mm/vma: update do_mmap() to use vma_flags_t

The core do_mmap() function accepts a vm_flags_t parameter which it then
manipulates before passing to mmap_region() to do the heavy lifting of the
memory mapping.

Update do_mmap() to instead accept a vma_flags_t parameter, and adjust all
the logic within do_mmap() to manipulate this instead.

This is as part of the ongoing effort to convert VMA flags from a system
word size to a bitmap type which allows us to unrestrict the number of VMA
flags, as well as gain control over how VMA flag manipulation occurs.

We do not cascade these changes to all functions which accept vm_flags_t,
but rather use vma_flags_to_legacy() where necessary, specifically
deferring converting calc_vm_prot_bits(), calc_vm_flag_bits() and
__get_unmapped_area() to vma_flags_t.

Also utilise the new vma_flags_can_grow() predicate which correctly
handles the case of architectures without upward growing stacks.

As part of this change, introduce VMA_SHADOW_STACK so we can correctly
handle the case of the shadow stack not being defined.

No functional change intended.

Link: https://lore.kernel.org/20260711-b4-vma-flags-mm-v2-2-0fa2357d5431@kernel.org
Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dave Airlie <airlied@gmail.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 7 insertions, 5 deletions

diff --git a/include/linux/memfd.h b/include/linux/memfd.h
index b4fda09dab9f..c159e40e3f34 100644
--- a/include/linux/memfd.h
+++ b/include/linux/memfd.h
@@ -14,9 +14,9 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx);
  * to sealing, or 0 otherwise.
  *
  * We also update VMA flags if appropriate by manipulating the VMA flags pointed
- * to by vm_flags_ptr.
+ * to by vma_flags_ptr.
  */
-int memfd_check_seals_mmap(struct file *file, vm_flags_t *vm_flags_ptr);
+int memfd_check_seals_mmap(struct file *file, vma_flags_t *vma_flags_ptr);
 struct file *memfd_alloc_file(const char *name, unsigned int flags);
 int memfd_get_seals(struct file *file);
 int memfd_add_seals(struct file *file, unsigned int seals);
@@ -30,7 +30,7 @@ static inline struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx)
 	return ERR_PTR(-EINVAL);
 }
 static inline int memfd_check_seals_mmap(struct file *file,
-					 vm_flags_t *vm_flags_ptr)
+					 vma_flags_t *vma_flags_ptr)
 {
 	return 0;
 }
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7a7f559b3df0..d20aa2f80472 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -465,9 +465,11 @@ enum {
 #if defined(CONFIG_X86_USER_SHADOW_STACK) || defined(CONFIG_ARM64_GCS) || \
 	defined(CONFIG_RISCV_USER_CFI)
 #define VM_SHADOW_STACK	INIT_VM_FLAG(SHADOW_STACK)
+#define VMA_SHADOW_STACK mk_vma_flags(VMA_SHADOW_STACK_BIT)
 #define VMA_STARTGAP_FLAGS mk_vma_flags(VMA_GROWSDOWN_BIT, VMA_SHADOW_STACK_BIT)
 #else
 #define VM_SHADOW_STACK	VM_NONE
+#define VMA_SHADOW_STACK EMPTY_VMA_FLAGS
 #define VMA_STARTGAP_FLAGS mk_vma_flags(VMA_GROWSDOWN_BIT)
 #endif
 #if defined(CONFIG_PPC64)
@@ -4198,9 +4200,9 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 	return __get_unmapped_area(file, addr, len, pgoff, flags, 0);
 }
 
-extern 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,
+	vma_flags_t vma_flags, unsigned long pgoff, unsigned long *populate,
 	struct list_head *uf);
 extern int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
 			 unsigned long start, size_t len, struct list_head *uf,