Generic wear-leveling algorithm (#16996)

* Initial import of wear-leveling algorithm.

* Alignment.

* Docs tweaks.

* Lock/unlock.

* Update quantum/wear_leveling/wear_leveling_internal.h

Co-authored-by: Stefan Kerkmann <karlk90@pm.me>

* More tests, fix issue with consolidation when unlocked.

* More tests.

* Review comments.

* Add plumbing for FNV1a.

* Another test checking that checksum mismatch clears the cache.

* Check that the write log still gets played back.

Co-authored-by: Stefan Kerkmann <karlk90@pm.me>

1 files changed, 178 insertions, 0 deletions

diff --git a/quantum/wear_leveling/tests/wear_leveling_8byte.cpp b/quantum/wear_leveling/tests/wear_leveling_8byte.cpp
new file mode 100644
index 0000000000..c27c21d034
--- /dev/null
+++ b/quantum/wear_leveling/tests/wear_leveling_8byte.cpp
@@ -0,0 +1,178 @@
+// Copyright 2022 Nick Brassel (@tzarc)
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <numeric>
+#include "gtest/gtest.h"
+#include "gmock/gmock.h"
+#include "backing_mocks.hpp"
+
+class WearLeveling8Byte : public ::testing::Test {
+   protected:
+    void SetUp() override {
+        MockBackingStore::Instance().reset_instance();
+        wear_leveling_init();
+    }
+};
+
+static std::array<std::uint8_t, WEAR_LEVELING_LOGICAL_SIZE> verify_data;
+
+static wear_leveling_status_t test_write(const uint32_t address, const void* value, size_t length) {
+    memcpy(&verify_data[address], value, length);
+    return wear_leveling_write(address, value, length);
+}
+
+/**
+ * This test verifies that the first write after initialisation occurs after the FNV1a_64 hash location.
+ */
+TEST_F(WearLeveling8Byte, FirstWriteOccursAfterHash) {
+    auto&   inst       = MockBackingStore::Instance();
+    uint8_t test_value = 0x15;
+    test_write(0x02, &test_value, sizeof(test_value));
+    EXPECT_EQ(inst.log_begin()->address, WEAR_LEVELING_LOGICAL_SIZE + 8) << "Invalid first write address.";
+}
+
+/**
+ * This test verifies that the first write after initialisation occurs after the FNV1a_64 hash location, after an erase has occurred.
+ */
+TEST_F(WearLeveling8Byte, FirstWriteOccursAfterHash_AfterErase) {
+    auto&   inst       = MockBackingStore::Instance();
+    uint8_t test_value = 0x15;
+    wear_leveling_erase();
+    test_write(0x02, &test_value, sizeof(test_value));
+    EXPECT_EQ((inst.log_begin() + 1)->address, WEAR_LEVELING_LOGICAL_SIZE + 8) << "Invalid first write address.";
+}
+
+/**
+ * This test ensures the correct number of backing store writes occurs with a multibyte write, given the input buffer size.
+ */
+TEST_F(WearLeveling8Byte, MultibyteBackingStoreWriteCounts) {
+    auto& inst = MockBackingStore::Instance();
+
+    for (std::size_t length = 1; length <= 5; ++length) {
+        // Clear things out
+        std::fill(verify_data.begin(), verify_data.end(), 0);
+        inst.reset_instance();
+        wear_leveling_init();
+
+        // Generate a test block of data
+        std::vector<std::uint8_t> testvalue(length);
+        std::iota(testvalue.begin(), testvalue.end(), 0x20);
+
+        // Write the data
+        EXPECT_EQ(test_write(0, testvalue.data(), testvalue.size()), WEAR_LEVELING_SUCCESS) << "Write failed with incorrect status";
+
+        // Check that we got the expected number of write log entries
+        EXPECT_EQ(std::distance(inst.log_begin(), inst.log_end()), 1);
+    }
+}
+
+/**
+ * This test forces consolidation by writing enough to the write log that it overflows, consolidating the data into the
+ * base logical area.
+ */
+TEST_F(WearLeveling8Byte, ConsolidationOverflow) {
+    auto& inst = MockBackingStore::Instance();
+
+    // Generate a test block of data
+    std::array<std::uint8_t, WEAR_LEVELING_LOGICAL_SIZE> testvalue;
+
+    // Write the data
+    std::iota(testvalue.begin(), testvalue.end(), 0x20);
+    EXPECT_EQ(test_write(0, testvalue.data(), testvalue.size()), WEAR_LEVELING_CONSOLIDATED) << "Write returned incorrect status";
+    uint8_t dummy = 0x40;
+    EXPECT_EQ(test_write(0x04, &dummy, sizeof(dummy)), WEAR_LEVELING_SUCCESS) << "Write returned incorrect status";
+
+    // Expected log:
+    // [0]: multibyte, 5 bytes, backing address 0x18, logical address 0x00
+    // [1]: multibyte, 5 bytes, backing address 0x20, logical address 0x05
+    // [2]: multibyte, 5 bytes, backing address 0x28, logical address 0x0A, triggers consolidation
+    // [3]: erase
+    // [4]: consolidated data, backing address 0x00, logical address 0x00
+    // [5]: consolidated data, backing address 0x08, logical address 0x08
+    // [6]: FNV1a_64 result, backing address 0x10
+    // [7]: multibyte, 1 byte,  backing address 0x18, logical address 0x04
+    EXPECT_EQ(std::distance(inst.log_begin(), inst.log_end()), 8);
+
+    // Verify the backing store writes for the write log
+    std::size_t       index;
+    write_log_entry_t e;
+    for (index = 0; index < 3; ++index) {
+        auto write_iter = inst.log_begin() + index;
+        EXPECT_EQ(write_iter->address, WEAR_LEVELING_LOGICAL_SIZE + 8 + (index * BACKING_STORE_WRITE_SIZE)) << "Invalid write log address";
+
+        write_log_entry_t e;
+        e.raw64 = write_iter->value;
+        EXPECT_EQ(LOG_ENTRY_GET_TYPE(e), LOG_ENTRY_TYPE_MULTIBYTE) << "Invalid write log entry type";
+    }
+
+    // Verify the backing store erase
+    {
+        index           = 3;
+        auto write_iter = inst.log_begin() + index;
+        e.raw64         = write_iter->value;
+        EXPECT_TRUE(write_iter->erased) << "Backing store erase did not occur as required";
+    }
+
+    // Verify the backing store writes for consolidation
+    for (index = 4; index < 6; ++index) {
+        auto write_iter = inst.log_begin() + index;
+        EXPECT_EQ(write_iter->address, (index - 4) * BACKING_STORE_WRITE_SIZE) << "Invalid write log entry address";
+    }
+
+    // Verify the FNV1a_64 write
+    {
+        EXPECT_EQ((inst.log_begin() + 6)->address, WEAR_LEVELING_LOGICAL_SIZE) << "Invalid write log address";
+        e.raw64 = (inst.log_begin() + 6)->value;
+        EXPECT_EQ(e.raw64, fnv_64a_buf(testvalue.data(), testvalue.size(), FNV1A_64_INIT)) << "Invalid checksum"; // Note that checksum is based on testvalue, as we overwrote one byte and need to consult the consolidated data, not the current
+    }
+
+    // Verify the final write
+    EXPECT_EQ((inst.log_begin() + 7)->address, WEAR_LEVELING_LOGICAL_SIZE + 8) << "Invalid write log address";
+
+    // Verify the data is what we expected
+    std::array<std::uint8_t, WEAR_LEVELING_LOGICAL_SIZE> readback;
+    EXPECT_EQ(wear_leveling_read(0, readback.data(), WEAR_LEVELING_LOGICAL_SIZE), WEAR_LEVELING_SUCCESS) << "Failed to read back the saved data";
+    EXPECT_TRUE(memcmp(readback.data(), verify_data.data(), WEAR_LEVELING_LOGICAL_SIZE) == 0) << "Readback did not match";
+
+    // Re-init and re-read, verifying the reload capability
+    EXPECT_NE(wear_leveling_init(), WEAR_LEVELING_FAILED) << "Re-initialisation failed";
+    EXPECT_EQ(wear_leveling_read(0, readback.data(), WEAR_LEVELING_LOGICAL_SIZE), WEAR_LEVELING_SUCCESS) << "Failed to read back the saved data";
+    EXPECT_TRUE(memcmp(readback.data(), verify_data.data(), WEAR_LEVELING_LOGICAL_SIZE) == 0) << "Readback did not match";
+}
+
+/**
+ * This test verifies multibyte readback gets canceled with an out-of-bounds address.
+ */
+TEST_F(WearLeveling8Byte, PlaybackReadbackMultibyte_OOB) {
+    auto& inst     = MockBackingStore::Instance();
+    auto  logstart = inst.storage_begin() + (WEAR_LEVELING_LOGICAL_SIZE / sizeof(backing_store_int_t));
+
+    // Invalid FNV1a_64 hash
+    (logstart + 0)->set(0);
+
+    // Set up a 2-byte logical write of [0x11,0x12] at logical offset 0x01
+    auto entry0    = LOG_ENTRY_MAKE_MULTIBYTE(0x01, 2);
+    entry0.raw8[3] = 0x11;
+    entry0.raw8[4] = 0x12;
+    (logstart + 1)->set(~entry0.raw64);
+
+    // Set up a 2-byte logical write of [0x13,0x14] at logical offset 0x1000 (out of bounds)
+    auto entry1    = LOG_ENTRY_MAKE_MULTIBYTE(0x1000, 2);
+    entry1.raw8[3] = 0x13;
+    entry1.raw8[4] = 0x14;
+    (logstart + 2)->set(~entry1.raw64);
+
+    // Set up a 2-byte logical write of [0x15,0x16] at logical offset 0x10
+    auto entry2    = LOG_ENTRY_MAKE_MULTIBYTE(0x01, 2);
+    entry2.raw8[3] = 0x15;
+    entry2.raw8[4] = 0x16;
+    (logstart + 3)->set(~entry2.raw64);
+
+    EXPECT_EQ(inst.erasure_count(), 0) << "Invalid initial erase count";
+    EXPECT_EQ(wear_leveling_init(), WEAR_LEVELING_CONSOLIDATED) << "Readback should have failed and triggered consolidation";
+    EXPECT_EQ(inst.erasure_count(), 1) << "Invalid final erase count";
+
+    uint8_t buf[2];
+    wear_leveling_read(0x01, buf, sizeof(buf));
+    EXPECT_EQ(buf[0], 0x11) << "Readback should have maintained the previous pre-failure value from the write log";
+    EXPECT_EQ(buf[1], 0x12) << "Readback should have maintained the previous pre-failure value from the write log";
+}