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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

/*

 * @test ReservedStackTest

 * @library /testlibrary

 * @modules java.base/jdk.internal.vm.annotation

 * @build jdk.test.lib.*

 * @run main/othervm -XX:-Inline -XX:CompileCommand=exclude,java/util/concurrent/locks/AbstractOwnableSynchronizer.setExclusiveOwnerThread ReservedStackTest

 */

/* The exclusion of java.util.concurrent.locks.AbstractOwnableSynchronizer.setExclusiveOwnerThread()

 * from the compilable methods is required to ensure that the test will be able

 * to trigger a StackOverflowError on the right method.

 */

/*

 * Notes about this test:

 * This test tries to reproduce a rare but nasty corruption bug that

 * occurs when a StackOverflowError is thrown in some critical sections

 * of the ReentrantLock implementation.

 *

 * Here's the critical section where a corruption could occur

 * (from java.util.concurrent.ReentrantLock.java)

 *

 * final void lock() {

 *     if (compareAndSetState(0, 1))

 *         setExclusiveOwnerThread(Thread.currentThread());

 *     else

 *         acquire(1);

 * }

 *

 * The corruption occurs when the compareAndSetState(0, 1)

 * successfully updates the status of the lock but the method

 * fails to set the owner because of a stack overflow.

 * HotSpot checks for stack overflow on method invocations.

 * The test must trigger a stack overflow either when

 * Thread.currentThread() or setExclusiveOwnerThread() is

 * invoked.

 *

 * The test starts with a recursive invocation loop until a

 * first StackOverflowError is thrown, the Error is caught

 * and a few dozen frames are exited. Now the thread has

 * little free space on its execution stack and will try

 * to trigger a stack overflow in the critical section.

 * The test has a huge array of ReentrantLocks instances.

 * The thread invokes a recursive method which, at each

 * of its invocations, tries to acquire the next lock

 * in the array. The execution continues until a

 * StackOverflowError is thrown or the end of the array

 * is reached.

 * If no StackOverflowError has been thrown, the test

 * is non conclusive (recommendation: increase the size

 * of the ReentrantLock array).

 * The status of all Reentrant locks in the array is checked,

 * if a corruption is detected, the test failed, otherwise

 * the test passed.

 *

 * To have a chance that the stack overflow occurs on one

 * of the two targeted method invocations, the test is

 * repeated in different threads. Each Java thread has a

 * random size area allocated at the beginning of its

 * stack to prevent false sharing. The test relies on this

 * to have different stack alignments when it hits the targeted

 * methods (the test could have been written with a native

 * method with alloca, but using different Java threads makes

 * the test 100% Java).

 *

 * One additional trick is required to ensure that the stack

 * overflow will occur on the Thread.currentThread() getter

 * or the setExclusiveOwnerThread() setter.

 *

 * Potential stack overflows are detected by stack banging,

 * at method invocation time.

 * In interpreted code, the stack banging performed for the

 * lock() method goes further than the stack banging performed

 * for the getter or the setter method, so the potential stack

 * overflow is detected before entering the critical section.

 * In compiled code, the getter and the setter are in-lined,

 * so the stack banging is only performed before entering the

 * critical section.

 * In order to have a stack banging that goes further for the

 * getter/setter methods than for the lock() method, the test

 * exploits the property that interpreter frames are (much)

 * bigger than compiled code frames. When the test is run,

 * a compiler option disables the compilation of the

 * setExclusiveOwnerThread() method.

 *

 */

import java.util.concurrent.locks.ReentrantLock;

import jdk.test.lib.Platform;

public class ReservedStackTest {

    static class ReentrantLockTest {

        private ReentrantLock lockArray[];

        // Frame sizes vary a lot between interpreted code and compiled code

        // so the lock array has to be big enough to cover all cases.

        // If test fails with message "Not conclusive test", try to increase

        // LOCK_ARRAY_SIZE value

        private static final int LOCK_ARRAY_SIZE = 8192;

        private boolean stackOverflowErrorReceived;

        StackOverflowError soe = null;

        private int index = -1;

        public void initialize() {

            lockArray = new ReentrantLock[LOCK_ARRAY_SIZE];

            for (int i = 0; i < LOCK_ARRAY_SIZE; i++) {

                lockArray[i] = new ReentrantLock();

            }

            stackOverflowErrorReceived = false;

        }

        public String getResult() {

            if (!stackOverflowErrorReceived) {

                return "ERROR: Not conclusive test: no StackOverflowError received";

            }

            for (int i = 0; i < LOCK_ARRAY_SIZE; i++) {

                if (lockArray[i].isLocked()) {

                    if (!lockArray[i].isHeldByCurrentThread()) {

                        StringBuilder s = new StringBuilder();

                        s.append("FAILED: ReentrantLock ");

                        s.append(i);

                        s.append(" looks corrupted");

                        return s.toString();

                    }

                }

            }

            return "PASSED";

        }

        public void run() {

            try {

                lockAndCall(0);

            } catch (StackOverflowError e) {

                soe = e;

                stackOverflowErrorReceived = true;

            }

        }

        private void lockAndCall(int i) {

            index = i;

            if (i < LOCK_ARRAY_SIZE) {

                lockArray[i].lock();

                lockAndCall(i + 1);

            }

        }

    }

    static class RunWithSOEContext implements Runnable {

        int counter;

        int deframe;

        int decounter;

        int setupSOEFrame;

        int testStartFrame;

        ReentrantLockTest test;

        public RunWithSOEContext(ReentrantLockTest test, int deframe) {

            this.test = test;

            this.deframe = deframe;

        }

        @Override

        @jdk.internal.vm.annotation.ReservedStackAccess

        public void run() {

            counter = 0;

            decounter = deframe;

            test.initialize();

            recursiveCall();

            System.out.println("Framework got StackOverflowError at frame = " + counter);

            System.out.println("Test started execution at frame = " + (counter - deframe));

            String result = test.getResult();

            // The feature is not fully implemented on all platforms,

            // corruptions are still possible

            boolean supportedPlatform = Platform.isSolaris() || Platform.isOSX()

                || (Platform.isLinux() && (Platform.isX86() || Platform.isX64()));

            if (supportedPlatform && !result.contains("PASSED")) {

                System.out.println(result);

                throw new Error(result);

            } else {

                // Either the test passed or this platform is not supported.

                // On not supported platforms, we only expect the VM to

                // not crash during the test. This is especially important

                // on Windows where the detection of SOE in annotated

                // sections is implemented but the reserved zone mechanism

                // to avoid the corruption cannot be implemented yet

                // because of JDK-8067946

                System.out.println("PASSED");

            }

        }

        void recursiveCall() {

            // Unused local variables to increase the frame size

            long l1, l2, l3, l4, l5, l6, l7, l8, l9, l10, l11, l12, l13, l14, l15, l16, l17, l18, l19;

            long l20, l21, l22, l23, l24, l25, l26, l27, l28, l30, l31, l32, l33, l34, l35, l36, l37;

            counter++;

            try {

                recursiveCall();

            } catch (StackOverflowError e) {

            }

            decounter--;

            if (decounter == 0) {

                setupSOEFrame = counter;

                testStartFrame = counter - deframe;

                test.run();

            }

        }

    }

    public static void main(String[] args) {

        for (int i = 0; i < 1000; i++) {

            // Each iteration has to be executed by a new thread. The test

            // relies on the random size area pushed by the VM at the beginning

            // of the stack of each Java thread it creates.

            Thread thread = new Thread(new RunWithSOEContext(new ReentrantLockTest(), 256));

            thread.start();

            try {

                thread.join();

            } catch (InterruptedException ex) { }

        }

    }

}