drm/selftests: add drm buddy alloc range testcase

- add a test to check the range allocation
- export get_buddy() function in drm_buddy.c
- export drm_prandom_u32_max_state() in lib/drm_random.c
- include helper functions
- include prime number header file

v2:
- add drm_get_buddy() function description (Matthew Auld)
- removed unnecessary test succeeded print

Signed-off-by: Arunpravin <[e-mail]>
Reviewed-by: Matthew Auld <[e-mail]>
Acked-by: Christian König <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Christian König <[e-mail]>

drivers/gpu/drm/drm_buddy.c

···
 }
 
 static struct drm_buddy_block *
-get_buddy(struct drm_buddy_block *block)
+__get_buddy(struct drm_buddy_block *block)
 {
 	struct drm_buddy_block *parent;
 
···
 	return parent->left;
 }
 
+/**
+ * drm_get_buddy - get buddy address
+ *
+ * @block: DRM buddy block
+ *
+ * Returns the corresponding buddy block for @block, or NULL
+ * if this is a root block and can't be merged further.
+ * Requires some kind of locking to protect against
+ * any concurrent allocate and free operations.
+ */
+struct drm_buddy_block *
+drm_get_buddy(struct drm_buddy_block *block)
+{
+	return __get_buddy(block);
+}
+EXPORT_SYMBOL(drm_get_buddy);
+
 static void __drm_buddy_free(struct drm_buddy *mm,
 			     struct drm_buddy_block *block)
 {
···
 	while ((parent = block->parent)) {
 		struct drm_buddy_block *buddy;
 
-		buddy = get_buddy(block);
+		buddy = __get_buddy(block);
 
 		if (!drm_buddy_block_is_free(buddy))
 			break;
···
 	 * bigger is better, so make sure we merge everything back before we
 	 * free the allocated blocks.
 	 */
-	buddy = get_buddy(block);
+	buddy = __get_buddy(block);
 	if (buddy &&
 	    (drm_buddy_block_is_free(block) &&
 	     drm_buddy_block_is_free(buddy)))
···
 	 * bigger is better, so make sure we merge everything back before we
 	 * free the allocated blocks.
 	 */
-	buddy = get_buddy(block);
+	buddy = __get_buddy(block);
 	if (buddy &&
 	    (drm_buddy_block_is_free(block) &&
 	     drm_buddy_block_is_free(buddy)))

drivers/gpu/drm/lib/drm_random.c

···
 
 #include "drm_random.h"
 
-static inline u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state)
+u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state)
 {
 	return upper_32_bits((u64)prandom_u32_state(state) * ep_ro);
 }
+EXPORT_SYMBOL(drm_prandom_u32_max_state);
 
 void drm_random_reorder(unsigned int *order, unsigned int count,
 			struct rnd_state *state)

drivers/gpu/drm/lib/drm_random.h

···
 void drm_random_reorder(unsigned int *order,
 			unsigned int count,
 			struct rnd_state *state);
+u32 drm_prandom_u32_max_state(u32 ep_ro,
+			      struct rnd_state *state);
 
 #endif /* !__DRM_RANDOM_H__ */

drivers/gpu/drm/selftests/drm_buddy_selftests.h

···
  */
 selftest(sanitycheck, igt_sanitycheck) /* keep first (selfcheck for igt) */
 selftest(buddy_alloc_limit, igt_buddy_alloc_limit)
+selftest(buddy_alloc_range, igt_buddy_alloc_range)

drivers/gpu/drm/selftests/test-drm_buddy.c

···
 #define pr_fmt(fmt) "drm_buddy: " fmt
 
 #include <linux/module.h>
+#include <linux/prime_numbers.h>
 
 #include <drm/drm_buddy.h>
 
···
 #include "drm_selftest.h"
 
 static unsigned int random_seed;
+
+static inline const char *yesno(bool v)
+{
+	return v ? "yes" : "no";
+}
+
+static void __igt_dump_block(struct drm_buddy *mm,
+			     struct drm_buddy_block *block,
+			     bool buddy)
+{
+	pr_err("block info: header=%llx, state=%u, order=%d, offset=%llx size=%llx root=%s buddy=%s\n",
+	       block->header,
+	       drm_buddy_block_state(block),
+	       drm_buddy_block_order(block),
+	       drm_buddy_block_offset(block),
+	       drm_buddy_block_size(mm, block),
+	       yesno(!block->parent),
+	       yesno(buddy));
+}
+
+static void igt_dump_block(struct drm_buddy *mm,
+			   struct drm_buddy_block *block)
+{
+	struct drm_buddy_block *buddy;
+
+	__igt_dump_block(mm, block, false);
+
+	buddy = drm_get_buddy(block);
+	if (buddy)
+		__igt_dump_block(mm, buddy, true);
+}
+
+static int igt_check_block(struct drm_buddy *mm,
+			   struct drm_buddy_block *block)
+{
+	struct drm_buddy_block *buddy;
+	unsigned int block_state;
+	u64 block_size;
+	u64 offset;
+	int err = 0;
+
+	block_state = drm_buddy_block_state(block);
+
+	if (block_state != DRM_BUDDY_ALLOCATED &&
+	    block_state != DRM_BUDDY_FREE &&
+	    block_state != DRM_BUDDY_SPLIT) {
+		pr_err("block state mismatch\n");
+		err = -EINVAL;
+	}
+
+	block_size = drm_buddy_block_size(mm, block);
+	offset = drm_buddy_block_offset(block);
+
+	if (block_size < mm->chunk_size) {
+		pr_err("block size smaller than min size\n");
+		err = -EINVAL;
+	}
+
+	if (!is_power_of_2(block_size)) {
+		pr_err("block size not power of two\n");
+		err = -EINVAL;
+	}
+
+	if (!IS_ALIGNED(block_size, mm->chunk_size)) {
+		pr_err("block size not aligned to min size\n");
+		err = -EINVAL;
+	}
+
+	if (!IS_ALIGNED(offset, mm->chunk_size)) {
+		pr_err("block offset not aligned to min size\n");
+		err = -EINVAL;
+	}
+
+	if (!IS_ALIGNED(offset, block_size)) {
+		pr_err("block offset not aligned to block size\n");
+		err = -EINVAL;
+	}
+
+	buddy = drm_get_buddy(block);
+
+	if (!buddy && block->parent) {
+		pr_err("buddy has gone fishing\n");
+		err = -EINVAL;
+	}
+
+	if (buddy) {
+		if (drm_buddy_block_offset(buddy) != (offset ^ block_size)) {
+			pr_err("buddy has wrong offset\n");
+			err = -EINVAL;
+		}
+
+		if (drm_buddy_block_size(mm, buddy) != block_size) {
+			pr_err("buddy size mismatch\n");
+			err = -EINVAL;
+		}
+
+		if (drm_buddy_block_state(buddy) == block_state &&
+		    block_state == DRM_BUDDY_FREE) {
+			pr_err("block and its buddy are free\n");
+			err = -EINVAL;
+		}
+	}
+
+	return err;
+}
+
+static int igt_check_blocks(struct drm_buddy *mm,
+			    struct list_head *blocks,
+			    u64 expected_size,
+			    bool is_contiguous)
+{
+	struct drm_buddy_block *block;
+	struct drm_buddy_block *prev;
+	u64 total;
+	int err = 0;
+
+	block = NULL;
+	prev = NULL;
+	total = 0;
+
+	list_for_each_entry(block, blocks, link) {
+		err = igt_check_block(mm, block);
+
+		if (!drm_buddy_block_is_allocated(block)) {
+			pr_err("block not allocated\n"),
+			       err = -EINVAL;
+		}
+
+		if (is_contiguous && prev) {
+			u64 prev_block_size;
+			u64 prev_offset;
+			u64 offset;
+
+			prev_offset = drm_buddy_block_offset(prev);
+			prev_block_size = drm_buddy_block_size(mm, prev);
+			offset = drm_buddy_block_offset(block);
+
+			if (offset != (prev_offset + prev_block_size)) {
+				pr_err("block offset mismatch\n");
+				err = -EINVAL;
+			}
+		}
+
+		if (err)
+			break;
+
+		total += drm_buddy_block_size(mm, block);
+		prev = block;
+	}
+
+	if (!err) {
+		if (total != expected_size) {
+			pr_err("size mismatch, expected=%llx, found=%llx\n",
+			       expected_size, total);
+			err = -EINVAL;
+		}
+		return err;
+	}
+
+	if (prev) {
+		pr_err("prev block, dump:\n");
+		igt_dump_block(mm, prev);
+	}
+
+	pr_err("bad block, dump:\n");
+	igt_dump_block(mm, block);
+
+	return err;
+}
+
+static int igt_check_mm(struct drm_buddy *mm)
+{
+	struct drm_buddy_block *root;
+	struct drm_buddy_block *prev;
+	unsigned int i;
+	u64 total;
+	int err = 0;
+
+	if (!mm->n_roots) {
+		pr_err("n_roots is zero\n");
+		return -EINVAL;
+	}
+
+	if (mm->n_roots != hweight64(mm->size)) {
+		pr_err("n_roots mismatch, n_roots=%u, expected=%lu\n",
+		       mm->n_roots, hweight64(mm->size));
+		return -EINVAL;
+	}
+
+	root = NULL;
+	prev = NULL;
+	total = 0;
+
+	for (i = 0; i < mm->n_roots; ++i) {
+		struct drm_buddy_block *block;
+		unsigned int order;
+
+		root = mm->roots[i];
+		if (!root) {
+			pr_err("root(%u) is NULL\n", i);
+			err = -EINVAL;
+			break;
+		}
+
+		err = igt_check_block(mm, root);
+
+		if (!drm_buddy_block_is_free(root)) {
+			pr_err("root not free\n");
+			err = -EINVAL;
+		}
+
+		order = drm_buddy_block_order(root);
+
+		if (!i) {
+			if (order != mm->max_order) {
+				pr_err("max order root missing\n");
+				err = -EINVAL;
+			}
+		}
+
+		if (prev) {
+			u64 prev_block_size;
+			u64 prev_offset;
+			u64 offset;
+
+			prev_offset = drm_buddy_block_offset(prev);
+			prev_block_size = drm_buddy_block_size(mm, prev);
+			offset = drm_buddy_block_offset(root);
+
+			if (offset != (prev_offset + prev_block_size)) {
+				pr_err("root offset mismatch\n");
+				err = -EINVAL;
+			}
+		}
+
+		block = list_first_entry_or_null(&mm->free_list[order],
+						 struct drm_buddy_block,
+						 link);
+		if (block != root) {
+			pr_err("root mismatch at order=%u\n", order);
+			err = -EINVAL;
+		}
+
+		if (err)
+			break;
+
+		prev = root;
+		total += drm_buddy_block_size(mm, root);
+	}
+
+	if (!err) {
+		if (total != mm->size) {
+			pr_err("expected mm size=%llx, found=%llx\n", mm->size,
+			       total);
+			err = -EINVAL;
+		}
+		return err;
+	}
+
+	if (prev) {
+		pr_err("prev root(%u), dump:\n", i - 1);
+		igt_dump_block(mm, prev);
+	}
+
+	if (root) {
+		pr_err("bad root(%u), dump:\n", i);
+		igt_dump_block(mm, root);
+	}
+
+	return err;
+}
+
+static void igt_mm_config(u64 *size, u64 *chunk_size)
+{
+	DRM_RND_STATE(prng, random_seed);
+	u32 s, ms;
+
+	/* Nothing fancy, just try to get an interesting bit pattern */
+
+	prandom_seed_state(&prng, random_seed);
+
+	/* Let size be a random number of pages up to 8 GB (2M pages) */
+	s = 1 + drm_prandom_u32_max_state((BIT(33 - 12)) - 1, &prng);
+	/* Let the chunk size be a random power of 2 less than size */
+	ms = BIT(drm_prandom_u32_max_state(ilog2(s), &prng));
+	/* Round size down to the chunk size */
+	s &= -ms;
+
+	/* Convert from pages to bytes */
+	*chunk_size = (u64)ms << 12;
+	*size = (u64)s << 12;
+}
+
+static int igt_buddy_alloc_range(void *arg)
+{
+	unsigned long flags = DRM_BUDDY_RANGE_ALLOCATION;
+	u64 offset, size, rem, chunk_size, end;
+	unsigned long page_num;
+	struct drm_buddy mm;
+	LIST_HEAD(blocks);
+	int err;
+
+	igt_mm_config(&size, &chunk_size);
+
+	err = drm_buddy_init(&mm, size, chunk_size);
+	if (err) {
+		pr_err("buddy_init failed(%d)\n", err);
+		return err;
+	}
+
+	err = igt_check_mm(&mm);
+	if (err) {
+		pr_err("pre-mm check failed, abort, abort, abort!\n");
+		goto err_fini;
+	}
+
+	rem = mm.size;
+	offset = 0;
+
+	for_each_prime_number_from(page_num, 1, ULONG_MAX - 1) {
+		struct drm_buddy_block *block;
+		LIST_HEAD(tmp);
+
+		size = min(page_num * mm.chunk_size, rem);
+		end = offset + size;
+
+		err = drm_buddy_alloc_blocks(&mm, offset, end, size, mm.chunk_size, &tmp, flags);
+		if (err) {
+			if (err == -ENOMEM) {
+				pr_info("alloc_range hit -ENOMEM with size=%llx\n",
+					size);
+			} else {
+				pr_err("alloc_range with offset=%llx, size=%llx failed(%d)\n",
+				       offset, size, err);
+			}
+
+			break;
+		}
+
+		block = list_first_entry_or_null(&tmp,
+						 struct drm_buddy_block,
+						 link);
+		if (!block) {
+			pr_err("alloc_range has no blocks\n");
+			err = -EINVAL;
+			break;
+		}
+
+		if (drm_buddy_block_offset(block) != offset) {
+			pr_err("alloc_range start offset mismatch, found=%llx, expected=%llx\n",
+			       drm_buddy_block_offset(block), offset);
+			err = -EINVAL;
+		}
+
+		if (!err)
+			err = igt_check_blocks(&mm, &tmp, size, true);
+
+		list_splice_tail(&tmp, &blocks);
+
+		if (err)
+			break;
+
+		offset += size;
+
+		rem -= size;
+		if (!rem)
+			break;
+
+		cond_resched();
+	}
+
+	if (err == -ENOMEM)
+		err = 0;
+
+	drm_buddy_free_list(&mm, &blocks);
+
+	if (!err) {
+		err = igt_check_mm(&mm);
+		if (err)
+			pr_err("post-mm check failed\n");
+	}
+
+err_fini:
+	drm_buddy_fini(&mm);
+
+	return err;
+}
 
 static int igt_buddy_alloc_limit(void *arg)
 {

include/drm/drm_buddy.h

···
 
 void drm_buddy_fini(struct drm_buddy *mm);
 
+struct drm_buddy_block *
+drm_get_buddy(struct drm_buddy_block *block);
+
 int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 			   u64 start, u64 end, u64 size,
 			   u64 min_page_size,