[mirror_ubuntu-jammy-kernel.git] / lib / seq_buf.c

// SPDX-License-Identifier: GPL-2.0
/*
 * seq_buf.c
 *
 * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
 *
 * The seq_buf 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 seq_buf must be initialized with seq_buf_init().
 * This will set up the counters within the descriptor. You can call
 * seq_buf_init() more than once to reset the seq_buf to start
 * from scratch.
 */
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/seq_buf.h>

/**
 * seq_buf_can_fit - can the new data fit in the current buffer?
 * @s: the seq_buf descriptor
 * @len: The length to see if it can fit in the current buffer
 *
 * Returns true if there's enough unused space in the seq_buf buffer
 * to fit the amount of new data according to @len.
 */
static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
{
	return s->len + len <= s->size;
}

/**
 * seq_buf_print_seq - move the contents of seq_buf into a seq_file
 * @m: the seq_file descriptor that is the destination
 * @s: the seq_buf descriptor that is the source.
 *
 * Returns zero on success, non zero otherwise
 */
int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
{
	unsigned int len = seq_buf_used(s);

	return seq_write(m, s->buffer, len);
}

/**
 * seq_buf_vprintf - sequence printing of information.
 * @s: seq_buf descriptor
 * @fmt: printf format string
 * @args: va_list of arguments from a printf() type function
 *
 * Writes a vnprintf() format into the sequencce buffer.
 *
 * Returns zero on success, -1 on overflow.
 */
int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
{
	int len;

	WARN_ON(s->size == 0);

	if (s->len < s->size) {
		len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
		if (s->len + len < s->size) {
			s->len += len;
			return 0;
		}
	}
	seq_buf_set_overflow(s);
	return -1;
}

/**
 * seq_buf_printf - sequence printing of information
 * @s: seq_buf descriptor
 * @fmt: printf format string
 *
 * Writes a printf() format into the sequence buffer.
 *
 * Returns zero on success, -1 on overflow.
 */
int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
{
	va_list ap;
	int ret;

	va_start(ap, fmt);
	ret = seq_buf_vprintf(s, fmt, ap);
	va_end(ap);

	return ret;
}
EXPORT_SYMBOL_GPL(seq_buf_printf);

#ifdef CONFIG_BINARY_PRINTF
/**
 * seq_buf_bprintf - Write the printf string from binary arguments
 * @s: seq_buf 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.
 *
 * Returns zero on success, -1 on overflow.
 */
int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
{
	unsigned int len = seq_buf_buffer_left(s);
	int ret;

	WARN_ON(s->size == 0);

	if (s->len < s->size) {
		ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
		if (s->len + ret < s->size) {
			s->len += ret;
			return 0;
		}
	}
	seq_buf_set_overflow(s);
	return -1;
}
#endif /* CONFIG_BINARY_PRINTF */

/**
 * seq_buf_puts - sequence printing of simple string
 * @s: seq_buf descriptor
 * @str: simple string to record
 *
 * Copy a simple string into the sequence buffer.
 *
 * Returns zero on success, -1 on overflow
 */
int seq_buf_puts(struct seq_buf *s, const char *str)
{
	size_t len = strlen(str);

	WARN_ON(s->size == 0);

	/* Add 1 to len for the trailing null byte which must be there */
	len += 1;

	if (seq_buf_can_fit(s, len)) {
		memcpy(s->buffer + s->len, str, len);
		/* Don't count the trailing null byte against the capacity */
		s->len += len - 1;
		return 0;
	}
	seq_buf_set_overflow(s);
	return -1;
}

/**
 * seq_buf_putc - sequence printing of simple character
 * @s: seq_buf descriptor
 * @c: simple character to record
 *
 * Copy a single character into the sequence buffer.
 *
 * Returns zero on success, -1 on overflow
 */
int seq_buf_putc(struct seq_buf *s, unsigned char c)
{
	WARN_ON(s->size == 0);

	if (seq_buf_can_fit(s, 1)) {
		s->buffer[s->len++] = c;
		return 0;
	}
	seq_buf_set_overflow(s);
	return -1;
}

/**
 * seq_buf_putmem - write raw data into the sequenc buffer
 * @s: seq_buf 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.
 *
 * Returns zero on success, -1 on overflow
 */
int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
{
	WARN_ON(s->size == 0);

	if (seq_buf_can_fit(s, len)) {
		memcpy(s->buffer + s->len, mem, len);
		s->len += len;
		return 0;
	}
	seq_buf_set_overflow(s);
	return -1;
}

#define MAX_MEMHEX_BYTES	8U
#define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)

/**
 * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
 * @s: seq_buf 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 seq_buf_putmem() except instead of just copying the
 * raw memory into the buffer it writes its ASCII representation of it
 * in hex characters.
 *
 * Returns zero on success, -1 on overflow
 */
int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
		       unsigned int len)
{
	unsigned char hex[HEX_CHARS];
	const unsigned char *data = mem;
	unsigned int start_len;
	int i, j;

	WARN_ON(s->size == 0);

	BUILD_BUG_ON(MAX_MEMHEX_BYTES * 2 >= HEX_CHARS);

	while (len) {
		start_len = min(len, MAX_MEMHEX_BYTES);
#ifdef __BIG_ENDIAN
		for (i = 0, j = 0; i < start_len; i++) {
#else
		for (i = start_len-1, j = 0; i >= 0; i--) {
#endif
			hex[j++] = hex_asc_hi(data[i]);
			hex[j++] = hex_asc_lo(data[i]);
		}
		if (WARN_ON_ONCE(j == 0 || j/2 > len))
			break;

		/* j increments twice per loop */
		hex[j++] = ' ';

		seq_buf_putmem(s, hex, j);
		if (seq_buf_has_overflowed(s))
			return -1;

		len -= start_len;
		data += start_len;
	}
	return 0;
}

/**
 * seq_buf_path - copy a path into the sequence buffer
 * @s: seq_buf descriptor
 * @path: path to write into the sequence buffer.
 * @esc: set of characters to escape in the output
 *
 * Write a path name into the sequence buffer.
 *
 * Returns the number of written bytes on success, -1 on overflow
 */
int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
{
	char *buf;
	size_t size = seq_buf_get_buf(s, &buf);
	int res = -1;

	WARN_ON(s->size == 0);

	if (size) {
		char *p = d_path(path, buf, size);
		if (!IS_ERR(p)) {
			char *end = mangle_path(buf, p, esc);
			if (end)
				res = end - buf;
		}
	}
	seq_buf_commit(s, res);

	return res;
}

/**
 * seq_buf_to_user - copy the sequence buffer to user space
 * @s: seq_buf 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 seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
{
	int len;
	int ret;

	if (!cnt)
		return 0;

	len = seq_buf_used(s);

	if (len <= s->readpos)
		return -EBUSY;

	len -= s->readpos;
	if (cnt > len)
		cnt = len;
	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
	if (ret == cnt)
		return -EFAULT;

	cnt -= ret;

	s->readpos += cnt;
	return cnt;
}

/**
 * seq_buf_hex_dump - print formatted hex dump into the sequence buffer
 * @s: seq_buf descriptor
 * @prefix_str: string to prefix each line with;
 *  caller supplies trailing spaces for alignment if desired
 * @prefix_type: controls whether prefix of an offset, address, or none
 *  is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
 * @rowsize: number of bytes to print per line; must be 16 or 32
 * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
 * @buf: data blob to dump
 * @len: number of bytes in the @buf
 * @ascii: include ASCII after the hex output
 *
 * Function is an analogue of print_hex_dump() and thus has similar interface.
 *
 * linebuf size is maximal length for one line.
 * 32 * 3 - maximum bytes per line, each printed into 2 chars + 1 for
 *	separating space
 * 2 - spaces separating hex dump and ascii representation
 * 32 - ascii representation
 * 1 - terminating '\0'
 *
 * Returns zero on success, -1 on overflow
 */
int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str, int prefix_type,
		     int rowsize, int groupsize,
		     const void *buf, size_t len, bool ascii)
{
	const u8 *ptr = buf;
	int i, linelen, remaining = len;
	unsigned char linebuf[32 * 3 + 2 + 32 + 1];
	int ret;

	if (rowsize != 16 && rowsize != 32)
		rowsize = 16;

	for (i = 0; i < len; i += rowsize) {
		linelen = min(remaining, rowsize);
		remaining -= rowsize;

		hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
				   linebuf, sizeof(linebuf), ascii);

		switch (prefix_type) {
		case DUMP_PREFIX_ADDRESS:
			ret = seq_buf_printf(s, "%s%p: %s\n",
			       prefix_str, ptr + i, linebuf);
			break;
		case DUMP_PREFIX_OFFSET:
			ret = seq_buf_printf(s, "%s%.8x: %s\n",
					     prefix_str, i, linebuf);
			break;
		default:
			ret = seq_buf_printf(s, "%s%s\n", prefix_str, linebuf);
			break;
		}
		if (ret)
			return ret;
	}
	return 0;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
3a161d99 SRRH	2	/*
	3	* seq_buf.c
	4	*
	5	* Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
	6	*
	7	* The seq_buf is a handy tool that allows you to pass a descriptor around
	8	* to a buffer that other functions can write to. It is similar to the
	9	* seq_file functionality but has some differences.
	10	*
	11	* To use it, the seq_buf must be initialized with seq_buf_init().
	12	* This will set up the counters within the descriptor. You can call
	13	* seq_buf_init() more than once to reset the seq_buf to start
	14	* from scratch.
	15	*/
	16	#include <linux/uaccess.h>
	17	#include <linux/seq_file.h>
	18	#include <linux/seq_buf.h>
	19
9b772153 SRRH	20	/**
	21	* seq_buf_can_fit - can the new data fit in the current buffer?
	22	* @s: the seq_buf descriptor
	23	* @len: The length to see if it can fit in the current buffer
	24	*
	25	* Returns true if there's enough unused space in the seq_buf buffer
	26	* to fit the amount of new data according to @len.
	27	*/
	28	static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
	29	{
8cd709ae	30	return s->len + len <= s->size;
9b772153 SRRH	31	}
9b772153 SRRH	32
3a161d99 SRRH	33	/**
	34	* seq_buf_print_seq - move the contents of seq_buf into a seq_file
	35	* @m: the seq_file descriptor that is the destination
	36	* @s: the seq_buf descriptor that is the source.
	37	*
	38	* Returns zero on success, non zero otherwise
	39	*/
	40	int seq_buf_print_seq(struct seq_file m, struct seq_buf s)
	41	{
eeab9815	42	unsigned int len = seq_buf_used(s);
3a161d99 SRRH	43
	44	return seq_write(m, s->buffer, len);
	45	}
	46
	47	/**
	48	* seq_buf_vprintf - sequence printing of information.
	49	* @s: seq_buf descriptor
	50	* @fmt: printf format string
	51	* @args: va_list of arguments from a printf() type function
	52	*
	53	* Writes a vnprintf() format into the sequencce buffer.
	54	*
	55	* Returns zero on success, -1 on overflow.
	56	*/
	57	int seq_buf_vprintf(struct seq_buf s, const char fmt, va_list args)
	58	{
	59	int len;
	60
	61	WARN_ON(s->size == 0);
	62
	63	if (s->len < s->size) {
	64	len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
4a8fe4e1	65	if (s->len + len < s->size) {
3a161d99 SRRH	66	s->len += len;
	67	return 0;
	68	}
	69	}
	70	seq_buf_set_overflow(s);
	71	return -1;
	72	}
	73
	74	/**
	75	* seq_buf_printf - sequence printing of information
	76	* @s: seq_buf descriptor
	77	* @fmt: printf format string
	78	*
	79	* Writes a printf() format into the sequence buffer.
	80	*
	81	* Returns zero on success, -1 on overflow.
	82	*/
	83	int seq_buf_printf(struct seq_buf s, const char fmt, ...)
	84	{
	85	va_list ap;
	86	int ret;
	87
	88	va_start(ap, fmt);
	89	ret = seq_buf_vprintf(s, fmt, ap);
	90	va_end(ap);
	91
	92	return ret;
	93	}
97c02c72	94	EXPORT_SYMBOL_GPL(seq_buf_printf);
3a161d99	95
2448913e	96	#ifdef CONFIG_BINARY_PRINTF
3a161d99 SRRH	97	/**
	98	* seq_buf_bprintf - Write the printf string from binary arguments
	99	* @s: seq_buf descriptor
	100	* @fmt: The format string for the @binary arguments
	101	* @binary: The binary arguments for @fmt.
	102	*
	103	* When recording in a fast path, a printf may be recorded with just
	104	* saving the format and the arguments as they were passed to the
	105	* function, instead of wasting cycles converting the arguments into
	106	* ASCII characters. Instead, the arguments are saved in a 32 bit
	107	* word array that is defined by the format string constraints.
	108	*
	109	* This function will take the format and the binary array and finish
	110	* the conversion into the ASCII string within the buffer.
	111	*
	112	* Returns zero on success, -1 on overflow.
	113	*/
	114	int seq_buf_bprintf(struct seq_buf s, const char fmt, const u32 *binary)
	115	{
	116	unsigned int len = seq_buf_buffer_left(s);
	117	int ret;
	118
	119	WARN_ON(s->size == 0);
	120
	121	if (s->len < s->size) {
	122	ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
4d4eb4d4	123	if (s->len + ret < s->size) {
3a161d99 SRRH	124	s->len += ret;
	125	return 0;
	126	}
	127	}
	128	seq_buf_set_overflow(s);
	129	return -1;
	130	}
2448913e	131	#endif /* CONFIG_BINARY_PRINTF */
3a161d99 SRRH	132
	133	/**
	134	* seq_buf_puts - sequence printing of simple string
	135	* @s: seq_buf descriptor
	136	* @str: simple string to record
	137	*
	138	* Copy a simple string into the sequence buffer.
	139	*
	140	* Returns zero on success, -1 on overflow
	141	*/
	142	int seq_buf_puts(struct seq_buf s, const char str)
	143	{
29924e50	144	size_t len = strlen(str);
3a161d99 SRRH	145
	146	WARN_ON(s->size == 0);
	147
0464ed24 ME	148	/* Add 1 to len for the trailing null byte which must be there */
	149	len += 1;
	150
9b772153	151	if (seq_buf_can_fit(s, len)) {
3a161d99	152	memcpy(s->buffer + s->len, str, len);
0464ed24 ME	153	/* Don't count the trailing null byte against the capacity */
0464ed24 ME	154	s->len += len - 1;
3a161d99 SRRH	155	return 0;
	156	}
	157	seq_buf_set_overflow(s);
	158	return -1;
	159	}
	160
	161	/**
	162	* seq_buf_putc - sequence printing of simple character
	163	* @s: seq_buf descriptor
	164	* @c: simple character to record
	165	*
	166	* Copy a single character into the sequence buffer.
	167	*
	168	* Returns zero on success, -1 on overflow
	169	*/
	170	int seq_buf_putc(struct seq_buf *s, unsigned char c)
	171	{
	172	WARN_ON(s->size == 0);
	173
9b772153	174	if (seq_buf_can_fit(s, 1)) {
3a161d99 SRRH	175	s->buffer[s->len++] = c;
	176	return 0;
	177	}
	178	seq_buf_set_overflow(s);
	179	return -1;
	180	}
	181
	182	/**
	183	* seq_buf_putmem - write raw data into the sequenc buffer
	184	* @s: seq_buf descriptor
	185	* @mem: The raw memory to copy into the buffer
	186	* @len: The length of the raw memory to copy (in bytes)
	187	*
	188	* There may be cases where raw memory needs to be written into the
	189	* buffer and a strcpy() would not work. Using this function allows
	190	* for such cases.
	191	*
	192	* Returns zero on success, -1 on overflow
	193	*/
	194	int seq_buf_putmem(struct seq_buf s, const void mem, unsigned int len)
	195	{
	196	WARN_ON(s->size == 0);
	197
9b772153	198	if (seq_buf_can_fit(s, len)) {
3a161d99 SRRH	199	memcpy(s->buffer + s->len, mem, len);
	200	s->len += len;
	201	return 0;
	202	}
	203	seq_buf_set_overflow(s);
	204	return -1;
	205	}
	206
	207	#define MAX_MEMHEX_BYTES 8U
	208	#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
	209
	210	/**
	211	* seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
	212	* @s: seq_buf descriptor
	213	* @mem: The raw memory to write its hex ASCII representation of
	214	* @len: The length of the raw memory to copy (in bytes)
	215	*
	216	* This is similar to seq_buf_putmem() except instead of just copying the
	217	* raw memory into the buffer it writes its ASCII representation of it
	218	* in hex characters.
	219	*
	220	* Returns zero on success, -1 on overflow
	221	*/
	222	int seq_buf_putmem_hex(struct seq_buf s, const void mem,
	223	unsigned int len)
	224	{
	225	unsigned char hex[HEX_CHARS];
	226	const unsigned char *data = mem;
	227	unsigned int start_len;
	228	int i, j;
	229
	230	WARN_ON(s->size == 0);
	231
d3b16034 YZ	232	BUILD_BUG_ON(MAX_MEMHEX_BYTES * 2 >= HEX_CHARS);
d3b16034 YZ	233
3a161d99	234	while (len) {
d3b16034	235	start_len = min(len, MAX_MEMHEX_BYTES);
3a161d99 SRRH	236	#ifdef __BIG_ENDIAN
	237	for (i = 0, j = 0; i < start_len; i++) {
	238	#else
	239	for (i = start_len-1, j = 0; i >= 0; i--) {
	240	#endif
	241	hex[j++] = hex_asc_hi(data[i]);
	242	hex[j++] = hex_asc_lo(data[i]);
	243	}
	244	if (WARN_ON_ONCE(j == 0 \|\| j/2 > len))
	245	break;
	246
	247	/* j increments twice per loop */
3a161d99 SRRH	248	hex[j++] = ' ';
	249
	250	seq_buf_putmem(s, hex, j);
	251	if (seq_buf_has_overflowed(s))
	252	return -1;
6a2cbc58 YZ	253
	254	len -= start_len;
	255	data += start_len;
3a161d99 SRRH	256	}
	257	return 0;
	258	}
	259
	260	/**
	261	* seq_buf_path - copy a path into the sequence buffer
	262	* @s: seq_buf descriptor
	263	* @path: path to write into the sequence buffer.
dd23180a	264	* @esc: set of characters to escape in the output
3a161d99 SRRH	265	*
	266	* Write a path name into the sequence buffer.
	267	*
dd23180a	268	* Returns the number of written bytes on success, -1 on overflow
3a161d99	269	*/
dd23180a	270	int seq_buf_path(struct seq_buf s, const struct path path, const char *esc)
3a161d99	271	{
01cb06a4 SRRH	272	char *buf;
01cb06a4 SRRH	273	size_t size = seq_buf_get_buf(s, &buf);
dd23180a	274	int res = -1;
3a161d99 SRRH	275
	276	WARN_ON(s->size == 0);
	277
dd23180a SRRH	278	if (size) {
	279	char *p = d_path(path, buf, size);
	280	if (!IS_ERR(p)) {
	281	char *end = mangle_path(buf, p, esc);
	282	if (end)
	283	res = end - buf;
3a161d99 SRRH	284	}
3a161d99 SRRH	285	}
01cb06a4	286	seq_buf_commit(s, res);
dd23180a SRRH	287
dd23180a SRRH	288	return res;
3a161d99 SRRH	289	}
	290
	291	/**
9dbbc3b9	292	* seq_buf_to_user - copy the sequence buffer to user space
3a161d99 SRRH	293	* @s: seq_buf descriptor
	294	* @ubuf: The userspace memory location to copy to
	295	* @cnt: The amount to copy
	296	*
	297	* Copies the sequence buffer into the userspace memory pointed to
	298	* by @ubuf. It starts from the last read position (@s->readpos)
	299	* and writes up to @cnt characters or till it reaches the end of
	300	* the content in the buffer (@s->len), which ever comes first.
	301	*
	302	* On success, it returns a positive number of the number of bytes
	303	* it copied.
	304	*
	305	* On failure it returns -EBUSY if all of the content in the
	306	* sequence has been already read, which includes nothing in the
	307	* sequence (@s->len == @s->readpos).
	308	*
	309	* Returns -EFAULT if the copy to userspace fails.
	310	*/
	311	int seq_buf_to_user(struct seq_buf s, char __user ubuf, int cnt)
	312	{
	313	int len;
	314	int ret;
	315
	316	if (!cnt)
	317	return 0;
	318
ff078d8f JS	319	len = seq_buf_used(s);
	320
	321	if (len <= s->readpos)
3a161d99 SRRH	322	return -EBUSY;
3a161d99 SRRH	323
ff078d8f	324	len -= s->readpos;
3a161d99 SRRH	325	if (cnt > len)
	326	cnt = len;
	327	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
	328	if (ret == cnt)
	329	return -EFAULT;
	330
	331	cnt -= ret;
	332
	333	s->readpos += cnt;
	334	return cnt;
	335	}
353cade3 PM	336
	337	/**
	338	* seq_buf_hex_dump - print formatted hex dump into the sequence buffer
	339	* @s: seq_buf descriptor
	340	* @prefix_str: string to prefix each line with;
	341	* caller supplies trailing spaces for alignment if desired
	342	* @prefix_type: controls whether prefix of an offset, address, or none
	343	* is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
	344	* @rowsize: number of bytes to print per line; must be 16 or 32
	345	* @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
	346	* @buf: data blob to dump
	347	* @len: number of bytes in the @buf
	348	* @ascii: include ASCII after the hex output
	349	*
	350	* Function is an analogue of print_hex_dump() and thus has similar interface.
	351	*
	352	* linebuf size is maximal length for one line.
	353	* 32 * 3 - maximum bytes per line, each printed into 2 chars + 1 for
	354	* separating space
	355	* 2 - spaces separating hex dump and ascii representation
	356	* 32 - ascii representation
	357	* 1 - terminating '\0'
	358	*
	359	* Returns zero on success, -1 on overflow
	360	*/
	361	int seq_buf_hex_dump(struct seq_buf s, const char prefix_str, int prefix_type,
	362	int rowsize, int groupsize,
	363	const void *buf, size_t len, bool ascii)
	364	{
	365	const u8 *ptr = buf;
	366	int i, linelen, remaining = len;
	367	unsigned char linebuf[32 * 3 + 2 + 32 + 1];
	368	int ret;
	369
	370	if (rowsize != 16 && rowsize != 32)
	371	rowsize = 16;
	372
	373	for (i = 0; i < len; i += rowsize) {
	374	linelen = min(remaining, rowsize);
	375	remaining -= rowsize;
	376
	377	hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
	378	linebuf, sizeof(linebuf), ascii);
	379
	380	switch (prefix_type) {
	381	case DUMP_PREFIX_ADDRESS:
	382	ret = seq_buf_printf(s, "%s%p: %s\n",
	383	prefix_str, ptr + i, linebuf);
	384	break;
	385	case DUMP_PREFIX_OFFSET:
	386	ret = seq_buf_printf(s, "%s%.8x: %s\n",
	387	prefix_str, i, linebuf);
	388	break;
	389	default:
	390	ret = seq_buf_printf(s, "%s%s\n", prefix_str, linebuf);
	391	break;
	392	}
	393	if (ret)
	394	return ret;
	395	}
	396	return 0;
	397	}