[PING] RFR(XS): 8208091: SA: jhsdb jstack --mixed throws UnmappedAddressException on i686

[Severin Gehwolf]

On Thu, 2018-07-26 at 10:04 -0700, Sharath Ballal wrote:
> Changes looks good Severin.

Thanks for the review, Sharath!

> I am not a reviewer though, so you still need a Reviewer to review.

Anyone?

Thanks,
Severin

> -----Original Message-----
> From: Severin Gehwolf [mailto:sgehwolf at redhat.com] 
> Sent: Thursday, July 26, 2018 1:04 PM
> To: serviceability-dev
> Subject: [PING] RFR(XS): 8208091: SA: jhsdb jstack --mixed throws UnmappedAddressException on i686
> 
> On Mon, 2018-07-23 at 18:27 +0200, Severin Gehwolf wrote:
> > Hi,
> > 
> > Could I please get a review of this one-liner change related to jhsdb 
> > --mixed when attaching to a running Java process? The issue arises 
> > when threads are in native code and that native code has frame 
> > pointers not properly preserved. In such a case the SA performs a 
> > simple frame pointer valididy check: ebp >= esp
> > 
> > However, the code of retrieving the value for esp is incorrect in as 
> > much as it's not in sync with native code in regards to the register
> > index:
> > 
> > native code => X86ThreadContext.SP
> > Java code   => X86ThreadContext.ESP
> > 
> > X86ThreadContext.ESP is never being set by the native code. Since
> > X86ThreadContext.getRegisterAsAddress(X86ThreadContext.ESP) then 
> > returns null, ebp.lessThan(esp) wrongly returns false causing the 
> > issue. This webrev fixes it by using SP as index on the Java side.
> > Thoughts?
> > 
> > webrev: 
> > http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8208091/webrev.01/
> > bug: https://bugs.openjdk.java.net/browse/JDK-8208091
> 
> Anyone willing to review this one-liner?
> 
> Thanks,
> Severin
> 
> > Thanks,
> > Severin
> 
>