[8u] RFR: fix of vtable self-patching routine

[Sergey Nazarkin]

Seems we forgot about this issue. I can’t find it in the logs at least. 


Sergey Nazarkin




> On 07 Apr 2016, at 20:14, Fedor Burdun <fedor.burdun at azulsystems.com> wrote:
> 
> Hi all,
> 
> I would like to ask you several reviews of proposed fix of issue below.
> 
> The problem is crash caused by using CDS.
> It occurs because c++ vtables self-patching routine (written in metaspaceShared_aarch32.cpp) corrupts r9 register, that can be used by c++ compiler to store locals.
> Usually it happens in Method::restore_vtable virtual call, that causes undefined behaviour (mostly crahes) in InstanceKlass::restore_unshareable_info function.
> 
> Reproduction steps:
> # dump shared space
>  $ java -Xint -XX:+UnlockDiagnosticVMOptions -XX:SharedArchiveFile=./sample.jsa -Xshare:dump
> 
> # restore from CDS (crash happens here)
>  $ java -Xint -XX:+UnlockDiagnosticVMOptions -XX:SharedArchiveFile=./sample.jsa -Xshare:on -version
> 
> Fix is in attachement.
> 
> Thanks,
> Fedor
> <CDS.patch>