path: root/net/ethtool/bitset.c

// SPDX-License-Identifier: GPL-2.0-only

#include <linux/ethtool_netlink.h>
#include <linux/bitmap.h>
#include "netlink.h"
#include "bitset.h"

/* Some bitmaps are internally represented as an array of unsigned long, some
 * as an array of u32 (some even as single u32 for now). To avoid the need of
 * wrappers on caller side, we provide two set of functions: those with "32"
 * suffix in their names expect u32 based bitmaps, those without it expect
 * unsigned long bitmaps.
 */

static u32 ethnl_lower_bits(unsigned int n)
{
	return ~(u32)0 >> (32 - n % 32);
}

static u32 ethnl_upper_bits(unsigned int n)
{
	return ~(u32)0 << (n % 32);
}

/**
 * ethnl_bitmap32_clear() - Clear u32 based bitmap
 * @dst:   bitmap to clear
 * @start: beginning of the interval
 * @end:   end of the interval
 * @mod:   set if bitmap was modified
 *
 * Clear @nbits bits of a bitmap with indices @start <= i < @end
 */
static void ethnl_bitmap32_clear(u32 *dst, unsigned int start, unsigned int end,
				 bool *mod)
{
	unsigned int start_word = start / 32;
	unsigned int end_word = end / 32;
	unsigned int i;
	u32 mask;

	if (end <= start)
		return;

	if (start % 32) {
		mask = ethnl_upper_bits(start);
		if (end_word == start_word) {
			mask &= ethnl_lower_bits(end);
			if (dst[start_word] & mask) {
				dst[start_word] &= ~mask;
				*mod = true;
			}
			return;
		}
		if (dst[start_word] & mask) {
			dst[start_word] &= ~mask;
			*mod = true;
		}
		start_word++;
	}

	for (i = start_word; i < end_word; i++) {
		if (dst[i]) {
			dst[i] = 0;
			*mod = true;
		}
	}
	if (end % 32) {
		mask = ethnl_lower_bits(end);
		if (dst[end_word] & mask) {
			dst[end_word] &= ~mask;
			*mod = true;
		}
	}
}

/**
 * ethnl_bitmap32_not_zero() - Check if any bit is set in an interval
 * @map:   bitmap to test
 * @start: beginning of the interval
 * @end:   end of the interval
 *
 * Return: true if there is non-zero bit with  index @start <= i < @end,
 *         false if the whole interval is zero
 */
static bool ethnl_bitmap32_not_zero(const u32 *map, unsigned int start,
				    unsigned int end)
{
	unsigned int start_word = start / 32;
	unsigned int end_word = end / 32;
	u32 mask;

	if (end <= start)
		return true;

	if (start % 32) {
		mask = ethnl_upper_bits(start);
		if (end_word == start_word) {
			mask &= ethnl_lower_bits(end);
			return map[start_word] & mask;
		}
		if (map[start_word] & mask)
			return true;
		start_word++;
	}

	if (!memchr_inv(map + start_word, '\0',
			(end_word - start_word) * sizeof(u32)))
		return true;
	if (end % 32 == 0)
		return true;
	return map[end_word] & ethnl_lower_bits(end);
}

/**
 * ethnl_bitmap32_update() - Modify u32 based bitmap according to value/mask
 *			     pair
 * @dst:   bitmap to update
 * @nbits: bit size of the bitmap
 * @value: values to set
 * @mask:  mask of bits to set
 * @mod:   set to true if bitmap is modified, preserve if not
 *
 * Set bits in @dst bitmap which are set in @mask to values from @value, leave
 * the rest untouched. If destination bitmap was modified, set @mod to true,
 * leave as it is if not.
 */
static void ethnl_bitmap32_update(u32 *dst, unsigned int nbits,
				  const u32 *value, const u32 *mask, bool *mod)
{
	while (nbits > 0) {
		u32 real_mask = mask ? *mask : ~(u32)0;
		u32 new_value;

		if (nbits < 32)
			real_mask &= ethnl_lower_bits(nbits);
		new_value = (*dst & ~real_mask) | (*value & real_mask);
		if (new_value != *dst) {
			*dst = new_value;
			*mod = true;
		}

		if (nbits <= 32)
			break;
		dst++;
		nbits -= 32;
		value++;
		if (mask)
			mask++;
	}
}

static bool ethnl_bitmap32_test_bit(const u32 *map, unsigned int index)
{
	return map[index / 32] & (1U << (index % 32));
}

/**
 * ethnl_bitset32_size() - Calculate size of bitset nested attribute
 * @val:     value bitmap (u32 based)
 * @mask:    mask bitmap (u32 based, optional)
 * @nbits:   bit length of the bitset
 * @names:   array of bit names (optional)
 * @compact: assume compact format for output
 *
 * Estimate length of netlink attribute composed by a later call to
 * ethnl_put_bitset32() call with the same arguments.
 *
 * Return: negative error code or attribute length estimate
 */
int ethnl_bitset32_size(const u32 *val, const u32 *mask, unsigned int nbits,
			ethnl_string_array_t names, bool compact)
{<