[PATCH v12 1/5] drm: improve drm_buddy_alloc function
Matthew Auld
matthew.william.auld at gmail.com
Mon Feb 14 08:36:22 UTC 2022
On Mon, 14 Feb 2022 at 06:32, Christian König
<ckoenig.leichtzumerken at gmail.com> wrote:
>
> Am 13.02.22 um 09:52 schrieb Arunpravin:
> > - Make drm_buddy_alloc a single function to handle
> > range allocation and non-range allocation demands
> >
> > - Implemented a new function alloc_range() which allocates
> > the requested power-of-two block comply with range limitations
> >
> > - Moved order computation and memory alignment logic from
> > i915 driver to drm buddy
> >
> > v2:
> > merged below changes to keep the build unbroken
> > - drm_buddy_alloc_range() becomes obsolete and may be removed
> > - enable ttm range allocation (fpfn / lpfn) support in i915 driver
> > - apply enhanced drm_buddy_alloc() function to i915 driver
> >
> > v3(Matthew Auld):
> > - Fix alignment issues and remove unnecessary list_empty check
> > - add more validation checks for input arguments
> > - make alloc_range() block allocations as bottom-up
> > - optimize order computation logic
> > - replace uint64_t with u64, which is preferred in the kernel
> >
> > v4(Matthew Auld):
> > - keep drm_buddy_alloc_range() function implementation for generic
> > actual range allocations
> > - keep alloc_range() implementation for end bias allocations
> >
> > v5(Matthew Auld):
> > - modify drm_buddy_alloc() passing argument place->lpfn to lpfn
> > as place->lpfn will currently always be zero for i915
> >
> > v6(Matthew Auld):
> > - fixup potential uaf - If we are unlucky and can't allocate
> > enough memory when splitting blocks, where we temporarily
> > end up with the given block and its buddy on the respective
> > free list, then we need to ensure we delete both blocks,
> > and no just the buddy, before potentially freeing them
> >
> > - fix warnings reported by kernel test robot <lkp at intel.com>
> >
> > v7(Matthew Auld):
> > - revert fixup potential uaf
> > - keep __alloc_range() add node to the list logic same as
> > drm_buddy_alloc_blocks() by having a temporary list variable
> > - at drm_buddy_alloc_blocks() keep i915 range_overflows macro
> > and add a new check for end variable
> >
> > v8:
> > - fix warnings reported by kernel test robot <lkp at intel.com>
> >
> > v9(Matthew Auld):
> > - remove DRM_BUDDY_RANGE_ALLOCATION flag
> > - remove unnecessary function description
> >
> > Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam at amd.com>
> > Reviewed-by: Matthew Auld <matthew.auld at intel.com>
>
> As long as nobody objects I'm going to push patches 1-3 to drm-misc-next
> in the next hour or so:
As part of this could you also push
https://patchwork.freedesktop.org/series/99842/ ?
>
> Then going to take a deeper look into patches 4 and 5 to get them reviewed.
>
> Thanks,
> Christian.
>
> > ---
> > drivers/gpu/drm/drm_buddy.c | 292 +++++++++++++-----
> > drivers/gpu/drm/i915/i915_ttm_buddy_manager.c | 63 ++--
> > drivers/gpu/drm/i915/i915_ttm_buddy_manager.h | 2 +
> > include/drm/drm_buddy.h | 11 +-
> > 4 files changed, 250 insertions(+), 118 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
> > index d60878bc9c20..e0c0d786a572 100644
> > --- a/drivers/gpu/drm/drm_buddy.c
> > +++ b/drivers/gpu/drm/drm_buddy.c
> > @@ -282,23 +282,97 @@ void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects)
> > }
> > EXPORT_SYMBOL(drm_buddy_free_list);
> >
> > -/**
> > - * drm_buddy_alloc_blocks - allocate power-of-two blocks
> > - *
> > - * @mm: DRM buddy manager to allocate from
> > - * @order: size of the allocation
> > - *
> > - * The order value here translates to:
> > - *
> > - * 0 = 2^0 * mm->chunk_size
> > - * 1 = 2^1 * mm->chunk_size
> > - * 2 = 2^2 * mm->chunk_size
> > - *
> > - * Returns:
> > - * allocated ptr to the &drm_buddy_block on success
> > - */
> > -struct drm_buddy_block *
> > -drm_buddy_alloc_blocks(struct drm_buddy *mm, unsigned int order)
> > +static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
> > +{
> > + return s1 <= e2 && e1 >= s2;
> > +}
> > +
> > +static inline bool contains(u64 s1, u64 e1, u64 s2, u64 e2)
> > +{
> > + return s1 <= s2 && e1 >= e2;
> > +}
> > +
> > +static struct drm_buddy_block *
> > +alloc_range_bias(struct drm_buddy *mm,
> > + u64 start, u64 end,
> > + unsigned int order)
> > +{
> > + struct drm_buddy_block *block;
> > + struct drm_buddy_block *buddy;
> > + LIST_HEAD(dfs);
> > + int err;
> > + int i;
> > +
> > + end = end - 1;
> > +
> > + for (i = 0; i < mm->n_roots; ++i)
> > + list_add_tail(&mm->roots[i]->tmp_link, &dfs);
> > +
> > + do {
> > + u64 block_start;
> > + u64 block_end;
> > +
> > + block = list_first_entry_or_null(&dfs,
> > + struct drm_buddy_block,
> > + tmp_link);
> > + if (!block)
> > + break;
> > +
> > + list_del(&block->tmp_link);
> > +
> > + if (drm_buddy_block_order(block) < order)
> > + continue;
> > +
> > + block_start = drm_buddy_block_offset(block);
> > + block_end = block_start + drm_buddy_block_size(mm, block) - 1;
> > +
> > + if (!overlaps(start, end, block_start, block_end))
> > + continue;
> > +
> > + if (drm_buddy_block_is_allocated(block))
> > + continue;
> > +
> > + if (contains(start, end, block_start, block_end) &&
> > + order == drm_buddy_block_order(block)) {
> > + /*
> > + * Find the free block within the range.
> > + */
> > + if (drm_buddy_block_is_free(block))
> > + return block;
> > +
> > + continue;
> > + }
> > +
> > + if (!drm_buddy_block_is_split(block)) {
> > + err = split_block(mm, block);
> > + if (unlikely(err))
> > + goto err_undo;
> > + }
> > +
> > + list_add(&block->right->tmp_link, &dfs);
> > + list_add(&block->left->tmp_link, &dfs);
> > + } while (1);
> > +
> > + return ERR_PTR(-ENOSPC);
> > +
> > +err_undo:
> > + /*
> > + * We really don't want to leave around a bunch of split blocks, since
> > + * bigger is better, so make sure we merge everything back before we
> > + * free the allocated blocks.
> > + */
> > + buddy = get_buddy(block);
> > + if (buddy &&
> > + (drm_buddy_block_is_free(block) &&
> > + drm_buddy_block_is_free(buddy)))
> > + __drm_buddy_free(mm, block);
> > + return ERR_PTR(err);
> > +}
> > +
> > +static struct drm_buddy_block *
> > +alloc_from_freelist(struct drm_buddy *mm,
> > + unsigned int order,
> > + unsigned long flags)
> > {
> > struct drm_buddy_block *block = NULL;
> > unsigned int i;
> > @@ -320,78 +394,29 @@ drm_buddy_alloc_blocks(struct drm_buddy *mm, unsigned int order)
> > while (i != order) {
> > err = split_block(mm, block);
> > if (unlikely(err))
> > - goto out_free;
> > + goto err_undo;
> >
> > - /* Go low */
> > - block = block->left;
> > + block = block->right;
> > i--;
> > }
> > -
> > - mark_allocated(block);
> > - mm->avail -= drm_buddy_block_size(mm, block);
> > - kmemleak_update_trace(block);
> > return block;
> >
> > -out_free:
> > +err_undo:
> > if (i != order)
> > __drm_buddy_free(mm, block);
> > return ERR_PTR(err);
> > }
> > -EXPORT_SYMBOL(drm_buddy_alloc_blocks);
> > -
> > -static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
> > -{
> > - return s1 <= e2 && e1 >= s2;
> > -}
> > -
> > -static inline bool contains(u64 s1, u64 e1, u64 s2, u64 e2)
> > -{
> > - return s1 <= s2 && e1 >= e2;
> > -}
> >
> > -/**
> > - * drm_buddy_alloc_range - allocate range
> > - *
> > - * @mm: DRM buddy manager to allocate from
> > - * @blocks: output list head to add allocated blocks
> > - * @start: start of the allowed range for this block
> > - * @size: size of the allocation
> > - *
> > - * Intended for pre-allocating portions of the address space, for example to
> > - * reserve a block for the initial framebuffer or similar, hence the expectation
> > - * here is that drm_buddy_alloc_blocks() is still the main vehicle for
> > - * allocations, so if that's not the case then the drm_mm range allocator is
> > - * probably a much better fit, and so you should probably go use that instead.
> > - *
> > - * Note that it's safe to chain together multiple alloc_ranges
> > - * with the same blocks list
> > - *
> > - * Returns:
> > - * 0 on success, error code on failure.
> > - */
> > -int drm_buddy_alloc_range(struct drm_buddy *mm,
> > - struct list_head *blocks,
> > - u64 start, u64 size)
> > +static int __alloc_range(struct drm_buddy *mm,
> > + struct list_head *dfs,
> > + u64 start, u64 size,
> > + struct list_head *blocks)
> > {
> > struct drm_buddy_block *block;
> > struct drm_buddy_block *buddy;
> > LIST_HEAD(allocated);
> > - LIST_HEAD(dfs);
> > u64 end;
> > int err;
> > - int i;
> > -
> > - if (size < mm->chunk_size)
> > - return -EINVAL;
> > -
> > - if (!IS_ALIGNED(size | start, mm->chunk_size))
> > - return -EINVAL;
> > -
> > - if (range_overflows(start, size, mm->size))
> > - return -EINVAL;
> > -
> > - for (i = 0; i < mm->n_roots; ++i)
> > - list_add_tail(&mm->roots[i]->tmp_link, &dfs);
> >
> > end = start + size - 1;
> >
> > @@ -399,7 +424,7 @@ int drm_buddy_alloc_range(struct drm_buddy *mm,
> > u64 block_start;
> > u64 block_end;
> >
> > - block = list_first_entry_or_null(&dfs,
> > + block = list_first_entry_or_null(dfs,
> > struct drm_buddy_block,
> > tmp_link);
> > if (!block)
> > @@ -436,8 +461,8 @@ int drm_buddy_alloc_range(struct drm_buddy *mm,
> > goto err_undo;
> > }
> >
> > - list_add(&block->right->tmp_link, &dfs);
> > - list_add(&block->left->tmp_link, &dfs);
> > + list_add(&block->right->tmp_link, dfs);
> > + list_add(&block->left->tmp_link, dfs);
> > } while (1);
> >
> > list_splice_tail(&allocated, blocks);
> > @@ -459,7 +484,120 @@ int drm_buddy_alloc_range(struct drm_buddy *mm,
> > drm_buddy_free_list(mm, &allocated);
> > return err;
> > }
> > -EXPORT_SYMBOL(drm_buddy_alloc_range);
> > +
> > +static int __drm_buddy_alloc_range(struct drm_buddy *mm,
> > + u64 start,
> > + u64 size,
> > + struct list_head *blocks)
> > +{
> > + LIST_HEAD(dfs);
> > + int i;
> > +
> > + for (i = 0; i < mm->n_roots; ++i)
> > + list_add_tail(&mm->roots[i]->tmp_link, &dfs);
> > +
> > + return __alloc_range(mm, &dfs, start, size, blocks);
> > +}
> > +
> > +/**
> > + * drm_buddy_alloc_blocks - allocate power-of-two blocks
> > + *
> > + * @mm: DRM buddy manager to allocate from
> > + * @start: start of the allowed range for this block
> > + * @end: end of the allowed range for this block
> > + * @size: size of the allocation
> > + * @min_page_size: alignment of the allocation
> > + * @blocks: output list head to add allocated blocks
> > + * @flags: DRM_BUDDY_*_ALLOCATION flags
> > + *
> > + * alloc_range_bias() called on range limitations, which traverses
> > + * the tree and returns the desired block.
> > + *
> > + * alloc_from_freelist() called when *no* range restrictions
> > + * are enforced, which picks the block from the freelist.
> > + *
> > + * Returns:
> > + * 0 on success, error code on failure.
> > + */
> > +int drm_buddy_alloc_blocks(struct drm_buddy *mm,
> > + u64 start, u64 end, u64 size,
> > + u64 min_page_size,
> > + struct list_head *blocks,
> > + unsigned long flags)
> > +{
> > + struct drm_buddy_block *block = NULL;
> > + unsigned int min_order, order;
> > + unsigned long pages;
> > + LIST_HEAD(allocated);
> > + int err;
> > +
> > + if (size < mm->chunk_size)
> > + return -EINVAL;
> > +
> > + if (min_page_size < mm->chunk_size)
> > + return -EINVAL;
> > +
> > + if (!is_power_of_2(min_page_size))
> > + return -EINVAL;
> > +
> > + if (!IS_ALIGNED(start | end | size, mm->chunk_size))
> > + return -EINVAL;
> > +
> > + if (end > mm->size)
> > + return -EINVAL;
> > +
> > + if (range_overflows(start, size, mm->size))
> > + return -EINVAL;
> > +
> > + /* Actual range allocation */
> > + if (start + size == end)
> > + return __drm_buddy_alloc_range(mm, start, size, blocks);
> > +
> > + pages = size >> ilog2(mm->chunk_size);
> > + order = fls(pages) - 1;
> > + min_order = ilog2(min_page_size) - ilog2(mm->chunk_size);
> > +
> > + do {
> > + order = min(order, (unsigned int)fls(pages) - 1);
> > + BUG_ON(order > mm->max_order);
> > + BUG_ON(order < min_order);
> > +
> > + do {
> > + if (start || end != size)
> > + /* Allocate traversing within the range */
> > + block = alloc_range_bias(mm, start, end, order);
> > + else
> > + /* Allocate from freelist */
> > + block = alloc_from_freelist(mm, order, flags);
> > +
> > + if (!IS_ERR(block))
> > + break;
> > +
> > + if (order-- == min_order) {
> > + err = -ENOSPC;
> > + goto err_free;
> > + }
> > + } while (1);
> > +
> > + mark_allocated(block);
> > + mm->avail -= drm_buddy_block_size(mm, block);
> > + kmemleak_update_trace(block);
> > + list_add_tail(&block->link, &allocated);
> > +
> > + pages -= BIT(order);
> > +
> > + if (!pages)
> > + break;
> > + } while (1);
> > +
> > + list_splice_tail(&allocated, blocks);
> > + return 0;
> > +
> > +err_free:
> > + drm_buddy_free_list(mm, &allocated);
> > + return err;
> > +}
> > +EXPORT_SYMBOL(drm_buddy_alloc_blocks);
> >
> > /**
> > * drm_buddy_block_print - print block information
> > diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> > index 247714bab044..7aef6ad9fe84 100644
> > --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> > +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> > @@ -36,13 +36,14 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
> > struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
> > struct i915_ttm_buddy_resource *bman_res;
> > struct drm_buddy *mm = &bman->mm;
> > - unsigned long n_pages;
> > - unsigned int min_order;
> > + unsigned long n_pages, lpfn;
> > u64 min_page_size;
> > u64 size;
> > int err;
> >
> > - GEM_BUG_ON(place->fpfn || place->lpfn);
> > + lpfn = place->lpfn;
> > + if (!lpfn)
> > + lpfn = man->size;
> >
> > bman_res = kzalloc(sizeof(*bman_res), GFP_KERNEL);
> > if (!bman_res)
> > @@ -60,10 +61,16 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
> > min_page_size = bo->page_alignment << PAGE_SHIFT;
> >
> > GEM_BUG_ON(min_page_size < mm->chunk_size);
> > - min_order = ilog2(min_page_size) - ilog2(mm->chunk_size);
> > +
> > if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
> > + unsigned long pages;
> > +
> > size = roundup_pow_of_two(size);
> > - min_order = ilog2(size) - ilog2(mm->chunk_size);
> > + min_page_size = size;
> > +
> > + pages = size >> ilog2(mm->chunk_size);
> > + if (pages > lpfn)
> > + lpfn = pages;
> > }
> >
> > if (size > mm->size) {
> > @@ -73,34 +80,16 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
> >
> > n_pages = size >> ilog2(mm->chunk_size);
> >
> > - do {
> > - struct drm_buddy_block *block;
> > - unsigned int order;
> > -
> > - order = fls(n_pages) - 1;
> > - GEM_BUG_ON(order > mm->max_order);
> > - GEM_BUG_ON(order < min_order);
> > -
> > - do {
> > - mutex_lock(&bman->lock);
> > - block = drm_buddy_alloc_blocks(mm, order);
> > - mutex_unlock(&bman->lock);
> > - if (!IS_ERR(block))
> > - break;
> > -
> > - if (order-- == min_order) {
> > - err = -ENOSPC;
> > - goto err_free_blocks;
> > - }
> > - } while (1);
> > -
> > - n_pages -= BIT(order);
> > -
> > - list_add_tail(&block->link, &bman_res->blocks);
> > -
> > - if (!n_pages)
> > - break;
> > - } while (1);
> > + mutex_lock(&bman->lock);
> > + err = drm_buddy_alloc_blocks(mm, (u64)place->fpfn << PAGE_SHIFT,
> > + (u64)lpfn << PAGE_SHIFT,
> > + (u64)n_pages << PAGE_SHIFT,
> > + min_page_size,
> > + &bman_res->blocks,
> > + bman_res->flags);
> > + mutex_unlock(&bman->lock);
> > + if (unlikely(err))
> > + goto err_free_blocks;
> >
> > *res = &bman_res->base;
> > return 0;
> > @@ -268,12 +257,16 @@ int i915_ttm_buddy_man_reserve(struct ttm_resource_manager *man,
> > {
> > struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
> > struct drm_buddy *mm = &bman->mm;
> > + unsigned long flags = 0;
> > int ret;
> >
> > mutex_lock(&bman->lock);
> > - ret = drm_buddy_alloc_range(mm, &bman->reserved, start, size);
> > + ret = drm_buddy_alloc_blocks(mm, start,
> > + start + size,
> > + size, mm->chunk_size,
> > + &bman->reserved,
> > + flags);
> > mutex_unlock(&bman->lock);
> >
> > return ret;
> > }
> > -
> > diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
> > index 312077941411..72c90b432e87 100644
> > --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
> > +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
> > @@ -20,6 +20,7 @@ struct drm_buddy;
> > *
> > * @base: struct ttm_resource base class we extend
> > * @blocks: the list of struct i915_buddy_block for this resource/allocation
> > + * @flags: DRM_BUDDY_*_ALLOCATION flags
> > * @mm: the struct i915_buddy_mm for this resource
> > *
> > * Extends the struct ttm_resource to manage an address space allocation with
> > @@ -28,6 +29,7 @@ struct drm_buddy;
> > struct i915_ttm_buddy_resource {
> > struct ttm_resource base;
> > struct list_head blocks;
> > + unsigned long flags;
> > struct drm_buddy *mm;
> > };
> >
> > diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
> > index f524db152413..1f2435426c69 100644
> > --- a/include/drm/drm_buddy.h
> > +++ b/include/drm/drm_buddy.h
> > @@ -131,12 +131,11 @@ int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size);
> >
> > void drm_buddy_fini(struct drm_buddy *mm);
> >
> > -struct drm_buddy_block *
> > -drm_buddy_alloc_blocks(struct drm_buddy *mm, unsigned int order);
> > -
> > -int drm_buddy_alloc_range(struct drm_buddy *mm,
> > - struct list_head *blocks,
> > - u64 start, u64 size);
> > +int drm_buddy_alloc_blocks(struct drm_buddy *mm,
> > + u64 start, u64 end, u64 size,
> > + u64 min_page_size,
> > + struct list_head *blocks,
> > + unsigned long flags);
> >
> > void drm_buddy_free_block(struct drm_buddy *mm, struct drm_buddy_block *block);
> >
>
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