Use cluster_cpus_list to detect clusters for ARM

On newer kernels (6.x+) a separate topology node exists to express the
list of cpus associated with each cluster. The cluster topology node
explicitly refers to cores that share some resources (e.g. cache) as
opposed to 'core_siblings', which only indicate they are on the same
physical package.

This distinction is relevant on 6.x, where some devices may have all
their cores on a single physical package but cores do not all share the
same resources on that package. In these cases, the existing logic
incorrectly reports that there is a single cluster (because all cores
are siblings), even though not all cores share the same resources.

Test: Verified on ARM64 Android device that has multiple clusters, where
core_siblings reports all cores are siblings.
Test: Added mock hardware tests, verified pass on ARM64 hardware.

CMakeLists.txt

@@ -737,6 +737,11 @@ IF(CPUINFO_SUPPORTED_PLATFORM AND CPUINFO_BUILD_MOCK_TESTS)
     TARGET_LINK_LIBRARIES(pixel-2-xl-test PRIVATE cpuinfo_mock gtest)
     ADD_TEST(NAME pixel-2-xl-test COMMAND pixel-2-xl-test)
 
+    ADD_EXECUTABLE(pixel-8-test test/mock/pixel-8.cc)
+    TARGET_INCLUDE_DIRECTORIES(pixel-8-test BEFORE PRIVATE test/mock)
+    TARGET_LINK_LIBRARIES(pixel-8-test PRIVATE cpuinfo_mock gtest)
+    ADD_TEST(NAME pixel-8-test COMMAND pixel-8-test)
+
     ADD_EXECUTABLE(xiaomi-mi-5c-test test/mock/xiaomi-mi-5c.cc)
     TARGET_INCLUDE_DIRECTORIES(xiaomi-mi-5c-test BEFORE PRIVATE test/mock)
     TARGET_LINK_LIBRARIES(xiaomi-mi-5c-test PRIVATE cpuinfo_mock gtest)

scripts/android-arm64-mock.sh

@@ -36,6 +36,7 @@ adb push build/android/arm64-v8a/pixel-c-test /data/local/tmp/pixel-c-test
 adb push build/android/arm64-v8a/pixel-xl-test /data/local/tmp/pixel-xl-test
 adb push build/android/arm64-v8a/pixel-test /data/local/tmp/pixel-test
 adb push build/android/arm64-v8a/pixel-2-xl-test /data/local/tmp/pixel-2-xl-test
+adb push build/android/arm64-v8a/pixel-8-test /data/local/tmp/pixel-8-test
 adb push build/android/arm64-v8a/xiaomi-mi-5c-test /data/local/tmp/xiaomi-mi-5c-test
 adb push build/android/arm64-v8a/xiaomi-redmi-note-3-test /data/local/tmp/xiaomi-redmi-note-3-test
 adb push build/android/arm64-v8a/xiaomi-redmi-note-4-test /data/local/tmp/xiaomi-redmi-note-4-test
@@ -75,6 +76,7 @@ adb shell "/data/local/tmp/pixel-c-test --gtest_color=yes"
 adb shell "/data/local/tmp/pixel-xl-test --gtest_color=yes"
 adb shell "/data/local/tmp/pixel-test --gtest_color=yes"
 adb shell "/data/local/tmp/pixel-2-xl-test --gtest_color=yes"
+adb shell "/data/local/tmp/pixel-8-test --gtest_color=yes"
 adb shell "/data/local/tmp/xiaomi-mi-5c-test --gtest_color=yes"
 adb shell "/data/local/tmp/xiaomi-redmi-note-3-test --gtest_color=yes"
 adb shell "/data/local/tmp/xiaomi-redmi-note-4-test --gtest_color=yes"

scripts/android-armv7-mock.sh

@@ -70,6 +70,7 @@ adb push build/android/armeabi-v7a/pixel-c-test /data/local/tmp/pixel-c-test
 adb push build/android/armeabi-v7a/pixel-xl-test /data/local/tmp/pixel-xl-test
 adb push build/android/armeabi-v7a/pixel-test /data/local/tmp/pixel-test
 adb push build/android/armeabi-v7a/pixel-2-xl-test /data/local/tmp/pixel-2-xl-test
+adb push build/android/armeabi-v7a/pixel-8-test /data/local/tmp/pixel-8-test
 adb push build/android/armeabi-v7a/xiaomi-mi-5c-test /data/local/tmp/xiaomi-mi-5c-test
 adb push build/android/armeabi-v7a/xiaomi-redmi-2a-test /data/local/tmp/xiaomi-redmi-2a-test
 adb push build/android/armeabi-v7a/xiaomi-redmi-note-3-test /data/local/tmp/xiaomi-redmi-note-3-test
@@ -145,6 +146,7 @@ adb shell "/data/local/tmp/pixel-c-test --gtest_color=yes"
 adb shell "/data/local/tmp/pixel-xl-test --gtest_color=yes"
 adb shell "/data/local/tmp/pixel-test --gtest_color=yes"
 adb shell "/data/local/tmp/pixel-2-xl-test --gtest_color=yes"
+adb shell "/data/local/tmp/pixel-8-test --gtest_color=yes"
 adb shell "/data/local/tmp/xiaomi-mi-5c-test --gtest_color=yes"
 adb shell "/data/local/tmp/xiaomi-redmi-2a-test --gtest_color=yes"
 adb shell "/data/local/tmp/xiaomi-redmi-note-3-test --gtest_color=yes"

src/arm/linux/init.c

@@ -333,18 +333,52 @@ void cpuinfo_arm_linux_init(void) {
 	}
 
 	/* Propagate topology group IDs among siblings */
+	bool detected_core_siblings_list_node = false;
+	bool detected_cluster_cpus_list_node = false;
 	for (uint32_t i = 0; i < arm_linux_processors_count; i++) {
 		if (!bitmask_all(arm_linux_processors[i].flags, CPUINFO_LINUX_FLAG_VALID)) {
 			continue;
 		}
 
-		if (arm_linux_processors[i].flags & CPUINFO_LINUX_FLAG_PACKAGE_ID) {
+		if (!bitmask_all(arm_linux_processors[i].flags, CPUINFO_LINUX_FLAG_PACKAGE_ID)) {
+			continue;
+		}
+
+		/* Use the cluster_cpus_list topology node if available. If not
+		 * found, cache the result to avoid repeatedly attempting to
+		 * read the non-existent paths.
+		 * */
+		if (!detected_core_siblings_list_node && !detected_cluster_cpus_list_node) {
+		    if (cpuinfo_linux_detect_cluster_cpus(
+				arm_linux_processors_count,
+				i,
+				(cpuinfo_siblings_callback)cluster_siblings_parser,
+				arm_linux_processors)) {
+			detected_cluster_cpus_list_node = true;
+			continue;
+		    } else {
+			detected_core_siblings_list_node = true;
+		    }
+		}
+
+		/* The cached result above will guarantee only one of the blocks
+		 * below will execute, with a bias towards cluster_cpus_list.
+		 **/
+		if (detected_core_siblings_list_node) {
 			cpuinfo_linux_detect_core_siblings(
 				arm_linux_processors_count,
 				i,
 				(cpuinfo_siblings_callback)cluster_siblings_parser,
 				arm_linux_processors);
 		}
+
+		if (detected_cluster_cpus_list_node) {
+			cpuinfo_linux_detect_cluster_cpus(
+				arm_linux_processors_count,
+				i,
+				(cpuinfo_siblings_callback)cluster_siblings_parser,
+				arm_linux_processors);
+		}
 	}
 
 	/* Propagate all cluster IDs */