backport/compat/backport-4.0.c

/*
 * Copyright (c) 2015  Hauke Mehrtens <hauke@hauke-m.de>
 *
 * Backport functionality introduced in Linux 4.0.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/ctype.h>
#include <linux/printk.h>
#include <linux/export.h>
#include <linux/trace_seq.h>
#include <linux/ftrace_event.h>
#include <asm/unaligned.h>

/**
 * hex_dump_to_buffer - convert a blob of data to "hex ASCII" in memory
 * @buf: data blob to dump
 * @len: number of bytes in the @buf
 * @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)
 * @linebuf: where to put the converted data
 * @linebuflen: total size of @linebuf, including space for terminating NUL
 * @ascii: include ASCII after the hex output
 *
 * hex_dump_to_buffer() works on one "line" of output at a time, i.e.,
 * 16 or 32 bytes of input data converted to hex + ASCII output.
 *
 * Given a buffer of u8 data, hex_dump_to_buffer() converts the input data
 * to a hex + ASCII dump at the supplied memory location.
 * The converted output is always NUL-terminated.
 *
 * E.g.:
 *   hex_dump_to_buffer(frame->data, frame->len, 16, 1,
 *			linebuf, sizeof(linebuf), true);
 *
 * example output buffer:
 * 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f  @ABCDEFGHIJKLMNO
 *
 * Return:
 * The amount of bytes placed in the buffer without terminating NUL. If the
 * output was truncated, then the return value is the number of bytes
 * (excluding the terminating NUL) which would have been written to the final
 * string if enough space had been available.
 */
int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize,
		       char *linebuf, size_t linebuflen, bool ascii)
{
	const u8 *ptr = buf;
	int ngroups;
	u8 ch;
	int j, lx = 0;
	int ascii_column;
	int ret;

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

	if (len > rowsize)		/* limit to one line at a time */
		len = rowsize;
	if (!is_power_of_2(groupsize) || groupsize > 8)
		groupsize = 1;
	if ((len % groupsize) != 0)	/* no mixed size output */
		groupsize = 1;

	ngroups = len / groupsize;
	ascii_column = rowsize * 2 + rowsize / groupsize + 1;

	if (!linebuflen)
		goto overflow1;

	if (!len)
		goto nil;

	if (groupsize == 8) {
		const u64 *ptr8 = buf;

		for (j = 0; j < ngroups; j++) {
			ret = snprintf(linebuf + lx, linebuflen - lx,
				       "%s%16.16llx", j ? " " : "",
				       get_unaligned(ptr8 + j));
			if (ret >= linebuflen - lx)
				goto overflow1;
			lx += ret;
		}
	} else if (groupsize == 4) {
		const u32 *ptr4 = buf;

		for (j = 0; j < ngroups; j++) {
			ret = snprintf(linebuf + lx, linebuflen - lx,
				       "%s%8.8x", j ? " " : "",
				       get_unaligned(ptr4 + j));
			if (ret >= linebuflen - lx)
				goto overflow1;
			lx += ret;
		}
	} else if (groupsize == 2) {
		const u16 *ptr2 = buf;

		for (j = 0; j < ngroups; j++) {
			ret = snprintf(linebuf + lx, linebuflen - lx,
				       "%s%4.4x", j ? " " : "",
				       get_unaligned(ptr2 + j));
			if (ret >= linebuflen - lx)
				goto overflow1;
			lx += ret;
		}
	} else {
		for (j = 0; j < len; j++) {
			if (linebuflen < lx + 3)
				goto overflow2;
			ch = ptr[j];
			linebuf[lx++] = hex_asc_hi(ch);
			linebuf[lx++] = hex_asc_lo(ch);
			linebuf[lx++] = ' ';
		}
		if (j)
			lx--;
	}
	if (!ascii)
		goto nil;

	while (lx < ascii_column) {
		if (linebuflen < lx + 2)
			goto overflow2;
		linebuf[lx++] = ' ';
	}
	for (j = 0; j < len; j++) {
		if (linebuflen < lx + 2)
			goto overflow2;
		ch = ptr[j];
		linebuf[lx++] = (isascii(ch) && isprint(ch)) ? ch : '.';
	}
nil:
	linebuf[lx] = '\0';
	return lx;
overflow2:
	linebuf[lx++] = '\0';
overflow1:
	return ascii ? ascii_column + len : (groupsize * 2 + 1) * ngroups - 1;
}
EXPORT_SYMBOL_GPL(hex_dump_to_buffer);

#if LINUX_VERSION_IS_LESS(3,17,0)
static inline unsigned char *
trace_seq_buffer_ptr(struct trace_seq *s)
{
	return s->buffer + s->len;
}
#endif

const char *
ftrace_print_array_seq(struct trace_seq *p, const void *buf, int buf_len,
		       size_t el_size)
{
	const char *ret = trace_seq_buffer_ptr(p);
	const char *prefix = "";
	void *ptr = (void *)buf;

	trace_seq_putc(p, '{');

	while (ptr < buf + buf_len) {
		switch (el_size) {
		case 1:
			trace_seq_printf(p, "%s0x%x", prefix,
					 *(u8 *)ptr);
			break;
		case 2:
			trace_seq_printf(p, "%s0x%x", prefix,
					 *(u16 *)ptr);
			break;
		case 4:
			trace_seq_printf(p, "%s0x%x", prefix,
					 *(u32 *)ptr);
			break;
		case 8:
			trace_seq_printf(p, "%s0x%llx", prefix,
					 *(u64 *)ptr);
			break;
		default:
			trace_seq_printf(p, "BAD SIZE:%zu 0x%x", el_size,
					 *(u8 *)ptr);
			el_size = 1;
		}
		prefix = ",";
		ptr += el_size;
	}

	trace_seq_putc(p, '}');
	trace_seq_putc(p, 0);

	return ret;
}
EXPORT_SYMBOL(ftrace_print_array_seq);