Re: [PATCH v2] random: vDSO: Avoid call to memset() when zeroing reserved in __cvdso_getrandom_data()

[Jason A. Donenfeld]

On Fri, Oct 2, 2026 at 12:57 PM Christophe Leroy (CS GROUP)
<chleroy@xxxxxxxxxx> wrote:
>
>
> On Fri, 25 Sep 2026 22:46:32 +0100, Nathan Chancellor wrote:
> > After a recent change in LLVM [1], builds with the random vDSO
> > implementation, such as PowerPC and RISC-V, fail when checking the vDSO:
> >
> >   arch/powerpc/kernel/vdso/vdso32.so.dbg: dynamic relocations are not supported
> >   arch/riscv/kernel/vdso/vdso.so.dbg: dynamic relocations are not supported
> >
> > memset() is now generated when zeroing params->reserved for some builds
> > because LLVM has an optimization (now run in more instances) that can
> > recognize at compile time when it is assigning a static value to a
> > contiguous area of memory and turn that into a call to memset(). Both
> > clang and GCC assume memset() is always available [2].
> >
> > [...]
>
> Applied, thanks!
>
> [1/1] random: vDSO: Avoid call to memset() when zeroing reserved in __cvdso_getrandom_data()
>       (no commit info)

That's not for you to apply. I'm sending this through my random tree,
along with a handful of other things I need to fix. But I wanted to
let this cook a bit more. I can add your reviewed-by line, though.

Jason