In preparation for mapping objects into an mshare region, create
__do_mmap() to allow mapping into a specified mm. There are no
functional changes otherwise.

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
---
 include/linux/mm.h | 16 ++++++++++++++++
 mm/mmap.c          | 10 +++++-----
 mm/vma.c           | 12 ++++++------
 mm/vma.h           |  2 +-
 4 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3a8dddb5925a..07e0a15a4618 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3434,10 +3434,26 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 	return __get_unmapped_area(file, addr, len, pgoff, flags, 0);
 }
 
+#ifdef CONFIG_MMU
+unsigned long __do_mmap(struct file *file, unsigned long addr,
+	unsigned long len, unsigned long prot, unsigned long flags,
+	vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate,
+	struct list_head *uf, struct mm_struct *mm);
+static inline unsigned long do_mmap(struct file *file, unsigned long addr,
+	unsigned long len, unsigned long prot, unsigned long flags,
+	vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate,
+	struct list_head *uf)
+{
+	return __do_mmap(file, addr, len, prot, flags, vm_flags, pgoff,
+			 populate, uf, current->mm);
+}
+#else
 extern unsigned long do_mmap(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot, unsigned long flags,
 	vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate,
 	struct list_head *uf);
+#endif
+
 extern int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
 			 unsigned long start, size_t len, struct list_head *uf,
 			 bool unlock);
diff --git a/mm/mmap.c b/mm/mmap.c
index 7a057e0e8da9..18f266a511e2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -275,7 +275,7 @@ static inline bool file_mmap_ok(struct file *file, struct inode *inode,
 }
 
 /**
- * do_mmap() - Perform a userland memory mapping into the current process
+ * __do_mmap() - Perform a userland memory mapping into the current process
  * address space of length @len with protection bits @prot, mmap flags @flags
  * (from which VMA flags will be inferred), and any additional VMA flags to
  * apply @vm_flags. If this is a file-backed mapping then the file is specified
@@ -327,17 +327,17 @@ static inline bool file_mmap_ok(struct file *file, struct inode *inode,
  * @uf: An optional pointer to a list head to track userfaultfd unmap events
  * should unmapping events arise. If provided, it is up to the caller to manage
  * this.
+ * @mm: The mm_struct
  *
  * Returns: Either an error, or the address at which the requested mapping has
  * been performed.
  */
-unsigned long do_mmap(struct file *file, unsigned long addr,
+unsigned long __do_mmap(struct file *file, unsigned long addr,
 			unsigned long len, unsigned long prot,
 			unsigned long flags, vm_flags_t vm_flags,
 			unsigned long pgoff, unsigned long *populate,
-			struct list_head *uf)
+			struct list_head *uf, struct mm_struct *mm)
 {
-	struct mm_struct *mm = current->mm;
 	int pkey = 0;
 
 	*populate = 0;
@@ -555,7 +555,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 			vm_flags |= VM_NORESERVE;
 	}
 
-	addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
+	addr = mmap_region(file, addr, len, vm_flags, pgoff, uf, mm);
 	if (!IS_ERR_VALUE(addr) &&
 	    ((vm_flags & VM_LOCKED) ||
 	     (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
diff --git a/mm/vma.c b/mm/vma.c
index 3b12c7579831..a7fbd339d259 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -2637,9 +2637,8 @@ static bool can_set_ksm_flags_early(struct mmap_state *map)
 
 static 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)
+		struct list_head *uf, struct mm_struct *mm)
 {
-	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma = NULL;
 	int error;
 	bool have_mmap_prepare = file && file->f_op->mmap_prepare;
@@ -2706,18 +2705,19 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr,
  * the virtual page offset in memory of the anonymous mapping.
  * @uf: Optionally, a pointer to a list head used for tracking userfaultfd unmap
  * events.
+ * @mm: The mm struct
  *
  * 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)
+			  struct list_head *uf, struct mm_struct *mm)
 {
 	unsigned long ret;
 	bool writable_file_mapping = false;
 
-	mmap_assert_write_locked(current->mm);
+	mmap_assert_write_locked(mm);
 
 	/* Check to see if MDWE is applicable. */
 	if (map_deny_write_exec(vm_flags, vm_flags))
@@ -2736,13 +2736,13 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		writable_file_mapping = true;
 	}
 
-	ret = __mmap_region(file, addr, len, vm_flags, pgoff, uf);
+	ret = __mmap_region(file, addr, len, vm_flags, pgoff, uf, mm);
 
 	/* Clear our write mapping regardless of error. */
 	if (writable_file_mapping)
 		mapping_unmap_writable(file->f_mapping);
 
-	validate_mm(current->mm);
+	validate_mm(mm);
 	return ret;
 }
 
diff --git a/mm/vma.h b/mm/vma.h
index bcdc261c5b15..20fc1c2a32fd 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -352,7 +352,7 @@ void mm_drop_all_locks(struct mm_struct *mm);
 
 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);
+		struct list_head *uf, struct mm_struct *mm);
 
 int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
 		 unsigned long addr, unsigned long request, unsigned long flags);
-- 
2.47.1