[PATCH 6.6 394/474] fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info

[PATCH 6.6 394/474] fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info

[Greg Kroah-Hartman]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Zimmermann <tzimmermann@suse.de>

[ Upstream commit 9ded47ad003f09a94b6a710b5c47f4aa5ceb7429 ]

Hold state of deferred I/O in struct fb_deferred_io_state. Allocate an
instance as part of initializing deferred I/O and remove it only after
the final mapping has been closed. If the fb_info and the contained
deferred I/O meanwhile goes away, clear struct fb_deferred_io_state.info
to invalidate the mapping. Any access will then result in a SIGBUS
signal.

Fixes a long-standing problem, where a device hot-unplug happens while
user space still has an active mapping of the graphics memory. The hot-
unplug frees the instance of struct fb_info. Accessing the memory will
operate on undefined state.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 60b59beafba8 ("fbdev: mm: Deferred IO support")
Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: stable@vger.kernel.org # v2.6.22+
Signed-off-by: Helge Deller <deller@gmx.de>
[ replaced `kzalloc_obj` with `kzalloc`, and dropped `mutex_destroy(&fbdefio->lock)` ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/video/fbdev/core/fb_defio.c |  179 ++++++++++++++++++++++++++++--------
 include/linux/fb.h                  |    4 
 2 files changed, 145 insertions(+), 38 deletions(-)

--- a/drivers/video/fbdev/core/fb_defio.c
+++ b/drivers/video/fbdev/core/fb_defio.c
@@ -23,6 +23,75 @@
 #include <linux/rmap.h>
 #include <linux/pagemap.h>
 
+/*
+ * struct fb_deferred_io_state
+ */
+
+struct fb_deferred_io_state {
+	struct kref ref;
+
+	struct mutex lock; /* mutex that protects the pageref list */
+	/* fields protected by lock */
+	struct fb_info *info;
+};
+
+static struct fb_deferred_io_state *fb_deferred_io_state_alloc(void)
+{
+	struct fb_deferred_io_state *fbdefio_state;
+
+	fbdefio_state = kzalloc(sizeof(*fbdefio_state), GFP_KERNEL);
+	if (!fbdefio_state)
+		return NULL;
+
+	kref_init(&fbdefio_state->ref);
+	mutex_init(&fbdefio_state->lock);
+
+	return fbdefio_state;
+}
+
+static void fb_deferred_io_state_release(struct fb_deferred_io_state *fbdefio_state)
+{
+	mutex_destroy(&fbdefio_state->lock);
+
+	kfree(fbdefio_state);
+}
+
+static void fb_deferred_io_state_get(struct fb_deferred_io_state *fbdefio_state)
+{
+	kref_get(&fbdefio_state->ref);
+}
+
+static void __fb_deferred_io_state_release(struct kref *ref)
+{
+	struct fb_deferred_io_state *fbdefio_state =
+		container_of(ref, struct fb_deferred_io_state, ref);
+
+	fb_deferred_io_state_release(fbdefio_state);
+}
+
+static void fb_deferred_io_state_put(struct fb_deferred_io_state *fbdefio_state)
+{
+	kref_put(&fbdefio_state->ref, __fb_deferred_io_state_release);
+}
+
+/*
+ * struct vm_operations_struct
+ */
+
+static void fb_deferred_io_vm_open(struct vm_area_struct *vma)
+{
+	struct fb_deferred_io_state *fbdefio_state = vma->vm_private_data;
+
+	fb_deferred_io_state_get(fbdefio_state);
+}
+
+static void fb_deferred_io_vm_close(struct vm_area_struct *vma)
+{
+	struct fb_deferred_io_state *fbdefio_state = vma->vm_private_data;
+
+	fb_deferred_io_state_put(fbdefio_state);
+}
+
 static struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs)
 {
 	void *screen_base = (void __force *) info->screen_base;
@@ -93,17 +162,31 @@ static void fb_deferred_io_pageref_put(s
 /* this is to find and return the vmalloc-ed fb pages */
 static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf)
 {
+	struct fb_info *info;
 	unsigned long offset;
 	struct page *page;
-	struct fb_info *info = vmf->vma->vm_private_data;
+	vm_fault_t ret;
+	struct fb_deferred_io_state *fbdefio_state = vmf->vma->vm_private_data;
+
+	mutex_lock(&fbdefio_state->lock);
+
+	info = fbdefio_state->info;
+	if (!info) {
+		ret = VM_FAULT_SIGBUS; /* our device is gone */
+		goto err_mutex_unlock;
+	}
 
 	offset = vmf->pgoff << PAGE_SHIFT;
-	if (offset >= info->fix.smem_len)
-		return VM_FAULT_SIGBUS;
+	if (offset >= info->fix.smem_len) {
+		ret = VM_FAULT_SIGBUS;
+		goto err_mutex_unlock;
+	}
 
 	page = fb_deferred_io_page(info, offset);
-	if (!page)
-		return VM_FAULT_SIGBUS;
+	if (!page) {
+		ret = VM_FAULT_SIGBUS;
+		goto err_mutex_unlock;
+	}
 
 	get_page(page);
 
@@ -115,8 +198,15 @@ static vm_fault_t fb_deferred_io_fault(s
 	BUG_ON(!page->mapping);
 	page->index = vmf->pgoff; /* for page_mkclean() */
 
+	mutex_unlock(&fbdefio_state->lock);
+
 	vmf->page = page;
+
 	return 0;
+
+err_mutex_unlock:
+	mutex_unlock(&fbdefio_state->lock);
+	return ret;
 }
 
 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
@@ -143,15 +233,24 @@ EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
  * Adds a page to the dirty list. Call this from struct
  * vm_operations_struct.page_mkwrite.
  */
-static vm_fault_t fb_deferred_io_track_page(struct fb_info *info, unsigned long offset,
-					    struct page *page)
+static vm_fault_t fb_deferred_io_track_page(struct fb_deferred_io_state *fbdefio_state,
+					    unsigned long offset, struct page *page)
 {
-	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct fb_info *info;
+	struct fb_deferred_io *fbdefio;
 	struct fb_deferred_io_pageref *pageref;
 	vm_fault_t ret;
 
 	/* protect against the workqueue changing the page list */
-	mutex_lock(&fbdefio->lock);
+	mutex_lock(&fbdefio_state->lock);
+
+	info = fbdefio_state->info;
+	if (!info) {
+		ret = VM_FAULT_SIGBUS; /* our device is gone */
+		goto err_mutex_unlock;
+	}
+
+	fbdefio = info->fbdefio;
 
 	pageref = fb_deferred_io_pageref_get(info, offset, page);
 	if (WARN_ON_ONCE(!pageref)) {
@@ -169,50 +268,38 @@ static vm_fault_t fb_deferred_io_track_p
 	 */
 	lock_page(pageref->page);
 
-	mutex_unlock(&fbdefio->lock);
+	mutex_unlock(&fbdefio_state->lock);
 
 	/* come back after delay to process the deferred IO */
 	schedule_delayed_work(&info->deferred_work, fbdefio->delay);
 	return VM_FAULT_LOCKED;
 
 err_mutex_unlock:
-	mutex_unlock(&fbdefio->lock);
+	mutex_unlock(&fbdefio_state->lock);
 	return ret;
 }
 
-/*
- * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O
- * @fb_info: The fbdev info structure
- * @vmf: The VM fault
- *
- * This is a callback we get when userspace first tries to
- * write to the page. We schedule a workqueue. That workqueue
- * will eventually mkclean the touched pages and execute the
- * deferred framebuffer IO. Then if userspace touches a page
- * again, we repeat the same scheme.
- *
- * Returns:
- * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise.
- */
-static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf)
+static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_deferred_io_state *fbdefio_state,
+					      struct vm_fault *vmf)
 {
 	unsigned long offset = vmf->pgoff << PAGE_SHIFT;
 	struct page *page = vmf->page;
 
 	file_update_time(vmf->vma->vm_file);
 
-	return fb_deferred_io_track_page(info, offset, page);
+	return fb_deferred_io_track_page(fbdefio_state, offset, page);
 }
 
-/* vm_ops->page_mkwrite handler */
 static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf)
 {
-	struct fb_info *info = vmf->vma->vm_private_data;
+	struct fb_deferred_io_state *fbdefio_state = vmf->vma->vm_private_data;
 
-	return fb_deferred_io_page_mkwrite(info, vmf);
+	return fb_deferred_io_page_mkwrite(fbdefio_state, vmf);
 }
 
 static const struct vm_operations_struct fb_deferred_io_vm_ops = {
+	.open		= fb_deferred_io_vm_open,
+	.close		= fb_deferred_io_vm_close,
 	.fault		= fb_deferred_io_fault,
 	.page_mkwrite	= fb_deferred_io_mkwrite,
 };
@@ -227,7 +314,10 @@ int fb_deferred_io_mmap(struct fb_info *
 	vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP);
 	if (!(info->flags & FBINFO_VIRTFB))
 		vm_flags_set(vma, VM_IO);
-	vma->vm_private_data = info;
+	vma->vm_private_data = info->fbdefio_state;
+
+	fb_deferred_io_state_get(info->fbdefio_state); /* released in vma->vm_ops->close() */
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_mmap);
@@ -238,9 +328,10 @@ static void fb_deferred_io_work(struct w
 	struct fb_info *info = container_of(work, struct fb_info, deferred_work.work);
 	struct fb_deferred_io_pageref *pageref, *next;
 	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct fb_deferred_io_state *fbdefio_state = info->fbdefio_state;
 
 	/* here we mkclean the pages, then do all deferred IO */
-	mutex_lock(&fbdefio->lock);
+	mutex_lock(&fbdefio_state->lock);
 	list_for_each_entry(pageref, &fbdefio->pagereflist, list) {
 		struct page *cur = pageref->page;
 		lock_page(cur);
@@ -255,12 +346,13 @@ static void fb_deferred_io_work(struct w
 	list_for_each_entry_safe(pageref, next, &fbdefio->pagereflist, list)
 		fb_deferred_io_pageref_put(pageref, info);
 
-	mutex_unlock(&fbdefio->lock);
+	mutex_unlock(&fbdefio_state->lock);
 }
 
 int fb_deferred_io_init(struct fb_info *info)
 {
 	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct fb_deferred_io_state *fbdefio_state;
 	struct fb_deferred_io_pageref *pagerefs;
 	unsigned long npagerefs, i;
 	int ret;
@@ -270,7 +362,11 @@ int fb_deferred_io_init(struct fb_info *
 	if (WARN_ON(!info->fix.smem_len))
 		return -EINVAL;
 
-	mutex_init(&fbdefio->lock);
+	fbdefio_state = fb_deferred_io_state_alloc();
+	if (!fbdefio_state)
+		return -ENOMEM;
+	fbdefio_state->info = info;
+
 	INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
 	INIT_LIST_HEAD(&fbdefio->pagereflist);
 	if (fbdefio->delay == 0) /* set a default of 1 s */
@@ -289,10 +385,12 @@ int fb_deferred_io_init(struct fb_info *
 	info->npagerefs = npagerefs;
 	info->pagerefs = pagerefs;
 
+	info->fbdefio_state = fbdefio_state;
+
 	return 0;
 
 err:
-	mutex_destroy(&fbdefio->lock);
+	fb_deferred_io_state_release(fbdefio_state);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
@@ -333,11 +431,18 @@ EXPORT_SYMBOL_GPL(fb_deferred_io_release
 
 void fb_deferred_io_cleanup(struct fb_info *info)
 {
-	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct fb_deferred_io_state *fbdefio_state = info->fbdefio_state;
 
 	fb_deferred_io_lastclose(info);
 
+	info->fbdefio_state = NULL;
+
+	mutex_lock(&fbdefio_state->lock);
+	fbdefio_state->info = NULL;
+	mutex_unlock(&fbdefio_state->lock);
+
+	fb_deferred_io_state_put(fbdefio_state);
+
 	kvfree(info->pagerefs);
-	mutex_destroy(&fbdefio->lock);
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -214,11 +214,12 @@ struct fb_deferred_io {
 	unsigned long delay;
 	bool sort_pagereflist; /* sort pagelist by offset */
 	int open_count; /* number of opened files; protected by fb_info lock */
-	struct mutex lock; /* mutex that protects the pageref list */
 	struct list_head pagereflist; /* list of pagerefs for touched pages */
 	/* callback */
 	void (*deferred_io)(struct fb_info *info, struct list_head *pagelist);
 };
+
+struct fb_deferred_io_state;
 #endif
 
 /*
@@ -476,6 +477,7 @@ struct fb_info {
 	unsigned long npagerefs;
 	struct fb_deferred_io_pageref *pagerefs;
 	struct fb_deferred_io *fbdefio;
+	struct fb_deferred_io_state *fbdefio_state;
 #endif
 
 	const struct fb_ops *fbops;

[PATCH 6.6 395/474] firmware: google: framebuffer: Do not unregister platform device

[Greg Kroah-Hartman]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Zimmermann <tzimmermann@suse.de>

[ Upstream commit 5cd28bd28c8ce426b56ce4230dbd17537181d5ad ]

The native driver takes over the framebuffer aperture by removing the
system- framebuffer platform device. Afterwards the pointer in drvdata
is dangling. Remove the entire logic around drvdata and let the kernel's
aperture helpers handle this. The platform device depends on the native
hardware device instead of the coreboot device anyway.

When commit 851b4c14532d ("firmware: coreboot: Add coreboot framebuffer
driver") added the coreboot framebuffer code, the kernel did not support
device-based aperture management. Instead native driviers only removed
the conflicting fbdev device. At that point, unregistering the framebuffer
device most likely worked correctly. It was definitely broken after
commit d9702b2a2171 ("fbdev/simplefb: Do not use struct
fb_info.apertures"). So take this commit for the Fixes tag. Earlier
releases might work depending on the native hardware driver.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: d9702b2a2171 ("fbdev/simplefb: Do not use struct fb_info.apertures")
Acked-by: Tzung-Bi Shih <tzungbi@kernel.org>
Acked-by: Julius Werner <jwerner@chromium.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Hans de Goede <hansg@kernel.org>
Cc: linux-fbdev@vger.kernel.org
Cc: <stable@vger.kernel.org> # v6.3+
Link: https://patch.msgid.link/20260217155836.96267-2-tzimmermann@suse.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/firmware/google/framebuffer-coreboot.c |   10 ----------
 1 file changed, 10 deletions(-)

--- a/drivers/firmware/google/framebuffer-coreboot.c
+++ b/drivers/firmware/google/framebuffer-coreboot.c
@@ -64,22 +64,12 @@ static int framebuffer_probe(struct core
 						 sizeof(pdata));
 	if (IS_ERR(pdev))
 		pr_warn("coreboot: could not register framebuffer\n");
-	else
-		dev_set_drvdata(&dev->dev, pdev);
 
 	return PTR_ERR_OR_ZERO(pdev);
 }
 
-static void framebuffer_remove(struct coreboot_device *dev)
-{
-	struct platform_device *pdev = dev_get_drvdata(&dev->dev);
-
-	platform_device_unregister(pdev);
-}
-
 static struct coreboot_driver framebuffer_driver = {
 	.probe = framebuffer_probe,
-	.remove = framebuffer_remove,
 	.drv = {
 		.name = "framebuffer",
 	},