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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isc.c (1743B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Functions for registration of I/O interruption subclasses on s390.
      4 *
      5 * Copyright IBM Corp. 2008
      6 * Authors: Sebastian Ott <sebott@linux.vnet.ibm.com>
      7 */
      8
      9#include <linux/spinlock.h>
     10#include <linux/module.h>
     11#include <asm/isc.h>
     12
     13static unsigned int isc_refs[MAX_ISC + 1];
     14static DEFINE_SPINLOCK(isc_ref_lock);
     15
     16
     17/**
     18 * isc_register - register an I/O interruption subclass.
     19 * @isc: I/O interruption subclass to register
     20 *
     21 * The number of users for @isc is increased. If this is the first user to
     22 * register @isc, the corresponding I/O interruption subclass mask is enabled.
     23 *
     24 * Context:
     25 *   This function must not be called in interrupt context.
     26 */
     27void isc_register(unsigned int isc)
     28{
     29	if (isc > MAX_ISC) {
     30		WARN_ON(1);
     31		return;
     32	}
     33
     34	spin_lock(&isc_ref_lock);
     35	if (isc_refs[isc] == 0)
     36		ctl_set_bit(6, 31 - isc);
     37	isc_refs[isc]++;
     38	spin_unlock(&isc_ref_lock);
     39}
     40EXPORT_SYMBOL_GPL(isc_register);
     41
     42/**
     43 * isc_unregister - unregister an I/O interruption subclass.
     44 * @isc: I/O interruption subclass to unregister
     45 *
     46 * The number of users for @isc is decreased. If this is the last user to
     47 * unregister @isc, the corresponding I/O interruption subclass mask is
     48 * disabled.
     49 * Note: This function must not be called if isc_register() hasn't been called
     50 * before by the driver for @isc.
     51 *
     52 * Context:
     53 *   This function must not be called in interrupt context.
     54 */
     55void isc_unregister(unsigned int isc)
     56{
     57	spin_lock(&isc_ref_lock);
     58	/* check for misuse */
     59	if (isc > MAX_ISC || isc_refs[isc] == 0) {
     60		WARN_ON(1);
     61		goto out_unlock;
     62	}
     63	if (isc_refs[isc] == 1)
     64		ctl_clear_bit(6, 31 - isc);
     65	isc_refs[isc]--;
     66out_unlock:
     67	spin_unlock(&isc_ref_lock);
     68}
     69EXPORT_SYMBOL_GPL(isc_unregister);