diff options
| -rw-r--r-- | include/linux/io-mapping.h | 3 | ||||
| -rw-r--r-- | mm/Kconfig | 3 | ||||
| -rw-r--r-- | mm/Makefile | 1 | ||||
| -rw-r--r-- | mm/io-mapping.c | 29 |
4 files changed, 36 insertions, 0 deletions
diff --git a/include/linux/io-mapping.h b/include/linux/io-mapping.h index c093e81310a9..e9743cfd8585 100644 --- a/include/linux/io-mapping.h +++ b/include/linux/io-mapping.h @@ -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); 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); |