[PATCH 09/13] mm/vma: update create_init_stack_vma() to use vma_flags_t

[Lorenzo Stoakes <ljs@kernel.org>]

Replace use of the legacy vm_flags_t flags with vma_flags_t values in
create_init_stack_vma().

As part of this change we add VMA_STACK_EARLY and VMA_STACK_INCOMPLETE
vma_flags_t defines, and slightly rework create_init_stack_vma() for
clarity.

No functional change intended.

Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
---
 include/linux/mm.h |  4 ++++
 mm/vma_exec.c      | 18 +++++++++++-------
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index b55790c75038..6e57d41677de 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -440,8 +440,10 @@ enum {
 #define VM_STACK	INIT_VM_FLAG(STACK)
 #ifdef CONFIG_STACK_GROWSUP
 #define VM_STACK_EARLY	INIT_VM_FLAG(STACK_EARLY)
+#define VMA_STACK_EARLY mk_vma_flags(VMA_STACK_EARLY_BIT)
 #else
 #define VM_STACK_EARLY	VM_NONE
+#define VMA_STACK_EARLY EMPTY_VMA_FLAGS
 #endif
 #ifdef CONFIG_ARCH_HAS_PKEYS
 #define VM_PKEY_SHIFT ((__force int)VMA_HIGH_ARCH_0_BIT)
@@ -532,6 +534,8 @@ enum {
 
 /* Bits set in the VMA until the stack is in its final location */
 #define VM_STACK_INCOMPLETE_SETUP (VM_RAND_READ | VM_SEQ_READ | VM_STACK_EARLY)
+#define VMA_STACK_INCOMPLETE_SETUP append_vma_flags(		\
+	VMA_STACK_EARLY, VMA_RAND_READ_BIT, VMA_SEQ_READ_BIT)
 
 #define TASK_EXEC_BIT ((current->personality & READ_IMPLIES_EXEC) ? \
 		       VMA_EXEC_BIT : VMA_READ_BIT)
diff --git a/mm/vma_exec.c b/mm/vma_exec.c
index b01c4964f2c9..48c783e73cf3 100644
--- a/mm/vma_exec.c
+++ b/mm/vma_exec.c
@@ -112,15 +112,17 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift)
 int create_init_stack_vma(struct mm_struct *mm, struct vm_area_struct **vmap,
 			  unsigned long *top_mem_p)
 {
-	unsigned long flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
+	vma_flags_t flags = VMA_STACK_INCOMPLETE_SETUP;
+	struct vm_area_struct *vma;
 	int err;
-	struct vm_area_struct *vma = vm_area_alloc(mm);
 
+	/* VMA_STACK_FLAGS and VMA_STACK_INCOMPLETE_SETUP must not overlap. */
+	VM_WARN_ON_ONCE(vma_flags_test_any_mask(&flags, VMA_STACK_FLAGS));
+
+	vma = vm_area_alloc(mm);
 	if (!vma)
 		return -ENOMEM;
 
-	vma_set_anonymous(vma);
-
 	if (mmap_write_lock_killable(mm)) {
 		err = -EINTR;
 		goto err_free;
@@ -134,18 +136,20 @@ int create_init_stack_vma(struct mm_struct *mm, struct vm_area_struct **vmap,
 	if (err)
 		goto err_ksm;
 
+	vma_flags_set_mask(&flags, VMA_STACK_FLAGS);
+	vma_set_anonymous(vma);
+
 	/*
 	 * Place the stack at the largest stack address the architecture
 	 * supports. Later, we'll move this to an appropriate place. We don't
 	 * use STACK_TOP because that can depend on attributes which aren't
 	 * configured yet.
 	 */
-	VM_WARN_ON_ONCE(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 	vma->vm_end = STACK_TOP_MAX;
 	vma->vm_start = vma->vm_end - PAGE_SIZE;
 	if (pgtable_supports_soft_dirty())
-		flags |= VM_SOFTDIRTY;
-	vm_flags_init(vma, flags);
+		vma_flags_set(&flags, VMA_SOFTDIRTY_BIT);
+	vma->flags = flags;
 	vma->vm_page_prot = vma_get_page_prot(vma);
 
 	err = insert_vm_struct(mm, vma);
-- 
2.54.0