root/arch/nds32/mm/mmap.c

DEFINITIONS

1. arch_get_unmapped_area

   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  */
  21 unsigned long
  22 arch_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 }