linux-kernel - Re: [PATCH] arm64/signal: Silence spurious sparse warning storing GCSPR

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Message-ID: <755660a1-0536-4520-8c01-9c254b02fae0@sirena.org.uk>
Date: Tue, 10 Dec 2024 14:45:53 +0000
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] arm64/signal: Silence spurious sparse warning storing
 GCSPR_EL0

On Tue, Dec 10, 2024 at 02:17:58PM +0000, Catalin Marinas wrote:
> On Tue, Dec 10, 2024 at 12:42:53AM +0000, Mark Brown wrote:

> > -	write_sysreg_s(gcspr_el0 + 1, SYS_GCSPR_EL0);
> > +	write_sysreg_s((unsigned long)(gcspr_el0 + 1), SYS_GCSPR_EL0);

> Would we now get a warning here?

No, like the changelog mentions converting to an unsigned long is
regarded by sparse as a (the AFAICT) valid way of discarding the
__userness of a pointer so it's that change that silences the warning.
It does the right thing with whatever sparse I have here.

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