mm: convert do_brk_flags() to use vma_flags_t

In order to be able to do this, we need to change VM_DATA_DEFAULT_FLAGS
and friends and update the architecture-specific definitions also.

We then have to update some KSM logic to handle VMA flags, and introduce
VMA_STACK_FLAGS to define the vma_flags_t equivalent of VM_STACK_FLAGS.

We also introduce two helper functions for use during the time we are
converting legacy flags to vma_flags_t values - vma_flags_to_legacy() and
legacy_to_vma_flags().

This enables us to iteratively make changes to break these changes up into
separate parts.

We use these explicitly here to keep VM_STACK_FLAGS around for certain
users which need to maintain the legacy vm_flags_t values for the time
being.

We are no longer able to rely on the simple VM_xxx being set to zero if
the feature is not enabled, so in the case of VM_DROPPABLE we introduce
VMA_DROPPABLE as the vma_flags_t equivalent, which is set to
EMPTY_VMA_FLAGS if the droppable flag is not available.

While we're here, we make the description of do_brk_flags() into a kdoc
comment, as it almost was already.

We use vma_flags_to_legacy() to not need to update the vm_get_page_prot()
logic as this time.

Note that in create_init_stack_vma() we have to replace the BUILD_BUG_ON()
with a VM_WARN_ON_ONCE() as the tested values are no longer build time
available.

We also update mprotect_fixup() to use VMA flags where possible, though we
have to live with a little duplication between vm_flags_t and vma_flags_t
values for the time being until further conversions are made.

While we're here, update VM_SPECIAL to be defined in terms of
VMA_SPECIAL_FLAGS now we have vma_flags_to_legacy().

Finally, we update the VMA tests to reflect these changes.

Link: https://lkml.kernel.org/r/d02e3e45d9a33d7904b149f5604904089fd640ae.1774034900.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>	[SELinux]
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 35 insertions, 24 deletions

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index c982694c987b..d39d0d5483a2 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -17,8 +17,8 @@
 #ifdef CONFIG_KSM
 int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
 		unsigned long end, int advice, vm_flags_t *vm_flags);
-vm_flags_t ksm_vma_flags(struct mm_struct *mm, const struct file *file,
-			 vm_flags_t vm_flags);
+vma_flags_t ksm_vma_flags(struct mm_struct *mm, const struct file *file,
+			  vma_flags_t vma_flags);
 int ksm_enable_merge_any(struct mm_struct *mm);
 int ksm_disable_merge_any(struct mm_struct *mm);
 int ksm_disable(struct mm_struct *mm);
@@ -103,10 +103,10 @@ bool ksm_process_mergeable(struct mm_struct *mm);
 
 #else  /* !CONFIG_KSM */
 
-static inline vm_flags_t ksm_vma_flags(struct mm_struct *mm,
-		const struct file *file, vm_flags_t vm_flags)
+static inline vma_flags_t ksm_vma_flags(struct mm_struct *mm,
+		const struct file *file, vma_flags_t vma_flags)
 {
-	return vm_flags;
+	return vma_flags;
 }
 
 static inline int ksm_disable(struct mm_struct *mm)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index de72382efac2..4042a584671e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -346,9 +346,9 @@ enum {
 	 * if KVM does not lock down the memory type.
 	 */
 	DECLARE_VMA_BIT(ALLOW_ANY_UNCACHED, 39),
-#ifdef CONFIG_PPC32
+#if defined(CONFIG_PPC32)
 	DECLARE_VMA_BIT_ALIAS(DROPPABLE, ARCH_1),
-#else
+#elif defined(CONFIG_64BIT)
 	DECLARE_VMA_BIT(DROPPABLE, 40),
 #endif
 	DECLARE_VMA_BIT(UFFD_MINOR, 41),
@@ -503,31 +503,42 @@ enum {
 #endif
 #if defined(CONFIG_64BIT) || defined(CONFIG_PPC32)
 #define VM_DROPPABLE		INIT_VM_FLAG(DROPPABLE)
+#define VMA_DROPPABLE		mk_vma_flags(VMA_DROPPABLE_BIT)
 #else
 #define VM_DROPPABLE		VM_NONE
+#define VMA_DROPPABLE		EMPTY_VMA_FLAGS
 #endif
 
 /* 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 TASK_EXEC ((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0)
+#define TASK_EXEC_BIT ((current->personality & READ_IMPLIES_EXEC) ? \
+		       VMA_EXEC_BIT : VMA_READ_BIT)
 
 /* Common data flag combinations */
-#define VM_DATA_FLAGS_TSK_EXEC	(VM_READ | VM_WRITE | TASK_EXEC | \
-				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
-#define VM_DATA_FLAGS_NON_EXEC	(VM_READ | VM_WRITE | VM_MAYREAD | \
-				 VM_MAYWRITE | VM_MAYEXEC)
-#define VM_DATA_FLAGS_EXEC	(VM_READ | VM_WRITE | VM_EXEC | \
-				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
-
-#ifndef VM_DATA_DEFAULT_FLAGS		/* arch can override this */
-#define VM_DATA_DEFAULT_FLAGS  VM_DATA_FLAGS_EXEC
+#define VMA_DATA_FLAGS_TSK_EXEC	mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, \
+		TASK_EXEC_BIT, VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT,	  \
+		VMA_MAYEXEC_BIT)
+#define VMA_DATA_FLAGS_NON_EXEC	mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, \
+		VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT, VMA_MAYEXEC_BIT)
+#define VMA_DATA_FLAGS_EXEC	mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, \
+		VMA_EXEC_BIT, VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT,	  \
+		VMA_MAYEXEC_BIT)
+
+#ifndef VMA_DATA_DEFAULT_FLAGS		/* arch can override this */
+#define VMA_DATA_DEFAULT_FLAGS  VMA_DATA_FLAGS_EXEC
 #endif
 
-#ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */
-#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
+#ifndef VMA_STACK_DEFAULT_FLAGS		/* arch can override this */
+#define VMA_STACK_DEFAULT_FLAGS VMA_DATA_DEFAULT_FLAGS
 #endif
 
+#define VMA_STACK_FLAGS	append_vma_flags(VMA_STACK_DEFAULT_FLAGS,	\
+		VMA_STACK_BIT, VMA_ACCOUNT_BIT)
+
+/* Temporary until VMA flags conversion complete. */
+#define VM_STACK_FLAGS vma_flags_to_legacy(VMA_STACK_FLAGS)
+
 #define VM_STARTGAP_FLAGS (VM_GROWSDOWN | VM_SHADOW_STACK)
 
 #ifdef CONFIG_MSEAL_SYSTEM_MAPPINGS
@@ -536,8 +547,6 @@ enum {
 #define VM_SEALED_SYSMAP	VM_NONE
 #endif
 
-#define VM_STACK_FLAGS	(VM_STACK | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)
-
 /* VMA basic access permission flags */
 #define VM_ACCESS_FLAGS (VM_READ | VM_WRITE | VM_EXEC)
 #define VMA_ACCESS_FLAGS mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, VMA_EXEC_BIT)
@@ -545,7 +554,10 @@ enum {
 /*
  * Special vmas that are non-mergable, non-mlock()able.
  */
-#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_PFNMAP | VM_MIXEDMAP)
+
+#define VMA_SPECIAL_FLAGS mk_vma_flags(VMA_IO_BIT, VMA_DONTEXPAND_BIT, \
+				       VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT)
+#define VM_SPECIAL vma_flags_to_legacy(VMA_SPECIAL_FLAGS)
 
 /*
  * Physically remapped pages are special. Tell the
@@ -1407,7 +1419,7 @@ static __always_inline void vma_desc_set_flags_mask(struct vm_area_desc *desc,
  * vm_area_desc object describing a proposed VMA, e.g.:
  *
  * vma_desc_set_flags(desc, VMA_IO_BIT, VMA_PFNMAP_BIT, VMA_DONTEXPAND_BIT,
- *		VMA_DONTDUMP_BIT);
+ * 		VMA_DONTDUMP_BIT);
  */
 #define vma_desc_set_flags(desc, ...) \
 	vma_desc_set_flags_mask(desc, mk_vma_flags(__VA_ARGS__))
@@ -4045,7 +4057,6 @@ extern int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file);
 extern struct file *get_mm_exe_file(struct mm_struct *mm);
 extern struct file *get_task_exe_file(struct task_struct *task);
 
-extern bool may_expand_vm(struct mm_struct *, vm_flags_t, unsigned long npages);
 extern void vm_stat_account(struct mm_struct *, vm_flags_t, long npages);
 
 extern bool vma_is_special_mapping(const struct vm_area_struct *vma,