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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mmap_unlock_work.h (1770B)

      1/* SPDX-License-Identifier: GPL-2.0-only */
      2/* Copyright (c) 2021 Facebook
      3 */
      4
      5#ifndef __MMAP_UNLOCK_WORK_H__
      6#define __MMAP_UNLOCK_WORK_H__
      7#include <linux/irq_work.h>
      8
      9/* irq_work to run mmap_read_unlock() in irq_work */
     10struct mmap_unlock_irq_work {
     11	struct irq_work irq_work;
     12	struct mm_struct *mm;
     13};
     14
     15DECLARE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
     16
     17/*
     18 * We cannot do mmap_read_unlock() when the irq is disabled, because of
     19 * risk to deadlock with rq_lock. To look up vma when the irqs are
     20 * disabled, we need to run mmap_read_unlock() in irq_work. We use a
     21 * percpu variable to do the irq_work. If the irq_work is already used
     22 * by another lookup, we fall over.
     23 */
     24static inline bool bpf_mmap_unlock_get_irq_work(struct mmap_unlock_irq_work **work_ptr)
     25{
     26	struct mmap_unlock_irq_work *work = NULL;
     27	bool irq_work_busy = false;
     28
     29	if (irqs_disabled()) {
     30		if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
     31			work = this_cpu_ptr(&mmap_unlock_work);
     32			if (irq_work_is_busy(&work->irq_work)) {
     33				/* cannot queue more up_read, fallback */
     34				irq_work_busy = true;
     35			}
     36		} else {
     37			/*
     38			 * PREEMPT_RT does not allow to trylock mmap sem in
     39			 * interrupt disabled context. Force the fallback code.
     40			 */
     41			irq_work_busy = true;
     42		}
     43	}
     44
     45	*work_ptr = work;
     46	return irq_work_busy;
     47}
     48
     49static inline void bpf_mmap_unlock_mm(struct mmap_unlock_irq_work *work, struct mm_struct *mm)
     50{
     51	if (!work) {
     52		mmap_read_unlock(mm);
     53	} else {
     54		work->mm = mm;
     55
     56		/* The lock will be released once we're out of interrupt
     57		 * context. Tell lockdep that we've released it now so
     58		 * it doesn't complain that we forgot to release it.
     59		 */
     60		rwsem_release(&mm->mmap_lock.dep_map, _RET_IP_);
     61		irq_work_queue(&work->irq_work);
     62	}
     63}
     64
     65#endif /* __MMAP_UNLOCK_WORK_H__ */