root/arch/csky/abiv1/mmap.c

DEFINITIONS

1. arch_get_unmapped_area

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
   3 
   4 #include <linux/fs.h>
   5 #include <linux/mm.h>
   6 #include <linux/mman.h>
   7 #include <linux/shm.h>
   8 #include <linux/sched.h>
   9 #include <linux/random.h>
  10 #include <linux/io.h>
  11 
  12 #define COLOUR_ALIGN(addr,pgoff)                \
  13         ((((addr)+SHMLBA-1)&~(SHMLBA-1)) +      \
  14          (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
  15 
  16 /*
  17  * We need to ensure that shared mappings are correctly aligned to
  18  * avoid aliasing issues with VIPT caches.  We need to ensure that
  19  * a specific page of an object is always mapped at a multiple of
  20  * SHMLBA bytes.
  21  *
  22  * We unconditionally provide this function for all cases.
  23  */
  24 unsigned long
  25 arch_get_unmapped_area(struct file *filp, unsigned long addr,
  26                 unsigned long len, unsigned long pgoff, unsigned long flags)
  27 {
  28         struct mm_struct *mm = current->mm;
  29         struct vm_area_struct *vma;
  30         int do_align = 0;
  31         struct vm_unmapped_area_info info;
  32 
  33         /*
  34          * We only need to do colour alignment if either the I or D
  35          * caches alias.
  36          */
  37         do_align = filp || (flags & MAP_SHARED);
  38 
  39         /*
  40          * We enforce the MAP_FIXED case.
  41          */
  42         if (flags & MAP_FIXED) {
  43                 if (flags & MAP_SHARED &&
  44                     (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
  45                         return -EINVAL;
  46                 return addr;
  47         }
  48 
  49         if (len > TASK_SIZE)
  50                 return -ENOMEM;
  51 
  52         if (addr) {
  53                 if (do_align)
  54                         addr = COLOUR_ALIGN(addr, pgoff);
  55                 else
  56                         addr = PAGE_ALIGN(addr);
  57 
  58                 vma = find_vma(mm, addr);
  59                 if (TASK_SIZE - len >= addr &&
  60                     (!vma || addr + len <= vm_start_gap(vma)))
  61                         return addr;
  62         }
  63 
  64         info.flags = 0;
  65         info.length = len;
  66         info.low_limit = mm->mmap_base;
  67         info.high_limit = TASK_SIZE;
  68         info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
  69         info.align_offset = pgoff << PAGE_SHIFT;
  70         return vm_unmapped_area(&info);
  71 }