cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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bitarray.c (2629B)

      1// SPDX-License-Identifier: GPL-2.0
      2/* Copyright (C) B.A.T.M.A.N. contributors:
      3 *
      4 * Simon Wunderlich, Marek Lindner
      5 */
      6
      7#include "bitarray.h"
      8#include "main.h"
      9
     10#include <linux/bitmap.h>
     11
     12#include "log.h"
     13
     14/* shift the packet array by n places. */
     15static void batadv_bitmap_shift_left(unsigned long *seq_bits, s32 n)
     16{
     17	if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE)
     18		return;
     19
     20	bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE);
     21}
     22
     23/**
     24 * batadv_bit_get_packet() - receive and process one packet within the sequence
     25 *  number window
     26 * @priv: the bat priv with all the soft interface information
     27 * @seq_bits: pointer to the sequence number receive packet
     28 * @seq_num_diff: difference between the current/received sequence number and
     29 *  the last sequence number
     30 * @set_mark: whether this packet should be marked in seq_bits
     31 *
     32 * Return: true if the window was moved (either new or very old),
     33 *  false if the window was not moved/shifted.
     34 */
     35bool batadv_bit_get_packet(void *priv, unsigned long *seq_bits,
     36			   s32 seq_num_diff, int set_mark)
     37{
     38	struct batadv_priv *bat_priv = priv;
     39
     40	/* sequence number is slightly older. We already got a sequence number
     41	 * higher than this one, so we just mark it.
     42	 */
     43	if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) {
     44		if (set_mark)
     45			batadv_set_bit(seq_bits, -seq_num_diff);
     46		return false;
     47	}
     48
     49	/* sequence number is slightly newer, so we shift the window and
     50	 * set the mark if required
     51	 */
     52	if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) {
     53		batadv_bitmap_shift_left(seq_bits, seq_num_diff);
     54
     55		if (set_mark)
     56			batadv_set_bit(seq_bits, 0);
     57		return true;
     58	}
     59
     60	/* sequence number is much newer, probably missed a lot of packets */
     61	if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE &&
     62	    seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) {
     63		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
     64			   "We missed a lot of packets (%i) !\n",
     65			   seq_num_diff - 1);
     66		bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE);
     67		if (set_mark)
     68			batadv_set_bit(seq_bits, 0);
     69		return true;
     70	}
     71
     72	/* received a much older packet. The other host either restarted
     73	 * or the old packet got delayed somewhere in the network. The
     74	 * packet should be dropped without calling this function if the
     75	 * seqno window is protected.
     76	 *
     77	 * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE
     78	 * or
     79	 * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE
     80	 */
     81	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
     82		   "Other host probably restarted!\n");
     83
     84	bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE);
     85	if (set_mark)
     86		batadv_set_bit(seq_bits, 0);
     87
     88	return true;
     89}