[PATCH] drm/amd: Permit DC_FP_START/END only in non-FP compilation units

[Ard Biesheuvel]

On Thu, 9 Oct 2025 at 13:41, Harry Wentland <harry.wentland at amd.com> wrote:
>
>
>
> On 2025-10-09 12:19, Christian König wrote:
> > On 09.10.25 17:06, Ard Biesheuvel wrote:
> >> From: Ard Biesheuvel <ardb at kernel.org>
> >>
> >> Test the existing CPP macro _LINUX_FPU_COMPILATION_UNIT, which is set
> >> when building source files that are permitted to use floating point,
> >> in the implementation of DC_FP_START/END so that those are only usable
> >> in non-FP code. This is a requirement of the generic kernel mode FPU
> >> API, as some architectures (i.e., arm64) cannot safely enable FP codegen
> >> in arbitrary code.
> >
> > If I'm not completely mistaken that is actually an issue on basically all architectures, at least x86 is affected as well if I'm not completely mistaken.
> >
> >> Cc: Austin Zheng <austin.zheng at amd.com>
> >> Cc: Jun Lei <jun.lei at amd.com>
> >> Cc: Harry Wentland <harry.wentland at amd.com>
> >> Cc: Leo Li <sunpeng.li at amd.com>
> >> Cc: Rodrigo Siqueira <siqueira at igalia.com>
> >> Cc: Alex Deucher <alexander.deucher at amd.com>
> >> Cc: "Christian König" <christian.koenig at amd.com>
> >> Cc: amd-gfx at lists.freedesktop.org
> >> Cc: dri-devel at lists.freedesktop.org
> >> Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
> >
> > Anyway, patch looks sane to me but I'm not so deep in the DC code to fully judge.
> >
> > Fell free to add Acked-by: Christian König <christian.koenig at amd.com>, but Harry and Leo need to take a look.
> >
>
> Thanks. Good safe-guard. Flags a bunch of issues in the
> current code. Let me fix them before merging it.
>
> Reviewed-by: Harry Wentland <harry.wentland at amd.com>
>

Thanks.

I already fixed a bunch here:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=ddbfac152830e38d488ff8e45ab7eaf5d72f8527