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

[David Holmes]

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.

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 ??

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?

 > 
http://cr.openjdk.java.net/~goetz/wr17/8187045-execstackLink/webrev.01-hs/

Test changes look okay to me.

Thanks,
David

> Best regards,
>    Goetz.
>