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>]

On 9/17/25 11:00 AM, ruggero rossi wrote:
> On Wed, 17 Sep 2025 10:30:04 +0200
> Christian Melki <christian.melki@t2data.com> wrote:
> 
>> Hi.
>>
>> Which version of gcc are we talking about?
> It is quite old, but I'm bound to it because some software does not
> compile with newer versions. It looks like that the -fzero-call-used-regs
> is supported from GCC 11 (released April 2021).
> 
>> 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 agree.... The option is a must, when it is supported.
> 
> Moreover, I found a comment in some openssh (not openssl) tracking,
> saying that to detect whether a version of gcc supports the option or not
> may be not trivial.
> 
>> 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.
> 
> OK - and these messages remain as a help if anyone else has the same
> problem.

Indeed. Appreciate the time taken to report it.

Christian

> 
> Regards,
> Ruggero
> 
>>
>> Regards,
>> Christian