RFR(S) 8205965: SIGSEGV on write to NativeCallStack::EMPTY_STACK

Daniel D. Daugherty daniel.daugherty at oracle.com
Fri Jun 29 13:07:04 UTC 2018

Please don't forget to do a jdk-submit run.


On 6/29/18 9:04 AM, Zhengyu Gu wrote:
> Hi,
> clang-6.0 and above, can deduce that NativeCallStack::EMPTY_STACK is 
> all zeros, and since it is a static constant, it places the object in 
> the read-only BSS data section.
> To workaround static initialization ordering issue, NMT has to ensure 
> EMPTY_STACK is initialized before turns itself on, which can happen in 
> the middle of initialization of other static objects. In this case, it 
> causes SIGSEGV while try to write to the read-only memory.
> The solution is to make EMPTY_STACk private and non-constant, but 
> hands out constant version.
> Bug: https://bugs.openjdk.java.net/browse/JDK-8205965
> Webrev: http://cr.openjdk.java.net/~zgu/8205965/webrev.00/
> Test:
>   hotspot_nmt on Linux 64 (fastdebug and release)
> Thanks,
> -Zhengyu

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