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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preempt.c (1986B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <config.h>
      3
      4#include "preempt.h"
      5
      6#include "assume.h"
      7#include "locks.h"
      8
      9/* Support NR_CPUS of at most 64 */
     10#define CPU_PREEMPTION_LOCKS_INIT0 LOCK_IMPL_INITIALIZER
     11#define CPU_PREEMPTION_LOCKS_INIT1 \
     12	CPU_PREEMPTION_LOCKS_INIT0, CPU_PREEMPTION_LOCKS_INIT0
     13#define CPU_PREEMPTION_LOCKS_INIT2 \
     14	CPU_PREEMPTION_LOCKS_INIT1, CPU_PREEMPTION_LOCKS_INIT1
     15#define CPU_PREEMPTION_LOCKS_INIT3 \
     16	CPU_PREEMPTION_LOCKS_INIT2, CPU_PREEMPTION_LOCKS_INIT2
     17#define CPU_PREEMPTION_LOCKS_INIT4 \
     18	CPU_PREEMPTION_LOCKS_INIT3, CPU_PREEMPTION_LOCKS_INIT3
     19#define CPU_PREEMPTION_LOCKS_INIT5 \
     20	CPU_PREEMPTION_LOCKS_INIT4, CPU_PREEMPTION_LOCKS_INIT4
     21
     22/*
     23 * Simulate disabling preemption by locking a particular cpu. NR_CPUS
     24 * should be the actual number of cpus, not just the maximum.
     25 */
     26struct lock_impl cpu_preemption_locks[NR_CPUS] = {
     27	CPU_PREEMPTION_LOCKS_INIT0
     28#if (NR_CPUS - 1) & 1
     29	, CPU_PREEMPTION_LOCKS_INIT0
     30#endif
     31#if (NR_CPUS - 1) & 2
     32	, CPU_PREEMPTION_LOCKS_INIT1
     33#endif
     34#if (NR_CPUS - 1) & 4
     35	, CPU_PREEMPTION_LOCKS_INIT2
     36#endif
     37#if (NR_CPUS - 1) & 8
     38	, CPU_PREEMPTION_LOCKS_INIT3
     39#endif
     40#if (NR_CPUS - 1) & 16
     41	, CPU_PREEMPTION_LOCKS_INIT4
     42#endif
     43#if (NR_CPUS - 1) & 32
     44	, CPU_PREEMPTION_LOCKS_INIT5
     45#endif
     46};
     47
     48#undef CPU_PREEMPTION_LOCKS_INIT0
     49#undef CPU_PREEMPTION_LOCKS_INIT1
     50#undef CPU_PREEMPTION_LOCKS_INIT2
     51#undef CPU_PREEMPTION_LOCKS_INIT3
     52#undef CPU_PREEMPTION_LOCKS_INIT4
     53#undef CPU_PREEMPTION_LOCKS_INIT5
     54
     55__thread int thread_cpu_id;
     56__thread int preempt_disable_count;
     57
     58void preempt_disable(void)
     59{
     60	BUG_ON(preempt_disable_count < 0 || preempt_disable_count == INT_MAX);
     61
     62	if (preempt_disable_count++)
     63		return;
     64
     65	thread_cpu_id = nondet_int();
     66	assume(thread_cpu_id >= 0);
     67	assume(thread_cpu_id < NR_CPUS);
     68	lock_impl_lock(&cpu_preemption_locks[thread_cpu_id]);
     69}
     70
     71void preempt_enable(void)
     72{
     73	BUG_ON(preempt_disable_count < 1);
     74
     75	if (--preempt_disable_count)
     76		return;
     77
     78	lock_impl_unlock(&cpu_preemption_locks[thread_cpu_id]);
     79}