linux-kernel - Re: [PATCH] [RFC] arm64: export this_cpu_has

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Message-ID: <YXw4H2BNx85KnLDh@arm.com>
Date:   Fri, 29 Oct 2021 19:06:23 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     Arnd Bergmann <arnd@...nel.org>, Will Deacon <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Arnd Bergmann <arnd@...db.de>, Marc Zyngier <maz@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        David Brazdil <dbrazdil@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [RFC] arm64: export this_cpu_has_cap

On Fri, Oct 29, 2021 at 02:31:23PM +0100, Suzuki K Poulose wrote:
> On 29/10/2021 12:30, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@...db.de>
> > 
> > It's now used in a coresight driver that can be a loadable module:
> > 
> > ERROR: modpost: "this_cpu_has_cap" [drivers/hwtracing/coresight/coresight-trbe.ko] undefined!
> > 
> > Fixes: 8a1065127d95 ("coresight: trbe: Add infrastructure for Errata handling")
> 
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
> Tested-by: Suzuki K Poulose <suzuki.poulose@....com>
> 
> Will, Catalin, Mathieu,
> 
> Do you have a preference on how this fix can be pulled in ? This may
> be safe to go via coresight tree if it is not too late. Otherwise,
> it could go via the arm64 tree.

I think Will already closed/tagged the arm64 tree for the upcoming
merging window, though he could take it as a fix afterwards.

If it doesn't conflict with the arm64 for-next/core, it's fine by me to
go through the coresight tree.

> > Signed-off-by: Arnd Bergmann <arnd@...db.de>
> > ---
> > Not sure if we actually want this to be exported, this is my local
> > workaround for the randconfig build bot.
> > ---
> >   arch/arm64/kernel/cpufeature.c | 1 +
> >   1 file changed, 1 insertion(+)
> > 
> > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> > index ecbdff795f5e..beccbcfa7391 100644
> > --- a/arch/arm64/kernel/cpufeature.c
> > +++ b/arch/arm64/kernel/cpufeature.c
> > @@ -2864,6 +2864,7 @@ bool this_cpu_has_cap(unsigned int n)
> >   	return false;
> >   }
> > +EXPORT_SYMBOL(this_cpu_has_cap);

EXPORT_SYMBOL_GPL? I think this_cpu_has_cap() is a bit more more
specialised than cpus_have_const_cap().

With that:

Acked-by: Catalin Marinas <catalin.marinas@....com>