diff options
| author | Christoph Hellwig <hch@lst.de> | 2021-04-29 22:57:32 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-04-30 11:20:39 -0700 |
| commit | 1fbaf8fc12a0136c7e62e7ad6fe886fe1749912c (patch) | |
| tree | 272f224698d871cd2ff65a5fc1fefb02de87fbcc /mm | |
| parent | 74ffa5a3e68504dd289135b1cf0422c19ffb3f2e (diff) | |
| download | lwn-1fbaf8fc12a0136c7e62e7ad6fe886fe1749912c.tar.gz lwn-1fbaf8fc12a0136c7e62e7ad6fe886fe1749912c.zip | |
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: Christoph 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig | 3 | ||||
| -rw-r--r-- | mm/Makefile | 1 | ||||
| -rw-r--r-- | mm/io-mapping.c | 29 |
3 files changed, 33 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig index d0808a23e54b..8a27c7c91428 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -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 diff --git a/mm/Makefile b/mm/Makefile index 72227b24a616..c0135e385984 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -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 diff --git a/mm/io-mapping.c b/mm/io-mapping.c new file mode 100644 index 000000000000..01b362799930 --- /dev/null +++ b/mm/io-mapping.c @@ -0,0 +1,29 @@ +// 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); |