linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright (C) 2014 Davidlohr Bueso.

 */

#include <linux/sched/signal.h>

#include <linux/sched/task.h>

#include <linux/mm.h>

#include <linux/vmacache.h>

#include <asm/pgtable.h>

​

/*

 * Hash based on the pmd of addr if configured with MMU, which provides a good

 * hit rate for workloads with spatial locality.  Otherwise, use pages.

 */

#ifdef CONFIG_MMU

#define VMACACHE_SHIFT  PMD_SHIFT

#else

#define VMACACHE_SHIFT  PAGE_SHIFT

#endif

#define VMACACHE_HASH(addr) ((addr >> VMACACHE_SHIFT) & VMACACHE_MASK)

​

/*

 * This task may be accessing a foreign mm via (for example)

 * get_user_pages()->find_vma().  The vmacache is task-local and this

 * task's vmacache pertains to a different mm (ie, its own).  There is

 * nothing we can do here.

 *

 * Also handle the case where a kernel thread has adopted this mm via use_mm().

 * That kernel thread's vmacache is not applicable to this mm.

 */

static inline bool vmacache_valid_mm(struct mm_struct *mm)

{

    return current->mm == mm && !(current->flags & PF_KTHREAD);

}

​

void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)

{

    if (vmacache_valid_mm(newvma->vm_mm))

        current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma;

}

​

static bool vmacache_valid(struct mm_struct *mm)

{

    struct task_struct *curr;

​

    if (!vmacache_valid_mm(mm))

        return false;

​

    curr = current;

    if (mm->vmacache_seqnum != curr->vmacache.seqnum) {

        /*

         * First attempt will always be invalid, initialize

         * the new cache for this task here.

         */

        curr->vmacache.seqnum = mm->vmacache_seqnum;

        vmacache_flush(curr);

        return false;

    }

    return true;

}

​

struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr)

{