LXR linux/arch/arc/mm/mmap.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * ARC700 mmap
   4 *
   5 * (started from arm version - for VIPT alias handling)
   6 *
   7 * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
   8 */
   9
  10#include <linux/fs.h>
  11#include <linux/mm.h>
  12#include <linux/mman.h>
  13#include <linux/sched/mm.h>
  14
  15#include <asm/cacheflush.h>
  16
  17#define COLOUR_ALIGN(addr, pgoff)                       \
  18        ((((addr) + SHMLBA - 1) & ~(SHMLBA - 1)) +      \
  19         (((pgoff) << PAGE_SHIFT) & (SHMLBA - 1)))
  20
  21/*
  22 * Ensure that shared mappings are correctly aligned to
  23 * avoid aliasing issues with VIPT caches.
  24 * We need to ensure that
  25 * a specific page of an object is always mapped at a multiple of
  26 * SHMLBA bytes.
  27 */
  28unsigned long
  29arch_get_unmapped_area(struct file *filp, unsigned long addr,
  30                unsigned long len, unsigned long pgoff, unsigned long flags)
  31{
  32        struct mm_struct *mm = current->mm;
  33        struct vm_area_struct *vma;
  34        int do_align = 0;
  35        int aliasing = cache_is_vipt_aliasing();
  36        struct vm_unmapped_area_info info;
  37
  38        /*
  39         * We only need to do colour alignment if D cache aliases.
  40         */
  41        if (aliasing)
  42                do_align = filp || (flags & MAP_SHARED);
  43
  44        /*
  45         * We enforce the MAP_FIXED case.
  46         */
  47        if (flags & MAP_FIXED) {
  48                if (aliasing && flags & MAP_SHARED &&
  49                    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
  50                        return -EINVAL;
  51                return addr;
  52        }
  53
  54        if (len > TASK_SIZE)
  55                return -ENOMEM;
  56
  57        if (addr) {
  58                if (do_align)
  59                        addr = COLOUR_ALIGN(addr, pgoff);
  60                else
  61                        addr = PAGE_ALIGN(addr);
  62
  63                vma = find_vma(mm, addr);
  64                if (TASK_SIZE - len >= addr &&
  65                    (!vma || addr + len <= vm_start_gap(vma)))
  66                        return addr;
  67        }
  68
  69        info.flags = 0;
  70        info.length = len;
  71        info.low_limit = mm->mmap_base;
  72        info.high_limit = TASK_SIZE;
  73        info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
  74        info.align_offset = pgoff << PAGE_SHIFT;
  75        return vm_unmapped_area(&info);
  76}
  77