mm/io-mapping.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 #include <linux/mm.h>
   4 #include <linux/io-mapping.h>
   5
   6 /**
   7  * io_mapping_map_user - remap an I/O mapping to userspace
   8  * @iomap: the source io_mapping
   9  * @vma: user vma to map to
  10  * @addr: target user address to start at
  11  * @pfn: physical address of kernel memory
  12  * @size: size of map area
  13  *
  14  *  Note: this is only safe if the mm semaphore is held when called.
  15  */
  16 int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,
  17                 unsigned long addr, unsigned long pfn, unsigned long size)
  18 {
  19         vm_flags_t expected_flags = VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
  20
  21         if (WARN_ON_ONCE((vma->vm_flags & expected_flags) != expected_flags))
  22                 return -EINVAL;
  23
  24         /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
  25         return remap_pfn_range_notrack(vma, addr, pfn, size,
  26                 __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
  27                          (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK)));
  28 }
  29 EXPORT_SYMBOL_GPL(io_mapping_map_user);