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>

4 files changed, 29 insertions, 28 deletions

diff --git a/tools/testing/vma/include/custom.h b/tools/testing/vma/include/custom.h
index b7d9eb0a44e4..744fe874c168 100644
--- a/tools/testing/vma/include/custom.h
+++ b/tools/testing/vma/include/custom.h
@@ -95,6 +95,3 @@ static inline unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
 {
 	return PAGE_SIZE;
 }
-
-#define VMA_SPECIAL_FLAGS mk_vma_flags(VMA_IO_BIT, VMA_DONTEXPAND_BIT, \
-				       VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT)
diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h
index 244ee02dc21d..36373b81ad24 100644
--- a/tools/testing/vma/include/dup.h
+++ b/tools/testing/vma/include/dup.h
@@ -314,27 +314,33 @@ 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 TASK_EXEC ((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0)
+#define TASK_EXEC_BIT ((current->personality & READ_IMPLIES_EXEC) ? \
+		       VM_EXEC_BIT : VM_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 VM_STARTGAP_FLAGS (VM_GROWSDOWN | VM_SHADOW_STACK)
+#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_STACK_FLAGS	(VM_STACK | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)
+#define VM_STARTGAP_FLAGS (VM_GROWSDOWN | VM_SHADOW_STACK)
 
 /* VMA basic access permission flags */
 #define VM_ACCESS_FLAGS (VM_READ | VM_WRITE | VM_EXEC)
@@ -345,6 +351,9 @@ enum {
  */
 #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 VMA_REMAP_FLAGS mk_vma_flags(VMA_IO_BIT, VMA_PFNMAP_BIT,	\
 				     VMA_DONTEXPAND_BIT, VMA_DONTDUMP_BIT)
 
@@ -357,11 +366,6 @@ enum {
 /* This mask represents all the VMA flag bits used by mlock */
 #define VM_LOCKED_MASK	(VM_LOCKED | VM_LOCKONFAULT)
 
-#define TASK_EXEC ((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0)
-
-#define VM_DATA_FLAGS_TSK_EXEC	(VM_READ | VM_WRITE | TASK_EXEC | \
-				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
-
 #define RLIMIT_STACK		3	/* max stack size */
 #define RLIMIT_MEMLOCK		8	/* max locked-in-memory address space */
 
diff --git a/tools/testing/vma/include/stubs.h b/tools/testing/vma/include/stubs.h
index 416bb93f5005..b5dced3b0bd4 100644
--- a/tools/testing/vma/include/stubs.h
+++ b/tools/testing/vma/include/stubs.h
@@ -101,10 +101,10 @@ static inline bool shmem_file(struct file *file)
 	return false;
 }
 
-static inline vm_flags_t ksm_vma_flags(const 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 void remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn)
@@ -239,7 +239,8 @@ static inline int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
 	return 0;
 }
 
-static inline bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags,
+static inline bool may_expand_vm(struct mm_struct *mm,
+				 const vma_flags_t *vma_flags,
 				 unsigned long npages)
 {
 	return true;
diff --git a/tools/testing/vma/tests/merge.c b/tools/testing/vma/tests/merge.c
index d3e725dc0000..44e3977e3fc0 100644
--- a/tools/testing/vma/tests/merge.c
+++ b/tools/testing/vma/tests/merge.c
@@ -1429,11 +1429,10 @@ static bool test_expand_only_mode(void)
 {
 	vma_flags_t vma_flags = mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT,
 					     VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT);
-	vm_flags_t legacy_flags = VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE;
 	struct mm_struct mm = {};
 	VMA_ITERATOR(vmi, &mm, 0);
 	struct vm_area_struct *vma_prev, *vma;
-	VMG_STATE(vmg, &mm, &vmi, 0x5000, 0x9000, legacy_flags, 5);
+	VMG_STATE(vmg, &mm, &vmi, 0x5000, 0x9000, vma_flags, 5);
 
 	/*
 	 * Place a VMA prior to the one we're expanding so we assert that we do