Re: [PATCH v2 00/11] x86-64: Stack protector and percpu improvements

Brian Gerst
2023-10-30T00:02:40Z

On Sun, Oct 29, 2023 at 5:42 PM David Laight <David.Laight@aculab.com> wrote:
>
> From: Brian Gerst
> > Sent: 26 October 2023 17:01
> >
> > Currently, x86-64 uses an unusual percpu layout, where the percpu section
> > is linked at absolute address 0. The reason behind this is that older GCC
> > versions placed the stack protector (if enabled) at a fixed offset from the
> > GS segment base. Since the GS segement is also used for percpu variables,
> > this forced the current layout.
> >
> > GCC since version 8.1 supports a configurable location for the stack
> > protector value, which allows removal of the restriction on how the percpu
> > section is linked. This allows the percpu section to be linked
> > normally, like most other architectures. In turn, this allows removal
> > of code that was needed to support the zero-based percpu section.
>
> I didn't think the minimum gcc version was anything like 8.1.
> I'm using 7.5.0 and I don't think that is the oldest version.

What distribution are you using that still relies on that old of a compiler?

Brian Gerst