linux-kernel - Re: [PATCH v22 2/5] arm64: el2_setup.h: Make __init_el2

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Message-ID: <CAL_JsqKWY7rRGTbHXTmm4RC9F8fqrs133=75XFkVdm91bLHfaw@mail.gmail.com>
Date: Thu, 22 May 2025 12:20:35 -0500
From: Rob Herring <robh@...nel.org>
To: Dave Martin <Dave.Martin@....com>
Cc: Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	Catalin Marinas <catalin.marinas@....com>, Jonathan Corbet <corbet@....net>, Marc Zyngier <maz@...nel.org>, 
	Oliver Upton <oliver.upton@...ux.dev>, Joey Gouly <joey.gouly@....com>, 
	Suzuki K Poulose <suzuki.poulose@....com>, Zenghui Yu <yuzenghui@...wei.com>, 
	James Clark <james.clark@...aro.org>, Anshuman Khandual <anshuman.khandual@....com>, 
	Leo Yan <leo.yan@....com>, linux-arm-kernel@...ts.infradead.org, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-doc@...r.kernel.org, kvmarm@...ts.linux.dev
Subject: Re: [PATCH v22 2/5] arm64: el2_setup.h: Make __init_el2_fgt labels
 consistent, again

On Thu, May 22, 2025 at 11:15 AM Dave Martin <Dave.Martin@....com> wrote:
>
> On Tue, May 20, 2025 at 05:27:37PM -0500, Rob Herring (Arm) wrote:
> > From: Anshuman Khandual <anshuman.khandual@....com>
> >
> > Commit 5b39db6037e7 ("arm64: el2_setup.h: Rename some labels to be more
> > diff-friendly") reworked the labels in __init_el2_fgt to say what's
> > skipped rather than what the target location is. The exception was
> > "set_fgt_" which is where registers are written. In reviewing the BRBE
> > additions, Will suggested "set_debug_fgt_" where HDFGxTR_EL2 are
> > written. Doing that would partially revert commit 5b39db6037e7 undoing
> > the goal of minimizing additions here, but it would follow the
> > convention for labels where registers are written.
> >
> > So let's do both. Branches that skip something go to a "skip" label and
> > places that set registers have a "set" label. This results in some
> > double labels, but it makes things entirely consistent.
> >
> > While we're here, the SME skip label was incorrectly named, so fix it.
> >
> > Reported-by: Will Deacon <will@...nel.org>
> > Cc: Dave Martin <Dave.Martin@....com>
> > Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
> > ---
> > This one can be applied even if the rest of the series is not.
> >
> > v22:
> >  - New patch
> > ---
> >  arch/arm64/include/asm/el2_setup.h | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
> > index ebceaae3c749..30f57b0334a3 100644
> > --- a/arch/arm64/include/asm/el2_setup.h
> > +++ b/arch/arm64/include/asm/el2_setup.h
> > @@ -204,19 +204,21 @@
> >       orr     x0, x0, #(1 << 62)
> >
> >  .Lskip_spe_fgt_\@:
> > +
> > +.Lset_debug_fgt_\@:
>
> Dangling label?  There doesn't seem to be any branch to it in this
> series, unless I've missed something.

I tried to explain that in the commit message. To have both what you
wanted and what Will suggested, you end up with 2 labels in between
the last skip and setting registers.

Rob