/*
 * Copyright 2018 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

extern "C" {
#include "hf/mm.h"

#include "hf/arch/mm.h"

#include "hf/alloc.h"
}

#include <memory>

#include <gmock/gmock.h>

using ::testing::Eq;

constexpr size_t TEST_HEAP_SIZE = PAGE_SIZE * 10;
constexpr size_t ENTRY_COUNT = PAGE_SIZE / sizeof(pte_t);
const static int TOP_LEVEL = arch_mm_max_level(0);
const static pte_t ABSENT_ENTRY = arch_mm_absent_pte(TOP_LEVEL);

/**
 * Calculates the size of the address space represented by a page table entry at
 * the given level.
 */
static size_t mm_entry_size(int level)
{
	return UINT64_C(1) << (PAGE_BITS + level * PAGE_LEVEL_BITS);
}

/**
 * Fill a ptable with absent entries.
 */
static void init_absent(pte_t *table)
{
	for (uint64_t i = 0; i < ENTRY_COUNT; ++i) {
		table[i] = ABSENT_ENTRY;
	}
}

/**
 * Fill a ptable with block entries.
 */
static void init_blocks(pte_t *table, int level, paddr_t start_address,
			uint64_t attrs)
{
	for (uint64_t i = 0; i < ENTRY_COUNT; ++i) {
		table[i] = arch_mm_block_pte(
			level, pa_add(start_address, i * mm_entry_size(level)),
			attrs);
	}
}

/**
 * Defragging an entirely empty table should have no effect.
 */
TEST(mm, ptable_defrag_empty)
{
	auto test_heap = std::make_unique<uint8_t[]>(TEST_HEAP_SIZE);
	halloc_init((size_t)test_heap.get(), TEST_HEAP_SIZE);

	pte_t *table = (pte_t *)halloc_aligned(PAGE_SIZE, PAGE_SIZE);
	init_absent(table);
	struct mm_ptable ptable;
	ptable.table = pa_init((uintpaddr_t)table);

	mm_ptable_defrag(&ptable, 0);

	for (uint64_t i = 0; i < ENTRY_COUNT; ++i) {
		EXPECT_THAT(table[i], Eq(ABSENT_ENTRY)) << "i=" << i;
	}
}

/**
 * Defragging a table with some empty subtables (even nested) should result in
 * an empty table.
 */
TEST(mm, ptable_defrag_empty_subtables)
{
	auto test_heap = std::make_unique<uint8_t[]>(TEST_HEAP_SIZE);
	halloc_init((size_t)test_heap.get(), TEST_HEAP_SIZE);

	pte_t *subtable_a = (pte_t *)halloc_aligned(PAGE_SIZE, PAGE_SIZE);
	pte_t *subtable_aa = (pte_t *)halloc_aligned(PAGE_SIZE, PAGE_SIZE);
	pte_t *subtable_b = (pte_t *)halloc_aligned(PAGE_SIZE, PAGE_SIZE);
	pte_t *table = (pte_t *)halloc_aligned(PAGE_SIZE, PAGE_SIZE);
	init_absent(subtable_a);
	init_absent(subtable_aa);
	init_absent(subtable_b);
	init_absent(table);

	subtable_a[3] = arch_mm_table_pte(TOP_LEVEL - 1,
					  pa_init((uintpaddr_t)subtable_aa));
	table[0] =
		arch_mm_table_pte(TOP_LEVEL, pa_init((uintpaddr_t)subtable_a));
	table[5] =
		arch_mm_table_pte(TOP_LEVEL, pa_init((uintpaddr_t)subtable_b));

	struct mm_ptable ptable;
	ptable.table = pa_init((uintpaddr_t)table);

	mm_ptable_defrag(&ptable, 0);

	for (uint64_t i = 0; i < ENTRY_COUNT; ++i) {
		EXPECT_THAT(table[i], Eq(ABSENT_ENTRY)) << "i=" << i;
	}
}

/**
 * Any subtable with all blocks with the same attributes should be replaced
 * with a single block.
 */
TEST(mm, ptable_defrag_block_subtables)
{
	auto test_heap = std::make_unique<uint8_t[]>(TEST_HEAP_SIZE);
	halloc_init((size_t)test_heap.get(), TEST_HEAP_SIZE);

	pte_t *subtable_a = (pte_t *)halloc_aligned(PAGE_SIZE, PAGE_SIZE);
	pte_t *subtable_aa = (pte_t *)halloc_aligned(PAGE_SIZE, PAGE_SIZE);
	pte_t *subtable_b = (pte_t *)halloc_aligned(PAGE_SIZE, PAGE_SIZE);
	pte_t *table = (pte_t *)halloc_aligned(PAGE_SIZE, PAGE_SIZE);
	init_blocks(subtable_a, TOP_LEVEL - 1, pa_init(0), 0);
	init_blocks(subtable_aa, TOP_LEVEL - 2,
		    pa_init(3 * mm_entry_size(TOP_LEVEL - 1)), 0);
	init_blocks(subtable_b, TOP_LEVEL - 1,
		    pa_init(5 * mm_entry_size(TOP_LEVEL)), 0);
	init_blocks(table, TOP_LEVEL, pa_init(0), 0);

	subtable_a[3] = arch_mm_table_pte(TOP_LEVEL - 1,
					  pa_init((uintpaddr_t)subtable_aa));
	table[0] =
		arch_mm_table_pte(TOP_LEVEL, pa_init((uintpaddr_t)subtable_a));
	table[5] =
		arch_mm_table_pte(TOP_LEVEL, pa_init((uintpaddr_t)subtable_b));

	struct mm_ptable ptable;
	ptable.table = pa_init((uintpaddr_t)table);

	mm_ptable_defrag(&ptable, 0);

	for (uint64_t i = 0; i < ENTRY_COUNT; ++i) {
		EXPECT_TRUE(arch_mm_pte_is_present(table[i], TOP_LEVEL))
			<< "i=" << i;
		EXPECT_TRUE(arch_mm_pte_is_block(table[i], TOP_LEVEL))
			<< "i=" << i;
		EXPECT_THAT(pa_addr(arch_mm_block_from_pte(table[i])),
			    Eq(i * mm_entry_size(TOP_LEVEL)))
			<< "i=" << i;
	}
}