8274527: Minimal VM build fails after JDK-8273459

[DamonFool]

Hi all,

The broken was observed when

(gdb) bt
#0  MacroAssembler::align (this=0x7ffff0025b98, modulus=32) at /home/jvm/jiefu/docker/jdk/src/hotspot/cpu/x86/macroAssembler_x86.cpp:1182
#1  0x00007ffff67fc6c5 in MacroAssembler::kernel_crc32 (this=0x7ffff0025b98, crc=0x7, buf=0x6, len=0x2, table=0x1, tmp=0xb)
    at /home/jvm/jiefu/docker/jdk/src/hotspot/cpu/x86/macroAssembler_x86.cpp:6911
#2  0x00007ffff69a3555 in StubGenerator::generate_updateBytesCRC32 (this=0x7ffff5e9c900) at /home/jvm/jiefu/docker/jdk/src/hotspot/cpu/x86/stubGenerator_x86_64.cpp:6532
#3  0x00007ffff69a589b in StubGenerator::generate_initial (this=0x7ffff5e9c900) at /home/jvm/jiefu/docker/jdk/src/hotspot/cpu/x86/stubGenerator_x86_64.cpp:7583
#4  0x00007ffff69a6801 in StubGenerator::StubGenerator (this=0x7ffff5e9c900, code=0x7ffff5e9c9c0, all=false)
    at /home/jvm/jiefu/docker/jdk/src/hotspot/cpu/x86/stubGenerator_x86_64.cpp:7909
#5  0x00007ffff697fa21 in StubGenerator_generate (code=0x7ffff5e9c9c0, all=false) at /home/jvm/jiefu/docker/jdk/src/hotspot/cpu/x86/stubGenerator_x86_64.cpp:7919
#6  0x00007ffff69a6c13 in StubRoutines::initialize1 () at /home/jvm/jiefu/docker/jdk/src/hotspot/share/runtime/stubRoutines.cpp:223
#7  0x00007ffff69a790d in stubRoutines_init1 () at /home/jvm/jiefu/docker/jdk/src/hotspot/share/runtime/stubRoutines.cpp:366
#8  0x00007ffff672044d in init_globals () at /home/jvm/jiefu/docker/jdk/src/hotspot/share/runtime/init.cpp:119
#9  0x00007ffff69fb39f in Threads::create_vm (args=0x7ffff5e9ce10, canTryAgain=0x7ffff5e9cd33) at /home/jvm/jiefu/docker/jdk/src/hotspot/share/runtime/thread.cpp:2827
#10 0x00007ffff6787879 in JNI_CreateJavaVM_inner (vm=0x7ffff5e9ce68, penv=0x7ffff5e9ce70, args=0x7ffff5e9ce10)
    at /home/jvm/jiefu/docker/jdk/src/hotspot/share/prims/jni.cpp:3616
#11 0x00007ffff6787a72 in JNI_CreateJavaVM (vm=0x7ffff5e9ce68, penv=0x7ffff5e9ce70, args=0x7ffff5e9ce10)
    at /home/jvm/jiefu/docker/jdk/src/hotspot/share/prims/jni.cpp:3704
#12 0x00007ffff79b8141 in InitializeJVM (pvm=0x7ffff5e9ce68, penv=0x7ffff5e9ce70, ifn=0x7ffff5e9cec0)
    at /home/jvm/jiefu/docker/jdk/src/java.base/share/native/libjli/java.c:1459
#13 0x00007ffff79b4f39 in JavaMain (_args=0x7fffffffb1a0) at /home/jvm/jiefu/docker/jdk/src/java.base/share/native/libjli/java.c:411
#14 0x00007ffff79bba79 in ThreadJavaMain (args=0x7fffffffb1a0) at /home/jvm/jiefu/docker/jdk/src/java.base/unix/native/libjli/java_md.c:651
#15 0x00007ffff779cea5 in start_thread () from /lib64/libpthread.so.0
#16 0x00007ffff72c19fd in clone () from /lib64/libc.so.6

In this case, modulus=32 and CodeEntryAlignment=16.

So this assert shouldn't be added in align since we may use it (modulus > CodeEntryAlignment) in highly optimized hand-crafted assembly code.

Thanks.
Best regards,
Jie

---

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Issue

• JDK-8274527: Minimal VM build fails after JDK-8273459

Reviewers

• @asgibbons (no known github.com user name / role)
• Vladimir Kozlov (@vnkozlov - Reviewer)

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[bridgekeeper]

👋 Welcome back jiefu! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (cdd8743b)
• 00: Full (63d635bf)

[asgibbons]

Hi, Jie. With a value of 16 for CodeEntryAlignment, there is no way to ensure that the address of the byte following the align(32) is, in fact, 32-byte aligned. This is the exact case that I found that caused me to file the bug. I would suggest you verify this with an assert following your align(32) verifying that the alignment is correct. I think you'll discover that it will be unaligned ~50% of the time.

This is because align() uses the offset from the beginning of the segment to determine the number of nops to emit. If the segment has the starting address 0xXXXXXX10 (16-byte aligned), align(32) will calculate the offset() and align the pc to a multiple of 32 bytes from this starting address. This means that the address after the align(32) has the possibility of being 0xXXXXXX30 about half the time.

I would suggest that if you absolutely require 32-byte alignment, you take a similar path that I took for 64-byte alignment. That is, to create align32() and have it call align(32, pc()). This will ensure (for stub code) that the alignment is correct.

[DamonFool]

Hi, Jie. With a value of 16 for CodeEntryAlignment, there is no way to ensure that the address of the byte following the align(32) is, in fact, 32-byte aligned. This is the exact case that I found that caused me to file the bug. I would suggest you verify this with an assert following your align(32) verifying that the alignment is correct. I think you'll discover that it will be unaligned ~50% of the time.

This is because align() uses the offset from the beginning of the segment to determine the number of nops to emit. If the segment has the starting address 0xXXXXXX10 (16-byte aligned), align(32) will calculate the offset() and align the pc to a multiple of 32 bytes from this starting address. This means that the address after the align(32) has the possibility of being 0xXXXXXX30 about half the time.

I would suggest that if you absolutely require 32-byte alignment, you take a similar path that I took for 64-byte alignment. That is, to create align32() and have it call align(32, pc()). This will ensure (for stub code) that the alignment is correct.

Ah, you are right.
I missed that align is with the offset() not the pc().
So the assert should make sense.

Updated.
Thanks.

[asgibbons]

Looks good to me.

[vnkozlov]

Good.

[openjdk]

@DamonFool This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8274527: Minimal VM build fails after JDK-8273459

Reviewed-by: kvn

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 15 new commits pushed to the master branch:

• 7326481: 8274393: Suppress more warnings on non-serializable non-transient instance fields in security libs
• 8215b2e: 8274398: Suppress more warnings on non-serializable non-transient instance fields in management libs
• 9573022: 8253197: vmTestbase/nsk/jvmti/StopThread/stopthrd007/TestDescription.java fails with "ERROR: DebuggeeSleepingThread: ThreadDeath lost"
• f08180f: 8274501: c2i entry barriers read int as long on AArch64
• c57ed22: 8274528: Add comment to explain an HKDF optimization in SSLSecretDerivation
• 9180d9a: 8273216: JCMD does not work across container boundaries with Podman
• 3e0d7c3: 8270290: NTLM authentication fails if HEAD request is used
• bfd6163: 8274196: Crashes in VM_HeapDumper::work after JDK-8252842
• bb95dda: 8248001: javadoc generates invalid HTML pages whose ftp:// links are broken
• 2f955d6: 8273142: Remove dependancy of TestHttpServer, HttpTransaction, HttpCallback from open/test/jdk/sun/net/www/protocol/http/ tests
• ... and 5 more: https://git.openjdk.java.net/jdk/compare/355356c405adb9287b786b0b045c2eb974d2ffca...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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[DamonFool]

Thanks @asgibbons and @vnkozlov for your review.
/integrate

[openjdk]

Going to push as commit a8edd1b.
Since your change was applied there have been 15 commits pushed to the master branch:

• 7326481: 8274393: Suppress more warnings on non-serializable non-transient instance fields in security libs
• 8215b2e: 8274398: Suppress more warnings on non-serializable non-transient instance fields in management libs
• 9573022: 8253197: vmTestbase/nsk/jvmti/StopThread/stopthrd007/TestDescription.java fails with "ERROR: DebuggeeSleepingThread: ThreadDeath lost"
• f08180f: 8274501: c2i entry barriers read int as long on AArch64
• c57ed22: 8274528: Add comment to explain an HKDF optimization in SSLSecretDerivation
• 9180d9a: 8273216: JCMD does not work across container boundaries with Podman
• 3e0d7c3: 8270290: NTLM authentication fails if HEAD request is used
• bfd6163: 8274196: Crashes in VM_HeapDumper::work after JDK-8252842
• bb95dda: 8248001: javadoc generates invalid HTML pages whose ftp:// links are broken
• 2f955d6: 8273142: Remove dependancy of TestHttpServer, HttpTransaction, HttpCallback from open/test/jdk/sun/net/www/protocol/http/ tests
• ... and 5 more: https://git.openjdk.java.net/jdk/compare/355356c405adb9287b786b0b045c2eb974d2ffca...master

Your commit was automatically rebased without conflicts.

[openjdk]

@DamonFool Pushed as commit a8edd1b.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

[sviswa7]

/backport jdk17u-dev

[openjdk]

@sviswa7 the backport was successfully created on the branch sviswa7-backport-a8edd1b3 in my personal fork of openjdk/jdk17u-dev. To create a pull request with this backport targeting openjdk/jdk17u-dev:master, just click the following link:

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The title of the pull request is automatically filled in correctly and below you find a suggestion for the pull request body:

Hi all,

This pull request contains a backport of commit a8edd1b3 from the openjdk/jdk repository.

The commit being backported was authored by Jie Fu on 30 Sep 2021 and was reviewed by Vladimir Kozlov.

Thanks!

If you need to update the source branch of the pull then run the following commands in a local clone of your personal fork of openjdk/jdk17u-dev:

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$ git checkout sviswa7-backport-a8edd1b3
# make changes
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