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.
Dan
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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