Merge "switch netd_configuration_map from hash map to array"
diff --git a/bpf_progs/bpf_shared.h b/bpf_progs/bpf_shared.h
index dd9fb07..fd449a3 100644
--- a/bpf_progs/bpf_shared.h
+++ b/bpf_progs/bpf_shared.h
@@ -190,9 +190,9 @@
 STRUCT_SIZE(UidOwnerValue, 2 * 4);  // 8
 
 // Entry in the configuration map that stores which UID rules are enabled.
-#define UID_RULES_CONFIGURATION_KEY 1
+#define UID_RULES_CONFIGURATION_KEY 0
 // Entry in the configuration map that stores which stats map is currently in use.
-#define CURRENT_STATS_MAP_CONFIGURATION_KEY 2
+#define CURRENT_STATS_MAP_CONFIGURATION_KEY 1
 
 typedef struct {
     uint32_t iif;            // The input interface index
diff --git a/bpf_progs/netd.c b/bpf_progs/netd.c
index 8f72f7c..17c18c9 100644
--- a/bpf_progs/netd.c
+++ b/bpf_progs/netd.c
@@ -63,13 +63,18 @@
 #define DEFINE_BPF_MAP_RW_NETD(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
     DEFINE_BPF_MAP_UGM(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, AID_ROOT, AID_NET_BW_ACCT, 0660)
 
+// Bpf map arrays on creation are preinitialized to 0 and do not support deletion of a key,
+// see: kernel/bpf/arraymap.c array_map_delete_elem() returns -EINVAL (from both syscall and ebpf)
+// Additionally on newer kernels the bpf jit can optimize out the lookups.
+// only valid indexes are [0..CONFIGURATION_MAP_SIZE-1]
+DEFINE_BPF_MAP_RO_NETD(configuration_map, ARRAY, uint32_t, uint32_t, CONFIGURATION_MAP_SIZE)
+
 DEFINE_BPF_MAP_RW_NETD(cookie_tag_map, HASH, uint64_t, UidTagValue, COOKIE_UID_MAP_SIZE)
 DEFINE_BPF_MAP_NO_NETD(uid_counterset_map, HASH, uint32_t, uint8_t, UID_COUNTERSET_MAP_SIZE)
 DEFINE_BPF_MAP_NO_NETD(app_uid_stats_map, HASH, uint32_t, StatsValue, APP_STATS_MAP_SIZE)
 DEFINE_BPF_MAP_RW_NETD(stats_map_A, HASH, StatsKey, StatsValue, STATS_MAP_SIZE)
 DEFINE_BPF_MAP_RO_NETD(stats_map_B, HASH, StatsKey, StatsValue, STATS_MAP_SIZE)
 DEFINE_BPF_MAP_NO_NETD(iface_stats_map, HASH, uint32_t, StatsValue, IFACE_STATS_MAP_SIZE)
-DEFINE_BPF_MAP_RW_NETD(configuration_map, HASH, uint32_t, uint32_t, CONFIGURATION_MAP_SIZE)
 DEFINE_BPF_MAP_NO_NETD(uid_owner_map, HASH, uint32_t, UidOwnerValue, UID_OWNER_MAP_SIZE)
 DEFINE_BPF_MAP_RW_NETD(uid_permission_map, HASH, uint32_t, uint8_t, UID_OWNER_MAP_SIZE)
 
diff --git a/netd/BpfHandler.cpp b/netd/BpfHandler.cpp
index 5ae8ab6..fad6bbb 100644
--- a/netd/BpfHandler.cpp
+++ b/netd/BpfHandler.cpp
@@ -101,8 +101,6 @@
     RETURN_IF_NOT_OK(mStatsMapA.init(STATS_MAP_A_PATH));
     RETURN_IF_NOT_OK(mStatsMapB.init(STATS_MAP_B_PATH));
     RETURN_IF_NOT_OK(mConfigurationMap.init(CONFIGURATION_MAP_PATH));
-    RETURN_IF_NOT_OK(mConfigurationMap.writeValue(CURRENT_STATS_MAP_CONFIGURATION_KEY, SELECT_MAP_A,
-                                                  BPF_ANY));
     RETURN_IF_NOT_OK(mUidPermissionMap.init(UID_PERMISSION_MAP_PATH));
     ALOGI("%s successfully", __func__);
 
diff --git a/netd/BpfHandler.h b/netd/BpfHandler.h
index 7e3b94d..5ee04d1 100644
--- a/netd/BpfHandler.h
+++ b/netd/BpfHandler.h
@@ -63,7 +63,7 @@
     BpfMap<uint64_t, UidTagValue> mCookieTagMap;
     BpfMap<StatsKey, StatsValue> mStatsMapA;
     BpfMapRO<StatsKey, StatsValue> mStatsMapB;
-    BpfMap<uint32_t, uint32_t> mConfigurationMap;
+    BpfMapRO<uint32_t, uint32_t> mConfigurationMap;
     BpfMap<uint32_t, uint8_t> mUidPermissionMap;
 
     std::mutex mMutex;
diff --git a/netd/BpfHandlerTest.cpp b/netd/BpfHandlerTest.cpp
index c0f7e45..99160da 100644
--- a/netd/BpfHandlerTest.cpp
+++ b/netd/BpfHandlerTest.cpp
@@ -49,7 +49,7 @@
     BpfHandler mBh;
     BpfMap<uint64_t, UidTagValue> mFakeCookieTagMap;
     BpfMap<StatsKey, StatsValue> mFakeStatsMapA;
-    BpfMap<uint32_t, uint32_t> mFakeConfigurationMap;
+    BpfMapRO<uint32_t, uint32_t> mFakeConfigurationMap;
     BpfMap<uint32_t, uint8_t> mFakeUidPermissionMap;
 
     void SetUp() {
@@ -62,7 +62,7 @@
         mFakeStatsMapA.resetMap(BPF_MAP_TYPE_HASH, TEST_MAP_SIZE);
         ASSERT_VALID(mFakeStatsMapA);
 
-        mFakeConfigurationMap.resetMap(BPF_MAP_TYPE_HASH, 1);
+        mFakeConfigurationMap.resetMap(BPF_MAP_TYPE_ARRAY, CONFIGURATION_MAP_SIZE);
         ASSERT_VALID(mFakeConfigurationMap);
 
         mFakeUidPermissionMap.resetMap(BPF_MAP_TYPE_HASH, TEST_MAP_SIZE);
@@ -75,8 +75,8 @@
         mBh.mConfigurationMap = mFakeConfigurationMap;
         ASSERT_VALID(mBh.mConfigurationMap);
         // Always write to stats map A by default.
-        ASSERT_RESULT_OK(mBh.mConfigurationMap.writeValue(CURRENT_STATS_MAP_CONFIGURATION_KEY,
-                                                          SELECT_MAP_A, BPF_ANY));
+        static_assert(SELECT_MAP_A == 0, "bpf map arrays are zero-initialized");
+
         mBh.mUidPermissionMap = mFakeUidPermissionMap;
         ASSERT_VALID(mBh.mUidPermissionMap);
     }
diff --git a/service/native/TrafficControllerTest.cpp b/service/native/TrafficControllerTest.cpp
index b77c465..7730c13 100644
--- a/service/native/TrafficControllerTest.cpp
+++ b/service/native/TrafficControllerTest.cpp
@@ -98,7 +98,7 @@
         mFakeStatsMapA.resetMap(BPF_MAP_TYPE_HASH, TEST_MAP_SIZE);
         ASSERT_VALID(mFakeStatsMapA);
 
-        mFakeConfigurationMap.resetMap(BPF_MAP_TYPE_HASH, 1);
+        mFakeConfigurationMap.resetMap(BPF_MAP_TYPE_ARRAY, CONFIGURATION_MAP_SIZE);
         ASSERT_VALID(mFakeConfigurationMap);
 
         mFakeUidOwnerMap.resetMap(BPF_MAP_TYPE_HASH, TEST_MAP_SIZE);
@@ -122,8 +122,8 @@
         ASSERT_VALID(mTc.mConfigurationMap);
 
         // Always write to stats map A by default.
-        ASSERT_RESULT_OK(mTc.mConfigurationMap.writeValue(CURRENT_STATS_MAP_CONFIGURATION_KEY,
-                                                          SELECT_MAP_A, BPF_ANY));
+        static_assert(SELECT_MAP_A == 0);
+
         mTc.mUidOwnerMap = mFakeUidOwnerMap;
         ASSERT_VALID(mTc.mUidOwnerMap);
         mTc.mUidPermissionMap = mFakeUidPermissionMap;