linux/mm/io-mapping.c

// SPDX-License-Identifier: GPL-2.0-only

#include <linux/mm.h>
#include <linux/io-mapping.h>

/**
 * io_mapping_map_user - remap an I/O mapping to userspace
 * @iomap: the source io_mapping
 * @vma: user vma to map to
 * @addr: target user address to start at
 * @pfn: physical address of kernel memory
 * @size: size of map area
 *
 *  Note: this is only safe if the mm semaphore is held when called.
 */
int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,
		unsigned long addr, unsigned long pfn, unsigned long size)
{
	vm_flags_t expected_flags = VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;

	if (WARN_ON_ONCE((vma->vm_flags & expected_flags) != expected_flags))
		return -EINVAL;

	pgprot_t remap_prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
				       (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));

	/* We rely on prevalidation of the io-mapping to skip pfnmap tracking. */
	return remap_pfn_range_notrack(vma, addr, pfn, size, remap_prot);
}
EXPORT_SYMBOL_GPL(io_mapping_map_user);