mm/vma: move stack expansion logic to mm/vma.c

We build on previous work making expand_downwards() an entirely internal
function.

This logic is subtle and so it is highly useful to get it into vma.c so we
can then userland unit test.

We must additionally move acct_stack_growth() to vma.c as it is a helper
function used by both expand_downwards() and expand_upwards().

We are also then able to mark anon_vma_interval_tree_pre_update_vma() and
anon_vma_interval_tree_post_update_vma() static as these are no longer
used by anything else.

Link: https://lkml.kernel.org/r/0feb104eff85922019d4fb29280f3afb130c5204.1733248985.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 67 insertions, 0 deletions

diff --git a/tools/testing/vma/vma.c b/tools/testing/vma/vma.c
index 39ee61e55634..891d87a9ad6b 100644
--- a/tools/testing/vma/vma.c
+++ b/tools/testing/vma/vma.c
@@ -53,6 +53,11 @@ struct task_struct *get_current(void)
 	return &__current;
 }
 
+unsigned long rlimit(unsigned int limit)
+{
+	return (unsigned long)-1;
+}
+
 /* Helper function to simply allocate a VMA. */
 static struct vm_area_struct *alloc_vma(struct mm_struct *mm,
 					unsigned long start,
diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h
index 6ad8bd8edaad..fab3f3bdf2f0 100644
--- a/tools/testing/vma/vma_internal.h
+++ b/tools/testing/vma/vma_internal.h
@@ -79,6 +79,11 @@ extern unsigned long dac_mmap_min_addr;
 
 #define VM_STARTGAP_FLAGS (VM_GROWSDOWN | VM_SHADOW_STACK)
 
+#define RLIMIT_STACK		3	/* max stack size */
+#define RLIMIT_MEMLOCK		8	/* max locked-in-memory address space */
+
+#define CAP_IPC_LOCK         14
+
 #ifdef CONFIG_64BIT
 /* VM is sealed, in vm_flags */
 #define VM_SEALED	_BITUL(63)
@@ -478,6 +483,8 @@ static inline void vma_mark_detached(struct vm_area_struct *vma, bool detached)
 
 extern const struct vm_operations_struct vma_dummy_vm_ops;
 
+extern unsigned long rlimit(unsigned int limit);
+
 static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm)
 {
 	memset(vma, 0, sizeof(*vma));
@@ -1114,4 +1121,59 @@ static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
 	return vm_end;
 }
 
+static inline int is_hugepage_only_range(struct mm_struct *mm,
+					unsigned long addr, unsigned long len)
+{
+	return 0;
+}
+
+static inline bool vma_is_accessible(struct vm_area_struct *vma)
+{
+	return vma->vm_flags & VM_ACCESS_FLAGS;
+}
+
+static inline bool capable(int cap)
+{
+	return true;
+}
+
+static inline bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
+			unsigned long bytes)
+{
+	unsigned long locked_pages, limit_pages;
+
+	if (!(flags & VM_LOCKED) || capable(CAP_IPC_LOCK))
+		return true;
+
+	locked_pages = bytes >> PAGE_SHIFT;
+	locked_pages += mm->locked_vm;
+
+	limit_pages = rlimit(RLIMIT_MEMLOCK);
+	limit_pages >>= PAGE_SHIFT;
+
+	return locked_pages <= limit_pages;
+}
+
+static inline int __anon_vma_prepare(struct vm_area_struct *vma)
+{
+	struct anon_vma *anon_vma = calloc(1, sizeof(struct anon_vma));
+
+	if (!anon_vma)
+		return -ENOMEM;
+
+	anon_vma->root = anon_vma;
+	vma->anon_vma = anon_vma;
+
+	return 0;
+}
+
+static inline int anon_vma_prepare(struct vm_area_struct *vma)
+{
+	if (likely(vma->anon_vma))
+		return 0;
+
+	return __anon_vma_prepare(vma);
+}
+
+
 #endif	/* __MM_VMA_INTERNAL_H */