memblock tests: Add memblock_add tests

Add checks for adding a new region in different scenarios:
 - The region does not overlap with existing entries
 - The region overlaps with one of the previous entries: from the top
  (its end address is bigger than the base of the existing region) or
  from the bottom (its base address is smaller than the end address of
  one of the regions)
 - The region is within an already defined region
 - The same region is added twice to the collection of available memory
   regions

Add checks for memblock initialization to verify it sets memblock data
structures to expected values.
Signed-off-by: Karolina Drobnik <karolinadrobnik@gmail.com>
Signed-off-by: Mike Rapoport <rppt@kernel.org>
Link: https://lore.kernel.org/r/b6c26525025bccec0bf7419473d4d1293eb82b3b.1643796665.git.karolinadrobnik@gmail.com

tools/testing/memblock/tests/basic_api.c

 // SPDX-License-Identifier: GPL-2.0-or-later
 #include <string.h>
 #include <linux/memblock.h>
+#include <linux/sizes.h>
 #include "basic_api.h"
 
 #define EXPECTED_MEMBLOCK_REGIONS			128
@@ -25,8 +26,222 @@ static int memblock_initialization_check(void)
 	return 0;
 }
 
+/*
+ * A simple test that adds a memory block of a specified base address
+ * and size to the collection of available memory regions (memblock.memory).
+ * It checks if a new entry was created and if region counter and total memory
+ * were correctly updated.
+ */
+static int memblock_add_simple_check(void)
+{
+	struct memblock_region *rgn;
+
+	rgn = &memblock.memory.regions[0];
+
+	struct region r = {
+		.base = SZ_1G,
+		.size = SZ_4M
+	};
+
+	reset_memblock();
+	memblock_add(r.base, r.size);
+
+	assert(rgn->base == r.base);
+	assert(rgn->size == r.size);
+
+	assert(memblock.memory.cnt == 1);
+	assert(memblock.memory.total_size == r.size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to add two memory blocks that don't overlap with one
+ * another. It checks if two correctly initialized entries were added to the
+ * collection of available memory regions (memblock.memory) and if this
+ * change was reflected in memblock.memory's total size and region counter.
+ */
+static int memblock_add_disjoint_check(void)
+{
+	struct memblock_region *rgn1, *rgn2;
+
+	rgn1 = &memblock.memory.regions[0];
+	rgn2 = &memblock.memory.regions[1];
+
+	struct region r1 = {
+		.base = SZ_1G,
+		.size = SZ_8K
+	};
+	struct region r2 = {
+		.base = SZ_1G + SZ_16K,
+		.size = SZ_8K
+	};
+
+	reset_memblock();
+	memblock_add(r1.base, r1.size);
+	memblock_add(r2.base, r2.size);
+
+	assert(rgn1->base == r1.base);
+	assert(rgn1->size == r1.size);
+
+	assert(rgn2->base == r2.base);
+	assert(rgn2->size == r2.size);
+
+	assert(memblock.memory.cnt == 2);
+	assert(memblock.memory.total_size == r1.size + r2.size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to add two memory blocks, where the second one overlaps
+ * with the beginning of the first entry (that is r1.base < r2.base + r2.size).
+ * After this, it checks if two entries are merged into one region that starts
+ * at r2.base and has size of two regions minus their intersection. It also
+ * verifies the reported total size of the available memory and region counter.
+ */
+static int memblock_add_overlap_top_check(void)
+{
+	struct memblock_region *rgn;
+	phys_addr_t total_size;
+
+	rgn = &memblock.memory.regions[0];
+
+	struct region r1 = {
+		.base = SZ_512M,
+		.size = SZ_1G
+	};
+	struct region r2 = {
+		.base = SZ_256M,
+		.size = SZ_512M
+	};
+
+	total_size = (r1.base - r2.base) + r1.size;
+
+	reset_memblock();
+	memblock_add(r1.base, r1.size);
+	memblock_add(r2.base, r2.size);
+
+	assert(rgn->base == r2.base);
+	assert(rgn->size == total_size);
+
+	assert(memblock.memory.cnt == 1);
+	assert(memblock.memory.total_size == total_size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to add two memory blocks, where the second one overlaps
+ * with the end of the first entry (that is r2.base < r1.base + r1.size).
+ * After this, it checks if two entries are merged into one region that starts
+ * at r1.base and has size of two regions minus their intersection. It verifies
+ * that memblock can still see only one entry and has a correct total size of
+ * the available memory.
+ */
+static int memblock_add_overlap_bottom_check(void)
+{
+	struct memblock_region *rgn;
+	phys_addr_t total_size;
+
+	rgn = &memblock.memory.regions[0];
+
+	struct region r1 = {
+		.base = SZ_128M,
+		.size = SZ_512M
+	};
+	struct region r2 = {
+		.base = SZ_256M,
+		.size = SZ_1G
+	};
+
+	total_size = (r2.base - r1.base) + r2.size;
+
+	reset_memblock();
+	memblock_add(r1.base, r1.size);
+	memblock_add(r2.base, r2.size);
+
+	assert(rgn->base == r1.base);
+	assert(rgn->size == total_size);
+
+	assert(memblock.memory.cnt == 1);
+	assert(memblock.memory.total_size == total_size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to add two memory blocks, where the second one is
+ * within the range of the first entry (that is r1.base < r2.base &&
+ * r2.base + r2.size < r1.base + r1.size). It checks if two entries are merged
+ * into one region that stays the same. The counter and total size of available
+ * memory are expected to not be updated.
+ */
+static int memblock_add_within_check(void)
+{
+	struct memblock_region *rgn;
+
+	rgn = &memblock.memory.regions[0];
+
+	struct region r1 = {
+		.base = SZ_8M,
+		.size = SZ_32M
+	};
+	struct region r2 = {
+		.base = SZ_16M,
+		.size = SZ_1M
+	};
+
+	reset_memblock();
+	memblock_add(r1.base, r1.size);
+	memblock_add(r2.base, r2.size);
+
+	assert(rgn->base == r1.base);
+	assert(rgn->size == r1.size);
+
+	assert(memblock.memory.cnt == 1);
+	assert(memblock.memory.total_size == r1.size);
+
+	return 0;
+}
+
+/*
+ * A simple test that tries to add the same memory block twice. The counter
+ * and total size of available memory are expected to not be updated.
+ */
+static int memblock_add_twice_check(void)
+{
+	struct region r = {
+		.base = SZ_16K,
+		.size = SZ_2M
+	};
+
+	reset_memblock();
+
+	memblock_add(r.base, r.size);
+	memblock_add(r.base, r.size);
+
+	assert(memblock.memory.cnt == 1);
+	assert(memblock.memory.total_size == r.size);
+
+	return 0;
+}
+
+static int memblock_add_checks(void)
+{
+	memblock_add_simple_check();
+	memblock_add_disjoint_check();
+	memblock_add_overlap_top_check();
+	memblock_add_overlap_bottom_check();
+	memblock_add_within_check();
+	memblock_add_twice_check();
+
+	return 0;
+}
+
 int memblock_basic_checks(void)
 {
 	memblock_initialization_check();
+	memblock_add_checks();
 	return 0;
 }