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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linkmode.c (3418B)

      1// SPDX-License-Identifier: GPL-2.0+
      2#include <linux/linkmode.h>
      3
      4/**
      5 * linkmode_resolve_pause - resolve the allowable pause modes
      6 * @local_adv: local advertisement in ethtool format
      7 * @partner_adv: partner advertisement in ethtool format
      8 * @tx_pause: pointer to bool to indicate whether transmit pause should be
      9 * enabled.
     10 * @rx_pause: pointer to bool to indicate whether receive pause should be
     11 * enabled.
     12 *
     13 * Flow control is resolved according to our and the link partners
     14 * advertisements using the following drawn from the 802.3 specs:
     15 *  Local device  Link partner
     16 *  Pause AsymDir Pause AsymDir Result
     17 *    0     X       0     X     Disabled
     18 *    0     1       1     0     Disabled
     19 *    0     1       1     1     TX
     20 *    1     0       0     X     Disabled
     21 *    1     X       1     X     TX+RX
     22 *    1     1       0     1     RX
     23 */
     24void linkmode_resolve_pause(const unsigned long *local_adv,
     25			    const unsigned long *partner_adv,
     26			    bool *tx_pause, bool *rx_pause)
     27{
     28	__ETHTOOL_DECLARE_LINK_MODE_MASK(m);
     29
     30	linkmode_and(m, local_adv, partner_adv);
     31	if (linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT, m)) {
     32		*tx_pause = true;
     33		*rx_pause = true;
     34	} else if (linkmode_test_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, m)) {
     35		*tx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
     36					      partner_adv);
     37		*rx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
     38					      local_adv);
     39	} else {
     40		*tx_pause = false;
     41		*rx_pause = false;
     42	}
     43}
     44EXPORT_SYMBOL_GPL(linkmode_resolve_pause);
     45
     46/**
     47 * linkmode_set_pause - set the pause mode advertisement
     48 * @advertisement: advertisement in ethtool format
     49 * @tx: boolean from ethtool struct ethtool_pauseparam tx_pause member
     50 * @rx: boolean from ethtool struct ethtool_pauseparam rx_pause member
     51 *
     52 * Configure the advertised Pause and Asym_Pause bits according to the
     53 * capabilities of provided in @tx and @rx.
     54 *
     55 * We convert as follows:
     56 *  tx rx  Pause AsymDir
     57 *  0  0   0     0
     58 *  0  1   1     1
     59 *  1  0   0     1
     60 *  1  1   1     0
     61 *
     62 * Note: this translation from ethtool tx/rx notation to the advertisement
     63 * is actually very problematical. Here are some examples:
     64 *
     65 * For tx=0 rx=1, meaning transmit is unsupported, receive is supported:
     66 *
     67 *  Local device  Link partner
     68 *  Pause AsymDir Pause AsymDir Result
     69 *    1     1       1     0     TX + RX - but we have no TX support.
     70 *    1     1       0     1	Only this gives RX only
     71 *
     72 * For tx=1 rx=1, meaning we have the capability to transmit and receive
     73 * pause frames:
     74 *
     75 *  Local device  Link partner
     76 *  Pause AsymDir Pause AsymDir Result
     77 *    1     0       0     1     Disabled - but since we do support tx and rx,
     78 *				this should resolve to RX only.
     79 *
     80 * Hence, asking for:
     81 *  rx=1 tx=0 gives Pause+AsymDir advertisement, but we may end up
     82 *            resolving to tx+rx pause or only rx pause depending on
     83 *            the partners advertisement.
     84 *  rx=0 tx=1 gives AsymDir only, which will only give tx pause if
     85 *            the partners advertisement allows it.
     86 *  rx=1 tx=1 gives Pause only, which will only allow tx+rx pause
     87 *            if the other end also advertises Pause.
     88 */
     89void linkmode_set_pause(unsigned long *advertisement, bool tx, bool rx)
     90{
     91	linkmode_mod_bit(ETHTOOL_LINK_MODE_Pause_BIT, advertisement, rx);
     92	linkmode_mod_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, advertisement,
     93			 rx ^ tx);
     94}
     95EXPORT_SYMBOL_GPL(linkmode_set_pause);