LXR linux/arch/nds32/mm/mmap.c

   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (C) 2005-2017 Andes Technology Corporation
   3
   4#include <linux/sched.h>
   5#include <linux/mman.h>
   6#include <linux/shm.h>
   7
   8#define COLOUR_ALIGN(addr,pgoff)                \
   9        ((((addr)+SHMLBA-1)&~(SHMLBA-1)) +      \
  10         (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
  11
  12/*
  13 * We need to ensure that shared mappings are correctly aligned to
  14 * avoid aliasing issues with VIPT caches.  We need to ensure that
  15 * a specific page of an object is always mapped at a multiple of
  16 * SHMLBA bytes.
  17 *
  18 * We unconditionally provide this function for all cases, however
  19 * in the VIVT case, we optimise out the alignment rules.
  20 */
  21unsigned long
  22arch_get_unmapped_area(struct file *filp, unsigned long addr,
  23                       unsigned long len, unsigned long pgoff,
  24                       unsigned long flags)
  25{
  26        struct mm_struct *mm = current->mm;
  27        struct vm_area_struct *vma;
  28        int do_align = 0;
  29        struct vm_unmapped_area_info info;
  30        int aliasing = 0;
  31        if(IS_ENABLED(CONFIG_CPU_CACHE_ALIASING))
  32                aliasing = 1;
  33
  34        /*
  35         * We only need to do colour alignment if either the I or D
  36         * caches alias.
  37         */
  38        if (aliasing)
  39                do_align = filp || (flags & MAP_SHARED);
  40
  41        /*
  42         * We enforce the MAP_FIXED case.
  43         */
  44        if (flags & MAP_FIXED) {
  45                if (aliasing && flags & MAP_SHARED &&
  46                    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
  47                        return -EINVAL;
  48                return addr;
  49        }
  50
  51        if (len > TASK_SIZE)
  52                return -ENOMEM;
  53
  54        if (addr) {
  55                if (do_align)
  56                        addr = COLOUR_ALIGN(addr, pgoff);
  57                else
  58                        addr = PAGE_ALIGN(addr);
  59
  60                vma = find_vma(mm, addr);
  61                if (TASK_SIZE - len >= addr &&
  62                    (!vma || addr + len <= vma->vm_start))
  63                        return addr;
  64        }
  65
  66        info.flags = 0;
  67        info.length = len;
  68        info.low_limit = mm->mmap_base;
  69        info.high_limit = TASK_SIZE;
  70        info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
  71        info.align_offset = pgoff << PAGE_SHIFT;
  72        return vm_unmapped_area(&info);
  73}
  74