/* * Created: Fri Jan 8 09:01:26 1999 by [email protected] * * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas. * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California. * All Rights Reserved. * * Author Rickard E. (Rik) Faith <[email protected]> * Author Gareth Hughes <[email protected]> * * 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 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS 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 <linux/nospec.h> #include <linux/pci.h> #include <linux/uaccess.h> #include <drm/drm_auth.h> #include <drm/drm_crtc.h> #include <drm/drm_drv.h> #include <drm/drm_file.h> #include <drm/drm_ioctl.h> #include <drm/drm_print.h> #include "drm_crtc_internal.h" #include "drm_internal.h" /** * DOC: getunique and setversion story * * BEWARE THE DRAGONS! MIND THE TRAPDOORS! * * In an attempt to warn anyone else who's trying to figure out what's going * on here, I'll try to summarize the story. First things first, let's clear up * the names, because the kernel internals, libdrm and the ioctls are all named * differently: * * - GET_UNIQUE ioctl, implemented by drm_getunique is wrapped up in libdrm * through the drmGetBusid function. * - The libdrm drmSetBusid function is backed by the SET_UNIQUE ioctl. All * that code is nerved in the kernel with drm_invalid_op(). * - The internal set_busid kernel functions and driver callbacks are * exclusively use by the SET_VERSION ioctl, because only drm 1.0 (which is * nerved) allowed userspace to set the busid through the above ioctl. * - Other ioctls and functions involved are named consistently. * * For anyone wondering what's the difference between drm 1.1 and 1.4: Correctly * handling pci domains in the busid on ppc. Doing this correctly was only * implemented in libdrm in 2010, hence can't be nerved yet. No one knows what's * special with drm 1.2 and 1.3. * * Now the actual horror story of how device lookup in drm works. At large, * there's 2 different ways, either by busid, or by device driver name. * * Opening by busid is fairly simple: * * 1. First call SET_VERSION to make sure pci domains are handled properly. As a * side-effect this fills out the unique name in the master structure. * 2. Call GET_UNIQUE to read out the unique name from the master structure, * which matches the busid thanks to step 1. If it doesn't, proceed to try * the next device node. * * Opening by name is slightly different: * * 1. Directly call VERSION to get the version and to match against the driver * name returned by that ioctl. Note that SET_VERSION is not called, which * means the unique name for the master node just opening is _not_ filled * out. This despite that with current drm device nodes are always bound to * one device, and can't be runtime assigned like with drm 1.0. * 2. Match driver name. If it mismatches, proceed to the next device node. * 3. Call GET_UNIQUE, and check whether the unique name has length zero (by * checking that the first byte in the string is 0). If that's not the case * libdrm skips and proceeds to the next device node. Probably this is just * copypasta from drm 1.0 times where a set unique name meant that the driver * was in use already, but that's just conjecture. * * Long story short: To keep the open by name logic working, GET_UNIQUE must * _not_ return a unique string when SET_VERSION hasn't been called yet, * otherwise libdrm breaks. Even when that unique string can't ever change, and * is totally irrelevant for actually opening the device because runtime * assignable device instances were only support in drm 1.0, which is long dead. * But the libdrm code in drmOpenByName somehow survived, hence this can't be * broken. */ /* * Get the bus id. * * \param inode device inode. * \param file_priv DRM file private. * \param cmd command. * \param arg user argument, pointing to a drm_unique structure. * \return zero on success or a negative number on failure. * * Copies the bus id from drm_device::unique into user space. */ int drm_getunique(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } static void drm_unset_busid(struct drm_device *dev, struct drm_master *master) { … } static int drm_set_busid(struct drm_device *dev, struct drm_file *file_priv) { … } /* * Get client information. * * \param inode device inode. * \param file_priv DRM file private. * \param cmd command. * \param arg user argument, pointing to a drm_client structure. * * \return zero on success or a negative number on failure. * * Searches for the client with the specified index and copies its information * into userspace */ int drm_getclient(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } /* * Get statistics information. * * \param inode device inode. * \param file_priv DRM file private. * \param cmd command. * \param arg user argument, pointing to a drm_stats structure. * * \return zero on success or a negative number on failure. */ static int drm_getstats(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } /* * Get device/driver capabilities */ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } /* * Set device/driver capabilities */ static int drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } /* * Setversion ioctl. * * \param inode device inode. * \param file_priv DRM file private. * \param cmd command. * \param arg user argument, pointing to a drm_lock structure. * \return zero on success or negative number on failure. * * Sets the requested interface version */ static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } /** * drm_noop - DRM no-op ioctl implementation * @dev: DRM device for the ioctl * @data: data pointer for the ioctl * @file_priv: DRM file for the ioctl call * * This no-op implementation for drm ioctls is useful for deprecated * functionality where we can't return a failure code because existing userspace * checks the result of the ioctl, but doesn't care about the action. * * Always returns successfully with 0. */ int drm_noop(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } EXPORT_SYMBOL(…); /** * drm_invalid_op - DRM invalid ioctl implementation * @dev: DRM device for the ioctl * @data: data pointer for the ioctl * @file_priv: DRM file for the ioctl call * * This no-op implementation for drm ioctls is useful for deprecated * functionality where we really don't want to allow userspace to call the ioctl * any more. This is the case for old ums interfaces for drivers that * transitioned to kms gradually and so kept the old legacy tables around. This * only applies to radeon and i915 kms drivers, other drivers shouldn't need to * use this function. * * Always fails with a return value of -EINVAL. */ int drm_invalid_op(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } EXPORT_SYMBOL(…); /* * Copy and IOCTL return string to user space */ static int drm_copy_field(char __user *buf, size_t *buf_len, const char *value) { … } /* * Get version information * * \param inode device inode. * \param filp file pointer. * \param cmd command. * \param arg user argument, pointing to a drm_version structure. * \return zero on success or negative number on failure. * * Fills in the version information in \p arg. */ int drm_version(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } static int drm_ioctl_permit(u32 flags, struct drm_file *file_priv) { … } #define DRM_IOCTL_DEF(ioctl, _func, _flags) … /* Ioctl table */ static const struct drm_ioctl_desc drm_ioctls[] = …; #define DRM_CORE_IOCTL_COUNT … /** * DOC: driver specific ioctls * * First things first, driver private IOCTLs should only be needed for drivers * supporting rendering. Kernel modesetting is all standardized, and extended * through properties. There are a few exceptions in some existing drivers, * which define IOCTL for use by the display DRM master, but they all predate * properties. * * Now if you do have a render driver you always have to support it through * driver private properties. There's a few steps needed to wire all the things * up. * * First you need to define the structure for your IOCTL in your driver private * UAPI header in ``include/uapi/drm/my_driver_drm.h``:: * * struct my_driver_operation { * u32 some_thing; * u32 another_thing; * }; * * Please make sure that you follow all the best practices from * ``Documentation/process/botching-up-ioctls.rst``. Note that drm_ioctl() * automatically zero-extends structures, hence make sure you can add more stuff * at the end, i.e. don't put a variable sized array there. * * Then you need to define your IOCTL number, using one of DRM_IO(), DRM_IOR(), * DRM_IOW() or DRM_IOWR(). It must start with the DRM_IOCTL\_ prefix:: * * ##define DRM_IOCTL_MY_DRIVER_OPERATION \ * DRM_IOW(DRM_COMMAND_BASE, struct my_driver_operation) * * DRM driver private IOCTL must be in the range from DRM_COMMAND_BASE to * DRM_COMMAND_END. Finally you need an array of &struct drm_ioctl_desc to wire * up the handlers and set the access rights:: * * static const struct drm_ioctl_desc my_driver_ioctls[] = { * DRM_IOCTL_DEF_DRV(MY_DRIVER_OPERATION, my_driver_operation, * DRM_AUTH|DRM_RENDER_ALLOW), * }; * * And then assign this to the &drm_driver.ioctls field in your driver * structure. * * See the separate chapter on :ref:`file operations<drm_driver_fops>` for how * the driver-specific IOCTLs are wired up. */ long drm_ioctl_kernel(struct file *file, drm_ioctl_t *func, void *kdata, u32 flags) { … } EXPORT_SYMBOL(…); /** * drm_ioctl - ioctl callback implementation for DRM drivers * @filp: file this ioctl is called on * @cmd: ioctl cmd number * @arg: user argument * * Looks up the ioctl function in the DRM core and the driver dispatch table, * stored in &drm_driver.ioctls. It checks for necessary permission by calling * drm_ioctl_permit(), and dispatches to the respective function. * * Returns: * Zero on success, negative error code on failure. */ long drm_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { … } EXPORT_SYMBOL(…); /** * drm_ioctl_flags - Check for core ioctl and return ioctl permission flags * @nr: ioctl number * @flags: where to return the ioctl permission flags * * This ioctl is only used by the vmwgfx driver to augment the access checks * done by the drm core and insofar a pretty decent layering violation. This * shouldn't be used by any drivers. * * Returns: * True if the @nr corresponds to a DRM core ioctl number, false otherwise. */ bool drm_ioctl_flags(unsigned int nr, unsigned int *flags) { … } EXPORT_SYMBOL(…);
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