Commit 1fbaf8fc authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Linus Torvalds
Browse files

mm: add a io_mapping_map_user helper 

Add a helper that calls remap_pfn_range for an struct io_mapping, relying
on the pgprot pre-validation done when creating the mapping instead of
doing it at runtime.

Link: https://lkml.kernel.org/r/20210326055505.1424432-3-hch@lst.de


Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 74ffa5a3

include/linux/io-mapping.h

+3 −0
Original line number Diff line number Diff line
@@ -220,3 +220,6 @@ io_mapping_free(struct io_mapping *iomap) 
}



#endif /* _LINUX_IO_MAPPING_H */



int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,

		unsigned long addr, unsigned long pfn, unsigned long size);

mm/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -871,4 +871,7 @@ config MAPPING_DIRTY_HELPERS 
config KMAP_LOCAL

	bool



# struct io_mapping based helper.  Selected by drivers that need them

config IO_MAPPING

	bool

endmenu

mm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -120,3 +120,4 @@ obj-$(CONFIG_MEMFD_CREATE) += memfd.o 
obj-$(CONFIG_MAPPING_DIRTY_HELPERS) += mapping_dirty_helpers.o

obj-$(CONFIG_PTDUMP_CORE) += ptdump.o

obj-$(CONFIG_PAGE_REPORTING) += page_reporting.o

obj-$(CONFIG_IO_MAPPING) += io-mapping.o

mm/io-mapping.c

0 → 100644
+29 −0
Original line number Diff line number Diff line 
// 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;



	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */

	return remap_pfn_range_notrack(vma, addr, pfn, size,

		__pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |

			 (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK)));

}

EXPORT_SYMBOL_GPL(io_mapping_map_user);