[PATCH RESEND 0/3] binder: rebase remaining alloc->vma patches

[PATCH RESEND 0/3] binder: rebase remaining alloc->vma patches

[Carlos Llamas]

This is a rebase of the remaining patches previously sent in [1], which
depended on commit 1da52815d5f1 ("binder: fix alloc->vma_vm_mm null-ptr
dereference") being merged into mainline. Now we can proceed with these
remaining patches rebased against the char-misc-next branch.

[1] https://lore.kernel.org/all/20220829201254.1814484-1-cmllamas@google.com/

--
Carlos Llamas

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Arve Hjønnevåg" <arve@android.com>
Cc: Todd Kjos <tkjos@android.com>
Cc: Martijn Coenen <maco@android.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: kernel-team@android.com
Cc: linux-kernel@vger.kernel.org

Carlos Llamas (3):
  binder: rename alloc->vma_vm_mm to alloc->mm
  binder: remove binder_alloc_set_vma()
  binder: fix binder_alloc kernel-doc warnings

 drivers/android/binder_alloc.c | 55 +++++++++++-----------------------
 drivers/android/binder_alloc.h |  9 +++---
 2 files changed, 21 insertions(+), 43 deletions(-)

-- 
2.37.2.789.g6183377224-goog

[PATCH RESEND 1/3] binder: rename alloc->vma_vm_mm to alloc->mm

[Carlos Llamas]

Rename ->vma_vm_mm to ->mm to reflect the fact that we no longer cache
this reference from vma->vm_mm but from current->mm instead.

No functional changes in this patch.

Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Acked-by: Todd Kjos <tkjos@google.com>
---
 drivers/android/binder_alloc.c | 34 +++++++++++++++++-----------------
 drivers/android/binder_alloc.h |  4 ++--
 2 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 9b1778c00610..749a4cd30a83 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -208,8 +208,8 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 		}
 	}
 
-	if (need_mm && mmget_not_zero(alloc->vma_vm_mm))
-		mm = alloc->vma_vm_mm;
+	if (need_mm && mmget_not_zero(alloc->mm))
+		mm = alloc->mm;
 
 	if (mm) {
 		mmap_read_lock(mm);
@@ -322,9 +322,9 @@ static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
 	 */
 	if (vma) {
 		vm_start = vma->vm_start;
-		mmap_assert_write_locked(alloc->vma_vm_mm);
+		mmap_assert_write_locked(alloc->mm);
 	} else {
-		mmap_assert_locked(alloc->vma_vm_mm);
+		mmap_assert_locked(alloc->mm);
 	}
 
 	alloc->vma_addr = vm_start;
@@ -336,7 +336,7 @@ static inline struct vm_area_struct *binder_alloc_get_vma(
 	struct vm_area_struct *vma = NULL;
 
 	if (alloc->vma_addr)
-		vma = vma_lookup(alloc->vma_vm_mm, alloc->vma_addr);
+		vma = vma_lookup(alloc->mm, alloc->vma_addr);
 
 	return vma;
 }
@@ -401,15 +401,15 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
 	size_t size, data_offsets_size;
 	int ret;
 
-	mmap_read_lock(alloc->vma_vm_mm);
+	mmap_read_lock(alloc->mm);
 	if (!binder_alloc_get_vma(alloc)) {
-		mmap_read_unlock(alloc->vma_vm_mm);
+		mmap_read_unlock(alloc->mm);
 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 				   "%d: binder_alloc_buf, no vma\n",
 				   alloc->pid);
 		return ERR_PTR(-ESRCH);
 	}
-	mmap_read_unlock(alloc->vma_vm_mm);
+	mmap_read_unlock(alloc->mm);
 
 	data_offsets_size = ALIGN(data_size, sizeof(void *)) +
 		ALIGN(offsets_size, sizeof(void *));
@@ -823,7 +823,7 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 	buffers = 0;
 	mutex_lock(&alloc->mutex);
 	BUG_ON(alloc->vma_addr &&
-	       vma_lookup(alloc->vma_vm_mm, alloc->vma_addr));
+	       vma_lookup(alloc->mm, alloc->vma_addr));
 
 	while ((n = rb_first(&alloc->allocated_buffers))) {
 		buffer = rb_entry(n, struct binder_buffer, rb_node);
@@ -873,8 +873,8 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 		kfree(alloc->pages);
 	}
 	mutex_unlock(&alloc->mutex);
-	if (alloc->vma_vm_mm)
-		mmdrop(alloc->vma_vm_mm);
+	if (alloc->mm)
+		mmdrop(alloc->mm);
 
 	binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
 		     "%s: %d buffers %d, pages %d\n",
@@ -931,13 +931,13 @@ void binder_alloc_print_pages(struct seq_file *m,
 	 * read inconsistent state.
 	 */
 
-	mmap_read_lock(alloc->vma_vm_mm);
+	mmap_read_lock(alloc->mm);
 	if (binder_alloc_get_vma(alloc) == NULL) {
-		mmap_read_unlock(alloc->vma_vm_mm);
+		mmap_read_unlock(alloc->mm);
 		goto uninitialized;
 	}
 
-	mmap_read_unlock(alloc->vma_vm_mm);
+	mmap_read_unlock(alloc->mm);
 	for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
 		page = &alloc->pages[i];
 		if (!page->page_ptr)
@@ -1020,7 +1020,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
 	index = page - alloc->pages;
 	page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
 
-	mm = alloc->vma_vm_mm;
+	mm = alloc->mm;
 	if (!mmget_not_zero(mm))
 		goto err_mmget;
 	if (!mmap_read_trylock(mm))
@@ -1089,8 +1089,8 @@ static struct shrinker binder_shrinker = {
 void binder_alloc_init(struct binder_alloc *alloc)
 {
 	alloc->pid = current->group_leader->pid;
-	alloc->vma_vm_mm = current->mm;
-	mmgrab(alloc->vma_vm_mm);
+	alloc->mm = current->mm;
+	mmgrab(alloc->mm);
 	mutex_init(&alloc->mutex);
 	INIT_LIST_HEAD(&alloc->buffers);
 }
diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h
index f61a12d5c1e7..ab3b027bcd29 100644
--- a/drivers/android/binder_alloc.h
+++ b/drivers/android/binder_alloc.h
@@ -78,7 +78,7 @@ struct binder_lru_page {
  *                      (invariant after mmap)
  * @tsk:                tid for task that called init for this proc
  *                      (invariant after init)
- * @vma_vm_mm:          copy of vma->vm_mm (invariant after mmap)
+ * @mm:                 copy of task->mm (invariant after open)
  * @buffer:             base of per-proc address space mapped via mmap
  * @buffers:            list of all buffers for this proc
  * @free_buffers:       rb tree of buffers available for allocation
@@ -101,7 +101,7 @@ struct binder_lru_page {
 struct binder_alloc {
 	struct mutex mutex;
 	unsigned long vma_addr;
-	struct mm_struct *vma_vm_mm;
+	struct mm_struct *mm;
 	void __user *buffer;
 	struct list_head buffers;
 	struct rb_root free_buffers;
-- 
2.37.2.789.g6183377224-goog

[PATCH RESEND 2/3] binder: remove binder_alloc_set_vma()

[Carlos Llamas]

The mmap_locked asserts here are not needed since this is only called
back from the mmap stack in ->mmap() and ->close() which always acquire
the lock first. Remove these asserts along with binder_alloc_set_vma()
altogether since it's trivial enough to be consumed by callers.

Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
---
 drivers/android/binder_alloc.c | 25 ++-----------------------
 1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 749a4cd30a83..1c39cfce32fa 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -309,27 +309,6 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 	return vma ? -ENOMEM : -ESRCH;
 }
 
-
-static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
-		struct vm_area_struct *vma)
-{
-	unsigned long vm_start = 0;
-
-	/*
-	 * Allow clearing the vma with holding just the read lock to allow
-	 * munmapping downgrade of the write lock before freeing and closing the
-	 * file using binder_alloc_vma_close().
-	 */
-	if (vma) {
-		vm_start = vma->vm_start;
-		mmap_assert_write_locked(alloc->mm);
-	} else {
-		mmap_assert_locked(alloc->mm);
-	}
-
-	alloc->vma_addr = vm_start;
-}
-
 static inline struct vm_area_struct *binder_alloc_get_vma(
 		struct binder_alloc *alloc)
 {
@@ -793,7 +772,7 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 	buffer->free = 1;
 	binder_insert_free_buffer(alloc, buffer);
 	alloc->free_async_space = alloc->buffer_size / 2;
-	binder_alloc_set_vma(alloc, vma);
+	alloc->vma_addr = vma->vm_start;
 
 	return 0;
 
@@ -983,7 +962,7 @@ int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
  */
 void binder_alloc_vma_close(struct binder_alloc *alloc)
 {
-	binder_alloc_set_vma(alloc, NULL);
+	alloc->vma_addr = 0;
 }
 
 /**
-- 
2.37.2.789.g6183377224-goog

[PATCH RESEND 3/3] binder: fix binder_alloc kernel-doc warnings

[Carlos Llamas]

Update the kernel-doc section of struct binder_alloc to fix the
following warnings reported by ./scripts/kernel-doc:

  warning: Function parameter or member 'mutex' not described in 'binder_alloc'
  warning: Function parameter or member 'vma_addr' not described in 'binder_alloc'

No functional changes in this patch.

Signed-off-by: Carlos Llamas <cmllamas@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
---
 drivers/android/binder_alloc.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h
index ab3b027bcd29..0f811ac4bcff 100644
--- a/drivers/android/binder_alloc.h
+++ b/drivers/android/binder_alloc.h
@@ -74,10 +74,9 @@ struct binder_lru_page {
 
 /**
  * struct binder_alloc - per-binder proc state for binder allocator
- * @vma:                vm_area_struct passed to mmap_handler
+ * @mutex:              protects binder_alloc fields
+ * @vma_addr:           vm_area_struct->vm_start passed to mmap_handler
  *                      (invariant after mmap)
- * @tsk:                tid for task that called init for this proc
- *                      (invariant after init)
  * @mm:                 copy of task->mm (invariant after open)
  * @buffer:             base of per-proc address space mapped via mmap
  * @buffers:            list of all buffers for this proc
-- 
2.37.2.789.g6183377224-goog