/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2014-2016 Intel Corporation
 */

#include "i915_drv.h"
#include "i915_gem_object.h"
#include "i915_scatterlist.h"
#include "i915_gem_lmem.h"
#include "i915_gem_mman.h"

void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
                                 struct sg_table *pages,
                                 unsigned int sg_page_sizes)
{
        struct drm_i915_private *i915 = to_i915(obj->base.dev);
        unsigned long supported = INTEL_INFO(i915)->page_sizes;
        int i;

        lockdep_assert_held(&obj->mm.lock);

        if (i915_gem_object_is_volatile(obj))
                obj->mm.madv = I915_MADV_DONTNEED;

        /* Make the pages coherent with the GPU (flushing any swapin). */
        if (obj->cache_dirty) {
                obj->write_domain = 0;
                if (i915_gem_object_has_struct_page(obj))
                        drm_clflush_sg(pages);
                obj->cache_dirty = false;
        }

        obj->mm.get_page.sg_pos = pages->sgl;
        obj->mm.get_page.sg_idx = 0;

        obj->mm.pages = pages;

        if (i915_gem_object_is_tiled(obj) &&
            i915->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
                GEM_BUG_ON(obj->mm.quirked);
                __i915_gem_object_pin_pages(obj);
                obj->mm.quirked = true;
        }

        GEM_BUG_ON(!sg_page_sizes);
        obj->mm.page_sizes.phys = sg_page_sizes;

        /*
         * Calculate the supported page-sizes which fit into the given
         * sg_page_sizes. This will give us the page-sizes which we may be able
         * to use opportunistically when later inserting into the GTT. For
         * example if phys=2G, then in theory we should be able to use 1G, 2M,
         * 64K or 4K pages, although in practice this will depend on a number of
         * other factors.
         */
        obj->mm.page_sizes.sg = 0;
        for_each_set_bit(i, &supported, ilog2(I915_GTT_MAX_PAGE_SIZE) + 1) {
                if (obj->mm.page_sizes.phys & ~0u << i)
                        obj->mm.page_sizes.sg |= BIT(i);
        }
        GEM_BUG_ON(!HAS_PAGE_SIZES(i915, obj->mm.page_sizes.sg));

        if (i915_gem_object_is_shrinkable(obj)) {
                struct list_head *list;
                unsigned long flags;

                spin_lock_irqsave(&i915->mm.obj_lock, flags);

                i915->mm.shrink_count++;
                i915->mm.shrink_memory += obj->base.size;

                if (obj->mm.madv != I915_MADV_WILLNEED)
                        list = &i915->mm.purge_list;
                else
                        list = &i915->mm.shrink_list;
                list_add_tail(&obj->mm.link, list);

                atomic_set(&obj->mm.shrink_pin, 0);
                spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
        }
}

int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *i915 = to_i915(obj->base.dev);
        int err;

        if (unlikely(obj->mm.madv != I915_MADV_WILLNEED)) {
                drm_dbg(&i915->drm,
                        "Attempting to obtain a purgeable object\n");
                return -EFAULT;
        }

        err = obj->ops->get_pages(obj);
        GEM_BUG_ON(!err && !i915_gem_object_has_pages(obj));

        return err;
}

/* Ensure that the associated pages are gathered from the backing storage
 * and pinned into our object. i915_gem_object_pin_pages() may be called
 * multiple times before they are released by a single call to
 * i915_gem_object_unpin_pages() - once the pages are no longer referenced
 * either as a result of memory pressure (reaping pages under the shrinker)
 * or as the object is itself released.
 */
int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
{
        int err;

        err = mutex_lock_interruptible_nested(&obj->mm.lock, I915_MM_GET_PAGES);
        if (err)
                return err;

        if (unlikely(!i915_gem_object_has_pages(obj))) {
                GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));

                err = ____i915_gem_object_get_pages(obj);
                if (err)
                        goto unlock;

                smp_mb__before_atomic();
        }
        atomic_inc(&obj->mm.pages_pin_count);

unlock:
        mutex_unlock(&obj->mm.lock);
        return err;
}

/* Immediately discard the backing storage */
void i915_gem_object_truncate(struct drm_i915_gem_object *obj)
{
        drm_gem_free_mmap_offset(&obj->base);
        if (obj->ops->truncate)
                obj->ops->truncate(obj);
}

/* Try to discard unwanted pages */
void i915_gem_object_writeback(struct drm_i915_gem_object *obj)
{
        lockdep_assert_held(&obj->mm.lock);
        GEM_BUG_ON(i915_gem_object_has_pages(obj));

        if (obj->ops->writeback)
                obj->ops->writeback(obj);
}

static void __i915_gem_object_reset_page_iter(struct drm_i915_gem_object *obj)
{
        struct radix_tree_iter iter;
        void __rcu **slot;

        rcu_read_lock();
        radix_tree_for_each_slot(slot, &obj->mm.get_page.radix, &iter, 0)
                radix_tree_delete(&obj->mm.get_page.radix, iter.index);
        rcu_read_unlock();
}

static void unmap_object(struct drm_i915_gem_object *obj, void *ptr)
{
        if (is_vmalloc_addr(ptr))
                vunmap(ptr);
        else
                kunmap(kmap_to_page(ptr));
}

struct sg_table *
__i915_gem_object_unset_pages(struct drm_i915_gem_object *obj)
{
        struct sg_table *pages;

        pages = fetch_and_zero(&obj->mm.pages);
        if (IS_ERR_OR_NULL(pages))
                return pages;

        if (i915_gem_object_is_volatile(obj))
                obj->mm.madv = I915_MADV_WILLNEED;

        i915_gem_object_make_unshrinkable(obj);

        if (obj->mm.mapping) {
                unmap_object(obj, page_mask_bits(obj->mm.mapping));
                obj->mm.mapping = NULL;
        }

        __i915_gem_object_reset_page_iter(obj);
        obj->mm.page_sizes.phys = obj->mm.page_sizes.sg = 0;

        return pages;
}

int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
{
        struct sg_table *pages;
        int err;

        if (i915_gem_object_has_pinned_pages(obj))
                return -EBUSY;

        /* May be called by shrinker from within get_pages() (on another bo) */
        mutex_lock(&obj->mm.lock);
        if (unlikely(atomic_read(&obj->mm.pages_pin_count))) {
                err = -EBUSY;
                goto unlock;
        }

        i915_gem_object_release_mmap_offset(obj);

        /*
         * ->put_pages might need to allocate memory for the bit17 swizzle
         * array, hence protect them from being reaped by removing them from gtt
         * lists early.
         */
        pages = __i915_gem_object_unset_pages(obj);

        /*
         * XXX Temporary hijinx to avoid updating all backends to handle
         * NULL pages. In the future, when we have more asynchronous
         * get_pages backends we should be better able to handle the
         * cancellation of the async task in a more uniform manner.
         */
        if (!pages && !i915_gem_object_needs_async_cancel(obj))
                pages = ERR_PTR(-EINVAL);

        if (!IS_ERR(pages))
                obj->ops->put_pages(obj, pages);

        err = 0;
unlock:
        mutex_unlock(&obj->mm.lock);

        return err;
}

static inline pte_t iomap_pte(resource_size_t base,
                              dma_addr_t offset,
                              pgprot_t prot)
{
        return pte_mkspecial(pfn_pte((base + offset) >> PAGE_SHIFT, prot));
}

/* The 'mapping' part of i915_gem_object_pin_map() below */
static void *i915_gem_object_map(struct drm_i915_gem_object *obj,
                                 enum i915_map_type type)
{
        unsigned long n_pte = obj->base.size >> PAGE_SHIFT;
        struct sg_table *sgt = obj->mm.pages;
        pte_t *stack[32], **mem;
        struct vm_struct *area;
        pgprot_t pgprot;

        if (!i915_gem_object_has_struct_page(obj) && type != I915_MAP_WC)
                return NULL;

        /* A single page can always be kmapped */
        if (n_pte == 1 && type == I915_MAP_WB)
                return kmap(sg_page(sgt->sgl));

        mem = stack;
        if (n_pte > ARRAY_SIZE(stack)) {
                /* Too big for stack -- allocate temporary array instead */
                mem = kvmalloc_array(n_pte, sizeof(*mem), GFP_KERNEL);
                if (!mem)
                        return NULL;
        }

        area = alloc_vm_area(obj->base.size, mem);
        if (!area) {
                if (mem != stack)
                        kvfree(mem);
                return NULL;
        }

        switch (type) {
        default:
                MISSING_CASE(type);
                fallthrough;    /* to use PAGE_KERNEL anyway */
        case I915_MAP_WB:
                pgprot = PAGE_KERNEL;
                break;
        case I915_MAP_WC:
                pgprot = pgprot_writecombine(PAGE_KERNEL_IO);
                break;
        }

        if (i915_gem_object_has_struct_page(obj)) {
                struct sgt_iter iter;
                struct page *page;
                pte_t **ptes = mem;

                for_each_sgt_page(page, iter, sgt)
                        **ptes++ = mk_pte(page, pgprot);
        } else {
                resource_size_t iomap;
                struct sgt_iter iter;
                pte_t **ptes = mem;
                dma_addr_t addr;

                iomap = obj->mm.region->iomap.base;
                iomap -= obj->mm.region->region.start;

                for_each_sgt_daddr(addr, iter, sgt)
                        **ptes++ = iomap_pte(iomap, addr, pgprot);
        }

        if (mem != stack)
                kvfree(mem);

        return area->addr;
}

/* get, pin, and map the pages of the object into kernel space */
void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
                              enum i915_map_type type)
{
        enum i915_map_type has_type;
        unsigned int flags;
        bool pinned;
        void *ptr;
        int err;

        flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE | I915_GEM_OBJECT_HAS_IOMEM;
        if (!i915_gem_object_type_has(obj, flags))
                return ERR_PTR(-ENXIO);

        err = mutex_lock_interruptible_nested(&obj->mm.lock, I915_MM_GET_PAGES);
        if (err)
                return ERR_PTR(err);

        pinned = !(type & I915_MAP_OVERRIDE);
        type &= ~I915_MAP_OVERRIDE;

        if (!atomic_inc_not_zero(&obj->mm.pages_pin_count)) {
                if (unlikely(!i915_gem_object_has_pages(obj))) {
                        GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));

                        err = ____i915_gem_object_get_pages(obj);
                        if (err)
                                goto err_unlock;

                        smp_mb__before_atomic();
                }
                atomic_inc(&obj->mm.pages_pin_count);
                pinned = false;
        }
        GEM_BUG_ON(!i915_gem_object_has_pages(obj));

        ptr = page_unpack_bits(obj->mm.mapping, &has_type);
        if (ptr && has_type != type) {
                if (pinned) {
                        err = -EBUSY;
                        goto err_unpin;
                }

                unmap_object(obj, ptr);

                ptr = obj->mm.mapping = NULL;
        }

        if (!ptr) {
                ptr = i915_gem_object_map(obj, type);
                if (!ptr) {
                        err = -ENOMEM;
                        goto err_unpin;
                }

                obj->mm.mapping = page_pack_bits(ptr, type);
        }

out_unlock:
        mutex_unlock(&obj->mm.lock);
        return ptr;

err_unpin:
        atomic_dec(&obj->mm.pages_pin_count);
err_unlock:
        ptr = ERR_PTR(err);
        goto out_unlock;
}

void __i915_gem_object_flush_map(struct drm_i915_gem_object *obj,
                                 unsigned long offset,
                                 unsigned long size)
{
        enum i915_map_type has_type;
        void *ptr;

        GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
        GEM_BUG_ON(range_overflows_t(typeof(obj->base.size),
                                     offset, size, obj->base.size));

        wmb(); /* let all previous writes be visible to coherent partners */
        obj->mm.dirty = true;

        if (obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_WRITE)
                return;

        ptr = page_unpack_bits(obj->mm.mapping, &has_type);
        if (has_type == I915_MAP_WC)
                return;

        drm_clflush_virt_range(ptr + offset, size);
        if (size == obj->base.size) {
                obj->write_domain &= ~I915_GEM_DOMAIN_CPU;
                obj->cache_dirty = false;
        }
}

void __i915_gem_object_release_map(struct drm_i915_gem_object *obj)
{
        GEM_BUG_ON(!obj->mm.mapping);

        /*
         * We allow removing the mapping from underneath pinned pages!
         *
         * Furthermore, since this is an unsafe operation reserved only
         * for construction time manipulation, we ignore locking prudence.
         */
        unmap_object(obj, page_mask_bits(fetch_and_zero(&obj->mm.mapping)));

        i915_gem_object_unpin_map(obj);
}

struct scatterlist *
i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
                       unsigned int n,
                       unsigned int *offset)
{
        struct i915_gem_object_page_iter *iter = &obj->mm.get_page;
        struct scatterlist *sg;
        unsigned int idx, count;

        might_sleep();
        GEM_BUG_ON(n >= obj->base.size >> PAGE_SHIFT);
        GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));

        /* As we iterate forward through the sg, we record each entry in a
         * radixtree for quick repeated (backwards) lookups. If we have seen
         * this index previously, we will have an entry for it.
         *
         * Initial lookup is O(N), but this is amortized to O(1) for
         * sequential page access (where each new request is consecutive
         * to the previous one). Repeated lookups are O(lg(obj->base.size)),
         * i.e. O(1) with a large constant!
         */
        if (n < READ_ONCE(iter->sg_idx))
                goto lookup;

        mutex_lock(&iter->lock);

        /* We prefer to reuse the last sg so that repeated lookup of this
         * (or the subsequent) sg are fast - comparing against the last
         * sg is faster than going through the radixtree.
         */

        sg = iter->sg_pos;
        idx = iter->sg_idx;
        count = __sg_page_count(sg);

        while (idx + count <= n) {
                void *entry;
                unsigned long i;
                int ret;

                /* If we cannot allocate and insert this entry, or the
                 * individual pages from this range, cancel updating the
                 * sg_idx so that on this lookup we are forced to linearly
                 * scan onwards, but on future lookups we will try the
                 * insertion again (in which case we need to be careful of
                 * the error return reporting that we have already inserted
                 * this index).
                 */
                ret = radix_tree_insert(&iter->radix, idx, sg);
                if (ret && ret != -EEXIST)
                        goto scan;

                entry = xa_mk_value(idx);
                for (i = 1; i < count; i++) {
                        ret = radix_tree_insert(&iter->radix, idx + i, entry);
                        if (ret && ret != -EEXIST)
                                goto scan;
                }

                idx += count;
                sg = ____sg_next(sg);
                count = __sg_page_count(sg);
        }

scan:
        iter->sg_pos = sg;
        iter->sg_idx = idx;

        mutex_unlock(&iter->lock);

        if (unlikely(n < idx)) /* insertion completed by another thread */
                goto lookup;

        /* In case we failed to insert the entry into the radixtree, we need
         * to look beyond the current sg.
         */
        while (idx + count <= n) {
                idx += count;
                sg = ____sg_next(sg);
                count = __sg_page_count(sg);
        }

        *offset = n - idx;
        return sg;

lookup:
        rcu_read_lock();

        sg = radix_tree_lookup(&iter->radix, n);
        GEM_BUG_ON(!sg);

        /* If this index is in the middle of multi-page sg entry,
         * the radix tree will contain a value entry that points
         * to the start of that range. We will return the pointer to
         * the base page and the offset of this page within the
         * sg entry's range.
         */
        *offset = 0;
        if (unlikely(xa_is_value(sg))) {
                unsigned long base = xa_to_value(sg);

                sg = radix_tree_lookup(&iter->radix, base);
                GEM_BUG_ON(!sg);

                *offset = n - base;
        }

        rcu_read_unlock();

        return sg;
}

struct page *
i915_gem_object_get_page(struct drm_i915_gem_object *obj, unsigned int n)
{
        struct scatterlist *sg;
        unsigned int offset;

        GEM_BUG_ON(!i915_gem_object_has_struct_page(obj));

        sg = i915_gem_object_get_sg(obj, n, &offset);
        return nth_page(sg_page(sg), offset);
}

/* Like i915_gem_object_get_page(), but mark the returned page dirty */
struct page *
i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj,
                               unsigned int n)
{
        struct page *page;

        page = i915_gem_object_get_page(obj, n);
        if (!obj->mm.dirty)
                set_page_dirty(page);

        return page;
}

dma_addr_t
i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj,
                                    unsigned long n,
                                    unsigned int *len)
{
        struct scatterlist *sg;
        unsigned int offset;

        sg = i915_gem_object_get_sg(obj, n, &offset);

        if (len)
                *len = sg_dma_len(sg) - (offset << PAGE_SHIFT);

        return sg_dma_address(sg) + (offset << PAGE_SHIFT);
}

dma_addr_t
i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj,
                                unsigned long n)
{
        return i915_gem_object_get_dma_address_len(obj, n, NULL);
}