diff --git a/debuggerd/Android.bp b/debuggerd/Android.bp
index 7b6f6c0..198e4de 100644
--- a/debuggerd/Android.bp
+++ b/debuggerd/Android.bp
@@ -276,6 +276,12 @@
     ],
 }
 
+cc_test_library {
+    name: "libcrash_test",
+    defaults: ["debuggerd_defaults"],
+    srcs: ["crash_test.cpp"],
+}
+
 cc_test {
     name: "debuggerd_test",
     defaults: ["debuggerd_defaults"],
@@ -341,6 +347,10 @@
         },
     },
 
+    data: [
+        ":libcrash_test",
+    ],
+
     test_suites: ["device-tests"],
 }
 
diff --git a/debuggerd/crash_test.cpp b/debuggerd/crash_test.cpp
new file mode 100644
index 0000000..c15145f
--- /dev/null
+++ b/debuggerd/crash_test.cpp
@@ -0,0 +1,21 @@
+/*
+ * Copyright 2021, 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 <stdint.h>
+
+extern "C" void crash() {
+  *reinterpret_cast<volatile char*>(0xdead) = '1';
+}
diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index 93725b9..eb3738e 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -15,6 +15,7 @@
  */
 
 #include <dirent.h>
+#include <dlfcn.h>
 #include <err.h>
 #include <fcntl.h>
 #include <malloc.h>
@@ -30,6 +31,7 @@
 
 #include <chrono>
 #include <regex>
+#include <string>
 #include <thread>
 
 #include <android/fdsan.h>
@@ -1510,6 +1512,60 @@
   ASSERT_MATCH(result, R"(Cause: stack pointer[^\n]*stack overflow.\n)");
 }
 
+static bool CopySharedLibrary(const char* tmp_dir, std::string* tmp_so_name) {
+  std::string test_lib(testing::internal::GetArgvs()[0]);
+  auto const value = test_lib.find_last_of('/');
+  if (value == std::string::npos) {
+    test_lib = "./";
+  } else {
+    test_lib = test_lib.substr(0, value + 1) + "./";
+  }
+  test_lib += "libcrash_test.so";
+
+  *tmp_so_name = std::string(tmp_dir) + "/libcrash_test.so";
+  std::string cp_cmd = android::base::StringPrintf("cp %s %s", test_lib.c_str(), tmp_dir);
+
+  // Copy the shared so to a tempory directory.
+  return system(cp_cmd.c_str()) == 0;
+}
+
+TEST_F(CrasherTest, unreadable_elf) {
+  int intercept_result;
+  unique_fd output_fd;
+  StartProcess([]() {
+    TemporaryDir td;
+    std::string tmp_so_name;
+    if (!CopySharedLibrary(td.path, &tmp_so_name)) {
+      _exit(1);
+    }
+    void* handle = dlopen(tmp_so_name.c_str(), RTLD_NOW);
+    if (handle == nullptr) {
+      _exit(1);
+    }
+    // Delete the original shared library so that we get the warning
+    // about unreadable elf files.
+    if (unlink(tmp_so_name.c_str()) == -1) {
+      _exit(1);
+    }
+    void (*crash_func)() = reinterpret_cast<void (*)()>(dlsym(handle, "crash"));
+    if (crash_func == nullptr) {
+      _exit(1);
+    }
+    crash_func();
+  });
+
+  StartIntercept(&output_fd);
+  FinishCrasher();
+  AssertDeath(SIGSEGV);
+  FinishIntercept(&intercept_result);
+
+  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+  std::string result;
+  ConsumeFd(std::move(output_fd), &result);
+  ASSERT_MATCH(result, R"(NOTE: Function names and BuildId information is missing )");
+}
+
 TEST(tombstoned, proto) {
   const pid_t self = getpid();
   unique_fd tombstoned_socket, text_fd, proto_fd;
diff --git a/debuggerd/libdebuggerd/tombstone_proto.cpp b/debuggerd/libdebuggerd/tombstone_proto.cpp
index 7657001..d4a35b3 100644
--- a/debuggerd/libdebuggerd/tombstone_proto.cpp
+++ b/debuggerd/libdebuggerd/tombstone_proto.cpp
@@ -395,6 +395,15 @@
                             unwinder->LastErrorAddress());
     }
   } else {
+    if (unwinder->elf_from_memory_not_file()) {
+      auto backtrace_note = thread.mutable_backtrace_note();
+      *backtrace_note->Add() =
+          "Function names and BuildId information is missing for some frames due";
+      *backtrace_note->Add() =
+          "to unreadable libraries. For unwinds of apps, only shared libraries";
+      *backtrace_note->Add() = "found under the lib/ directory are readable.";
+      *backtrace_note->Add() = "On this device, run setenforce 0 to make the libraries readable.";
+    }
     unwinder->SetDisplayBuildID(true);
     for (const auto& frame : unwinder->frames()) {
       BacktraceFrame* f = thread.add_current_backtrace();
diff --git a/debuggerd/libdebuggerd/tombstone_proto_to_text.cpp b/debuggerd/libdebuggerd/tombstone_proto_to_text.cpp
index 020b0a5..b780b22 100644
--- a/debuggerd/libdebuggerd/tombstone_proto_to_text.cpp
+++ b/debuggerd/libdebuggerd/tombstone_proto_to_text.cpp
@@ -171,6 +171,10 @@
                                    const Thread& thread, bool should_log) {
   CBS("");
   CB(should_log, "backtrace:");
+  if (!thread.backtrace_note().empty()) {
+    CB(should_log, "  NOTE: %s",
+       android::base::Join(thread.backtrace_note(), "\n  NOTE: ").c_str());
+  }
   print_backtrace(callback, tombstone, thread.current_backtrace(), should_log);
 }
 
diff --git a/debuggerd/proto/tombstone.proto b/debuggerd/proto/tombstone.proto
index 294e4e5..22fc30e 100644
--- a/debuggerd/proto/tombstone.proto
+++ b/debuggerd/proto/tombstone.proto
@@ -119,11 +119,12 @@
   int32 id = 1;
   string name = 2;
   repeated Register registers = 3;
+  repeated string backtrace_note = 7;
   repeated BacktraceFrame current_backtrace = 4;
   repeated MemoryDump memory_dump = 5;
   int64 tagged_addr_ctrl = 6;
 
-  reserved 7 to 999;
+  reserved 8 to 999;
 }
 
 message BacktraceFrame {