arch/arc/mm/mmap.c

   1 /*
   2  * ARC700 mmap
   3  *
   4  * (started from arm version - for VIPT alias handling)
   5  *
   6  * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/fs.h>
  14 #include <linux/mm.h>
  15 #include <linux/mman.h>
  16 #include <linux/sched.h>
  17 #include <asm/cacheflush.h>
  18
  19 #define COLOUR_ALIGN(addr, pgoff)                       \
  20         ((((addr) + SHMLBA - 1) & ~(SHMLBA - 1)) +      \
  21          (((pgoff) << PAGE_SHIFT) & (SHMLBA - 1)))
  22
  23 /*
  24  * Ensure that shared mappings are correctly aligned to
  25  * avoid aliasing issues with VIPT caches.
  26  * We need to ensure that
  27  * a specific page of an object is always mapped at a multiple of
  28  * SHMLBA bytes.
  29  */
  30 unsigned long
  31 arch_get_unmapped_area(struct file *filp, unsigned long addr,
  32                 unsigned long len, unsigned long pgoff, unsigned long flags)
  33 {
  34         struct mm_struct *mm = current->mm;
  35         struct vm_area_struct *vma;
  36         int do_align = 0;
  37         int aliasing = cache_is_vipt_aliasing();
  38         struct vm_unmapped_area_info info;
  39
  40         /*
  41          * We only need to do colour alignment if D cache aliases.
  42          */
  43         if (aliasing)
  44                 do_align = filp || (flags & MAP_SHARED);
  45
  46         /*
  47          * We enforce the MAP_FIXED case.
  48          */
  49         if (flags & MAP_FIXED) {
  50                 if (aliasing && flags & MAP_SHARED &&
  51                     (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
  52                         return -EINVAL;
  53                 return addr;
  54         }
  55
  56         if (len > TASK_SIZE)
  57                 return -ENOMEM;
  58
  59         if (addr) {
  60                 if (do_align)
  61                         addr = COLOUR_ALIGN(addr, pgoff);
  62                 else
  63                         addr = PAGE_ALIGN(addr);
  64
  65                 vma = find_vma(mm, addr);
  66                 if (TASK_SIZE - len >= addr &&
  67                     (!vma || addr + len <= vma->vm_start))
  68                         return addr;
  69         }
  70
  71         info.flags = 0;
  72         info.length = len;
  73         info.low_limit = mm->mmap_base;
  74         info.high_limit = TASK_SIZE;
  75         info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
  76         info.align_offset = pgoff << PAGE_SHIFT;
  77         return vm_unmapped_area(&info);
  78 }