the-tree/mm/io-mapping.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002
0003 #include <linux/mm.h>
0004 #include <linux/io-mapping.h>
0005
0006 /**
0007  * io_mapping_map_user - remap an I/O mapping to userspace
0008  * @iomap: the source io_mapping
0009  * @vma: user vma to map to
0010  * @addr: target user address to start at
0011  * @pfn: physical address of kernel memory
0012  * @size: size of map area
0013  *
0014  *  Note: this is only safe if the mm semaphore is held when called.
0015  */
0016 int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,
0017         unsigned long addr, unsigned long pfn, unsigned long size)
0018 {
0019     vm_flags_t expected_flags = VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
0020
0021     if (WARN_ON_ONCE((vma->vm_flags & expected_flags) != expected_flags))
0022         return -EINVAL;
0023
0024     /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
0025     return remap_pfn_range_notrack(vma, addr, pfn, size,
0026         __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
0027              (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK)));
0028 }
0029 EXPORT_SYMBOL_GPL(io_mapping_map_user);