linux/drivers/gpu/drm/drm_platform.c
David Herrmann 1793126fce drm: implement experimental render nodes
Render nodes provide an API for userspace to use non-privileged GPU
commands without any running DRM-Master. It is useful for offscreen
rendering, GPGPU clients, and normal render clients which do not perform
modesetting.

Compared to legacy clients, render clients no longer need any
authentication to perform client ioctls. Instead, user-space controls
render/client access to GPUs via filesystem access-modes on the
render-node. Once a render-node was opened, a client has full access to
the client/render operations on the GPU. However, no modesetting or ioctls
that affect global state are allowed on render nodes.

To prevent privilege-escalation, drivers must explicitly state that they
support render nodes. They must mark their render-only ioctls as
DRM_RENDER_ALLOW so render clients can use them. Furthermore, they must
support clients without any attached master.

If filesystem access-modes are not enough for fine-grained access control
to render nodes (very unlikely, considering the versaitlity of FS-ACLs),
you may still fall-back to fd-passing from server to client (which allows
arbitrary access-control). However, note that revoking access is
currently impossible and unlikely to get implemented.

Note: Render clients no longer have any associated DRM-Master as they are
supposed to be independent of any server state. DRM core highly depends on
file_priv->master to be non-NULL for modesetting/ctx/etc. commands.
Therefore, drivers must be very careful to not require DRM-Master if they
support DRIVER_RENDER.

So far render-nodes are protected by "drm_rnodes". As long as this
module-parameter is not set to 1, a driver will not create render nodes.
This allows us to experiment with the API a bit before we stabilize it.

v2: drop insecure GEM_FLINK to force use of dmabuf

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2013-08-30 08:43:57 +10:00

214 lines
5.5 KiB
C

/*
* Derived from drm_pci.c
*
* Copyright 2003 José Fonseca.
* Copyright 2003 Leif Delgass.
* Copyright (c) 2009, Code Aurora Forum.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <linux/export.h>
#include <drm/drmP.h>
/*
* Register.
*
* \param platdev - Platform device struture
* \return zero on success or a negative number on failure.
*
* Attempt to gets inter module "drm" information. If we are first
* then register the character device and inter module information.
* Try and register, if we fail to register, backout previous work.
*/
static int drm_get_platform_dev(struct platform_device *platdev,
struct drm_driver *driver)
{
struct drm_device *dev;
int ret;
DRM_DEBUG("\n");
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
return -ENOMEM;
dev->platformdev = platdev;
dev->dev = &platdev->dev;
mutex_lock(&drm_global_mutex);
ret = drm_fill_in_dev(dev, NULL, driver);
if (ret) {
printk(KERN_ERR "DRM: Fill_in_dev failed.\n");
goto err_g1;
}
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
ret = drm_get_minor(dev, &dev->control, DRM_MINOR_CONTROL);
if (ret)
goto err_g1;
}
if (drm_core_check_feature(dev, DRIVER_RENDER) && drm_rnodes) {
ret = drm_get_minor(dev, &dev->render, DRM_MINOR_RENDER);
if (ret)
goto err_g11;
}
ret = drm_get_minor(dev, &dev->primary, DRM_MINOR_LEGACY);
if (ret)
goto err_g2;
if (dev->driver->load) {
ret = dev->driver->load(dev, 0);
if (ret)
goto err_g3;
}
/* setup the grouping for the legacy output */
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
ret = drm_mode_group_init_legacy_group(dev,
&dev->primary->mode_group);
if (ret)
goto err_g3;
}
list_add_tail(&dev->driver_item, &driver->device_list);
mutex_unlock(&drm_global_mutex);
DRM_INFO("Initialized %s %d.%d.%d %s on minor %d\n",
driver->name, driver->major, driver->minor, driver->patchlevel,
driver->date, dev->primary->index);
return 0;
err_g3:
drm_put_minor(&dev->primary);
err_g2:
if (dev->render)
drm_put_minor(&dev->render);
err_g11:
if (drm_core_check_feature(dev, DRIVER_MODESET))
drm_put_minor(&dev->control);
err_g1:
kfree(dev);
mutex_unlock(&drm_global_mutex);
return ret;
}
static int drm_platform_get_irq(struct drm_device *dev)
{
return platform_get_irq(dev->platformdev, 0);
}
static const char *drm_platform_get_name(struct drm_device *dev)
{
return dev->platformdev->name;
}
static int drm_platform_set_busid(struct drm_device *dev, struct drm_master *master)
{
int len, ret, id;
master->unique_len = 13 + strlen(dev->platformdev->name);
master->unique_size = master->unique_len;
master->unique = kmalloc(master->unique_len + 1, GFP_KERNEL);
if (master->unique == NULL)
return -ENOMEM;
id = dev->platformdev->id;
/* if only a single instance of the platform device, id will be
* set to -1.. use 0 instead to avoid a funny looking bus-id:
*/
if (id == -1)
id = 0;
len = snprintf(master->unique, master->unique_len,
"platform:%s:%02d", dev->platformdev->name, id);
if (len > master->unique_len) {
DRM_ERROR("Unique buffer overflowed\n");
ret = -EINVAL;
goto err;
}
dev->devname =
kmalloc(strlen(dev->platformdev->name) +
master->unique_len + 2, GFP_KERNEL);
if (dev->devname == NULL) {
ret = -ENOMEM;
goto err;
}
sprintf(dev->devname, "%s@%s", dev->platformdev->name,
master->unique);
return 0;
err:
return ret;
}
static struct drm_bus drm_platform_bus = {
.bus_type = DRIVER_BUS_PLATFORM,
.get_irq = drm_platform_get_irq,
.get_name = drm_platform_get_name,
.set_busid = drm_platform_set_busid,
};
/**
* Platform device initialization. Called direct from modules.
*
* \return zero on success or a negative number on failure.
*
* Initializes a drm_device structures,registering the
* stubs
*
* Expands the \c DRIVER_PREINIT and \c DRIVER_POST_INIT macros before and
* after the initialization for driver customization.
*/
int drm_platform_init(struct drm_driver *driver, struct platform_device *platform_device)
{
DRM_DEBUG("\n");
driver->kdriver.platform_device = platform_device;
driver->bus = &drm_platform_bus;
INIT_LIST_HEAD(&driver->device_list);
return drm_get_platform_dev(platform_device, driver);
}
EXPORT_SYMBOL(drm_platform_init);
void drm_platform_exit(struct drm_driver *driver, struct platform_device *platform_device)
{
struct drm_device *dev, *tmp;
DRM_DEBUG("\n");
list_for_each_entry_safe(dev, tmp, &driver->device_list, driver_item)
drm_put_dev(dev);
DRM_INFO("Module unloaded\n");
}
EXPORT_SYMBOL(drm_platform_exit);