linux/drivers/gpu/drm/drm_dumb_buffers.c

/*
 * Copyright (c) 2006-2008 Intel Corporation
 * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
 * Copyright (c) 2008 Red Hat Inc.
 * Copyright (c) 2016 Intel Corporation
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#include <drm/drmP.h>

#include "drm_crtc_internal.h"

/**
 * drm_mode_create_dumb_ioctl - create a dumb backing storage buffer
 * @dev: DRM device
 * @data: ioctl data
 * @file_priv: DRM file info
 *
 * This creates a new dumb buffer in the driver's backing storage manager (GEM,
 * TTM or something else entirely) and returns the resulting buffer handle. This
 * handle can then be wrapped up into a framebuffer modeset object.
 *
 * Note that userspace is not allowed to use such objects for render
 * acceleration - drivers must create their own private ioctls for such a use
 * case.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int drm_mode_create_dumb_ioctl(struct drm_device *dev,
			       void *data, struct drm_file *file_priv)
{
	struct drm_mode_create_dumb *args = data;
	u32 cpp, stride, size;

	if (!dev->driver->dumb_create)
		return -ENOSYS;
	if (!args->width || !args->height || !args->bpp)
		return -EINVAL;

	/* overflow checks for 32bit size calculations */
	/* NOTE: DIV_ROUND_UP() can overflow */
	cpp = DIV_ROUND_UP(args->bpp, 8);
	if (!cpp || cpp > 0xffffffffU / args->width)
		return -EINVAL;
	stride = cpp * args->width;
	if (args->height > 0xffffffffU / stride)
		return -EINVAL;

	/* test for wrap-around */
	size = args->height * stride;
	if (PAGE_ALIGN(size) == 0)
		return -EINVAL;

	/*
	 * handle, pitch and size are output parameters. Zero them out to
	 * prevent drivers from accidentally using uninitialized data. Since
	 * not all existing userspace is clearing these fields properly we
	 * cannot reject IOCTL with garbage in them.
	 */
	args->handle = 0;
	args->pitch = 0;
	args->size = 0;

	return dev->driver->dumb_create(file_priv, dev, args);
}

/**
 * drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
 * @dev: DRM device
 * @data: ioctl data
 * @file_priv: DRM file info
 *
 * Allocate an offset in the drm device node's address space to be able to
 * memory map a dumb buffer.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
			     void *data, struct drm_file *file_priv)
{
	struct drm_mode_map_dumb *args = data;

	/* call driver ioctl to get mmap offset */
	if (!dev->driver->dumb_map_offset)
		return -ENOSYS;

	return dev->driver->dumb_map_offset(file_priv, dev, args->handle, &args->offset);
}

/**
 * drm_mode_destroy_dumb_ioctl - destroy a dumb backing strage buffer
 * @dev: DRM device
 * @data: ioctl data
 * @file_priv: DRM file info
 *
 * This destroys the userspace handle for the given dumb backing storage buffer.
 * Since buffer objects must be reference counted in the kernel a buffer object
 * won't be immediately freed if a framebuffer modeset object still uses it.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
				void *data, struct drm_file *file_priv)
{
	struct drm_mode_destroy_dumb *args = data;

	if (!dev->driver->dumb_destroy)
		return -ENOSYS;

	return dev->driver->dumb_destroy(file_priv, dev, args->handle);
}