diff --git a/libs/binderthreadstate/1.0/Android.bp b/libs/binderthreadstate/1.0/Android.bp
new file mode 100644
index 0000000..ebdc932
--- /dev/null
+++ b/libs/binderthreadstate/1.0/Android.bp
@@ -0,0 +1,14 @@
+// This file is autogenerated by hidl-gen -Landroidbp.
+
+hidl_interface {
+    name: "binderthreadstateutilstest@1.0",
+    root: "binderthreadstateutilstest",
+    system_ext_specific: true,
+    srcs: [
+        "IHidlStuff.hal",
+    ],
+    interfaces: [
+        "android.hidl.base@1.0",
+    ],
+    gen_java: true,
+}
diff --git a/libs/binderthreadstate/1.0/IHidlStuff.hal b/libs/binderthreadstate/1.0/IHidlStuff.hal
new file mode 100644
index 0000000..ffb6499
--- /dev/null
+++ b/libs/binderthreadstate/1.0/IHidlStuff.hal
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+package binderthreadstateutilstest@1.0;
+
+interface IHidlStuff {
+    callLocal();
+    call(int32_t idx);
+};
diff --git a/libs/binderthreadstate/Android.bp b/libs/binderthreadstate/Android.bp
index ee1a6a4..4655e1d 100644
--- a/libs/binderthreadstate/Android.bp
+++ b/libs/binderthreadstate/Android.bp
@@ -12,6 +12,59 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// DO NOT ADD NEW USAGES OF THIS
+// See comments in header file.
+cc_library_static {
+    name: "libbinderthreadstateutils",
+    double_loadable: true,
+    vendor_available: true,
+    host_supported: true,
+
+    shared_libs: [
+        "libbinder",
+        "libhidlbase",  // libhwbinder is in here
+    ],
+
+    export_include_dirs: ["include"],
+
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+}
+
+hidl_package_root {
+    name: "binderthreadstateutilstest",
+}
+
+aidl_interface {
+    name: "binderthreadstateutilstest.aidl",
+    srcs: ["IAidlStuff.aidl"],
+}
+
+cc_test {
+    name: "libbinderthreadstateutils_test",
+    srcs: ["test.cpp"],
+    static_libs: [
+        "binderthreadstateutilstest@1.0",
+        "binderthreadstateutilstest.aidl-cpp",
+        "libbinderthreadstateutils",
+    ],
+    shared_libs: [
+        "libbase",
+        "libbinder",
+        "libcutils",
+        "libhidlbase",
+        "libutils",
+        "liblog",
+    ],
+    test_suites: [
+        "general-tests",
+    ],
+    require_root: true,
+}
+
+// TODO(b/148692216): remove empty lib
 cc_library {
     name: "libbinderthreadstate",
     recovery_available: true,
@@ -21,28 +74,4 @@
         support_system_process: true,
     },
     host_supported: true,
-
-    srcs: [
-        "IPCThreadStateBase.cpp",
-    ],
-
-    header_libs: [
-        "libbase_headers",
-        "libutils_headers",
-    ],
-
-    shared_libs: [
-        "liblog",
-    ],
-
-    export_include_dirs: ["include"],
-
-    sanitize: {
-        misc_undefined: ["integer"],
-    },
-
-    cflags: [
-        "-Wall",
-        "-Werror",
-    ],
 }
diff --git a/libs/binderthreadstate/IAidlStuff.aidl b/libs/binderthreadstate/IAidlStuff.aidl
new file mode 100644
index 0000000..0c81c42
--- /dev/null
+++ b/libs/binderthreadstate/IAidlStuff.aidl
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+
+interface IAidlStuff {
+    void callLocal();
+    void call(int idx);
+}
diff --git a/libs/binderthreadstate/IPCThreadStateBase.cpp b/libs/binderthreadstate/IPCThreadStateBase.cpp
deleted file mode 100644
index fede151..0000000
--- a/libs/binderthreadstate/IPCThreadStateBase.cpp
+++ /dev/null
@@ -1,89 +0,0 @@
-/*
- * Copyright (C) 2018 The Android Open Source Project
- *
- * 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
- *
- *      http://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.
- */
-
-#define LOG_TAG "IPCThreadStateBase"
-
-#include <binderthreadstate/IPCThreadStateBase.h>
-#include <android-base/macros.h>
-
-#include <utils/Log.h>
-
-#include <errno.h>
-#include <inttypes.h>
-#include <pthread.h>
-
-namespace android {
-
-static pthread_mutex_t gTLSMutex = PTHREAD_MUTEX_INITIALIZER;
-static bool gHaveTLS = false;
-static pthread_key_t gTLS = 0;
-
-IPCThreadStateBase::IPCThreadStateBase() {
-    pthread_setspecific(gTLS, this);
-}
-
-IPCThreadStateBase* IPCThreadStateBase::self()
-{
-    if (gHaveTLS) {
-restart:
-        const pthread_key_t k = gTLS;
-        IPCThreadStateBase* st = (IPCThreadStateBase*)pthread_getspecific(k);
-        if (st) return st;
-        return new IPCThreadStateBase;
-    }
-
-    pthread_mutex_lock(&gTLSMutex);
-    if (!gHaveTLS) {
-        int key_create_value = pthread_key_create(&gTLS, threadDestructor);
-        if (key_create_value != 0) {
-            pthread_mutex_unlock(&gTLSMutex);
-            ALOGW("IPCThreadStateBase::self() unable to create TLS key, expect a crash: %s\n",
-                    strerror(key_create_value));
-            return nullptr;
-        }
-        gHaveTLS = true;
-    }
-    pthread_mutex_unlock(&gTLSMutex);
-    goto restart;
-}
-
-void IPCThreadStateBase::pushCurrentState(CallState callState) {
-    mCallStateStack.emplace(callState);
-}
-
-IPCThreadStateBase::CallState IPCThreadStateBase::popCurrentState() {
-    ALOG_ASSERT(mCallStateStack.size > 0);
-    CallState val = mCallStateStack.top();
-    mCallStateStack.pop();
-    return val;
-}
-
-IPCThreadStateBase::CallState IPCThreadStateBase::getCurrentBinderCallState() {
-    if (mCallStateStack.size() > 0) {
-        return mCallStateStack.top();
-    }
-    return CallState::NONE;
-}
-
-void IPCThreadStateBase::threadDestructor(void *st)
-{
-    IPCThreadStateBase* const self = static_cast<IPCThreadStateBase*>(st);
-    if (self) {
-        delete self;
-    }
-}
-
-}; // namespace android
diff --git a/libs/binderthreadstate/TEST_MAPPING b/libs/binderthreadstate/TEST_MAPPING
new file mode 100644
index 0000000..2bd0463
--- /dev/null
+++ b/libs/binderthreadstate/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "presubmit": [
+    {
+      "name": "libbinderthreadstateutils_test"
+    }
+  ]
+}
diff --git a/libs/binderthreadstate/include/binderthreadstate/CallerUtils.h b/libs/binderthreadstate/include/binderthreadstate/CallerUtils.h
new file mode 100644
index 0000000..a3e5026
--- /dev/null
+++ b/libs/binderthreadstate/include/binderthreadstate/CallerUtils.h
@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+#pragma once
+
+// WARNING: DO NOT USE THIS
+// You should:
+// - have code know how it is handling things. Pass in caller information rather
+//   than assuming that code is running in a specific global context
+// - use AIDL exclusively in your stack (HIDL is no longer required anywhere)
+
+#include <binder/IPCThreadState.h>
+#include <hwbinder/IPCThreadState.h>
+
+namespace android {
+
+enum class BinderCallType {
+    NONE,
+    BINDER,
+    HWBINDER,
+};
+
+// Based on where we are in recursion of nested binder/hwbinder calls, determine
+// which one we are closer to.
+inline static BinderCallType getCurrentServingCall() {
+    const void* hwbinderSp = android::hardware::IPCThreadState::self()->getServingStackPointer();
+    const void* binderSp = android::IPCThreadState::self()->getServingStackPointer();
+
+    if (hwbinderSp == nullptr && binderSp == nullptr) return BinderCallType::NONE;
+    if (hwbinderSp == nullptr) return BinderCallType::BINDER;
+    if (binderSp == nullptr) return BinderCallType::HWBINDER;
+
+    if (hwbinderSp < binderSp) return BinderCallType::HWBINDER;
+    return BinderCallType::BINDER;
+}
+
+} // namespace android
diff --git a/libs/binderthreadstate/include/binderthreadstate/IPCThreadStateBase.h b/libs/binderthreadstate/include/binderthreadstate/IPCThreadStateBase.h
deleted file mode 100644
index 6fdcc84..0000000
--- a/libs/binderthreadstate/include/binderthreadstate/IPCThreadStateBase.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Copyright (C) 2018 The Android Open Source Project
- *
- * 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
- *
- *      http://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.
- */
-
-#ifndef BINDER_THREADSTATE_IPC_THREADSTATE_BASE_H
-#define BINDER_THREADSTATE_IPC_THREADSTATE_BASE_H
-
-#include <stack>
-namespace android {
-
-class IPCThreadStateBase {
-public:
-    enum CallState {
-        HWBINDER,
-        BINDER,
-        NONE,
-    };
-    static IPCThreadStateBase* self();
-    void pushCurrentState(CallState callState);
-    CallState popCurrentState();
-    CallState getCurrentBinderCallState();
-
-private:
-    IPCThreadStateBase();
-    static void threadDestructor(void *st);
-
-    std::stack<CallState> mCallStateStack;
-};
-
-}; // namespace android
-
-#endif // BINDER_THREADSTATE_IPC_THREADSTATE_BASE_H
diff --git a/libs/binderthreadstate/test.cpp b/libs/binderthreadstate/test.cpp
new file mode 100644
index 0000000..68cc225
--- /dev/null
+++ b/libs/binderthreadstate/test.cpp
@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+#include <BnAidlStuff.h>
+#include <android-base/logging.h>
+#include <binder/IServiceManager.h>
+#include <binderthreadstate/CallerUtils.h>
+#include <binderthreadstateutilstest/1.0/IHidlStuff.h>
+#include <gtest/gtest.h>
+#include <hidl/HidlTransportSupport.h>
+#include <linux/prctl.h>
+#include <sys/prctl.h>
+
+using android::BinderCallType;
+using android::defaultServiceManager;
+using android::getCurrentServingCall;
+using android::getService;
+using android::OK;
+using android::sp;
+using android::String16;
+using android::binder::Status;
+using android::hardware::Return;
+using binderthreadstateutilstest::V1_0::IHidlStuff;
+
+constexpr size_t kP1Id = 1;
+constexpr size_t kP2Id = 2;
+
+// AIDL and HIDL are in separate namespaces so using same service names
+std::string id2name(size_t id) {
+    return "libbinderthreadstateutils-" + std::to_string(id);
+}
+
+// There are two servers calling each other recursively like this.
+//
+// P1           P2
+// |  --HIDL-->  |
+// |  <--HIDL--  |
+// |  --AIDL-->  |
+// |  <--AIDL--  |
+// |  --HIDL-->  |
+// |  <--HIDL--  |
+// |  --AIDL-->  |
+// |  <--AIDL--  |
+//   ..........
+//
+// Calls always come in pairs (AIDL returns AIDL, HIDL returns HIDL) because
+// this means that P1 always has a 'waitForResponse' call which can service the
+// returning call and continue the recursion. Of course, with more threads, more
+// complicated calls are possible, but this should do here.
+
+static void callHidl(size_t id, int32_t idx) {
+    auto stuff = IHidlStuff::getService(id2name(id));
+    CHECK(stuff->call(idx).isOk());
+}
+
+static void callAidl(size_t id, int32_t idx) {
+    sp<IAidlStuff> stuff;
+    CHECK(OK == android::getService<IAidlStuff>(String16(id2name(id).c_str()), &stuff));
+    CHECK(stuff->call(idx).isOk());
+}
+
+class HidlServer : public IHidlStuff {
+public:
+    HidlServer(size_t thisId, size_t otherId) : thisId(thisId), otherId(otherId) {}
+    size_t thisId;
+    size_t otherId;
+
+    Return<void> callLocal() {
+        CHECK(BinderCallType::NONE == getCurrentServingCall());
+        return android::hardware::Status::ok();
+    }
+    Return<void> call(int32_t idx) {
+        LOG(INFO) << "HidlServer CALL " << thisId << " to " << otherId << " at idx: " << idx
+                  << " with tid: " << gettid();
+        CHECK(BinderCallType::HWBINDER == getCurrentServingCall());
+        if (idx > 0) {
+            if (thisId == kP1Id && idx % 4 < 2) {
+                callHidl(otherId, idx - 1);
+            } else {
+                callAidl(otherId, idx - 1);
+            }
+        }
+        CHECK(BinderCallType::HWBINDER == getCurrentServingCall());
+        return android::hardware::Status::ok();
+    }
+};
+class AidlServer : public BnAidlStuff {
+public:
+    AidlServer(size_t thisId, size_t otherId) : thisId(thisId), otherId(otherId) {}
+    size_t thisId;
+    size_t otherId;
+
+    Status callLocal() {
+        CHECK(BinderCallType::NONE == getCurrentServingCall());
+        return Status::ok();
+    }
+    Status call(int32_t idx) {
+        LOG(INFO) << "AidlServer CALL " << thisId << " to " << otherId << " at idx: " << idx
+                  << " with tid: " << gettid();
+        CHECK(BinderCallType::BINDER == getCurrentServingCall());
+        if (idx > 0) {
+            if (thisId == kP2Id && idx % 4 < 2) {
+                callHidl(otherId, idx - 1);
+            } else {
+                callAidl(otherId, idx - 1);
+            }
+        }
+        CHECK(BinderCallType::BINDER == getCurrentServingCall());
+        return Status::ok();
+    }
+};
+
+TEST(BinderThreadState, LocalHidlCall) {
+    sp<IHidlStuff> server = new HidlServer(0, 0);
+    EXPECT_TRUE(server->callLocal().isOk());
+}
+
+TEST(BinderThreadState, LocalAidlCall) {
+    sp<IAidlStuff> server = new AidlServer(0, 0);
+    EXPECT_TRUE(server->callLocal().isOk());
+}
+
+TEST(BindThreadState, RemoteHidlCall) {
+    auto stuff = IHidlStuff::getService(id2name(kP1Id));
+    ASSERT_NE(nullptr, stuff);
+    ASSERT_TRUE(stuff->call(0).isOk());
+}
+TEST(BindThreadState, RemoteAidlCall) {
+    sp<IAidlStuff> stuff;
+    ASSERT_EQ(OK, android::getService<IAidlStuff>(String16(id2name(kP1Id).c_str()), &stuff));
+    ASSERT_NE(nullptr, stuff);
+    ASSERT_TRUE(stuff->call(0).isOk());
+}
+
+TEST(BindThreadState, RemoteNestedStartHidlCall) {
+    auto stuff = IHidlStuff::getService(id2name(kP1Id));
+    ASSERT_NE(nullptr, stuff);
+    ASSERT_TRUE(stuff->call(100).isOk());
+}
+TEST(BindThreadState, RemoteNestedStartAidlCall) {
+    sp<IAidlStuff> stuff;
+    ASSERT_EQ(OK, android::getService<IAidlStuff>(String16(id2name(kP1Id).c_str()), &stuff));
+    ASSERT_NE(nullptr, stuff);
+    EXPECT_TRUE(stuff->call(100).isOk());
+}
+
+int server(size_t thisId, size_t otherId) {
+    // AIDL
+    android::ProcessState::self()->setThreadPoolMaxThreadCount(1);
+    sp<AidlServer> aidlServer = new AidlServer(thisId, otherId);
+    CHECK(OK == defaultServiceManager()->addService(String16(id2name(thisId).c_str()), aidlServer));
+    android::ProcessState::self()->startThreadPool();
+
+    // HIDL
+    setenv("TREBLE_TESTING_OVERRIDE", "true", true);
+    android::hardware::configureRpcThreadpool(1, true /*callerWillJoin*/);
+    sp<IHidlStuff> hidlServer = new HidlServer(thisId, otherId);
+    CHECK(OK == hidlServer->registerAsService(id2name(thisId).c_str()));
+    android::hardware::joinRpcThreadpool();
+
+    return EXIT_FAILURE;
+}
+
+int main(int argc, char** argv) {
+    ::testing::InitGoogleTest(&argc, argv);
+    setenv("TREBLE_TESTING_OVERRIDE", "true", true);
+    if (fork() == 0) {
+        prctl(PR_SET_PDEATHSIG, SIGHUP);
+        return server(kP1Id, kP2Id);
+    }
+    if (fork() == 0) {
+        prctl(PR_SET_PDEATHSIG, SIGHUP);
+        return server(kP2Id, kP1Id);
+    }
+
+    android::waitForService<IAidlStuff>(String16(id2name(kP1Id).c_str()));
+    android::hardware::details::waitForHwService(IHidlStuff::descriptor, id2name(kP1Id).c_str());
+    android::waitForService<IAidlStuff>(String16(id2name(kP2Id).c_str()));
+    android::hardware::details::waitForHwService(IHidlStuff::descriptor, id2name(kP2Id).c_str());
+
+    return RUN_ALL_TESTS();
+}