memblock tests: Add memblock_alloc tests for top down

Add checks for memblock_alloc for top down allocation direction.
The tested scenarios are:
  - Region can be allocated on the first fit (with and without
    region merging)
  - Region can be allocated on the second fit (with and without
    region merging)

Add checks for both allocation directions:
  - Region can be allocated between two already existing entries
  - Limited memory available
  - All memory is reserved
  - No available memory registered with memblock
Signed-off-by: Karolina Drobnik <karolinadrobnik@gmail.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Link: https://lore.kernel.org/r/26ccf409b8ff0394559d38d792b2afb24b55887c.1646055639.git.karolinadrobnik@gmail.com

tools/testing/memblock/Makefile

@@ -6,7 +6,7 @@ CFLAGS += -I. -I../../include -Wall -O2 -fsanitize=address \
 	  -fsanitize=undefined -D CONFIG_PHYS_ADDR_T_64BIT
 LDFLAGS += -fsanitize=address -fsanitize=undefined
 TARGETS = main
-TEST_OFILES = tests/basic_api.o tests/common.o
+TEST_OFILES = tests/alloc_api.o tests/basic_api.o tests/common.o
 DEP_OFILES = memblock.o lib/slab.o mmzone.o slab.o
 OFILES = main.o $(DEP_OFILES) $(TEST_OFILES)
 EXTR_SRC = ../../../mm/memblock.c

tools/testing/memblock/main.c

 // SPDX-License-Identifier: GPL-2.0-or-later
 #include "tests/basic_api.h"
+#include "tests/alloc_api.h"
 
 int main(int argc, char **argv)
 {
 	memblock_basic_checks();
+	memblock_alloc_checks();
+
 	return 0;
 }

tools/testing/memblock/tests/alloc_api.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _MEMBLOCK_ALLOCS_H
+#define _MEMBLOCK_ALLOCS_H
+
+#include "common.h"
+
+int memblock_alloc_checks(void);
+
+#endif