Re: [ptxdist] PTXDIST 2025.09.0: build failure of openssl-3.5.2 when gcc option -fzero-call-used-regs is not supported

[Christian Melki <christian.melki@t2data.com>]

Hi.

Which version of gcc are we talking about?
GCC 11 should support this, but I don't know over which archs.
It is there as a security enhancement. I would say something like less gadgets for ROP style attacks?
And while it does slow down execution, for something like OpenSSL, it usually is worth it imho.
I don't see a suitable toolchain option or hardening flag in ptxdist that currently fits this cleanly.
Not sure if something like this fits for a its own global pass either.
Maybe someone else has another opinion.

So my immediate suggestion would be to keep this local at your end for now.

Regards,
Christian

On 9/17/25 8:32 AM, ruggero rossi via ptxdist wrote:
> Hello everybody,
> 
> On my system, the gcc toolchain does not support the
> -fzero-call-used-regs option.
> 
> With PTXDIST 2025.09.0 this causes the build of OpenSSL 3.5.2 to fail.
> 
> An ad-hoc patch is trivial:
> I removed the -fzero-call-used-regs=used-gpr flag from
> openssl-3.5.2/Configurations/20-debian.conf (see attached patch).
> 
> My question is: would it be possible to integrate a more general solution
> into PTXDIST, so that the build works regardless of whether the toolchain
> supports this GCC option?
> 
> Best regards,
> 
> Ruggero Rossi
> 
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