root/include/drm/drm_gem.h
#ifndef __DRM_GEM_H__
#define __DRM_GEM_H__

/*
 * GEM Graphics Execution Manager Driver Interfaces
 *
 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * Copyright (c) 2009-2010, Code Aurora Forum.
 * All rights reserved.
 * Copyright © 2014 Intel Corporation
 *   Daniel Vetter <daniel.vetter@ffwll.ch>
 *
 * Author: Rickard E. (Rik) Faith <faith@valinux.com>
 * Author: Gareth Hughes <gareth@valinux.com>
 *
 * 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/kref.h>
#include <linux/dma-buf.h>
#include <linux/dma-resv.h>
#include <linux/list.h>
#include <linux/mutex.h>

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#include <drm/drm_device.h>
#endif
#include <drm/drm_vma_manager.h>

struct iosys_map;
struct drm_gem_object;

/**
 * enum drm_gem_object_status - bitmask of object state for fdinfo reporting
 * @DRM_GEM_OBJECT_RESIDENT: object is resident in memory (ie. not unpinned)
 * @DRM_GEM_OBJECT_PURGEABLE: object marked as purgeable by userspace
 * @DRM_GEM_OBJECT_ACTIVE: object is currently used by an active submission
 *
 * Bitmask of status used for fdinfo memory stats, see &drm_gem_object_funcs.status
 * and drm_show_fdinfo().  Note that an object can report DRM_GEM_OBJECT_PURGEABLE
 * and be active or not resident, in which case drm_show_fdinfo() will not
 * account for it as purgeable.  So drivers do not need to check if the buffer
 * is idle and resident to return this bit, i.e. userspace can mark a buffer as
 * purgeable even while it is still busy on the GPU. It will not get reported in
 * the puregeable stats until it becomes idle.  The status gem object func does
 * not need to consider this.
 */
enum drm_gem_object_status {
        DRM_GEM_OBJECT_RESIDENT  = BIT(0),
        DRM_GEM_OBJECT_PURGEABLE = BIT(1),
        DRM_GEM_OBJECT_ACTIVE    = BIT(2),
};

/**
 * struct drm_gem_object_funcs - GEM object functions
 */
struct drm_gem_object_funcs {
        /**
         * @free:
         *
         * Deconstructor for drm_gem_objects.
         *
         * This callback is mandatory.
         */
        void (*free)(struct drm_gem_object *obj);

        /**
         * @open:
         *
         * Called upon GEM handle creation.
         *
         * This callback is optional.
         */
        int (*open)(struct drm_gem_object *obj, struct drm_file *file);

        /**
         * @close:
         *
         * Called upon GEM handle release.
         *
         * This callback is optional.
         */
        void (*close)(struct drm_gem_object *obj, struct drm_file *file);

        /**
         * @print_info:
         *
         * If driver subclasses struct &drm_gem_object, it can implement this
         * optional hook for printing additional driver specific info.
         *
         * drm_printf_indent() should be used in the callback passing it the
         * indent argument.
         *
         * This callback is called from drm_gem_print_info().
         *
         * This callback is optional.
         */
        void (*print_info)(struct drm_printer *p, unsigned int indent,
                           const struct drm_gem_object *obj);

        /**
         * @export:
         *
         * Export backing buffer as a &dma_buf.
         * If this is not set drm_gem_prime_export() is used.
         *
         * This callback is optional.
         */
        struct dma_buf *(*export)(struct drm_gem_object *obj, int flags);

        /**
         * @pin:
         *
         * Pin backing buffer in memory, such that dma-buf importers can
         * access it. Used by the drm_gem_map_attach() helper.
         *
         * This callback is optional.
         */
        int (*pin)(struct drm_gem_object *obj);

        /**
         * @unpin:
         *
         * Unpin backing buffer. Used by the drm_gem_map_detach() helper.
         *
         * This callback is optional.
         */
        void (*unpin)(struct drm_gem_object *obj);

        /**
         * @get_sg_table:
         *
         * Returns a Scatter-Gather table representation of the buffer.
         * Used when exporting a buffer by the drm_gem_map_dma_buf() helper.
         * Releasing is done by calling dma_unmap_sg_attrs() and sg_free_table()
         * in drm_gem_unmap_buf(), therefore these helpers and this callback
         * here cannot be used for sg tables pointing at driver private memory
         * ranges.
         *
         * See also drm_prime_pages_to_sg().
         */
        struct sg_table *(*get_sg_table)(struct drm_gem_object *obj);

        /**
         * @vmap:
         *
         * Returns a virtual address for the buffer. Used by the
         * drm_gem_dmabuf_vmap() helper. Called with a held GEM reservation
         * lock.
         *
         * This callback is optional.
         */
        int (*vmap)(struct drm_gem_object *obj, struct iosys_map *map);

        /**
         * @vunmap:
         *
         * Releases the address previously returned by @vmap. Used by the
         * drm_gem_dmabuf_vunmap() helper. Called with a held GEM reservation
         * lock.
         *
         * This callback is optional.
         */
        void (*vunmap)(struct drm_gem_object *obj, struct iosys_map *map);

        /**
         * @mmap:
         *
         * Handle mmap() of the gem object, setup vma accordingly.
         *
         * This callback is optional.
         *
         * The callback is used by both drm_gem_mmap_obj() and
         * drm_gem_prime_mmap().  When @mmap is present @vm_ops is not
         * used, the @mmap callback must set vma->vm_ops instead.
         */
        int (*mmap)(struct drm_gem_object *obj, struct vm_area_struct *vma);

        /**
         * @evict:
         *
         * Evicts gem object out from memory. Used by the drm_gem_object_evict()
         * helper. Returns 0 on success, -errno otherwise. Called with a held
         * GEM reservation lock.
         *
         * This callback is optional.
         */
        int (*evict)(struct drm_gem_object *obj);

        /**
         * @status:
         *
         * The optional status callback can return additional object state
         * which determines which stats the object is counted against.  The
         * callback is called under table_lock.  Racing against object status
         * change is "harmless", and the callback can expect to not race
         * against object destruction.
         *
         * Called by drm_show_memory_stats().
         */
        enum drm_gem_object_status (*status)(struct drm_gem_object *obj);

        /**
         * @rss:
         *
         * Return resident size of the object in physical memory.
         *
         * Called by drm_show_memory_stats().
         */
        size_t (*rss)(struct drm_gem_object *obj);

        /**
         * @vm_ops:
         *
         * Virtual memory operations used with mmap.
         *
         * This is optional but necessary for mmap support.
         */
        const struct vm_operations_struct *vm_ops;
};

/**
 * struct drm_gem_lru - A simple LRU helper
 *
 * A helper for tracking GEM objects in a given state, to aid in
 * driver's shrinker implementation.  Tracks the count of pages
 * for lockless &shrinker.count_objects, and provides
 * &drm_gem_lru_scan for driver's &shrinker.scan_objects
 * implementation.
 */
struct drm_gem_lru {
        /**
         * @lock:
         *
         * Lock protecting movement of GEM objects between LRUs.  All
         * LRUs that the object can move between should be protected
         * by the same lock.
         */
        struct mutex *lock;

        /**
         * @count:
         *
         * The total number of backing pages of the GEM objects in
         * this LRU.
         */
        long count;

        /**
         * @list:
         *
         * The LRU list.
         */
        struct list_head list;
};

/**
 * struct drm_gem_object - GEM buffer object
 *
 * This structure defines the generic parts for GEM buffer objects, which are
 * mostly around handling mmap and userspace handles.
 *
 * Buffer objects are often abbreviated to BO.
 */
struct drm_gem_object {
        /**
         * @refcount:
         *
         * Reference count of this object
         *
         * Please use drm_gem_object_get() to acquire and drm_gem_object_put_locked()
         * or drm_gem_object_put() to release a reference to a GEM
         * buffer object.
         */
        struct kref refcount;

        /**
         * @handle_count:
         *
         * This is the GEM file_priv handle count of this object.
         *
         * Each handle also holds a reference. Note that when the handle_count
         * drops to 0 any global names (e.g. the id in the flink namespace) will
         * be cleared.
         *
         * Protected by &drm_device.object_name_lock.
         */
        unsigned handle_count;

        /**
         * @dev: DRM dev this object belongs to.
         */
        struct drm_device *dev;

        /**
         * @filp:
         *
         * SHMEM file node used as backing storage for swappable buffer objects.
         * GEM also supports driver private objects with driver-specific backing
         * storage (contiguous DMA memory, special reserved blocks). In this
         * case @filp is NULL.
         */
        struct file *filp;

        /**
         * @vma_node:
         *
         * Mapping info for this object to support mmap. Drivers are supposed to
         * allocate the mmap offset using drm_gem_create_mmap_offset(). The
         * offset itself can be retrieved using drm_vma_node_offset_addr().
         *
         * Memory mapping itself is handled by drm_gem_mmap(), which also checks
         * that userspace is allowed to access the object.
         */
        struct drm_vma_offset_node vma_node;

        /**
         * @size:
         *
         * Size of the object, in bytes.  Immutable over the object's
         * lifetime.
         */
        size_t size;

        /**
         * @name:
         *
         * Global name for this object, starts at 1. 0 means unnamed.
         * Access is covered by &drm_device.object_name_lock. This is used by
         * the GEM_FLINK and GEM_OPEN ioctls.
         */
        int name;

        /**
         * @dma_buf:
         *
         * dma-buf associated with this GEM object.
         *
         * Pointer to the dma-buf associated with this gem object (either
         * through importing or exporting). We break the resulting reference
         * loop when the last gem handle for this object is released.
         *
         * Protected by &drm_device.object_name_lock.
         */
        struct dma_buf *dma_buf;

        /**
         * @import_attach:
         *
         * dma-buf attachment backing this object.
         *
         * Any foreign dma_buf imported as a gem object has this set to the
         * attachment point for the device. This is invariant over the lifetime
         * of a gem object.
         *
         * The &drm_gem_object_funcs.free callback is responsible for
         * cleaning up the dma_buf attachment and references acquired at import
         * time.
         *
         * Note that the drm gem/prime core does not depend upon drivers setting
         * this field any more. So for drivers where this doesn't make sense
         * (e.g. virtual devices or a displaylink behind an usb bus) they can
         * simply leave it as NULL.
         */
        struct dma_buf_attachment *import_attach;

        /**
         * @resv:
         *
         * Pointer to reservation object associated with the this GEM object.
         *
         * Normally (@resv == &@_resv) except for imported GEM objects.
         */
        struct dma_resv *resv;

        /**
         * @_resv:
         *
         * A reservation object for this GEM object.
         *
         * This is unused for imported GEM objects.
         */
        struct dma_resv _resv;

        /**
         * @gpuva: Fields used by GPUVM to manage mappings pointing to this GEM object.
         *
         * When DRM_GPUVM_IMMEDIATE_MODE is set, this list is protected by the
         * mutex. Otherwise, the list is protected by the GEMs &dma_resv lock.
         *
         * Note that all entries in this list must agree on whether
         * DRM_GPUVM_IMMEDIATE_MODE is set.
         */
        struct {
                /**
                 * @gpuva.list: list of GPUVM mappings attached to this GEM object.
                 *
                 * Drivers should lock list accesses with either the GEMs
                 * &dma_resv lock (&drm_gem_object.resv) or the
                 * &drm_gem_object.gpuva.lock mutex.
                 */
                struct list_head list;

                /**
                 * @gpuva.lock: lock protecting access to &drm_gem_object.gpuva.list
                 * when DRM_GPUVM_IMMEDIATE_MODE is used.
                 *
                 * Only used when DRM_GPUVM_IMMEDIATE_MODE is set. It should be
                 * safe to take this mutex during the fence signalling path, so
                 * do not allocate memory while holding this lock. Otherwise,
                 * the &dma_resv lock should be used.
                 */
                struct mutex lock;
        } gpuva;

        /**
         * @funcs:
         *
         * Optional GEM object functions. If this is set, it will be used instead of the
         * corresponding &drm_driver GEM callbacks.
         *
         * New drivers should use this.
         *
         */
        const struct drm_gem_object_funcs *funcs;

        /**
         * @lru_node:
         *
         * List node in a &drm_gem_lru.
         */
        struct list_head lru_node;

        /**
         * @lru:
         *
         * The current LRU list that the GEM object is on.
         */
        struct drm_gem_lru *lru;
};

/**
 * DRM_GEM_FOPS - Default drm GEM file operations
 *
 * This macro provides a shorthand for setting the GEM file ops in the
 * &file_operations structure.  If all you need are the default ops, use
 * DEFINE_DRM_GEM_FOPS instead.
 */
#define DRM_GEM_FOPS \
        .open           = drm_open,\
        .release        = drm_release,\
        .unlocked_ioctl = drm_ioctl,\
        .compat_ioctl   = drm_compat_ioctl,\
        .poll           = drm_poll,\
        .read           = drm_read,\
        .llseek         = noop_llseek,\
        .get_unmapped_area      = drm_gem_get_unmapped_area,\
        .mmap           = drm_gem_mmap, \
        .fop_flags      = FOP_UNSIGNED_OFFSET

/**
 * DEFINE_DRM_GEM_FOPS() - macro to generate file operations for GEM drivers
 * @name: name for the generated structure
 *
 * This macro autogenerates a suitable &struct file_operations for GEM based
 * drivers, which can be assigned to &drm_driver.fops. Note that this structure
 * cannot be shared between drivers, because it contains a reference to the
 * current module using THIS_MODULE.
 *
 * Note that the declaration is already marked as static - if you need a
 * non-static version of this you're probably doing it wrong and will break the
 * THIS_MODULE reference by accident.
 */
#define DEFINE_DRM_GEM_FOPS(name) \
        static const struct file_operations name = {\
                .owner          = THIS_MODULE,\
                DRM_GEM_FOPS,\
        }

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
int drm_gem_huge_mnt_create(struct drm_device *dev, const char *value);
#else
static inline int drm_gem_huge_mnt_create(struct drm_device *dev,
                                          const char *value)
{
        return 0;
}
#endif

/**
 * drm_gem_get_huge_mnt - Get the huge tmpfs mountpoint used by a DRM device
 * @dev: DRM device
 *
 * This function gets the huge tmpfs mountpoint used by DRM device @dev. A huge
 * tmpfs mountpoint is used instead of `shm_mnt` after a successful call to
 * drm_gem_huge_mnt_create() when CONFIG_TRANSPARENT_HUGEPAGE is enabled.
 *
 * Returns:
 * The huge tmpfs mountpoint in use, NULL otherwise.
 */
static inline struct vfsmount *drm_gem_get_huge_mnt(struct drm_device *dev)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
        return dev->huge_mnt;
#else
        return NULL;
#endif
}

void drm_gem_object_release(struct drm_gem_object *obj);
void drm_gem_object_free(struct kref *kref);
int drm_gem_object_init(struct drm_device *dev,
                        struct drm_gem_object *obj, size_t size);
void drm_gem_private_object_init(struct drm_device *dev,
                                 struct drm_gem_object *obj, size_t size);
void drm_gem_private_object_fini(struct drm_gem_object *obj);
void drm_gem_vm_open(struct vm_area_struct *vma);
void drm_gem_vm_close(struct vm_area_struct *vma);
int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
                     struct vm_area_struct *vma);
int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);

#ifdef CONFIG_MMU
unsigned long drm_gem_get_unmapped_area(struct file *filp, unsigned long uaddr,
                                        unsigned long len, unsigned long pgoff,
                                        unsigned long flags);
#else
#define drm_gem_get_unmapped_area NULL
#endif

/**
 * drm_gem_object_get - acquire a GEM buffer object reference
 * @obj: GEM buffer object
 *
 * This function acquires an additional reference to @obj. It is illegal to
 * call this without already holding a reference. No locks required.
 */
static inline void drm_gem_object_get(struct drm_gem_object *obj)
{
        kref_get(&obj->refcount);
}

__attribute__((nonnull))
static inline void
__drm_gem_object_put(struct drm_gem_object *obj)
{
        kref_put(&obj->refcount, drm_gem_object_free);
}

/**
 * drm_gem_object_put - drop a GEM buffer object reference
 * @obj: GEM buffer object
 *
 * This releases a reference to @obj.
 */
static inline void
drm_gem_object_put(struct drm_gem_object *obj)
{
        if (obj)
                __drm_gem_object_put(obj);
}

int drm_gem_handle_create(struct drm_file *file_priv,
                          struct drm_gem_object *obj,
                          u32 *handlep);
int drm_gem_handle_delete(struct drm_file *filp, u32 handle);


void drm_gem_free_mmap_offset(struct drm_gem_object *obj);
int drm_gem_create_mmap_offset(struct drm_gem_object *obj);
int drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size);

struct page **drm_gem_get_pages(struct drm_gem_object *obj);
void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
                bool dirty, bool accessed);

void drm_gem_lock(struct drm_gem_object *obj);
void drm_gem_unlock(struct drm_gem_object *obj);

int drm_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map);
void drm_gem_vunmap(struct drm_gem_object *obj, struct iosys_map *map);

int drm_gem_objects_lookup(struct drm_file *filp, void __user *bo_handles,
                           int count, struct drm_gem_object ***objs_out);
struct drm_gem_object *drm_gem_object_lookup(struct drm_file *filp, u32 handle);
long drm_gem_dma_resv_wait(struct drm_file *filep, u32 handle,
                                    bool wait_all, unsigned long timeout);
int drm_gem_lock_reservations(struct drm_gem_object **objs, int count,
                              struct ww_acquire_ctx *acquire_ctx);
void drm_gem_unlock_reservations(struct drm_gem_object **objs, int count,
                                 struct ww_acquire_ctx *acquire_ctx);
int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
                            u32 handle, u64 *offset);

void drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock);
void drm_gem_lru_remove(struct drm_gem_object *obj);
void drm_gem_lru_move_tail_locked(struct drm_gem_lru *lru, struct drm_gem_object *obj);
void drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj);
unsigned long
drm_gem_lru_scan(struct drm_gem_lru *lru,
                 unsigned int nr_to_scan,
                 unsigned long *remaining,
                 bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket),
                 struct ww_acquire_ctx *ticket);

int drm_gem_evict_locked(struct drm_gem_object *obj);

/**
 * drm_gem_object_is_shared_for_memory_stats - helper for shared memory stats
 *
 * This helper should only be used for fdinfo shared memory stats to determine
 * if a GEM object is shared.
 *
 * @obj: obj in question
 */
static inline bool drm_gem_object_is_shared_for_memory_stats(struct drm_gem_object *obj)
{
        return (obj->handle_count > 1) || obj->dma_buf;
}

/**
 * drm_gem_is_imported() - Tests if GEM object's buffer has been imported
 * @obj: the GEM object
 *
 * Returns:
 * True if the GEM object's buffer has been imported, false otherwise
 */
static inline bool drm_gem_is_imported(const struct drm_gem_object *obj)
{
        return !!obj->import_attach;
}

#ifdef CONFIG_LOCKDEP
#define drm_gem_gpuva_assert_lock_held(gpuvm, obj) \
        lockdep_assert(drm_gpuvm_immediate_mode(gpuvm) ? \
                       lockdep_is_held(&(obj)->gpuva.lock) : \
                       dma_resv_held((obj)->resv))
#else
#define drm_gem_gpuva_assert_lock_held(gpuvm, obj) do {} while (0)
#endif

/**
 * drm_gem_gpuva_init() - initialize the gpuva list of a GEM object
 * @obj: the &drm_gem_object
 *
 * This initializes the &drm_gem_object's &drm_gpuvm_bo list.
 *
 * Calling this function is only necessary for drivers intending to support the
 * &drm_driver_feature DRIVER_GEM_GPUVA.
 *
 * See also drm_gem_gpuva_set_lock().
 */
static inline void drm_gem_gpuva_init(struct drm_gem_object *obj)
{
        INIT_LIST_HEAD(&obj->gpuva.list);
}

/**
 * drm_gem_for_each_gpuvm_bo() - iterator to walk over a list of &drm_gpuvm_bo
 * @entry__: &drm_gpuvm_bo structure to assign to in each iteration step
 * @obj__: the &drm_gem_object the &drm_gpuvm_bo to walk are associated with
 *
 * This iterator walks over all &drm_gpuvm_bo structures associated with the
 * &drm_gem_object.
 */
#define drm_gem_for_each_gpuvm_bo(entry__, obj__) \
        list_for_each_entry(entry__, &(obj__)->gpuva.list, list.entry.gem)

/**
 * drm_gem_for_each_gpuvm_bo_safe() - iterator to safely walk over a list of
 * &drm_gpuvm_bo
 * @entry__: &drm_gpuvm_bostructure to assign to in each iteration step
 * @next__: &next &drm_gpuvm_bo to store the next step
 * @obj__: the &drm_gem_object the &drm_gpuvm_bo to walk are associated with
 *
 * This iterator walks over all &drm_gpuvm_bo structures associated with the
 * &drm_gem_object. It is implemented with list_for_each_entry_safe(), hence
 * it is save against removal of elements.
 */
#define drm_gem_for_each_gpuvm_bo_safe(entry__, next__, obj__) \
        list_for_each_entry_safe(entry__, next__, &(obj__)->gpuva.list, list.entry.gem)

#endif /* __DRM_GEM_H__ */