SEQ_BUF_LEFT(s) < 1) {		s->full = 1;		return 0;	} 	seq_buf_hex_dump(&(s->seq), prefix_str,		   prefix_type, rowsize, groupsize,		   buf, len, ascii); 	if (unlikely(seq_buf_has_overflowed(&s->seq))) {		s->seq.len = save_len;		s->full = 1;		return 0;	} 	return 1;}EXPORT_SYMBOL(trace_seq_hex_dump); /* * trace_seq_acquire - acquire seq buffer with size len * @s: trace sequence descriptor * @len: size of buffer to be acquired * * acquire buffer with size of @len from trace_seq for output usage, * user can fill string into that buffer. * * Returns start address of acquired buffer. * * it allow multiple usage in one trace output function call. */char *trace_seq_acquire(struct trace_seq *s, unsigned int len){	char *ret = trace_seq_buffer_ptr(s); 	if (!WARN_ON_ONCE(seq_buf_buffer_left(&s->seq) < len))		seq_buf_commit(&s->seq, len); 	return ret;}EXPORT_SYMBOL(trace_seq_acquire);