Subject: Re: [PATCH v2 05/17] vdso: Avoid call to memset() by getrandom

From: Segher Boessenkool <[email-masked]>
Date: Thu, 29 Aug 2024 13:02:41 -0500

On Thu, Aug 29, 2024 at 07:36:38PM +0200, Christophe Leroy wrote:
> 
> 
> Le 28/08/2024 à 19:25, Segher Boessenkool a écrit :
> >
> >>Not sure about static binaries, though: do those even use the VDSO?
> >
> >With "static binary" people usually mean "a binary not using any DSOs",
> >I think the VDSO is a DSO, also in this respect?  As always, -static
> >builds are *way* less problematic (and faster and smaller :-) )
> >
> 
> AFAIK on powerpc even static binaries use the vDSO, otherwise signals 
> don't work.

How can that work?  Non-dynamic binaries do not use ld.so (that is the
definition of a dynamic binary, even).  So they cannot link (at runtime)
to any DSO (unless that is done manually?!)

Maybe there is something at a fixed offset in the vDSO, or something
like that?  Is this documented somewhere?

Segher