Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 15fee822 authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Fix thread unwind in CallStack. 

The CallStack unwind of a different thread was broken since it
wasn't properly setting the tid value.

Fix this problem and add new unit tests to verify the behavior.

Bug: 246405269

Test: New unit tests pass.
Test: Ran unit tests for 1000 operations to verify not flaky.
Change-Id: I00342e6cdcdb4bcb68f29734dadee6c987c98040
parent 61c82abe

libutils/Android.bp

+12 −5
Original line number Diff line number Diff line
@@ -299,6 +299,7 @@ cc_test { 


    srcs: [

        "BitSet_test.cpp",

        "CallStack_test.cpp",

        "Errors_test.cpp",

        "FileMap_test.cpp",

        "LruCache_test.cpp",
@@ -319,11 +320,14 @@ cc_test { 
                "SystemClock_test.cpp",

            ],

            shared_libs: [

                "libz",

                "liblog",

                "libbase",

                "libcutils",

                "liblog",

                "liblzma",

                "libunwindstack",

                "libutils",

                "libbase",

                "libutilscallstack",

                "libz",

            ],

        },

        linux: {
@@ -334,9 +338,12 @@ cc_test { 
        },

        host: {

            static_libs: [

                "libutils",

                "liblog",

                "libbase",

                "liblog",

                "liblzma",

                "libunwindstack_no_dex",

                "libutils",

                "libutilscallstack",

            ],

        },

    },

libutils/CallStack.cpp

+1 −1
Original line number Diff line number Diff line
@@ -49,7 +49,7 @@ void CallStack::update(int32_t ignoreDepth, pid_t tid) { 
    unwindstack::AndroidUnwinderData data;

    std::optional<pid_t> tid_val;

    if (tid != -1) {

        *tid_val = tid;

        tid_val = tid;

    }

    if (!unwinder.Unwind(tid_val, data)) {

        ALOGW("%s: Failed to unwind callstack: %s", __FUNCTION__, data.GetErrorString().c_str());

libutils/CallStack_test.cpp

0 → 100644
+62 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2022 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 <unistd.h>



#include <thread>



#include <android-base/threads.h>

#include <gtest/gtest.h>

#include <utils/CallStack.h>



[[clang::noinline]] extern "C" void CurrentCaller(android::String8& backtrace) {

    android::CallStack cs;

    cs.update();

    backtrace = cs.toString();

}



TEST(CallStackTest, current_backtrace) {

    android::String8 backtrace;

    CurrentCaller(backtrace);



    ASSERT_NE(-1, backtrace.find("(CurrentCaller")) << "Full backtrace:\n" << backtrace;

}



[[clang::noinline]] extern "C" void ThreadBusyWait(std::atomic<pid_t>* tid, volatile bool* done) {

    *tid = android::base::GetThreadId();

    while (!*done) {

    }

}



TEST(CallStackTest, thread_backtrace) {

    // Use a volatile to avoid any problems unwinding since sometimes

    // accessing a std::atomic does not include unwind data at every

    // instruction and leads to failed unwinds.

    volatile bool done = false;

    std::atomic<pid_t> tid = -1;

    std::thread thread([&tid, &done]() { ThreadBusyWait(&tid, &done); });



    while (tid == -1) {

    }



    android::CallStack cs;

    cs.update(0, tid);



    done = true;

    thread.join();



    ASSERT_NE(-1, cs.toString().find("(ThreadBusyWait")) << "Full backtrace:\n" << cs.toString();

}