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Date: Mon, 16 Feb 2026 18:04:27 +0000
From: Catalin Marinas <catalin.marinas@arm.com>
To: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
	kvmarm@lists.linux.dev, kvm@vger.kernel.org,
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	joey.gouly@arm.com, yuzenghui@huawei.com, pbonzini@redhat.com,
	shuah@kernel.org, mark.rutland@arm.com, arnd@arndb.de
Subject: Re: [PATCH v12 6/7] arm64: futex: support futex with FEAT_LSUI
Message-ID: <aZNbXlvCHxDmsmOA@arm.com>
References: <20260121190622.2218669-1-yeoreum.yun@arm.com>
 <20260121190622.2218669-7-yeoreum.yun@arm.com>
 <aYtgmZZhAKAvtfaK@arm.com>
 <aYtoOktjE18YNtB+@e129823.arm.com>
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In-Reply-To: <aYtoOktjE18YNtB+@e129823.arm.com>

On Tue, Feb 10, 2026 at 05:17:46PM +0000, Yeoreum Yun wrote:
> > On Wed, Jan 21, 2026 at 07:06:21PM +0000, Yeoreum Yun wrote:
> > > +
> > > +	if (futex_on_lo) {
> > > +		oval64.lo_futex.val = oldval;
> > > +		ret = get_user(oval64.lo_futex.other, uaddr + 1);
> > > +	} else {
> > > +		oval64.hi_futex.val = oldval;
> > > +		ret = get_user(oval64.hi_futex.other, uaddr - 1);
> > > +	}
> >
> > and here use
> >
> > 	get_user(oval64.raw, uaddr64);
> > 	futex[futex_pos] = oldval;
> 
> But there is another feedback about this
> (though I did first similarly with your suggestion -- use oval64.raw):
>   https://lore.kernel.org/all/aXDZGhFQDvoSwdc_@willie-the-truck/

Do you mean the 64-bit read? You can do a 32-bit uaccess, something
like:

	int other_pos = futex_pos ^ 1;
	get_user(futex[other_pos], (u32 __user *)uaddr64 + other_pos);

-- 
Catalin