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 <[e-mail]>
Signed-off-by: Mike Rapoport <[e-mail]>
Link: https://lore.kernel.org/r/26ccf40[e-mail]

tools/testing/memblock/Makefile

···
 	  -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.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include "alloc_api.h"
+
+/*
+ * A simple test that tries to allocate a small memory region.
+ * Expect to allocate an aligned region near the end of the available memory.
+ */
+static int alloc_top_down_simple_check(void)
+{
+	struct memblock_region *rgn = &memblock.reserved.regions[0];
+	void *allocated_ptr = NULL;
+
+	phys_addr_t size = SZ_2;
+	phys_addr_t expected_start;
+
+	setup_memblock();
+
+	expected_start = memblock_end_of_DRAM() - SMP_CACHE_BYTES;
+
+	allocated_ptr = memblock_alloc(size, SMP_CACHE_BYTES);
+
+	assert(allocated_ptr);
+	assert(rgn->size == size);
+	assert(rgn->base == expected_start);
+
+	assert(memblock.reserved.cnt == 1);
+	assert(memblock.reserved.total_size == size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory next to a reserved region that starts at
+ * the misaligned address. Expect to create two separate entries, with the new
+ * entry aligned to the provided alignment:
+ *
+ *              +
+ * |            +--------+         +--------|
+ * |            |  rgn2  |         |  rgn1  |
+ * +------------+--------+---------+--------+
+ *              ^
+ *              |
+ *              Aligned address boundary
+ *
+ * The allocation direction is top-down and region arrays are sorted from lower
+ * to higher addresses, so the new region will be the first entry in
+ * memory.reserved array. The previously reserved region does not get modified.
+ * Region counter and total size get updated.
+ */
+static int alloc_top_down_disjoint_check(void)
+{
+	/* After allocation, this will point to the "old" region */
+	struct memblock_region *rgn1 = &memblock.reserved.regions[1];
+	struct memblock_region *rgn2 = &memblock.reserved.regions[0];
+	struct region r1;
+	void *allocated_ptr = NULL;
+
+	phys_addr_t r2_size = SZ_16;
+	/* Use custom alignment */
+	phys_addr_t alignment = SMP_CACHE_BYTES * 2;
+	phys_addr_t total_size;
+	phys_addr_t expected_start;
+
+	setup_memblock();
+
+	r1.base = memblock_end_of_DRAM() - SZ_2;
+	r1.size = SZ_2;
+
+	total_size = r1.size + r2_size;
+	expected_start = memblock_end_of_DRAM() - alignment;
+
+	memblock_reserve(r1.base, r1.size);
+
+	allocated_ptr = memblock_alloc(r2_size, alignment);
+
+	assert(allocated_ptr);
+	assert(rgn1->size == r1.size);
+	assert(rgn1->base == r1.base);
+
+	assert(rgn2->size == r2_size);
+	assert(rgn2->base == expected_start);
+
+	assert(memblock.reserved.cnt == 2);
+	assert(memblock.reserved.total_size == total_size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory when there is enough space at the end
+ * of the previously reserved block (i.e. first fit):
+ *
+ *  |              +--------+--------------|
+ *  |              |   r1   |      r2      |
+ *  +--------------+--------+--------------+
+ *
+ * Expect a merge of both regions. Only the region size gets updated.
+ */
+static int alloc_top_down_before_check(void)
+{
+	struct memblock_region *rgn = &memblock.reserved.regions[0];
+	void *allocated_ptr = NULL;
+
+	/*
+	 * The first region ends at the aligned address to test region merging
+	 */
+	phys_addr_t r1_size = SMP_CACHE_BYTES;
+	phys_addr_t r2_size = SZ_512;
+	phys_addr_t total_size = r1_size + r2_size;
+
+	setup_memblock();
+
+	memblock_reserve(memblock_end_of_DRAM() - total_size, r1_size);
+
+	allocated_ptr = memblock_alloc(r2_size, SMP_CACHE_BYTES);
+
+	assert(allocated_ptr);
+	assert(rgn->size == total_size);
+	assert(rgn->base == memblock_end_of_DRAM() - total_size);
+
+	assert(memblock.reserved.cnt == 1);
+	assert(memblock.reserved.total_size == total_size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory when there is not enough space at the
+ * end of the previously reserved block (i.e. second fit):
+ *
+ *  |            +-----------+------+     |
+ *  |            |     r2    |  r1  |     |
+ *  +------------+-----------+------+-----+
+ *
+ * Expect a merge of both regions. Both the base address and size of the region
+ * get updated.
+ */
+static int alloc_top_down_after_check(void)
+{
+	struct memblock_region *rgn = &memblock.reserved.regions[0];
+	struct region r1;
+	void *allocated_ptr = NULL;
+
+	phys_addr_t r2_size = SZ_512;
+	phys_addr_t total_size;
+
+	setup_memblock();
+
+	/*
+	 * The first region starts at the aligned address to test region merging
+	 */
+	r1.base = memblock_end_of_DRAM() - SMP_CACHE_BYTES;
+	r1.size = SZ_8;
+
+	total_size = r1.size + r2_size;
+
+	memblock_reserve(r1.base, r1.size);
+
+	allocated_ptr = memblock_alloc(r2_size, SMP_CACHE_BYTES);
+
+	assert(allocated_ptr);
+	assert(rgn->size == total_size);
+	assert(rgn->base == r1.base - r2_size);
+
+	assert(memblock.reserved.cnt == 1);
+	assert(memblock.reserved.total_size == total_size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory when there are two reserved regions with
+ * a gap too small to fit the new region:
+ *
+ *  |       +--------+----------+   +------|
+ *  |       |   r3   |    r2    |   |  r1  |
+ *  +-------+--------+----------+---+------+
+ *
+ * Expect to allocate a region before the one that starts at the lower address,
+ * and merge them into one. The region counter and total size fields get
+ * updated.
+ */
+static int alloc_top_down_second_fit_check(void)
+{
+	struct memblock_region *rgn = &memblock.reserved.regions[0];
+	struct region r1, r2;
+	void *allocated_ptr = NULL;
+
+	phys_addr_t r3_size = SZ_1K;
+	phys_addr_t total_size;
+
+	setup_memblock();
+
+	r1.base = memblock_end_of_DRAM() - SZ_512;
+	r1.size = SZ_512;
+
+	r2.base = r1.base - SZ_512;
+	r2.size = SZ_256;
+
+	total_size = r1.size + r2.size + r3_size;
+
+	memblock_reserve(r1.base, r1.size);
+	memblock_reserve(r2.base, r2.size);
+
+	allocated_ptr = memblock_alloc(r3_size, SMP_CACHE_BYTES);
+
+	assert(allocated_ptr);
+	assert(rgn->size == r2.size + r3_size);
+	assert(rgn->base == r2.base - r3_size);
+
+	assert(memblock.reserved.cnt == 2);
+	assert(memblock.reserved.total_size == total_size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory when there are two reserved regions with
+ * a gap big enough to accommodate the new region:
+ *
+ *  |     +--------+--------+--------+     |
+ *  |     |   r2   |   r3   |   r1   |     |
+ *  +-----+--------+--------+--------+-----+
+ *
+ * Expect to merge all of them, creating one big entry in memblock.reserved
+ * array. The region counter and total size fields get updated.
+ */
+static int alloc_in_between_generic_check(void)
+{
+	struct memblock_region *rgn = &memblock.reserved.regions[0];
+	struct region r1, r2;
+	void *allocated_ptr = NULL;
+
+	phys_addr_t gap_size = SMP_CACHE_BYTES;
+	phys_addr_t r3_size = SZ_64;
+	/*
+	 * Calculate regions size so there's just enough space for the new entry
+	 */
+	phys_addr_t rgn_size = (MEM_SIZE - (2 * gap_size + r3_size)) / 2;
+	phys_addr_t total_size;
+
+	setup_memblock();
+
+	r1.size = rgn_size;
+	r1.base = memblock_end_of_DRAM() - (gap_size + rgn_size);
+
+	r2.size = rgn_size;
+	r2.base = memblock_start_of_DRAM() + gap_size;
+
+	total_size = r1.size + r2.size + r3_size;
+
+	memblock_reserve(r1.base, r1.size);
+	memblock_reserve(r2.base, r2.size);
+
+	allocated_ptr = memblock_alloc(r3_size, SMP_CACHE_BYTES);
+
+	assert(allocated_ptr);
+	assert(rgn->size == total_size);
+	assert(rgn->base == r1.base - r2.size - r3_size);
+
+	assert(memblock.reserved.cnt == 1);
+	assert(memblock.reserved.total_size == total_size);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory when the memory is filled with reserved
+ * regions with memory gaps too small to fit the new region:
+ *
+ * +-------+
+ * |  new  |
+ * +--+----+
+ *    |    +-----+    +-----+    +-----+    |
+ *    |    | res |    | res |    | res |    |
+ *    +----+-----+----+-----+----+-----+----+
+ *
+ * Expect no allocation to happen.
+ */
+static int alloc_small_gaps_generic_check(void)
+{
+	void *allocated_ptr = NULL;
+
+	phys_addr_t region_size = SZ_1K;
+	phys_addr_t gap_size = SZ_256;
+	phys_addr_t region_end;
+
+	setup_memblock();
+
+	region_end = memblock_start_of_DRAM();
+
+	while (region_end < memblock_end_of_DRAM()) {
+		memblock_reserve(region_end + gap_size, region_size);
+		region_end += gap_size + region_size;
+	}
+
+	allocated_ptr = memblock_alloc(region_size, SMP_CACHE_BYTES);
+
+	assert(!allocated_ptr);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory when all memory is reserved.
+ * Expect no allocation to happen.
+ */
+static int alloc_all_reserved_generic_check(void)
+{
+	void *allocated_ptr = NULL;
+
+	setup_memblock();
+
+	/* Simulate full memory */
+	memblock_reserve(memblock_start_of_DRAM(), MEM_SIZE);
+
+	allocated_ptr = memblock_alloc(SZ_256, SMP_CACHE_BYTES);
+
+	assert(!allocated_ptr);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory when the memory is almost full,
+ * with not enough space left for the new region:
+ *
+ *                                +-------+
+ *                                |  new  |
+ *                                +-------+
+ *  |-----------------------------+   |
+ *  |          reserved           |   |
+ *  +-----------------------------+---+
+ *
+ * Expect no allocation to happen.
+ */
+static int alloc_no_space_generic_check(void)
+{
+	void *allocated_ptr = NULL;
+
+	setup_memblock();
+
+	phys_addr_t available_size = SZ_256;
+	phys_addr_t reserved_size = MEM_SIZE - available_size;
+
+	/* Simulate almost-full memory */
+	memblock_reserve(memblock_start_of_DRAM(), reserved_size);
+
+	allocated_ptr = memblock_alloc(SZ_1K, SMP_CACHE_BYTES);
+
+	assert(!allocated_ptr);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory when the memory is almost full,
+ * but there is just enough space left:
+ *
+ *  |---------------------------+---------|
+ *  |          reserved         |   new   |
+ *  +---------------------------+---------+
+ *
+ * Expect to allocate memory and merge all the regions. The total size field
+ * gets updated.
+ */
+static int alloc_limited_space_generic_check(void)
+{
+	struct memblock_region *rgn = &memblock.reserved.regions[0];
+	void *allocated_ptr = NULL;
+
+	phys_addr_t available_size = SZ_256;
+	phys_addr_t reserved_size = MEM_SIZE - available_size;
+
+	setup_memblock();
+
+	/* Simulate almost-full memory */
+	memblock_reserve(memblock_start_of_DRAM(), reserved_size);
+
+	allocated_ptr = memblock_alloc(available_size, SMP_CACHE_BYTES);
+
+	assert(allocated_ptr);
+	assert(rgn->size == MEM_SIZE);
+	assert(rgn->base == memblock_start_of_DRAM());
+
+	assert(memblock.reserved.cnt == 1);
+	assert(memblock.reserved.total_size == MEM_SIZE);
+
+	return 0;
+}
+
+/*
+ * A test that tries to allocate memory when there is no available memory
+ * registered (i.e. memblock.memory has only a dummy entry).
+ * Expect no allocation to happen.
+ */
+static int alloc_no_memory_generic_check(void)
+{
+	struct memblock_region *rgn = &memblock.reserved.regions[0];
+	void *allocated_ptr = NULL;
+
+	reset_memblock_regions();
+
+	allocated_ptr = memblock_alloc(SZ_1K, SMP_CACHE_BYTES);
+
+	assert(!allocated_ptr);
+	assert(rgn->size == 0);
+	assert(rgn->base == 0);
+	assert(memblock.reserved.total_size == 0);
+
+	return 0;
+}
+
+int memblock_alloc_checks(void)
+{
+	reset_memblock_attributes();
+	dummy_physical_memory_init();
+
+	alloc_top_down_simple_check();
+	alloc_top_down_disjoint_check();
+	alloc_top_down_before_check();
+	alloc_top_down_after_check();
+	alloc_top_down_second_fit_check();
+	alloc_in_between_generic_check();
+	alloc_small_gaps_generic_check();
+	alloc_all_reserved_generic_check();
+	alloc_no_space_generic_check();
+	alloc_limited_space_generic_check();
+	alloc_no_memory_generic_check();
+
+	dummy_physical_memory_cleanup();
+
+	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