From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1FFB39A7E9 for ; Thu, 19 Mar 2026 07:10:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773904217; cv=none; b=eB9f6WaeTK3cNwXcUvZNXvgxUaxvuEiMCfyiZl+EKkYd7hURH0Yz5u5svJiFpg4oQas1vY/FPtp8jiMXwo62taTsvzmg8LQMPFFc4zqFmCEc9mQ3aorKmxM8/lAeQFZEsH2Y7crlQRWBuF8hFFMxd9LlctSnxnz4WH4eT97h/XU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773904217; c=relaxed/simple; bh=5+WC9TSKKCBKCfGCkItREf/Xtyr1H8nh6oygjJPul5Y=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=ugbNbNw+WHseBK67IBnq800H/uWOvclukgFhvG+ZdKW3fK+P66fPHThsESqRXJIR15LkLfYmbHM2DzzUU/EkumYDjqqYkNguTweK/2+zmHjWiAQ0UoGgzUEbmQ84Ii5kfEcGNiPJQjfQpagmdKLDwgcFeen3k+azUBUQbqa8HI0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jhnehPnC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jhnehPnC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E1FFC19424; Thu, 19 Mar 2026 07:10:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773904217; bh=5+WC9TSKKCBKCfGCkItREf/Xtyr1H8nh6oygjJPul5Y=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=jhnehPnCqeU0VuSXvieKgexWsO2Z+nSqLjmDgflYXjNtJIJimv/tANzUvMH5+tf7s thRDzJ5eFe1Opp2l0Qz3W4GdPCQCvWO7gKiSyU0drKKnYQDrw7zC810oLRinR3Grqj o31pIsso/indELcJZ6aDk0hgPa4QV6JxWC6y+KQwGs4e0n+xR2Vmgoo9svWAmlCRhz TTiZ7X/NrlDr9rFM8iSGFuA9TJSSQOdbxES3TagJrJ09hbfvcr/9bscS+AtUlIG4dx uxkLfqF6rMvQp+nrzQ9aJc21McSjlpzoJCzE/K2ZVqTUKq5DkbhMb4wG48EDgp73Bt 5dshmo1rbdl9A== From: Thomas Gleixner To: =?utf-8?Q?Andr=C3=A9?= Almeida Cc: LKML , Mathieu Desnoyers , Sebastian Andrzej Siewior , Florian Weimer , Carlos O'Donell , Peter Zijlstra , Rich Felker , Torvald Riegel , Darren Hart , Ingo Molnar , Davidlohr Bueso , Arnd Bergmann , "Liam R . Howlett" Subject: Re: [patch 8/8] x86/vdso: Implement __vdso_futex_robust_try_unlock() In-Reply-To: <31beed0c-f7f4-44d8-9a70-a0f27118f089@igalia.com> References: <20260316162316.356674433@kernel.org> <20260316164951.484640267@kernel.org> <87ecliokzz.ffs@tglx> <87zf46m6j1.ffs@tglx> <87fr5wn63p.ffs@tglx> <31beed0c-f7f4-44d8-9a70-a0f27118f089@igalia.com> Date: Thu, 19 Mar 2026 08:10:12 +0100 Message-ID: <87cy10mh0r.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Wed, Mar 18 2026 at 23:05, Andr=C3=A9 Almeida wrote: > Em 18/03/2026 19:08, Thomas Gleixner escreveu: >>=20 >> 2) Make that mixed size mode depend on a config option >>=20 >> 3) Require that such a use case issues a prctl to switch into that >> special case mode. >>=20 >> or a combination of those. >>=20 >> Andre? >>=20 > > Those two last options works for me, if it helps to make the code more=20 > readable. However, I think that QEMU might be interested in those=20 > features as well :) I'm going to ping them I already came up with something. It makes the fixup range larger as it has to cover two functions and then pick the right one. So the range check becomes: if (likely(!ip_within(regs, mm->futex.cs_start, mm->futex.cs_end))) return; if (likely(!mm->futex.cs_multi)) { fixup(regs, NULL); return; } csr =3D mm->futex.cs_ranges; for (range =3D 0; range < mm->futex.cs_multi; range++, csr++) { if (ip_within(regs, csr->cs_start, csr->cs_end)) { fixup(regs, csr); return; } } Or something daft like that. That makes the multi CS range check generic and still optimizes for the single entry case. The ASM functions become minimal w/o extra pointer size conditionals. Thanks, tglx