RFR(M): 8187045: [linux] Not all libraries in the VM are linked with -z,noexecstack

[Lindenmaier, Goetz]

Hi,

I updated my webrev to the directory structure:
http://cr.openjdk.java.net/~goetz/wr17/8187045-execstackLink/webrev.02/
I also ran it through our tests again.

Could someone please sponsor this change?

Thanks,
  Goetz.


> -----Original Message-----
> From: Lindenmaier, Goetz
> Sent: Dienstag, 5. September 2017 10:05
> To: David Holmes <david.holmes at oracle.com>; hotspot-runtime-
> dev at openjdk.java.net; build-dev <build-dev at openjdk.java.net>
> Subject: RE: RFR(M): 8187045: [linux] Not all libraries in the VM are linked
> with -z,noexecstack
> 
> Hi David,
> 
> thanks for looking at my change!
> > Hi Goetz,
> >
> > On 1/09/2017 11:05 PM, Lindenmaier, Goetz wrote:
> > > Hi,
> > >
> > > I found that not all libraries are linked with -z,noexecstack.
> > > This lead to errors with our linuxppc64 build.  The linker omitted
> > > the flag altogether, which is interpreted as a lib with execstack.
> > >
> > > This change contains a small test that scans all libraries in the tested VM
> > > to have the noexecstack flag set. It utilizes the elf parser in the VM for
> this.
> > > Further -z,noexecstack is now passed to all libraries.
> > >
> > > Please review this change. I please need a sponsor.
> > > http://cr.openjdk.java.net/~goetz/wr17/8187045-
> > execstackLink/webrev.01/
> >
> > So IIUC presently we only set noexecstack for gcc on linux when building
> > libjvm - via the JVM_LDFLAGS settings.
> Yes.
> 
> > With this change we also set it for building JDK libraries via the
> > LDFLAGS_JDKLIB setting. But this seems to be unconditional, not limited
> > to gcc and linux ??
> LDFLAGS_NO_EXEC_STACK="-Wl,-z,noexecstack" is only assigned on linux,
> on other platforms its empty.
> 
> > In addition we want to build libjsig with noexecstack, and we do that by
> > exposing LDFLAGS_NO_EXEC_STACK in spec.gmk, and using it in
> > CompileLibjsig.gmk. I don't have an issue with the use of noexecstack
> > but I think it could just have been hard-wired for linux just as the
> > bulk of the flags set in that file are. Granted you copied what is done
> > for LDFLAGS_HASH_STYLE - but in that case I'm assuming it is important
> > that the same hash style be used throughout. Anyway minor stylistic nit
> > which may be moot soon as once we have the consolidated repo I think
> > libjsig could be handled the same as others libs?
> I had hoped to find a location where flags that should be used in all linking
> steps are assembled.  Noexecstack should really be set in any lib we build.
> But I didn't find that, so I implemented it as with the HASH_STYLE. I don't
> really like it this way because if a new lib is added it might be forgotten
> to add the noexecstack.
> But I assume after the repo consolidation the build will be reshaped,
> so now is not the right time to seek for optimal setups.
> 
> Best regards,
>   Goetz.
> 
> >  >
> > http://cr.openjdk.java.net/~goetz/wr17/8187045-
> execstackLink/webrev.01-
> > hs/
> >
> > Test changes look okay to me.
> >
> > Thanks,
> > David
> >
> > > Best regards,
> > >    Goetz.
> > >