// SPDX-License-Identifier: GPL-2.0 or MIT
/* Copyright 2019 Linaro, Ltd, Rob Herring <robh@kernel.org> */
/* Copyright 2023 Collabora ltd. */
/* Copyright 2025 Amazon.com, Inc. or its affiliates */
/* Copyright 2025 ARM Limited. All rights reserved. */

#include <linux/cleanup.h>
#include <linux/debugfs.h>
#include <linux/dma-buf.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include <drm/drm_debugfs.h>
#include <drm/drm_file.h>
#include <drm/drm_gpuvm.h>
#include <drm/drm_managed.h>
#include <drm/drm_prime.h>
#include <drm/drm_print.h>
#include <drm/panthor_drm.h>

#include "panthor_device.h"
#include "panthor_drv.h"
#include "panthor_fw.h"
#include "panthor_gem.h"
#include "panthor_mmu.h"

void panthor_gem_init(struct panthor_device *ptdev)
{
        int err;

        if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
            !panthor_transparent_hugepage)
                return;

        err = drm_gem_huge_mnt_create(&ptdev->base, "within_size");
        if (drm_gem_get_huge_mnt(&ptdev->base))
                drm_info(&ptdev->base, "Using Transparent Hugepage\n");
        else if (err)
                drm_warn(&ptdev->base, "Can't use Transparent Hugepage (%d)\n",
                         err);
}

#ifdef CONFIG_DEBUG_FS
static void panthor_gem_debugfs_bo_init(struct panthor_gem_object *bo)
{
        INIT_LIST_HEAD(&bo->debugfs.node);
}

static void panthor_gem_debugfs_bo_add(struct panthor_gem_object *bo)
{
        struct panthor_device *ptdev = container_of(bo->base.dev,
                                                    struct panthor_device, base);

        bo->debugfs.creator.tgid = current->tgid;
        get_task_comm(bo->debugfs.creator.process_name, current->group_leader);

        mutex_lock(&ptdev->gems.lock);
        list_add_tail(&bo->debugfs.node, &ptdev->gems.node);
        mutex_unlock(&ptdev->gems.lock);
}

static void panthor_gem_debugfs_bo_rm(struct panthor_gem_object *bo)
{
        struct panthor_device *ptdev = container_of(bo->base.dev,
                                                    struct panthor_device, base);

        if (list_empty(&bo->debugfs.node))
                return;

        mutex_lock(&ptdev->gems.lock);
        list_del_init(&bo->debugfs.node);
        mutex_unlock(&ptdev->gems.lock);
}

static void panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo, u32 usage_flags)
{
        bo->debugfs.flags = usage_flags;
        panthor_gem_debugfs_bo_add(bo);
}
#else
static void panthor_gem_debugfs_bo_rm(struct panthor_gem_object *bo) {}
static void panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo, u32 usage_flags) {}
static void panthor_gem_debugfs_bo_init(struct panthor_gem_object *bo) {}
#endif

static bool
should_map_wc(struct panthor_gem_object *bo)
{
        struct panthor_device *ptdev = container_of(bo->base.dev, struct panthor_device, base);

        /* We can't do uncached mappings if the device is coherent,
         * because the zeroing done by the shmem layer at page allocation
         * time happens on a cached mapping which isn't CPU-flushed (at least
         * not on Arm64 where the flush is deferred to PTE setup time, and
         * only done conditionally based on the mapping permissions). We can't
         * rely on dma_map_sgtable()/dma_sync_sgtable_for_xxx() either to flush
         * those, because they are NOPed if dma_dev_coherent() returns true.
         *
         * FIXME: Note that this problem is going to pop up again when we
         * decide to support mapping buffers with the NO_MMAP flag as
         * non-shareable (AKA buffers accessed only by the GPU), because we
         * need the same CPU flush to happen after page allocation, otherwise
         * there's a risk of data leak or late corruption caused by a dirty
         * cacheline being evicted. At this point we'll need a way to force
         * CPU cache maintenance regardless of whether the device is coherent
         * or not.
         */
        if (ptdev->coherent)
                return false;

        /* Cached mappings are explicitly requested, so no write-combine. */
        if (bo->flags & DRM_PANTHOR_BO_WB_MMAP)
                return false;

        /* The default is write-combine. */
        return true;
}

static bool is_gpu_mapped(struct panthor_gem_object *bo,
                          enum panthor_gem_reclaim_state *state)
{
        struct drm_gpuvm_bo *vm_bo;
        u32 vm_count = 0;

        drm_gem_for_each_gpuvm_bo(vm_bo, &bo->base) {
                /* Skip evicted GPU mappings. */
                if (vm_bo->evicted)
                        continue;

                if (vm_count++) {
                        *state = PANTHOR_GEM_GPU_MAPPED_MULTI_VM;
                        break;
                }

                *state = PANTHOR_GEM_GPU_MAPPED_SINGLE_VM;
        }

        return vm_count > 0;
}

static enum panthor_gem_reclaim_state
panthor_gem_evaluate_reclaim_state_locked(struct panthor_gem_object *bo)
{
        enum panthor_gem_reclaim_state gpu_mapped_state;

        dma_resv_assert_held(bo->base.resv);
        lockdep_assert_held(&bo->base.gpuva.lock);

        /* If pages have not been allocated, there's nothing to reclaim. */
        if (!bo->backing.pages)
                return PANTHOR_GEM_UNRECLAIMABLE;

        /* If memory is pinned, we prevent reclaim. */
        if (refcount_read(&bo->backing.pin_count))
                return PANTHOR_GEM_UNRECLAIMABLE;

        if (is_gpu_mapped(bo, &gpu_mapped_state))
                return gpu_mapped_state;

        if (refcount_read(&bo->cmap.mmap_count))
                return PANTHOR_GEM_MMAPPED;

        return PANTHOR_GEM_UNUSED;
}

void panthor_gem_update_reclaim_state_locked(struct panthor_gem_object *bo,
                                             enum panthor_gem_reclaim_state *old_statep)
{
        struct panthor_device *ptdev = container_of(bo->base.dev, struct panthor_device, base);
        enum panthor_gem_reclaim_state old_state = bo->reclaim_state;
        enum panthor_gem_reclaim_state new_state;
        bool was_gpu_mapped, is_gpu_mapped;

        if (old_statep)
                *old_statep = old_state;

        new_state = panthor_gem_evaluate_reclaim_state_locked(bo);
        if (new_state == old_state)
                return;

        was_gpu_mapped = old_state == PANTHOR_GEM_GPU_MAPPED_MULTI_VM ||
                         old_state == PANTHOR_GEM_GPU_MAPPED_SINGLE_VM;
        is_gpu_mapped = new_state == PANTHOR_GEM_GPU_MAPPED_MULTI_VM ||
                        new_state == PANTHOR_GEM_GPU_MAPPED_SINGLE_VM;

        if (is_gpu_mapped && !was_gpu_mapped)
                ptdev->reclaim.gpu_mapped_count += bo->base.size >> PAGE_SHIFT;
        else if (!is_gpu_mapped && was_gpu_mapped)
                ptdev->reclaim.gpu_mapped_count -= bo->base.size >> PAGE_SHIFT;

        switch (new_state) {
        case PANTHOR_GEM_UNUSED:
                drm_gem_lru_move_tail(&ptdev->reclaim.unused, &bo->base);
                break;
        case PANTHOR_GEM_MMAPPED:
                drm_gem_lru_move_tail(&ptdev->reclaim.mmapped, &bo->base);
                break;
        case PANTHOR_GEM_GPU_MAPPED_SINGLE_VM:
                panthor_vm_update_bo_reclaim_lru_locked(bo);
                break;
        case PANTHOR_GEM_GPU_MAPPED_MULTI_VM:
                drm_gem_lru_move_tail(&ptdev->reclaim.gpu_mapped_shared, &bo->base);
                break;
        case PANTHOR_GEM_UNRECLAIMABLE:
                drm_gem_lru_remove(&bo->base);
                break;
        default:
                drm_WARN(&ptdev->base, true, "invalid GEM reclaim state (%d)\n", new_state);
                break;
        }

        bo->reclaim_state = new_state;
}

static void
bo_assert_locked_or_gone(struct panthor_gem_object *bo)
{
        /* If the refcount is zero, the BO is being freed, and we
         * allow the lock to not be held in that particular case.
         */
        if (kref_read(&bo->base.refcount))
                dma_resv_assert_held(bo->base.resv);
}

static void
panthor_gem_backing_cleanup_locked(struct panthor_gem_object *bo)
{
        bo_assert_locked_or_gone(bo);

        if (!bo->backing.pages)
                return;

        drm_gem_put_pages(&bo->base, bo->backing.pages, true, false);
        bo->backing.pages = NULL;
}

static int
panthor_gem_backing_get_pages_locked(struct panthor_gem_object *bo)
{
        struct page **pages;

        dma_resv_assert_held(bo->base.resv);

        if (bo->backing.pages)
                return 0;

        pages = drm_gem_get_pages(&bo->base);
        if (IS_ERR(pages)) {
                drm_dbg_driver(bo->base.dev, "Failed to get pages (%pe)\n", pages);
                return PTR_ERR(pages);
        }

        bo->backing.pages = pages;
        return 0;
}

static int panthor_gem_backing_pin_locked(struct panthor_gem_object *bo)
{
        int ret;

        dma_resv_assert_held(bo->base.resv);
        drm_WARN_ON_ONCE(bo->base.dev, drm_gem_is_imported(&bo->base));

        if (refcount_inc_not_zero(&bo->backing.pin_count))
                return 0;

        ret = panthor_gem_backing_get_pages_locked(bo);
        if (!ret) {
                refcount_set(&bo->backing.pin_count, 1);
                mutex_lock(&bo->base.gpuva.lock);
                panthor_gem_update_reclaim_state_locked(bo, NULL);
                mutex_unlock(&bo->base.gpuva.lock);
        }

        return ret;
}

static void panthor_gem_backing_unpin_locked(struct panthor_gem_object *bo)
{
        bo_assert_locked_or_gone(bo);
        drm_WARN_ON_ONCE(bo->base.dev, drm_gem_is_imported(&bo->base));

        if (refcount_dec_and_test(&bo->backing.pin_count)) {
                /* We don't release anything when pin_count drops to zero.
                 * Pages stay there until an explicit cleanup is requested.
                 */
                mutex_lock(&bo->base.gpuva.lock);
                panthor_gem_update_reclaim_state_locked(bo, NULL);
                mutex_unlock(&bo->base.gpuva.lock);
        }
}

static void
panthor_gem_dev_map_cleanup_locked(struct panthor_gem_object *bo)
{
        bo_assert_locked_or_gone(bo);

        if (!bo->dmap.sgt)
                return;

        dma_unmap_sgtable(drm_dev_dma_dev(bo->base.dev), bo->dmap.sgt, DMA_BIDIRECTIONAL, 0);
        sg_free_table(bo->dmap.sgt);
        kfree(bo->dmap.sgt);
        bo->dmap.sgt = NULL;
}

static struct sg_table *
panthor_gem_dev_map_get_sgt_locked(struct panthor_gem_object *bo)
{
        struct sg_table *sgt;
        int ret;

        dma_resv_assert_held(bo->base.resv);

        if (bo->dmap.sgt)
                return bo->dmap.sgt;

        ret = panthor_gem_backing_get_pages_locked(bo);
        if (ret)
                return ERR_PTR(ret);

        sgt = drm_prime_pages_to_sg(bo->base.dev, bo->backing.pages,
                                    bo->base.size >> PAGE_SHIFT);
        if (IS_ERR(sgt))
                return sgt;

        /* Map the pages for use by the h/w. */
        ret = dma_map_sgtable(drm_dev_dma_dev(bo->base.dev), sgt, DMA_BIDIRECTIONAL, 0);
        if (ret)
                goto err_free_sgt;

        bo->dmap.sgt = sgt;
        return sgt;

err_free_sgt:
        sg_free_table(sgt);
        kfree(sgt);
        return ERR_PTR(ret);
}

struct sg_table *
panthor_gem_get_dev_sgt(struct panthor_gem_object *bo)
{
        struct sg_table *sgt;

        dma_resv_lock(bo->base.resv, NULL);
        sgt = panthor_gem_dev_map_get_sgt_locked(bo);
        dma_resv_unlock(bo->base.resv);

        return sgt;
}

static void
panthor_gem_vmap_cleanup_locked(struct panthor_gem_object *bo)
{
        if (!bo->cmap.vaddr)
                return;

        vunmap(bo->cmap.vaddr);
        bo->cmap.vaddr = NULL;
        panthor_gem_backing_unpin_locked(bo);
}

static int
panthor_gem_prep_for_cpu_map_locked(struct panthor_gem_object *bo)
{
        if (should_map_wc(bo)) {
                struct sg_table *sgt;

                sgt = panthor_gem_dev_map_get_sgt_locked(bo);
                if (IS_ERR(sgt))
                        return PTR_ERR(sgt);
        }

        return 0;
}

static void *
panthor_gem_vmap_get_locked(struct panthor_gem_object *bo)
{
        pgprot_t prot = PAGE_KERNEL;
        void *vaddr;
        int ret;

        dma_resv_assert_held(bo->base.resv);

        if (drm_WARN_ON_ONCE(bo->base.dev, drm_gem_is_imported(&bo->base)))
                return ERR_PTR(-EINVAL);

        if (refcount_inc_not_zero(&bo->cmap.vaddr_use_count)) {
                drm_WARN_ON_ONCE(bo->base.dev, !bo->cmap.vaddr);
                return bo->cmap.vaddr;
        }

        ret = panthor_gem_backing_pin_locked(bo);
        if (ret)
                return ERR_PTR(ret);

        ret = panthor_gem_prep_for_cpu_map_locked(bo);
        if (ret)
                goto err_unpin;

        if (should_map_wc(bo))
                prot = pgprot_writecombine(prot);

        vaddr = vmap(bo->backing.pages, bo->base.size >> PAGE_SHIFT, VM_MAP, prot);
        if (!vaddr) {
                ret = -ENOMEM;
                goto err_unpin;
        }

        bo->cmap.vaddr = vaddr;
        refcount_set(&bo->cmap.vaddr_use_count, 1);
        return vaddr;

err_unpin:
        panthor_gem_backing_unpin_locked(bo);
        return ERR_PTR(ret);
}

static void
panthor_gem_vmap_put_locked(struct panthor_gem_object *bo)
{
        dma_resv_assert_held(bo->base.resv);

        if (drm_WARN_ON_ONCE(bo->base.dev, drm_gem_is_imported(&bo->base)))
                return;

        if (refcount_dec_and_test(&bo->cmap.vaddr_use_count))
                panthor_gem_vmap_cleanup_locked(bo);
}

static void panthor_gem_free_object(struct drm_gem_object *obj)
{
        struct panthor_gem_object *bo = to_panthor_bo(obj);
        struct drm_gem_object *vm_root_gem = bo->exclusive_vm_root_gem;

        panthor_gem_debugfs_bo_rm(bo);

        /*
         * Label might have been allocated with kstrdup_const(),
         * we need to take that into account when freeing the memory
         */
        kfree_const(bo->label.str);

        mutex_destroy(&bo->label.lock);

        if (drm_gem_is_imported(obj)) {
                drm_prime_gem_destroy(obj, bo->dmap.sgt);
        } else {
                /* The last ref on the GEM object can be released
                 * by the shrinker, which can't block on the resv
                 * lock acquisition. In practice, even if we were
                 * taking the lock, it wouldn't block because we're
                 * the last piece of code having a visibility on
                 * this GEM, but lockdep can't see that, so we've
                 * just tought the _cleanup_locked() helpers about
                 * this "being freed" exception, and we call those
                 * without the lock held here.
                 */
                panthor_gem_vmap_cleanup_locked(bo);
                panthor_gem_dev_map_cleanup_locked(bo);
                panthor_gem_backing_cleanup_locked(bo);
        }

        drm_gem_object_release(obj);

        kfree(bo);
        drm_gem_object_put(vm_root_gem);
}

static struct sg_table *
panthor_gem_prime_map_dma_buf(struct dma_buf_attachment *attach,
                              enum dma_data_direction dir)
{
        struct sg_table *sgt = drm_gem_map_dma_buf(attach, dir);

        if (!IS_ERR(sgt))
                attach->priv = sgt;

        return sgt;
}

static void
panthor_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach,
                                struct sg_table *sgt,
                                enum dma_data_direction dir)
{
        attach->priv = NULL;
        drm_gem_unmap_dma_buf(attach, sgt, dir);
}

static int
panthor_gem_prime_begin_cpu_access(struct dma_buf *dma_buf,
                                   enum dma_data_direction dir)
{
        struct drm_gem_object *obj = dma_buf->priv;
        struct drm_device *dev = obj->dev;
        struct panthor_gem_object *bo = to_panthor_bo(obj);
        struct dma_buf_attachment *attach;

        dma_resv_lock(obj->resv, NULL);
        if (bo->dmap.sgt)
                dma_sync_sgtable_for_cpu(drm_dev_dma_dev(dev), bo->dmap.sgt, dir);

        if (bo->cmap.vaddr)
                invalidate_kernel_vmap_range(bo->cmap.vaddr, bo->base.size);

        list_for_each_entry(attach, &dma_buf->attachments, node) {
                struct sg_table *sgt = attach->priv;

                if (sgt)
                        dma_sync_sgtable_for_cpu(attach->dev, sgt, dir);
        }
        dma_resv_unlock(obj->resv);

        return 0;
}

static int
panthor_gem_prime_end_cpu_access(struct dma_buf *dma_buf,
                                 enum dma_data_direction dir)
{
        struct drm_gem_object *obj = dma_buf->priv;
        struct drm_device *dev = obj->dev;
        struct panthor_gem_object *bo = to_panthor_bo(obj);
        struct dma_buf_attachment *attach;

        dma_resv_lock(obj->resv, NULL);
        list_for_each_entry(attach, &dma_buf->attachments, node) {
                struct sg_table *sgt = attach->priv;

                if (sgt)
                        dma_sync_sgtable_for_device(attach->dev, sgt, dir);
        }

        if (bo->cmap.vaddr)
                flush_kernel_vmap_range(bo->cmap.vaddr, bo->base.size);

        if (bo->dmap.sgt)
                dma_sync_sgtable_for_device(drm_dev_dma_dev(dev), bo->dmap.sgt, dir);

        dma_resv_unlock(obj->resv);
        return 0;
}

static const struct dma_buf_ops panthor_dma_buf_ops = {
        .attach = drm_gem_map_attach,
        .detach = drm_gem_map_detach,
        .map_dma_buf = panthor_gem_prime_map_dma_buf,
        .unmap_dma_buf = panthor_gem_prime_unmap_dma_buf,
        .release = drm_gem_dmabuf_release,
        .mmap = drm_gem_dmabuf_mmap,
        .vmap = drm_gem_dmabuf_vmap,
        .vunmap = drm_gem_dmabuf_vunmap,
        .begin_cpu_access = panthor_gem_prime_begin_cpu_access,
        .end_cpu_access = panthor_gem_prime_end_cpu_access,
};

static struct dma_buf *
panthor_gem_prime_export(struct drm_gem_object *obj, int flags)
{
        struct drm_device *dev = obj->dev;
        struct dma_buf_export_info exp_info = {
                .exp_name = KBUILD_MODNAME,
                .owner = THIS_MODULE,
                .ops = &panthor_dma_buf_ops,
                .size = obj->size,
                .flags = flags,
                .priv = obj,
                .resv = obj->resv,
        };

        /* We can't export GEMs that have an exclusive VM. */
        if (to_panthor_bo(obj)->exclusive_vm_root_gem)
                return ERR_PTR(-EINVAL);

        return drm_gem_dmabuf_export(dev, &exp_info);
}

struct drm_gem_object *
panthor_gem_prime_import(struct drm_device *dev,
                         struct dma_buf *dma_buf)
{
        struct drm_gem_object *obj = dma_buf->priv;

        if (dma_buf->ops == &panthor_dma_buf_ops && obj->dev == dev) {
                /* Importing dmabuf exported from our own gem increases
                 * refcount on gem itself instead of f_count of dmabuf.
                 */
                drm_gem_object_get(obj);
                return obj;
        }

        return drm_gem_prime_import(dev, dma_buf);
}

static void panthor_gem_print_info(struct drm_printer *p, unsigned int indent,
                                   const struct drm_gem_object *obj)
{
        const struct panthor_gem_object *bo = to_panthor_bo(obj);

        if (drm_gem_is_imported(&bo->base))
                return;

        drm_printf_indent(p, indent, "resident=%s\n", str_true_false(bo->backing.pages));
        drm_printf_indent(p, indent, "pages_pin_count=%u\n", refcount_read(&bo->backing.pin_count));
        drm_printf_indent(p, indent, "vmap_use_count=%u\n",
                          refcount_read(&bo->cmap.vaddr_use_count));
        drm_printf_indent(p, indent, "vaddr=%p\n", bo->cmap.vaddr);
        drm_printf_indent(p, indent, "mmap_count=%u\n", refcount_read(&bo->cmap.mmap_count));
}

static int panthor_gem_pin_locked(struct drm_gem_object *obj)
{
        if (!drm_gem_is_imported(obj))
                return panthor_gem_backing_pin_locked(to_panthor_bo(obj));

        return 0;
}

static void panthor_gem_unpin_locked(struct drm_gem_object *obj)
{
        if (!drm_gem_is_imported(obj))
                panthor_gem_backing_unpin_locked(to_panthor_bo(obj));
}

int panthor_gem_pin(struct panthor_gem_object *bo)
{
        int ret = 0;

        if (drm_gem_is_imported(&bo->base))
                return 0;

        if (refcount_inc_not_zero(&bo->backing.pin_count))
                return 0;

        dma_resv_lock(bo->base.resv, NULL);
        ret = panthor_gem_backing_pin_locked(bo);
        dma_resv_unlock(bo->base.resv);

        return ret;
}

void panthor_gem_unpin(struct panthor_gem_object *bo)
{
        if (drm_gem_is_imported(&bo->base))
                return;

        if (refcount_dec_not_one(&bo->backing.pin_count))
                return;

        dma_resv_lock(bo->base.resv, NULL);
        panthor_gem_backing_unpin_locked(bo);
        dma_resv_unlock(bo->base.resv);
}

int panthor_gem_swapin_locked(struct panthor_gem_object *bo)
{
        struct sg_table *sgt;

        dma_resv_assert_held(bo->base.resv);

        if (drm_WARN_ON_ONCE(bo->base.dev, drm_gem_is_imported(&bo->base)))
                return -EINVAL;

        sgt = panthor_gem_dev_map_get_sgt_locked(bo);
        if (IS_ERR(sgt))
                return PTR_ERR(sgt);

        return 0;
}

static void panthor_gem_evict_locked(struct panthor_gem_object *bo)
{
        dma_resv_assert_held(bo->base.resv);
        lockdep_assert_held(&bo->base.gpuva.lock);

        if (drm_WARN_ON_ONCE(bo->base.dev, drm_gem_is_imported(&bo->base)))
                return;

        if (drm_WARN_ON_ONCE(bo->base.dev, refcount_read(&bo->backing.pin_count)))
                return;

        if (drm_WARN_ON_ONCE(bo->base.dev, !bo->backing.pages))
                return;

        atomic_add_unless(&bo->reclaimed_count, 1, INT_MAX);

        panthor_gem_dev_map_cleanup_locked(bo);
        panthor_gem_backing_cleanup_locked(bo);
        panthor_gem_update_reclaim_state_locked(bo, NULL);
}

static struct sg_table *panthor_gem_get_sg_table(struct drm_gem_object *obj)
{
        struct panthor_gem_object *bo = to_panthor_bo(obj);

        drm_WARN_ON_ONCE(obj->dev, drm_gem_is_imported(obj));
        drm_WARN_ON_ONCE(obj->dev, !bo->backing.pages);
        drm_WARN_ON_ONCE(obj->dev, !refcount_read(&bo->backing.pin_count));

        return drm_prime_pages_to_sg(obj->dev, bo->backing.pages, obj->size >> PAGE_SHIFT);
}

static int panthor_gem_vmap_locked(struct drm_gem_object *obj,
                                   struct iosys_map *map)
{
        struct panthor_gem_object *bo = to_panthor_bo(obj);
        void *vaddr;

        dma_resv_assert_held(obj->resv);

        if (drm_gem_is_imported(obj))
                return dma_buf_vmap(obj->import_attach->dmabuf, map);

        vaddr = panthor_gem_vmap_get_locked(bo);
        if (IS_ERR(vaddr))
                return PTR_ERR(vaddr);

        iosys_map_set_vaddr(map, vaddr);
        return 0;
}

static void panthor_gem_vunmap_locked(struct drm_gem_object *obj,
                                      struct iosys_map *map)
{
        struct panthor_gem_object *bo = to_panthor_bo(obj);

        dma_resv_assert_held(obj->resv);

        if (drm_gem_is_imported(obj)) {
                dma_buf_vunmap(obj->import_attach->dmabuf, map);
        } else {
                drm_WARN_ON_ONCE(obj->dev, bo->cmap.vaddr != map->vaddr);
                panthor_gem_vmap_put_locked(bo);
        }
}

static int panthor_gem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
{
        struct panthor_gem_object *bo = to_panthor_bo(obj);
        int ret;

        if (drm_gem_is_imported(obj)) {
                /* Reset both vm_ops and vm_private_data, so we don't end up with
                 * vm_ops pointing to our implementation if the dma-buf backend
                 * doesn't set those fields.
                 */
                vma->vm_private_data = NULL;
                vma->vm_ops = NULL;

                ret = dma_buf_mmap(obj->dma_buf, vma, 0);

                /* Drop the reference drm_gem_mmap_obj() acquired.*/
                if (!ret)
                        drm_gem_object_put(obj);

                return ret;
        }

        if (is_cow_mapping(vma->vm_flags))
                return -EINVAL;

        if (!refcount_inc_not_zero(&bo->cmap.mmap_count)) {
                dma_resv_lock(obj->resv, NULL);
                if (!refcount_inc_not_zero(&bo->cmap.mmap_count)) {
                        refcount_set(&bo->cmap.mmap_count, 1);
                        mutex_lock(&bo->base.gpuva.lock);
                        panthor_gem_update_reclaim_state_locked(bo, NULL);
                        mutex_unlock(&bo->base.gpuva.lock);
                }
                dma_resv_unlock(obj->resv);
        }

        vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
        if (should_map_wc(bo))
                vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);

        return 0;
}

static enum drm_gem_object_status panthor_gem_status(struct drm_gem_object *obj)
{
        struct panthor_gem_object *bo = to_panthor_bo(obj);
        enum drm_gem_object_status res = 0;

        if (drm_gem_is_imported(&bo->base) || bo->backing.pages)
                res |= DRM_GEM_OBJECT_RESIDENT;

        return res;
}

static vm_fault_t insert_page(struct vm_fault *vmf, unsigned int order, struct page *page)
{
        if (!order) {
                return vmf_insert_pfn(vmf->vma, vmf->address, page_to_pfn(page));
#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
        } else if (order == PMD_ORDER) {
                unsigned long pfn = page_to_pfn(page);
                unsigned long paddr = pfn << PAGE_SHIFT;
                bool aligned = (vmf->address & ~PMD_MASK) == (paddr & ~PMD_MASK);

                if (aligned &&
                    folio_test_pmd_mappable(page_folio(page))) {
                        pfn &= PMD_MASK >> PAGE_SHIFT;
                        return vmf_insert_pfn_pmd(vmf, pfn, vmf->flags & FAULT_FLAG_WRITE);
                }
#endif
        }

        return VM_FAULT_FALLBACK;
}

static vm_fault_t nonblocking_page_setup(struct vm_fault *vmf,
                                         unsigned int order,
                                         pgoff_t page_offset)
{
        struct vm_area_struct *vma = vmf->vma;
        struct panthor_gem_object *bo = to_panthor_bo(vma->vm_private_data);
        vm_fault_t ret;

        if (!dma_resv_trylock(bo->base.resv))
                return VM_FAULT_RETRY;

        if (bo->backing.pages)
                ret = insert_page(vmf, order, bo->backing.pages[page_offset]);
        else
                ret = VM_FAULT_RETRY;

        dma_resv_unlock(bo->base.resv);
        return ret;
}

static vm_fault_t blocking_page_setup(struct vm_fault *vmf, unsigned int order,
                                      struct panthor_gem_object *bo,
                                      pgoff_t page_offset, bool mmap_lock_held)
{
        vm_fault_t ret;
        int err;

        err = dma_resv_lock_interruptible(bo->base.resv, NULL);
        if (err)
                return mmap_lock_held ? VM_FAULT_NOPAGE : VM_FAULT_RETRY;

        err = panthor_gem_backing_get_pages_locked(bo);
        if (!err)
                err = panthor_gem_prep_for_cpu_map_locked(bo);

        if (err) {
                ret = mmap_lock_held ? VM_FAULT_SIGBUS : VM_FAULT_RETRY;
        } else {
                struct page *page = bo->backing.pages[page_offset];

                mutex_lock(&bo->base.gpuva.lock);
                panthor_gem_update_reclaim_state_locked(bo, NULL);
                mutex_unlock(&bo->base.gpuva.lock);

                if (mmap_lock_held)
                        ret = insert_page(vmf, order, page);
                else
                        ret = VM_FAULT_RETRY;
        }

        dma_resv_unlock(bo->base.resv);

        return ret;
}

static vm_fault_t panthor_gem_any_fault(struct vm_fault *vmf, unsigned int order)
{
        struct vm_area_struct *vma = vmf->vma;
        struct panthor_gem_object *bo = to_panthor_bo(vma->vm_private_data);
        loff_t num_pages = bo->base.size >> PAGE_SHIFT;
        pgoff_t page_offset;
        vm_fault_t ret;

        if (order && order != PMD_ORDER)
                return VM_FAULT_FALLBACK;

        /* Offset to faulty address in the VMA. */
        page_offset = vmf->pgoff - vma->vm_pgoff;
        if (page_offset >= num_pages)
                return VM_FAULT_SIGBUS;

        ret = nonblocking_page_setup(vmf, order, page_offset);
        if (ret != VM_FAULT_RETRY)
                return ret;

        /* Check if we're allowed to retry. */
        if (fault_flag_allow_retry_first(vmf->flags)) {
                /* If we're allowed to retry but not wait here, return
                 * immediately, the wait will be done when the fault
                 * handler is called again, with the mmap_lock held.
                 */
                if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
                        return VM_FAULT_RETRY;

                /* Wait with the mmap lock released, if we're allowed to. */
                drm_gem_object_get(&bo->base);

                if (vmf->flags & FAULT_FLAG_VMA_LOCK)
                        vma_end_read(vmf->vma);
                else
                        mmap_read_unlock(vmf->vma->vm_mm);

                ret = blocking_page_setup(vmf, order, bo, page_offset, false);
                drm_gem_object_put(&bo->base);
                return ret;
        }

        return blocking_page_setup(vmf, order, bo, page_offset, true);
}

static vm_fault_t panthor_gem_fault(struct vm_fault *vmf)
{
        return panthor_gem_any_fault(vmf, 0);
}

static void panthor_gem_vm_open(struct vm_area_struct *vma)
{
        struct panthor_gem_object *bo = to_panthor_bo(vma->vm_private_data);

        drm_WARN_ON(bo->base.dev, drm_gem_is_imported(&bo->base));
        drm_WARN_ON(bo->base.dev, !refcount_inc_not_zero(&bo->cmap.mmap_count));

        drm_gem_vm_open(vma);
}

static void panthor_gem_vm_close(struct vm_area_struct *vma)
{
        struct panthor_gem_object *bo = to_panthor_bo(vma->vm_private_data);

        if (drm_gem_is_imported(&bo->base))
                goto out;

        if (refcount_dec_not_one(&bo->cmap.mmap_count))
                goto out;

        dma_resv_lock(bo->base.resv, NULL);
        if (refcount_dec_and_test(&bo->cmap.mmap_count)) {
                mutex_lock(&bo->base.gpuva.lock);
                panthor_gem_update_reclaim_state_locked(bo, NULL);
                mutex_unlock(&bo->base.gpuva.lock);
        }
        dma_resv_unlock(bo->base.resv);

out:
        drm_gem_object_put(&bo->base);
}

static const struct vm_operations_struct panthor_gem_vm_ops = {
        .fault = panthor_gem_fault,
#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
        .huge_fault = panthor_gem_any_fault,
#endif
        .open = panthor_gem_vm_open,
        .close = panthor_gem_vm_close,
};

static const struct drm_gem_object_funcs panthor_gem_funcs = {
        .free = panthor_gem_free_object,
        .print_info = panthor_gem_print_info,
        .pin = panthor_gem_pin_locked,
        .unpin = panthor_gem_unpin_locked,
        .get_sg_table = panthor_gem_get_sg_table,
        .vmap = panthor_gem_vmap_locked,
        .vunmap = panthor_gem_vunmap_locked,
        .mmap = panthor_gem_mmap,
        .status = panthor_gem_status,
        .export = panthor_gem_prime_export,
        .vm_ops = &panthor_gem_vm_ops,
};

static struct panthor_gem_object *
panthor_gem_alloc_object(u32 flags)
{
        struct panthor_gem_object *bo;

        bo = kzalloc_obj(*bo);
        if (!bo)
                return ERR_PTR(-ENOMEM);

        bo->reclaim_state = PANTHOR_GEM_UNRECLAIMABLE;
        bo->base.funcs = &panthor_gem_funcs;
        bo->flags = flags;
        mutex_init(&bo->label.lock);
        panthor_gem_debugfs_bo_init(bo);
        return bo;
}

static struct panthor_gem_object *
panthor_gem_create(struct drm_device *dev, size_t size, uint32_t flags,
                   struct panthor_vm *exclusive_vm, u32 usage_flags)
{
        struct panthor_gem_object *bo;
        int ret;

        bo = panthor_gem_alloc_object(flags);
        if (IS_ERR(bo))
                return bo;

        size = PAGE_ALIGN(size);
        ret = drm_gem_object_init(dev, &bo->base, size);
        if (ret)
                goto err_put;

        /* Our buffers are kept pinned, so allocating them
         * from the MOVABLE zone is a really bad idea, and
         * conflicts with CMA. See comments above new_inode()
         * why this is required _and_ expected if you're
         * going to pin these pages.
         */
        mapping_set_gfp_mask(bo->base.filp->f_mapping,
                             GFP_HIGHUSER | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);

        ret = drm_gem_create_mmap_offset(&bo->base);
        if (ret)
                goto err_put;

        if (exclusive_vm) {
                bo->exclusive_vm_root_gem = panthor_vm_root_gem(exclusive_vm);
                drm_gem_object_get(bo->exclusive_vm_root_gem);
                bo->base.resv = bo->exclusive_vm_root_gem->resv;
        }

        panthor_gem_debugfs_set_usage_flags(bo, usage_flags);
        return bo;

err_put:
        drm_gem_object_put(&bo->base);
        return ERR_PTR(ret);
}

struct drm_gem_object *
panthor_gem_prime_import_sg_table(struct drm_device *dev,
                                  struct dma_buf_attachment *attach,
                                  struct sg_table *sgt)
{
        struct panthor_gem_object *bo;
        int ret;

        bo = panthor_gem_alloc_object(0);
        if (IS_ERR(bo))
                return ERR_CAST(bo);

        drm_gem_private_object_init(dev, &bo->base, attach->dmabuf->size);

        ret = drm_gem_create_mmap_offset(&bo->base);
        if (ret)
                goto err_put;

        bo->dmap.sgt = sgt;
        return &bo->base;

err_put:
        drm_gem_object_put(&bo->base);
        return ERR_PTR(ret);
}

/**
 * panthor_gem_create_with_handle() - Create a GEM object and attach it to a handle.
 * @file: DRM file.
 * @ddev: DRM device.
 * @exclusive_vm: Exclusive VM. Not NULL if the GEM object can't be shared.
 * @size: Size of the GEM object to allocate.
 * @flags: Combination of drm_panthor_bo_flags flags.
 * @handle: Pointer holding the handle pointing to the new GEM object.
 *
 * Return: Zero on success
 */
int
panthor_gem_create_with_handle(struct drm_file *file,
                               struct drm_device *ddev,
                               struct panthor_vm *exclusive_vm,
                               u64 *size, u32 flags, u32 *handle)
{
        int ret;
        struct panthor_gem_object *bo;

        bo = panthor_gem_create(ddev, *size, flags, exclusive_vm, 0);
        if (IS_ERR(bo))
                return PTR_ERR(bo);

        /*
         * Allocate an id of idr table where the obj is registered
         * and handle has the id what user can see.
         */
        ret = drm_gem_handle_create(file, &bo->base, handle);
        if (!ret)
                *size = bo->base.size;

        /* drop reference from allocate - handle holds it now. */
        drm_gem_object_put(&bo->base);
        return ret;
}

void
panthor_gem_bo_set_label(struct drm_gem_object *obj, const char *label)
{
        struct panthor_gem_object *bo = to_panthor_bo(obj);
        const char *old_label;

        scoped_guard(mutex, &bo->label.lock) {
                old_label = bo->label.str;
                bo->label.str = label;
        }

        kfree_const(old_label);
}

void
panthor_gem_kernel_bo_set_label(struct panthor_kernel_bo *bo, const char *label)
{
        const char *str;

        /* We should never attempt labelling a UM-exposed GEM object */
        if (drm_WARN_ON(bo->obj->dev, bo->obj->handle_count > 0))
                return;

        if (!label)
                return;

        str = kstrdup_const(label, GFP_KERNEL);
        if (!str) {
                /* Failing to allocate memory for a label isn't a fatal condition */
                drm_warn(bo->obj->dev, "Not enough memory to allocate BO label");
                return;
        }

        panthor_gem_bo_set_label(bo->obj, str);
}

int
panthor_gem_sync(struct drm_gem_object *obj, u32 type,
                 u64 offset, u64 size)
{
        struct panthor_gem_object *bo = to_panthor_bo(obj);
        struct device *dma_dev = drm_dev_dma_dev(bo->base.dev);
        struct sg_table *sgt;
        struct scatterlist *sgl;
        unsigned int count;
        int ret;

        /* Make sure the range is in bounds. */
        if (offset + size < offset || offset + size > bo->base.size)
                return -EINVAL;

        /* Disallow CPU-cache maintenance on imported buffers. */
        if (drm_gem_is_imported(&bo->base))
                return -EINVAL;

        switch (type) {
        case DRM_PANTHOR_BO_SYNC_CPU_CACHE_FLUSH:
        case DRM_PANTHOR_BO_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE:
                break;

        default:
                return -EINVAL;
        }

        /* Don't bother if it's WC-mapped */
        if (should_map_wc(bo))
                return 0;

        /* Nothing to do if the size is zero. */
        if (size == 0)
                return 0;

        ret = dma_resv_lock_interruptible(bo->base.resv, NULL);
        if (ret)
                return ret;

        /* If there's no pages, there's no point pulling those back, bail out early. */
        if (!bo->backing.pages) {
                ret = 0;
                goto out_unlock;
        }

        sgt = panthor_gem_dev_map_get_sgt_locked(bo);
        if (IS_ERR(sgt)) {
                ret = PTR_ERR(sgt);
                goto out_unlock;
        }

        for_each_sgtable_dma_sg(sgt, sgl, count) {
                if (size == 0)
                        break;

                dma_addr_t paddr = sg_dma_address(sgl);
                size_t len = sg_dma_len(sgl);

                if (len <= offset) {
                        offset -= len;
                        continue;
                }

                paddr += offset;
                len -= offset;
                len = min_t(size_t, len, size);
                size -= len;
                offset = 0;

                /* It's unclear whether dma_sync_xxx() is the right API to do CPU
                 * cache maintenance given an IOMMU can register their own
                 * implementation doing more than just CPU cache flushes/invalidation,
                 * and what we really care about here is CPU caches only, but that's
                 * the best we have that is both arch-agnostic and does at least the
                 * CPU cache maintenance on a <page,offset,size> tuple.
                 *
                 * Also, I wish we could do a single
                 *
                 *      dma_sync_single_for_device(BIDIR)
                 *
                 * and get a flush+invalidate, but that's not how it's implemented
                 * in practice (at least on arm64), so we have to make it
                 *
                 *      dma_sync_single_for_device(TO_DEVICE)
                 *      dma_sync_single_for_cpu(FROM_DEVICE)
                 *
                 * for the flush+invalidate case.
                 */
                dma_sync_single_for_device(dma_dev, paddr, len, DMA_TO_DEVICE);
                if (type == DRM_PANTHOR_BO_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE)
                        dma_sync_single_for_cpu(dma_dev, paddr, len, DMA_FROM_DEVICE);
        }

        ret = 0;

out_unlock:
        dma_resv_unlock(bo->base.resv);
        return ret;
}

/**
 * panthor_kernel_bo_destroy() - Destroy a kernel buffer object
 * @bo: Kernel buffer object to destroy. If NULL or an ERR_PTR(), the destruction
 * is skipped.
 */
void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)
{
        struct panthor_device *ptdev;
        struct panthor_vm *vm;

        if (IS_ERR_OR_NULL(bo))
                return;

        ptdev = container_of(bo->obj->dev, struct panthor_device, base);
        vm = bo->vm;
        panthor_kernel_bo_vunmap(bo);

        drm_WARN_ON(bo->obj->dev,
                    to_panthor_bo(bo->obj)->exclusive_vm_root_gem != panthor_vm_root_gem(vm));
        panthor_vm_unmap_range(vm, bo->va_node.start, bo->va_node.size);
        panthor_vm_free_va(vm, &bo->va_node);
        if (vm == panthor_fw_vm(ptdev))
                panthor_gem_unpin(to_panthor_bo(bo->obj));
        drm_gem_object_put(bo->obj);
        panthor_vm_put(vm);
        kfree(bo);
}

/**
 * panthor_kernel_bo_create() - Create and map a GEM object to a VM
 * @ptdev: Device.
 * @vm: VM to map the GEM to.
 * @size: Size of the buffer object.
 * @bo_flags: Combination of drm_panthor_bo_flags flags.
 * @vm_map_flags: Combination of drm_panthor_vm_bind_op_flags (only those
 * that are related to map operations).
 * @gpu_va: GPU address assigned when mapping to the VM.
 * If gpu_va == PANTHOR_VM_KERNEL_AUTO_VA, the virtual address will be
 * automatically allocated.
 * @name: Descriptive label of the BO's contents
 *
 * Return: A valid pointer in case of success, an ERR_PTR() otherwise.
 */
struct panthor_kernel_bo *
panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
                         size_t size, u32 bo_flags, u32 vm_map_flags,
                         u64 gpu_va, const char *name)
{
        struct panthor_kernel_bo *kbo;
        struct panthor_gem_object *bo;
        u32 debug_flags = PANTHOR_DEBUGFS_GEM_USAGE_FLAG_KERNEL;
        int ret;

        if (drm_WARN_ON(&ptdev->base, !vm))
                return ERR_PTR(-EINVAL);

        kbo = kzalloc_obj(*kbo);
        if (!kbo)
                return ERR_PTR(-ENOMEM);

        if (vm == panthor_fw_vm(ptdev))
                debug_flags |= PANTHOR_DEBUGFS_GEM_USAGE_FLAG_FW_MAPPED;

        bo = panthor_gem_create(&ptdev->base, size, bo_flags, vm, debug_flags);
        if (IS_ERR(bo)) {
                ret = PTR_ERR(bo);
                goto err_free_kbo;
        }

        kbo->obj = &bo->base;

        if (vm == panthor_fw_vm(ptdev)) {
                ret = panthor_gem_pin(bo);
                if (ret)
                        goto err_put_obj;
        }

        panthor_gem_kernel_bo_set_label(kbo, name);

        /* The system and GPU MMU page size might differ, which becomes a
         * problem for FW sections that need to be mapped at explicit address
         * since our PAGE_SIZE alignment might cover a VA range that's
         * expected to be used for another section.
         * Make sure we never map more than we need.
         */
        size = ALIGN(size, panthor_vm_page_size(vm));
        ret = panthor_vm_alloc_va(vm, gpu_va, size, &kbo->va_node);
        if (ret)
                goto err_unpin;

        ret = panthor_vm_map_bo_range(vm, bo, 0, size, kbo->va_node.start, vm_map_flags);
        if (ret)
                goto err_free_va;

        kbo->vm = panthor_vm_get(vm);
        return kbo;

err_free_va:
        panthor_vm_free_va(vm, &kbo->va_node);

err_unpin:
        if (vm == panthor_fw_vm(ptdev))
                panthor_gem_unpin(bo);

err_put_obj:
        drm_gem_object_put(&bo->base);

err_free_kbo:
        kfree(kbo);
        return ERR_PTR(ret);
}

static bool can_swap(void)
{
        return get_nr_swap_pages() > 0;
}

static bool can_block(struct shrink_control *sc)
{
        /* If direct reclaim is allowed, we can always block.
         * If kswapd reclaim is allowed, we can block, but only if we're called
         * by the kswapd thread.
         */
        return (sc->gfp_mask & __GFP_DIRECT_RECLAIM) ||
               ((sc->gfp_mask & __GFP_KSWAPD_RECLAIM) && current_is_kswapd());
}

static unsigned long
panthor_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
{
        struct panthor_device *ptdev = shrinker->private_data;
        unsigned long count;

        /* We currently don't have a flag to tell when the content of a
         * BO can be discarded.
         */
        if (!can_swap())
                return 0;

        /* This is racy, but that's okay because the returned count is just a
         * hint. That's also what MSM is doing (no atomic var, it's relying on
         * the fact unsigned long access is usually atomic), so if it's good
         * enough for them, it's good enough for us too.
         */
        count = ptdev->reclaim.unused.count;
        count += ptdev->reclaim.mmapped.count;

        if (can_block(sc))
                count += ptdev->reclaim.gpu_mapped_count;

        return count ? count : SHRINK_EMPTY;
}

static bool panthor_gem_try_evict_no_resv_wait(struct drm_gem_object *obj,
                                               struct ww_acquire_ctx *ticket)
{
        /*
         * Track last locked entry for unwinding locks in error and
         * success paths
         */
        struct panthor_gem_object *bo = to_panthor_bo(obj);
        struct drm_gpuvm_bo *vm_bo, *last_locked = NULL;
        enum panthor_gem_reclaim_state old_state;
        int ret = 0;

        /* To avoid potential lock ordering issue between bo_gpuva and
         * mapping->i_mmap_rwsem, unmap the pages from CPU side before
         * acquring the bo_gpuva lock. As the bo_resv lock is held, CPU
         * page fault handler won't be able to map in the pages whilst
         * eviction is in progress.
         */
        drm_vma_node_unmap(&bo->base.vma_node, bo->base.dev->anon_inode->i_mapping);

        /* We take this lock when walking the list to prevent
         * insertion/deletion.
         */
        /* We can only trylock in that path, because
         * - allocation might happen while some of these locks are held
         * - lock ordering is different in other paths
         *     vm_resv -> bo_resv -> bo_gpuva
         *     vs
         *     bo_resv -> bo_gpuva -> vm_resv
         *
         * If we fail to lock that's fine, we back off and will get
         * back to it later.
         */
        if (!mutex_trylock(&bo->base.gpuva.lock))
                return false;

        drm_gem_for_each_gpuvm_bo(vm_bo, obj) {
                struct dma_resv *resv = drm_gpuvm_resv(vm_bo->vm);

                if (resv == obj->resv)
                        continue;

                if (!dma_resv_trylock(resv)) {
                        ret = -EDEADLK;
                        goto out_unlock;
                }

                last_locked = vm_bo;
        }

        /* Update the state before trying to evict the buffer, if the state was
         * updated to something that's harder to reclaim (higher value in the
         * enum), skip it (will be processed when the relevant LRU is).
         */
        panthor_gem_update_reclaim_state_locked(bo, &old_state);
        if (old_state < bo->reclaim_state) {
                ret = -EAGAIN;
                goto out_unlock;
        }

        /* Couldn't teardown the GPU mappings? Skip. */
        ret = panthor_vm_evict_bo_mappings_locked(bo);
        if (ret)
                goto out_unlock;

        /* If everything went fine, evict the object. */
        panthor_gem_evict_locked(bo);

out_unlock:
        if (last_locked) {
                drm_gem_for_each_gpuvm_bo(vm_bo, obj) {
                        struct dma_resv *resv = drm_gpuvm_resv(vm_bo->vm);

                        if (resv == obj->resv)
                                continue;

                        dma_resv_unlock(resv);

                        if (last_locked == vm_bo)
                                break;
                }
        }
        mutex_unlock(&bo->base.gpuva.lock);

        return ret == 0;
}

static bool panthor_gem_try_evict(struct drm_gem_object *obj,
                                  struct ww_acquire_ctx *ticket)
{
        struct panthor_gem_object *bo = to_panthor_bo(obj);

        /* Wait was too long, skip. */
        if (dma_resv_wait_timeout(obj->resv, DMA_RESV_USAGE_BOOKKEEP, false, 10) <= 0)
                return false;

        return panthor_gem_try_evict_no_resv_wait(&bo->base, ticket);
}

static unsigned long
panthor_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
{
        struct panthor_device *ptdev = shrinker->private_data;
        unsigned long remaining = 0;
        unsigned long freed = 0;

        if (!can_swap())
                goto out;

        freed += drm_gem_lru_scan(&ptdev->base, &ptdev->reclaim.unused,
                                  sc->nr_to_scan - freed, &remaining,
                                  panthor_gem_try_evict_no_resv_wait, NULL);
        if (freed >= sc->nr_to_scan)
                goto out;

        freed += drm_gem_lru_scan(&ptdev->base, &ptdev->reclaim.mmapped,
                                  sc->nr_to_scan - freed, &remaining,
                                  panthor_gem_try_evict_no_resv_wait, NULL);
        if (freed >= sc->nr_to_scan)
                goto out;

        if (!can_block(sc))
                goto out;

        freed += panthor_mmu_reclaim_priv_bos(ptdev, sc->nr_to_scan - freed,
                                              &remaining, panthor_gem_try_evict);
        if (freed >= sc->nr_to_scan)
                goto out;

        freed += drm_gem_lru_scan(&ptdev->base, &ptdev->reclaim.gpu_mapped_shared,
                                  sc->nr_to_scan - freed, &remaining,
                                  panthor_gem_try_evict, NULL);

out:
#ifdef CONFIG_DEBUG_FS
        /* This is racy, but that's okay, because this is just debugfs
         * reporting and doesn't need to be accurate.
         */
        ptdev->reclaim.nr_pages_reclaimed_on_last_scan = freed;
#endif

        /* If there are things to reclaim, try a couple times before giving up. */
        if (!freed && remaining > 0 &&
            atomic_inc_return(&ptdev->reclaim.retry_count) < 2)
                return 0;

        atomic_set(&ptdev->reclaim.retry_count, 0);

        if (freed)
                return freed;

        /* There's nothing left to reclaim, or the resources are contended. Give up now. */
        return SHRINK_STOP;
}

int panthor_gem_shrinker_init(struct panthor_device *ptdev)
{
        struct shrinker *shrinker;

        INIT_LIST_HEAD(&ptdev->reclaim.vms);
        drm_gem_lru_init(&ptdev->reclaim.unused);
        drm_gem_lru_init(&ptdev->reclaim.mmapped);
        drm_gem_lru_init(&ptdev->reclaim.gpu_mapped_shared);
        ptdev->reclaim.gpu_mapped_count = 0;

        /* Teach lockdep about lock ordering wrt. shrinker: */
        fs_reclaim_acquire(GFP_KERNEL);
        might_lock(&ptdev->base.gem_lru_mutex);
        fs_reclaim_release(GFP_KERNEL);

        shrinker = shrinker_alloc(0, "drm-panthor-gem");
        if (!shrinker)
                return -ENOMEM;

        shrinker->count_objects = panthor_gem_shrinker_count;
        shrinker->scan_objects = panthor_gem_shrinker_scan;
        shrinker->private_data = ptdev;
        ptdev->reclaim.shrinker = shrinker;

        shrinker_register(shrinker);
        return 0;
}

void panthor_gem_shrinker_unplug(struct panthor_device *ptdev)
{
        if (ptdev->reclaim.shrinker)
                shrinker_free(ptdev->reclaim.shrinker);
}

#ifdef CONFIG_DEBUG_FS
struct gem_size_totals {
        size_t size;
        size_t resident;
        size_t reclaimable;
};

static void panthor_gem_debugfs_print_flag_names(struct seq_file *m)
{
        int len;
        int i;

        static const char * const gem_state_flags_names[] = {
                [PANTHOR_DEBUGFS_GEM_STATE_IMPORTED_BIT] = "imported",
                [PANTHOR_DEBUGFS_GEM_STATE_EXPORTED_BIT] = "exported",
                [PANTHOR_DEBUGFS_GEM_STATE_EVICTED_BIT] = "evicted",
        };

        static const char * const gem_usage_flags_names[] = {
                [PANTHOR_DEBUGFS_GEM_USAGE_KERNEL_BIT] = "kernel",
                [PANTHOR_DEBUGFS_GEM_USAGE_FW_MAPPED_BIT] = "fw-mapped",
        };

        seq_puts(m, "GEM state flags: ");
        for (i = 0, len = ARRAY_SIZE(gem_state_flags_names); i < len; i++) {
                if (!gem_state_flags_names[i])
                        continue;
                seq_printf(m, "%s (0x%x)%s", gem_state_flags_names[i],
                           (u32)BIT(i), (i < len - 1) ? ", " : "\n");
        }

        seq_puts(m, "GEM usage flags: ");
        for (i = 0, len = ARRAY_SIZE(gem_usage_flags_names); i < len; i++) {
                if (!gem_usage_flags_names[i])
                        continue;
                seq_printf(m, "%s (0x%x)%s", gem_usage_flags_names[i],
                           (u32)BIT(i), (i < len - 1) ? ", " : "\n\n");
        }
}

static void panthor_gem_debugfs_bo_print(struct panthor_gem_object *bo,
                                         struct seq_file *m,
                                         struct gem_size_totals *totals)
{
        enum panthor_gem_reclaim_state reclaim_state = bo->reclaim_state;
        unsigned int refcount = kref_read(&bo->base.refcount);
        int reclaimed_count = atomic_read(&bo->reclaimed_count);
        char creator_info[32] = {};
        size_t resident_size;
        u32 gem_usage_flags = bo->debugfs.flags;
        u32 gem_state_flags = 0;

        /* Skip BOs being destroyed. */
        if (!refcount)
                return;

        resident_size = bo->backing.pages ? bo->base.size : 0;

        snprintf(creator_info, sizeof(creator_info),
                 "%s/%d", bo->debugfs.creator.process_name, bo->debugfs.creator.tgid);
        seq_printf(m, "%-32s%-16d%-11d%-11d%-16zd%-16zd0x%-16lx",
                   creator_info,
                   bo->base.name,
                   refcount,
                   reclaimed_count,
                   bo->base.size,
                   resident_size,
                   drm_vma_node_start(&bo->base.vma_node));

        if (drm_gem_is_imported(&bo->base))
                gem_state_flags |= PANTHOR_DEBUGFS_GEM_STATE_FLAG_IMPORTED;
        else if (!resident_size && reclaimed_count)
                gem_state_flags |= PANTHOR_DEBUGFS_GEM_STATE_FLAG_EVICTED;

        if (bo->base.dma_buf)
                gem_state_flags |= PANTHOR_DEBUGFS_GEM_STATE_FLAG_EXPORTED;

        seq_printf(m, "0x%-8x 0x%-10x", gem_state_flags, gem_usage_flags);

        scoped_guard(mutex, &bo->label.lock) {
                seq_printf(m, "%s\n", bo->label.str ? : "");
        }

        totals->size += bo->base.size;
        totals->resident += resident_size;
        if (reclaim_state != PANTHOR_GEM_UNRECLAIMABLE)
                totals->reclaimable += resident_size;
}

static void panthor_gem_debugfs_print_bos(struct panthor_device *ptdev,
                                          struct seq_file *m)
{
        struct gem_size_totals totals = {0};
        struct panthor_gem_object *bo;

        panthor_gem_debugfs_print_flag_names(m);

        seq_puts(m, "created-by                      global-name     refcount   evictions  size            resident-size   file-offset       state      usage       label\n");
        seq_puts(m, "----------------------------------------------------------------------------------------------------------------------------------------------------\n");

        scoped_guard(mutex, &ptdev->gems.lock) {
                list_for_each_entry(bo, &ptdev->gems.node, debugfs.node) {
                        panthor_gem_debugfs_bo_print(bo, m, &totals);
                }
        }

        seq_puts(m, "====================================================================================================================================================\n");
        seq_printf(m, "Total size: %zd, Total resident: %zd, Total reclaimable: %zd\n",
                   totals.size, totals.resident, totals.reclaimable);
}

static int panthor_gem_show_bos(struct seq_file *m, void *data)
{
        struct drm_info_node *node = m->private;
        struct drm_device *dev = node->minor->dev;
        struct panthor_device *ptdev =
                container_of(dev, struct panthor_device, base);

        panthor_gem_debugfs_print_bos(ptdev, m);

        return 0;
}

static struct drm_info_list panthor_gem_debugfs_list[] = {
        { "gems", panthor_gem_show_bos, 0, NULL },
};

static int shrink_get(void *data, u64 *val)
{
        struct panthor_device *ptdev =
                container_of(data, struct panthor_device, base);

        *val = ptdev->reclaim.nr_pages_reclaimed_on_last_scan;
        return 0;
}

static int shrink_set(void *data, u64 val)
{
        struct panthor_device *ptdev =
                container_of(data, struct panthor_device, base);
        struct shrink_control sc = {
                .gfp_mask = GFP_KERNEL,
                .nr_to_scan = val,
        };

        fs_reclaim_acquire(GFP_KERNEL);
        if (ptdev->reclaim.shrinker)
                panthor_gem_shrinker_scan(ptdev->reclaim.shrinker, &sc);
        fs_reclaim_release(GFP_KERNEL);

        return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(panthor_gem_debugfs_shrink_fops,
                         shrink_get, shrink_set,
                         "0x%08llx\n");

void panthor_gem_debugfs_init(struct drm_minor *minor)
{
        drm_debugfs_create_files(panthor_gem_debugfs_list,
                                 ARRAY_SIZE(panthor_gem_debugfs_list),
                                 minor->debugfs_root, minor);
        debugfs_create_file("shrink", 0600, minor->debugfs_root,
                            minor->dev, &panthor_gem_debugfs_shrink_fops);
}
#endif