// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Copyright © 2015 Broadcom
 */

/**
 * DOC: VC4 GEM BO management support
 *
 * The VC4 GPU architecture (both scanout and rendering) has direct
 * access to system memory with no MMU in between.  To support it, we
 * use the GEM CMA helper functions to allocate contiguous ranges of
 * physical memory for our BOs.
 *
 * Since the CMA allocator is very slow, we keep a cache of recently
 * freed BOs around so that the kernel's allocation of objects for 3D
 * rendering can return quickly.
 */

#include <linux/dma-buf.h>

#include "vc4_drv.h"
#include "uapi/drm/vc4_drm.h"

static const char * const bo_type_names[] = {
        "kernel",
        "V3D",
        "V3D shader",
        "dumb",
        "binner",
        "RCL",
        "BCL",
        "kernel BO cache",
};

static bool is_user_label(int label)
{
        return label >= VC4_BO_TYPE_COUNT;
}

static void vc4_bo_stats_print(struct drm_printer *p, struct vc4_dev *vc4)
{
        int i;

        for (i = 0; i < vc4->num_labels; i++) {
                if (!vc4->bo_labels[i].num_allocated)
                        continue;

                drm_printf(p, "%30s: %6dkb BOs (%d)\n",
                           vc4->bo_labels[i].name,
                           vc4->bo_labels[i].size_allocated / 1024,
                           vc4->bo_labels[i].num_allocated);
        }

        mutex_lock(&vc4->purgeable.lock);
        if (vc4->purgeable.num)
                drm_printf(p, "%30s: %6zdkb BOs (%d)\n", "userspace BO cache",
                           vc4->purgeable.size / 1024, vc4->purgeable.num);

        if (vc4->purgeable.purged_num)
                drm_printf(p, "%30s: %6zdkb BOs (%d)\n", "total purged BO",
                           vc4->purgeable.purged_size / 1024,
                           vc4->purgeable.purged_num);
        mutex_unlock(&vc4->purgeable.lock);
}

static int vc4_bo_stats_debugfs(struct seq_file *m, void *unused)
{
        struct drm_info_node *node = (struct drm_info_node *)m->private;
        struct drm_device *dev = node->minor->dev;
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct drm_printer p = drm_seq_file_printer(m);

        vc4_bo_stats_print(&p, vc4);

        return 0;
}

/* Takes ownership of *name and returns the appropriate slot for it in
 * the bo_labels[] array, extending it as necessary.
 *
 * This is inefficient and could use a hash table instead of walking
 * an array and strcmp()ing.  However, the assumption is that user
 * labeling will be infrequent (scanout buffers and other long-lived
 * objects, or debug driver builds), so we can live with it for now.
 */
static int vc4_get_user_label(struct vc4_dev *vc4, const char *name)
{
        int i;
        int free_slot = -1;

        for (i = 0; i < vc4->num_labels; i++) {
                if (!vc4->bo_labels[i].name) {
                        free_slot = i;
                } else if (strcmp(vc4->bo_labels[i].name, name) == 0) {
                        kfree(name);
                        return i;
                }
        }

        if (free_slot != -1) {
                WARN_ON(vc4->bo_labels[free_slot].num_allocated != 0);
                vc4->bo_labels[free_slot].name = name;
                return free_slot;
        } else {
                u32 new_label_count = vc4->num_labels + 1;
                struct vc4_label *new_labels =
                        krealloc(vc4->bo_labels,
                                 new_label_count * sizeof(*new_labels),
                                 GFP_KERNEL);

                if (!new_labels) {
                        kfree(name);
                        return -1;
                }

                free_slot = vc4->num_labels;
                vc4->bo_labels = new_labels;
                vc4->num_labels = new_label_count;

                vc4->bo_labels[free_slot].name = name;
                vc4->bo_labels[free_slot].num_allocated = 0;
                vc4->bo_labels[free_slot].size_allocated = 0;

                return free_slot;
        }
}

static void vc4_bo_set_label(struct drm_gem_object *gem_obj, int label)
{
        struct vc4_bo *bo = to_vc4_bo(gem_obj);
        struct vc4_dev *vc4 = to_vc4_dev(gem_obj->dev);

        lockdep_assert_held(&vc4->bo_lock);

        if (label != -1) {
                vc4->bo_labels[label].num_allocated++;
                vc4->bo_labels[label].size_allocated += gem_obj->size;
        }

        vc4->bo_labels[bo->label].num_allocated--;
        vc4->bo_labels[bo->label].size_allocated -= gem_obj->size;

        if (vc4->bo_labels[bo->label].num_allocated == 0 &&
            is_user_label(bo->label)) {
                /* Free user BO label slots on last unreference.
                 * Slots are just where we track the stats for a given
                 * name, and once a name is unused we can reuse that
                 * slot.
                 */
                kfree(vc4->bo_labels[bo->label].name);
                vc4->bo_labels[bo->label].name = NULL;
        }

        bo->label = label;
}

static uint32_t bo_page_index(size_t size)
{
        return (size / PAGE_SIZE) - 1;
}

static void vc4_bo_destroy(struct vc4_bo *bo)
{
        struct drm_gem_object *obj = &bo->base.base;
        struct vc4_dev *vc4 = to_vc4_dev(obj->dev);

        lockdep_assert_held(&vc4->bo_lock);

        vc4_bo_set_label(obj, -1);

        if (bo->validated_shader) {
                kfree(bo->validated_shader->uniform_addr_offsets);
                kfree(bo->validated_shader->texture_samples);
                kfree(bo->validated_shader);
                bo->validated_shader = NULL;
        }

        drm_gem_cma_free_object(obj);
}

static void vc4_bo_remove_from_cache(struct vc4_bo *bo)
{
        struct vc4_dev *vc4 = to_vc4_dev(bo->base.base.dev);

        lockdep_assert_held(&vc4->bo_lock);
        list_del(&bo->unref_head);
        list_del(&bo->size_head);
}

static struct list_head *vc4_get_cache_list_for_size(struct drm_device *dev,
                                                     size_t size)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        uint32_t page_index = bo_page_index(size);

        if (vc4->bo_cache.size_list_size <= page_index) {
                uint32_t new_size = max(vc4->bo_cache.size_list_size * 2,
                                        page_index + 1);
                struct list_head *new_list;
                uint32_t i;

                new_list = kmalloc_array(new_size, sizeof(struct list_head),
                                         GFP_KERNEL);
                if (!new_list)
                        return NULL;

                /* Rebase the old cached BO lists to their new list
                 * head locations.
                 */
                for (i = 0; i < vc4->bo_cache.size_list_size; i++) {
                        struct list_head *old_list =
                                &vc4->bo_cache.size_list[i];

                        if (list_empty(old_list))
                                INIT_LIST_HEAD(&new_list[i]);
                        else
                                list_replace(old_list, &new_list[i]);
                }
                /* And initialize the brand new BO list heads. */
                for (i = vc4->bo_cache.size_list_size; i < new_size; i++)
                        INIT_LIST_HEAD(&new_list[i]);

                kfree(vc4->bo_cache.size_list);
                vc4->bo_cache.size_list = new_list;
                vc4->bo_cache.size_list_size = new_size;
        }

        return &vc4->bo_cache.size_list[page_index];
}

static void vc4_bo_cache_purge(struct drm_device *dev)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);

        mutex_lock(&vc4->bo_lock);
        while (!list_empty(&vc4->bo_cache.time_list)) {
                struct vc4_bo *bo = list_last_entry(&vc4->bo_cache.time_list,
                                                    struct vc4_bo, unref_head);
                vc4_bo_remove_from_cache(bo);
                vc4_bo_destroy(bo);
        }
        mutex_unlock(&vc4->bo_lock);
}

void vc4_bo_add_to_purgeable_pool(struct vc4_bo *bo)
{
        struct vc4_dev *vc4 = to_vc4_dev(bo->base.base.dev);

        mutex_lock(&vc4->purgeable.lock);
        list_add_tail(&bo->size_head, &vc4->purgeable.list);
        vc4->purgeable.num++;
        vc4->purgeable.size += bo->base.base.size;
        mutex_unlock(&vc4->purgeable.lock);
}

static void vc4_bo_remove_from_purgeable_pool_locked(struct vc4_bo *bo)
{
        struct vc4_dev *vc4 = to_vc4_dev(bo->base.base.dev);

        /* list_del_init() is used here because the caller might release
         * the purgeable lock in order to acquire the madv one and update the
         * madv status.
         * During this short period of time a user might decide to mark
         * the BO as unpurgeable, and if bo->madv is set to
         * VC4_MADV_DONTNEED it will try to remove the BO from the
         * purgeable list which will fail if the ->next/prev fields
         * are set to LIST_POISON1/LIST_POISON2 (which is what
         * list_del() does).
         * Re-initializing the list element guarantees that list_del()
         * will work correctly even if it's a NOP.
         */
        list_del_init(&bo->size_head);
        vc4->purgeable.num--;
        vc4->purgeable.size -= bo->base.base.size;
}

void vc4_bo_remove_from_purgeable_pool(struct vc4_bo *bo)
{
        struct vc4_dev *vc4 = to_vc4_dev(bo->base.base.dev);

        mutex_lock(&vc4->purgeable.lock);
        vc4_bo_remove_from_purgeable_pool_locked(bo);
        mutex_unlock(&vc4->purgeable.lock);
}

static void vc4_bo_purge(struct drm_gem_object *obj)
{
        struct vc4_bo *bo = to_vc4_bo(obj);
        struct drm_device *dev = obj->dev;

        WARN_ON(!mutex_is_locked(&bo->madv_lock));
        WARN_ON(bo->madv != VC4_MADV_DONTNEED);

        drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);

        dma_free_wc(dev->dev, obj->size, bo->base.vaddr, bo->base.paddr);
        bo->base.vaddr = NULL;
        bo->madv = __VC4_MADV_PURGED;
}

static void vc4_bo_userspace_cache_purge(struct drm_device *dev)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);

        mutex_lock(&vc4->purgeable.lock);
        while (!list_empty(&vc4->purgeable.list)) {
                struct vc4_bo *bo = list_first_entry(&vc4->purgeable.list,
                                                     struct vc4_bo, size_head);
                struct drm_gem_object *obj = &bo->base.base;
                size_t purged_size = 0;

                vc4_bo_remove_from_purgeable_pool_locked(bo);

                /* Release the purgeable lock while we're purging the BO so
                 * that other people can continue inserting things in the
                 * purgeable pool without having to wait for all BOs to be
                 * purged.
                 */
                mutex_unlock(&vc4->purgeable.lock);
                mutex_lock(&bo->madv_lock);

                /* Since we released the purgeable pool lock before acquiring
                 * the BO madv one, the user may have marked the BO as WILLNEED
                 * and re-used it in the meantime.
                 * Before purging the BO we need to make sure
                 * - it is still marked as DONTNEED
                 * - it has not been re-inserted in the purgeable list
                 * - it is not used by HW blocks
                 * If one of these conditions is not met, just skip the entry.
                 */
                if (bo->madv == VC4_MADV_DONTNEED &&
                    list_empty(&bo->size_head) &&
                    !refcount_read(&bo->usecnt)) {
                        purged_size = bo->base.base.size;
                        vc4_bo_purge(obj);
                }
                mutex_unlock(&bo->madv_lock);
                mutex_lock(&vc4->purgeable.lock);

                if (purged_size) {
                        vc4->purgeable.purged_size += purged_size;
                        vc4->purgeable.purged_num++;
                }
        }
        mutex_unlock(&vc4->purgeable.lock);
}

static struct vc4_bo *vc4_bo_get_from_cache(struct drm_device *dev,
                                            uint32_t size,
                                            enum vc4_kernel_bo_type type)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        uint32_t page_index = bo_page_index(size);
        struct vc4_bo *bo = NULL;

        size = roundup(size, PAGE_SIZE);

        mutex_lock(&vc4->bo_lock);
        if (page_index >= vc4->bo_cache.size_list_size)
                goto out;

        if (list_empty(&vc4->bo_cache.size_list[page_index]))
                goto out;

        bo = list_first_entry(&vc4->bo_cache.size_list[page_index],
                              struct vc4_bo, size_head);
        vc4_bo_remove_from_cache(bo);
        kref_init(&bo->base.base.refcount);

out:
        if (bo)
                vc4_bo_set_label(&bo->base.base, type);
        mutex_unlock(&vc4->bo_lock);
        return bo;
}

/**
 * vc4_gem_create_object - Implementation of driver->gem_create_object.
 * @dev: DRM device
 * @size: Size in bytes of the memory the object will reference
 *
 * This lets the CMA helpers allocate object structs for us, and keep
 * our BO stats correct.
 */
struct drm_gem_object *vc4_create_object(struct drm_device *dev, size_t size)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct vc4_bo *bo;

        bo = kzalloc(sizeof(*bo), GFP_KERNEL);
        if (!bo)
                return ERR_PTR(-ENOMEM);

        bo->madv = VC4_MADV_WILLNEED;
        refcount_set(&bo->usecnt, 0);
        mutex_init(&bo->madv_lock);
        mutex_lock(&vc4->bo_lock);
        bo->label = VC4_BO_TYPE_KERNEL;
        vc4->bo_labels[VC4_BO_TYPE_KERNEL].num_allocated++;
        vc4->bo_labels[VC4_BO_TYPE_KERNEL].size_allocated += size;
        mutex_unlock(&vc4->bo_lock);

        return &bo->base.base;
}

struct vc4_bo *vc4_bo_create(struct drm_device *dev, size_t unaligned_size,
                             bool allow_unzeroed, enum vc4_kernel_bo_type type)
{
        size_t size = roundup(unaligned_size, PAGE_SIZE);
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct drm_gem_cma_object *cma_obj;
        struct vc4_bo *bo;

        if (size == 0)
                return ERR_PTR(-EINVAL);

        /* First, try to get a vc4_bo from the kernel BO cache. */
        bo = vc4_bo_get_from_cache(dev, size, type);
        if (bo) {
                if (!allow_unzeroed)
                        memset(bo->base.vaddr, 0, bo->base.base.size);
                return bo;
        }

        cma_obj = drm_gem_cma_create(dev, size);
        if (IS_ERR(cma_obj)) {
                /*
                 * If we've run out of CMA memory, kill the cache of
                 * CMA allocations we've got laying around and try again.
                 */
                vc4_bo_cache_purge(dev);
                cma_obj = drm_gem_cma_create(dev, size);
        }

        if (IS_ERR(cma_obj)) {
                /*
                 * Still not enough CMA memory, purge the userspace BO
                 * cache and retry.
                 * This is sub-optimal since we purge the whole userspace
                 * BO cache which forces user that want to re-use the BO to
                 * restore its initial content.
                 * Ideally, we should purge entries one by one and retry
                 * after each to see if CMA allocation succeeds. Or even
                 * better, try to find an entry with at least the same
                 * size.
                 */
                vc4_bo_userspace_cache_purge(dev);
                cma_obj = drm_gem_cma_create(dev, size);
        }

        if (IS_ERR(cma_obj)) {
                struct drm_printer p = drm_info_printer(vc4->dev->dev);
                DRM_ERROR("Failed to allocate from CMA:\n");
                vc4_bo_stats_print(&p, vc4);
                return ERR_PTR(-ENOMEM);
        }
        bo = to_vc4_bo(&cma_obj->base);

        /* By default, BOs do not support the MADV ioctl. This will be enabled
         * only on BOs that are exposed to userspace (V3D, V3D_SHADER and DUMB
         * BOs).
         */
        bo->madv = __VC4_MADV_NOTSUPP;

        mutex_lock(&vc4->bo_lock);
        vc4_bo_set_label(&cma_obj->base, type);
        mutex_unlock(&vc4->bo_lock);

        return bo;
}

int vc4_dumb_create(struct drm_file *file_priv,
                    struct drm_device *dev,
                    struct drm_mode_create_dumb *args)
{
        int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
        struct vc4_bo *bo = NULL;
        int ret;

        if (args->pitch < min_pitch)
                args->pitch = min_pitch;

        if (args->size < args->pitch * args->height)
                args->size = args->pitch * args->height;

        bo = vc4_bo_create(dev, args->size, false, VC4_BO_TYPE_DUMB);
        if (IS_ERR(bo))
                return PTR_ERR(bo);

        bo->madv = VC4_MADV_WILLNEED;

        ret = drm_gem_handle_create(file_priv, &bo->base.base, &args->handle);
        drm_gem_object_put_unlocked(&bo->base.base);

        return ret;
}

static void vc4_bo_cache_free_old(struct drm_device *dev)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        unsigned long expire_time = jiffies - msecs_to_jiffies(1000);

        lockdep_assert_held(&vc4->bo_lock);

        while (!list_empty(&vc4->bo_cache.time_list)) {
                struct vc4_bo *bo = list_last_entry(&vc4->bo_cache.time_list,
                                                    struct vc4_bo, unref_head);
                if (time_before(expire_time, bo->free_time)) {
                        mod_timer(&vc4->bo_cache.time_timer,
                                  round_jiffies_up(jiffies +
                                                   msecs_to_jiffies(1000)));
                        return;
                }

                vc4_bo_remove_from_cache(bo);
                vc4_bo_destroy(bo);
        }
}

/* Called on the last userspace/kernel unreference of the BO.  Returns
 * it to the BO cache if possible, otherwise frees it.
 */
void vc4_free_object(struct drm_gem_object *gem_bo)
{
        struct drm_device *dev = gem_bo->dev;
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct vc4_bo *bo = to_vc4_bo(gem_bo);
        struct list_head *cache_list;

        /* Remove the BO from the purgeable list. */
        mutex_lock(&bo->madv_lock);
        if (bo->madv == VC4_MADV_DONTNEED && !refcount_read(&bo->usecnt))
                vc4_bo_remove_from_purgeable_pool(bo);
        mutex_unlock(&bo->madv_lock);

        mutex_lock(&vc4->bo_lock);
        /* If the object references someone else's memory, we can't cache it.
         */
        if (gem_bo->import_attach) {
                vc4_bo_destroy(bo);
                goto out;
        }

        /* Don't cache if it was publicly named. */
        if (gem_bo->name) {
                vc4_bo_destroy(bo);
                goto out;
        }

        /* If this object was partially constructed but CMA allocation
         * had failed, just free it. Can also happen when the BO has been
         * purged.
         */
        if (!bo->base.vaddr) {
                vc4_bo_destroy(bo);
                goto out;
        }

        cache_list = vc4_get_cache_list_for_size(dev, gem_bo->size);
        if (!cache_list) {
                vc4_bo_destroy(bo);
                goto out;
        }

        if (bo->validated_shader) {
                kfree(bo->validated_shader->uniform_addr_offsets);
                kfree(bo->validated_shader->texture_samples);
                kfree(bo->validated_shader);
                bo->validated_shader = NULL;
        }

        /* Reset madv and usecnt before adding the BO to the cache. */
        bo->madv = __VC4_MADV_NOTSUPP;
        refcount_set(&bo->usecnt, 0);

        bo->t_format = false;
        bo->free_time = jiffies;
        list_add(&bo->size_head, cache_list);
        list_add(&bo->unref_head, &vc4->bo_cache.time_list);

        vc4_bo_set_label(&bo->base.base, VC4_BO_TYPE_KERNEL_CACHE);

        vc4_bo_cache_free_old(dev);

out:
        mutex_unlock(&vc4->bo_lock);
}

static void vc4_bo_cache_time_work(struct work_struct *work)
{
        struct vc4_dev *vc4 =
                container_of(work, struct vc4_dev, bo_cache.time_work);
        struct drm_device *dev = vc4->dev;

        mutex_lock(&vc4->bo_lock);
        vc4_bo_cache_free_old(dev);
        mutex_unlock(&vc4->bo_lock);
}

int vc4_bo_inc_usecnt(struct vc4_bo *bo)
{
        int ret;

        /* Fast path: if the BO is already retained by someone, no need to
         * check the madv status.
         */
        if (refcount_inc_not_zero(&bo->usecnt))
                return 0;

        mutex_lock(&bo->madv_lock);
        switch (bo->madv) {
        case VC4_MADV_WILLNEED:
                if (!refcount_inc_not_zero(&bo->usecnt))
                        refcount_set(&bo->usecnt, 1);
                ret = 0;
                break;
        case VC4_MADV_DONTNEED:
                /* We shouldn't use a BO marked as purgeable if at least
                 * someone else retained its content by incrementing usecnt.
                 * Luckily the BO hasn't been purged yet, but something wrong
                 * is happening here. Just throw an error instead of
                 * authorizing this use case.
                 */
        case __VC4_MADV_PURGED:
                /* We can't use a purged BO. */
        default:
                /* Invalid madv value. */
                ret = -EINVAL;
                break;
        }
        mutex_unlock(&bo->madv_lock);

        return ret;
}

void vc4_bo_dec_usecnt(struct vc4_bo *bo)
{
        /* Fast path: if the BO is still retained by someone, no need to test
         * the madv value.
         */
        if (refcount_dec_not_one(&bo->usecnt))
                return;

        mutex_lock(&bo->madv_lock);
        if (refcount_dec_and_test(&bo->usecnt) &&
            bo->madv == VC4_MADV_DONTNEED)
                vc4_bo_add_to_purgeable_pool(bo);
        mutex_unlock(&bo->madv_lock);
}

static void vc4_bo_cache_time_timer(struct timer_list *t)
{
        struct vc4_dev *vc4 = from_timer(vc4, t, bo_cache.time_timer);

        schedule_work(&vc4->bo_cache.time_work);
}

struct dma_buf * vc4_prime_export(struct drm_gem_object *obj, int flags)
{
        struct vc4_bo *bo = to_vc4_bo(obj);
        struct dma_buf *dmabuf;
        int ret;

        if (bo->validated_shader) {
                DRM_DEBUG("Attempting to export shader BO\n");
                return ERR_PTR(-EINVAL);
        }

        /* Note: as soon as the BO is exported it becomes unpurgeable, because
         * noone ever decrements the usecnt even if the reference held by the
         * exported BO is released. This shouldn't be a problem since we don't
         * expect exported BOs to be marked as purgeable.
         */
        ret = vc4_bo_inc_usecnt(bo);
        if (ret) {
                DRM_ERROR("Failed to increment BO usecnt\n");
                return ERR_PTR(ret);
        }

        dmabuf = drm_gem_prime_export(obj, flags);
        if (IS_ERR(dmabuf))
                vc4_bo_dec_usecnt(bo);

        return dmabuf;
}

vm_fault_t vc4_fault(struct vm_fault *vmf)
{
        struct vm_area_struct *vma = vmf->vma;
        struct drm_gem_object *obj = vma->vm_private_data;
        struct vc4_bo *bo = to_vc4_bo(obj);

        /* The only reason we would end up here is when user-space accesses
         * BO's memory after it's been purged.
         */
        mutex_lock(&bo->madv_lock);
        WARN_ON(bo->madv != __VC4_MADV_PURGED);
        mutex_unlock(&bo->madv_lock);

        return VM_FAULT_SIGBUS;
}

int vc4_mmap(struct file *filp, struct vm_area_struct *vma)
{
        struct drm_gem_object *gem_obj;
        unsigned long vm_pgoff;
        struct vc4_bo *bo;
        int ret;

        ret = drm_gem_mmap(filp, vma);
        if (ret)
                return ret;

        gem_obj = vma->vm_private_data;
        bo = to_vc4_bo(gem_obj);

        if (bo->validated_shader && (vma->vm_flags & VM_WRITE)) {
                DRM_DEBUG("mmaping of shader BOs for writing not allowed.\n");
                return -EINVAL;
        }

        if (bo->madv != VC4_MADV_WILLNEED) {
                DRM_DEBUG("mmaping of %s BO not allowed\n",
                          bo->madv == VC4_MADV_DONTNEED ?
                          "purgeable" : "purged");
                return -EINVAL;
        }

        /*
         * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
         * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
         * the whole buffer.
         */
        vma->vm_flags &= ~VM_PFNMAP;

        /* This ->vm_pgoff dance is needed to make all parties happy:
         * - dma_mmap_wc() uses ->vm_pgoff as an offset within the allocated
         *   mem-region, hence the need to set it to zero (the value set by
         *   the DRM core is a virtual offset encoding the GEM object-id)
         * - the mmap() core logic needs ->vm_pgoff to be restored to its
         *   initial value before returning from this function because it
         *   encodes the  offset of this GEM in the dev->anon_inode pseudo-file
         *   and this information will be used when we invalidate userspace
         *   mappings  with drm_vma_node_unmap() (called from vc4_gem_purge()).
         */
        vm_pgoff = vma->vm_pgoff;
        vma->vm_pgoff = 0;
        ret = dma_mmap_wc(bo->base.base.dev->dev, vma, bo->base.vaddr,
                          bo->base.paddr, vma->vm_end - vma->vm_start);
        vma->vm_pgoff = vm_pgoff;

        if (ret)
                drm_gem_vm_close(vma);

        return ret;
}

int vc4_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
{
        struct vc4_bo *bo = to_vc4_bo(obj);

        if (bo->validated_shader && (vma->vm_flags & VM_WRITE)) {
                DRM_DEBUG("mmaping of shader BOs for writing not allowed.\n");
                return -EINVAL;
        }

        return drm_gem_cma_prime_mmap(obj, vma);
}

void *vc4_prime_vmap(struct drm_gem_object *obj)
{
        struct vc4_bo *bo = to_vc4_bo(obj);

        if (bo->validated_shader) {
                DRM_DEBUG("mmaping of shader BOs not allowed.\n");
                return ERR_PTR(-EINVAL);
        }

        return drm_gem_cma_prime_vmap(obj);
}

struct drm_gem_object *
vc4_prime_import_sg_table(struct drm_device *dev,
                          struct dma_buf_attachment *attach,
                          struct sg_table *sgt)
{
        struct drm_gem_object *obj;

        obj = drm_gem_cma_prime_import_sg_table(dev, attach, sgt);
        if (IS_ERR(obj))
                return obj;

        return obj;
}

static int vc4_grab_bin_bo(struct vc4_dev *vc4, struct vc4_file *vc4file)
{
        int ret;

        if (!vc4->v3d)
                return -ENODEV;

        if (vc4file->bin_bo_used)
                return 0;

        ret = vc4_v3d_bin_bo_get(vc4, &vc4file->bin_bo_used);
        if (ret)
                return ret;

        return 0;
}

int vc4_create_bo_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file_priv)
{
        struct drm_vc4_create_bo *args = data;
        struct vc4_file *vc4file = file_priv->driver_priv;
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct vc4_bo *bo = NULL;
        int ret;

        ret = vc4_grab_bin_bo(vc4, vc4file);
        if (ret)
                return ret;

        /*
         * We can't allocate from the BO cache, because the BOs don't
         * get zeroed, and that might leak data between users.
         */
        bo = vc4_bo_create(dev, args->size, false, VC4_BO_TYPE_V3D);
        if (IS_ERR(bo))
                return PTR_ERR(bo);

        bo->madv = VC4_MADV_WILLNEED;

        ret = drm_gem_handle_create(file_priv, &bo->base.base, &args->handle);
        drm_gem_object_put_unlocked(&bo->base.base);

        return ret;
}

int vc4_mmap_bo_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file_priv)
{
        struct drm_vc4_mmap_bo *args = data;
        struct drm_gem_object *gem_obj;

        gem_obj = drm_gem_object_lookup(file_priv, args->handle);
        if (!gem_obj) {
                DRM_DEBUG("Failed to look up GEM BO %d\n", args->handle);
                return -EINVAL;
        }

        /* The mmap offset was set up at BO allocation time. */
        args->offset = drm_vma_node_offset_addr(&gem_obj->vma_node);

        drm_gem_object_put_unlocked(gem_obj);
        return 0;
}

int
vc4_create_shader_bo_ioctl(struct drm_device *dev, void *data,
                           struct drm_file *file_priv)
{
        struct drm_vc4_create_shader_bo *args = data;
        struct vc4_file *vc4file = file_priv->driver_priv;
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct vc4_bo *bo = NULL;
        int ret;

        if (args->size == 0)
                return -EINVAL;

        if (args->size % sizeof(u64) != 0)
                return -EINVAL;

        if (args->flags != 0) {
                DRM_INFO("Unknown flags set: 0x%08x\n", args->flags);
                return -EINVAL;
        }

        if (args->pad != 0) {
                DRM_INFO("Pad set: 0x%08x\n", args->pad);
                return -EINVAL;
        }

        ret = vc4_grab_bin_bo(vc4, vc4file);
        if (ret)
                return ret;

        bo = vc4_bo_create(dev, args->size, true, VC4_BO_TYPE_V3D_SHADER);
        if (IS_ERR(bo))
                return PTR_ERR(bo);

        bo->madv = VC4_MADV_WILLNEED;

        if (copy_from_user(bo->base.vaddr,
                             (void __user *)(uintptr_t)args->data,
                             args->size)) {
                ret = -EFAULT;
                goto fail;
        }
        /* Clear the rest of the memory from allocating from the BO
         * cache.
         */
        memset(bo->base.vaddr + args->size, 0,
               bo->base.base.size - args->size);

        bo->validated_shader = vc4_validate_shader(&bo->base);
        if (!bo->validated_shader) {
                ret = -EINVAL;
                goto fail;
        }

        /* We have to create the handle after validation, to avoid
         * races for users to do doing things like mmap the shader BO.
         */
        ret = drm_gem_handle_create(file_priv, &bo->base.base, &args->handle);

fail:
        drm_gem_object_put_unlocked(&bo->base.base);

        return ret;
}

/**
 * vc4_set_tiling_ioctl() - Sets the tiling modifier for a BO.
 * @dev: DRM device
 * @data: ioctl argument
 * @file_priv: DRM file for this fd
 *
 * The tiling state of the BO decides the default modifier of an fb if
 * no specific modifier was set by userspace, and the return value of
 * vc4_get_tiling_ioctl() (so that userspace can treat a BO it
 * received from dmabuf as the same tiling format as the producer
 * used).
 */
int vc4_set_tiling_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file_priv)
{
        struct drm_vc4_set_tiling *args = data;
        struct drm_gem_object *gem_obj;
        struct vc4_bo *bo;
        bool t_format;

        if (args->flags != 0)
                return -EINVAL;

        switch (args->modifier) {
        case DRM_FORMAT_MOD_NONE:
                t_format = false;
                break;
        case DRM_FORMAT_MOD_BROADCOM_VC4_T_TILED:
                t_format = true;
                break;
        default:
                return -EINVAL;
        }

        gem_obj = drm_gem_object_lookup(file_priv, args->handle);
        if (!gem_obj) {
                DRM_DEBUG("Failed to look up GEM BO %d\n", args->handle);
                return -ENOENT;
        }
        bo = to_vc4_bo(gem_obj);
        bo->t_format = t_format;

        drm_gem_object_put_unlocked(gem_obj);

        return 0;
}

/**
 * vc4_get_tiling_ioctl() - Gets the tiling modifier for a BO.
 * @dev: DRM device
 * @data: ioctl argument
 * @file_priv: DRM file for this fd
 *
 * Returns the tiling modifier for a BO as set by vc4_set_tiling_ioctl().
 */
int vc4_get_tiling_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file_priv)
{
        struct drm_vc4_get_tiling *args = data;
        struct drm_gem_object *gem_obj;
        struct vc4_bo *bo;

        if (args->flags != 0 || args->modifier != 0)
                return -EINVAL;

        gem_obj = drm_gem_object_lookup(file_priv, args->handle);
        if (!gem_obj) {
                DRM_DEBUG("Failed to look up GEM BO %d\n", args->handle);
                return -ENOENT;
        }
        bo = to_vc4_bo(gem_obj);

        if (bo->t_format)
                args->modifier = DRM_FORMAT_MOD_BROADCOM_VC4_T_TILED;
        else

                args->modifier = DRM_FORMAT_MOD_NONE;

        drm_gem_object_put_unlocked(gem_obj);

        return 0;
}

int vc4_bo_cache_init(struct drm_device *dev)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        int i;

        /* Create the initial set of BO labels that the kernel will
         * use.  This lets us avoid a bunch of string reallocation in
         * the kernel's draw and BO allocation paths.
         */
        vc4->bo_labels = kcalloc(VC4_BO_TYPE_COUNT, sizeof(*vc4->bo_labels),
                                 GFP_KERNEL);
        if (!vc4->bo_labels)
                return -ENOMEM;
        vc4->num_labels = VC4_BO_TYPE_COUNT;

        BUILD_BUG_ON(ARRAY_SIZE(bo_type_names) != VC4_BO_TYPE_COUNT);
        for (i = 0; i < VC4_BO_TYPE_COUNT; i++)
                vc4->bo_labels[i].name = bo_type_names[i];

        mutex_init(&vc4->bo_lock);

        vc4_debugfs_add_file(dev, "bo_stats", vc4_bo_stats_debugfs, NULL);

        INIT_LIST_HEAD(&vc4->bo_cache.time_list);

        INIT_WORK(&vc4->bo_cache.time_work, vc4_bo_cache_time_work);
        timer_setup(&vc4->bo_cache.time_timer, vc4_bo_cache_time_timer, 0);

        return 0;
}

void vc4_bo_cache_destroy(struct drm_device *dev)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        int i;

        del_timer(&vc4->bo_cache.time_timer);
        cancel_work_sync(&vc4->bo_cache.time_work);

        vc4_bo_cache_purge(dev);

        for (i = 0; i < vc4->num_labels; i++) {
                if (vc4->bo_labels[i].num_allocated) {
                        DRM_ERROR("Destroying BO cache with %d %s "
                                  "BOs still allocated\n",
                                  vc4->bo_labels[i].num_allocated,
                                  vc4->bo_labels[i].name);
                }

                if (is_user_label(i))
                        kfree(vc4->bo_labels[i].name);
        }
        kfree(vc4->bo_labels);
}

int vc4_label_bo_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct drm_vc4_label_bo *args = data;
        char *name;
        struct drm_gem_object *gem_obj;
        int ret = 0, label;

        if (!args->len)
                return -EINVAL;

        name = strndup_user(u64_to_user_ptr(args->name), args->len + 1);
        if (IS_ERR(name))
                return PTR_ERR(name);

        gem_obj = drm_gem_object_lookup(file_priv, args->handle);
        if (!gem_obj) {
                DRM_ERROR("Failed to look up GEM BO %d\n", args->handle);
                kfree(name);
                return -ENOENT;
        }

        mutex_lock(&vc4->bo_lock);
        label = vc4_get_user_label(vc4, name);
        if (label != -1)
                vc4_bo_set_label(gem_obj, label);
        else
                ret = -ENOMEM;
        mutex_unlock(&vc4->bo_lock);

        drm_gem_object_put_unlocked(gem_obj);

        return ret;
}