mm: make mmap_region() internal

Now that we have removed the one user of mmap_region() outside of mm, make
it internal and add it to vma.c so it can be userland tested.

This ensures that all external memory mappings are performed using the
appropriate interfaces and allows us to modify memory mapping logic as we
see fit.

Additionally expand test stubs to allow for the mmap_region() code to
compile and be userland testable.

Link: https://lkml.kernel.org/r/de5a3c574d35c26237edf20a1d8652d7305709c9.1735819274.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 0 insertions, 59 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 3cc8de07411d..cda01071c7b1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1072,65 +1072,6 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
 	return do_vmi_munmap(&vmi, mm, start, len, uf, false);
 }
 
-/**
- * mmap_region() - Actually perform the userland mapping of a VMA into
- * current->mm with known, aligned and overflow-checked @addr and @len, and
- * correctly determined VMA flags @vm_flags and page offset @pgoff.
- *
- * This is an internal memory management function, and should not be used
- * directly.
- *
- * The caller must write-lock current->mm->mmap_lock.
- *
- * @file: If a file-backed mapping, a pointer to the struct file describing the
- * file to be mapped, otherwise NULL.
- * @addr: The page-aligned address at which to perform the mapping.
- * @len: The page-aligned, non-zero, length of the mapping.
- * @vm_flags: The VMA flags which should be applied to the mapping.
- * @pgoff: If @file is specified, the page offset into the file, if not then
- * the virtual page offset in memory of the anonymous mapping.
- * @uf: Optionally, a pointer to a list head used for tracking userfaultfd unmap
- * events.
- *
- * Returns: Either an error, or the address at which the requested mapping has
- * been performed.
- */
-unsigned long mmap_region(struct file *file, unsigned long addr,
-			  unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
-			  struct list_head *uf)
-{
-	unsigned long ret;
-	bool writable_file_mapping = false;
-
-	mmap_assert_write_locked(current->mm);
-
-	/* Check to see if MDWE is applicable. */
-	if (map_deny_write_exec(vm_flags, vm_flags))
-		return -EACCES;
-
-	/* Allow architectures to sanity-check the vm_flags. */
-	if (!arch_validate_flags(vm_flags))
-		return -EINVAL;
-
-	/* Map writable and ensure this isn't a sealed memfd. */
-	if (file && is_shared_maywrite(vm_flags)) {
-		int error = mapping_map_writable(file->f_mapping);
-
-		if (error)
-			return error;
-		writable_file_mapping = true;
-	}
-
-	ret = __mmap_region(file, addr, len, vm_flags, pgoff, uf);
-
-	/* Clear our write mapping regardless of error. */
-	if (writable_file_mapping)
-		mapping_unmap_writable(file->f_mapping);
-
-	validate_mm(current->mm);
-	return ret;
-}
-
 int vm_munmap(unsigned long start, size_t len)
 {
 	return __vm_munmap(start, len, false);