root/arch/arc/mm/mmap.c

DEFINITIONS

1. arch_get_unmapped_area

   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  */
  28 unsigned long
  29 arch_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 }