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Nicolas Pitrenashif
Nicolas Pitre
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tests: arm64: exercize MMU page table allocation and recycling
This code was never formally tested before... and without the preceding commit it obviously didn't work either. Signed-off-by: Nicolas Pitre <[email protected]>
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‎arch/arm64/core/mmu.c‎

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@@ -102,6 +102,35 @@ static inline bool is_table_unused(uint64_t *table)
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return (table_usage(table, 0) & XLAT_PTE_COUNT_MASK) == 0;
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}
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#ifdef CONFIG_TEST
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/* Hooks to let test code peek at table states */
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int arm64_mmu_nb_free_tables(void)
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{
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int count = 0;
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for (int i = 0; i < CONFIG_MAX_XLAT_TABLES; i++) {
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if (xlat_use_count[i] == 0) {
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count++;
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}
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}
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return count;
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}
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int arm64_mmu_tables_total_usage(void)
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{
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int count = 0;
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for (int i = 0; i < CONFIG_MAX_XLAT_TABLES; i++) {
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count += xlat_use_count[i];
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}
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return count;
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}
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#endif /* CONFIG_TEST */
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static inline bool is_free_desc(uint64_t desc)
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{
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return (desc & PTE_DESC_TYPE_MASK) == PTE_INVALID_DESC;

‎tests/arch/arm64/arm64_mmu/CMakeLists.txt‎

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# SPDX-License-Identifier: Apache-2.0
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cmake_minimum_required(VERSION 3.20.0)
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find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
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project(arm64_mmu)
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target_include_directories(app PRIVATE
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${ZEPHYR_BASE}/kernel/include
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${ZEPHYR_BASE}/arch/${ARCH}/include
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)
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target_sources(app PRIVATE src/main.c)

‎tests/arch/arm64/arm64_mmu/prj.conf‎

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CONFIG_ASSERT=y
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CONFIG_LOG=y
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CONFIG_LOG_MODE_MINIMAL=y
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CONFIG_ZTEST=y
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CONFIG_ARM_MMU=y
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CONFIG_MMU_PAGE_SIZE=0x1000
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CONFIG_ARM64_VA_BITS_36=y
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CONFIG_ARM64_PA_BITS_36=y
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CONFIG_MAX_XLAT_TABLES=8

‎tests/arch/arm64/arm64_mmu/src/main.c‎

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/*
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* Copyright (c) 2024 BayLibre, SAS
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/kernel.h>
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#include <zephyr/ztest.h>
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#include <kernel_arch_interface.h>
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/*
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* Virtual and physical addresses used to exercize MMU page table recycling.
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* Those are completely arbitrary addresses away from any existing addresses
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* (no worry, the test will fail otherwise). Those addresses don't have
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* to be valid as we won't attempt any access to the mapped memory.
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*/
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#define TEST_VIRT_ADDR 0x456560000
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#define TEST_PHYS_ADDR 0x123230000
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/* special test hooks in arch/arm64/core/mmu.c for test purpose */
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extern int arm64_mmu_nb_free_tables(void);
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extern int arm64_mmu_tables_total_usage(void);
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/* initial states to compare against */
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static int initial_nb_free_tables;
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static int initial_tables_usage;
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static void *arm64_mmu_test_init(void)
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{
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/* get initial states */
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initial_nb_free_tables = arm64_mmu_nb_free_tables();
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initial_tables_usage = arm64_mmu_tables_total_usage();
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TC_PRINT(" Total page tables: %d\n", CONFIG_MAX_XLAT_TABLES);
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TC_PRINT(" Initial free tables: %d\n", initial_nb_free_tables);
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TC_PRINT(" Initial total table usage: %#x\n", initial_tables_usage);
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zassert_true(initial_nb_free_tables > 1,
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"initial_nb_free_tables = %d", initial_nb_free_tables);
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zassert_true(initial_tables_usage > 1,
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"initial_tables_usage = %d", initial_tables_usage);
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return NULL;
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}
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static int mem_map_test(uintptr_t virt_addr, uintptr_t phys_addr, size_t size)
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{
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/*
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* This is not defined to return any error but the implementation
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* will call k_panic() if an error occurs.
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*/
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arch_mem_map((void *)virt_addr, phys_addr, size, K_MEM_ARM_NORMAL_NC);
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int mapped_nb_free_tables = arm64_mmu_nb_free_tables();
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int mapped_tables_usage = arm64_mmu_tables_total_usage();
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TC_PRINT(" After arch_mem_map:\n");
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TC_PRINT(" current free tables: %d\n", mapped_nb_free_tables);
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TC_PRINT(" current total table usage: %#x\n", mapped_tables_usage);
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zassert_true(mapped_nb_free_tables < initial_nb_free_tables,
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"%d vs %d", mapped_nb_free_tables, initial_nb_free_tables);
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zassert_true(mapped_tables_usage > initial_tables_usage,
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"%#x vs %#x", mapped_tables_usage > initial_tables_usage);
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arch_mem_unmap((void *)virt_addr, size);
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int unmapped_nb_free_tables = arm64_mmu_nb_free_tables();
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int unmapped_tables_usage = arm64_mmu_tables_total_usage();
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TC_PRINT(" After arch_mem_unmap:\n");
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TC_PRINT(" current free tables: %d\n", unmapped_nb_free_tables);
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TC_PRINT(" current total table usage: %#x\n", unmapped_tables_usage);
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zassert_true(unmapped_nb_free_tables == initial_nb_free_tables,
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"%d vs %d", unmapped_nb_free_tables, initial_nb_free_tables);
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zassert_true(unmapped_tables_usage == initial_tables_usage,
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"%#x vs %#x", unmapped_tables_usage > initial_tables_usage);
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int tables_used = unmapped_nb_free_tables - mapped_nb_free_tables;
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return tables_used;
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}
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ZTEST(arm64_mmu, test_arm64_mmu_01_single_page)
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{
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/*
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* Let's map a single page to start with. This will allocate
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* multiple tables to reach the deepest level.
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*/
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uintptr_t virt = TEST_VIRT_ADDR;
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uintptr_t phys = TEST_PHYS_ADDR;
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size_t size = CONFIG_MMU_PAGE_SIZE;
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int tables_used = mem_map_test(virt, phys, size);
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zassert_true(tables_used == 2, "used %d tables", tables_used);
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}
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ZTEST(arm64_mmu, test_arm64_mmu_02_single_block)
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{
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/*
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* Same thing as above, except that we expect a block mapping
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* this time. Both addresses and the size must be properly aligned.
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* Table allocation won't go as deep as for a page.
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*/
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int table_entries = CONFIG_MMU_PAGE_SIZE / sizeof(uint64_t);
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size_t block_size = table_entries * CONFIG_MMU_PAGE_SIZE;
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uintptr_t virt = TEST_VIRT_ADDR & ~(block_size - 1);
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uintptr_t phys = TEST_PHYS_ADDR & ~(block_size - 1);
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int tables_used = mem_map_test(virt, phys, block_size);
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zassert_true(tables_used == 1, "used %d tables", tables_used);
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}
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ZTEST(arm64_mmu, test_arm64_mmu_03_block_and_page)
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{
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/*
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* Same thing as above, except that we expect a block mapping
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* followed by a page mapping to exercize range splitting.
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* To achieve that we simply increase the size by one page and keep
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* starting addresses aligned to a block.
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*/
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int table_entries = CONFIG_MMU_PAGE_SIZE / sizeof(uint64_t);
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size_t block_size = table_entries * CONFIG_MMU_PAGE_SIZE;
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uintptr_t virt = TEST_VIRT_ADDR & ~(block_size - 1);
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uintptr_t phys = TEST_PHYS_ADDR & ~(block_size - 1);
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size_t size = block_size + CONFIG_MMU_PAGE_SIZE;
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int tables_used = mem_map_test(virt, phys, size);
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zassert_true(tables_used == 2, "used %d tables", tables_used);
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}
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ZTEST(arm64_mmu, test_arm64_mmu_04_page_and_block)
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{
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/*
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* Same thing as above, except that we expect a page mapping
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* followed by a block mapping to exercize range splitting.
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* To achieve that we increase the size by one page and decrease
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* starting addresses by one page below block alignment.
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*/
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int table_entries = CONFIG_MMU_PAGE_SIZE / sizeof(uint64_t);
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size_t block_size = table_entries * CONFIG_MMU_PAGE_SIZE;
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uintptr_t virt = (TEST_VIRT_ADDR & ~(block_size - 1)) - CONFIG_MMU_PAGE_SIZE;
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uintptr_t phys = (TEST_PHYS_ADDR & ~(block_size - 1)) - CONFIG_MMU_PAGE_SIZE;
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size_t size = block_size + CONFIG_MMU_PAGE_SIZE;
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int tables_used = mem_map_test(virt, phys, size);
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zassert_true(tables_used == 2, "used %d tables", tables_used);
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}
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ZTEST_SUITE(arm64_mmu, NULL, arm64_mmu_test_init, NULL, NULL, NULL);

‎tests/arch/arm64/arm64_mmu/testcase.yaml‎

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tests:
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arch.arm64.mmu:
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platform_allow: qemu_cortex_a53

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