From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 BC20F47F2CD for ; Fri, 11 Sep 2026 12:57:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789131466; cv=none; b=OgNs7E0EJXdcPMnXGOKBbKUVgzX+Wqht62FDH3aKsmJNXGNfFWkffZJybX9hWHsrNMTY7d1GBePoaHZQWJD7CYQTh7Af6Jrdm8FnOasprM8qi1YqLHzZI853wg1K1hD02SRcBLIKBVV0leVZQRYxEagqrTl0DOVsGsQwZxWZwBE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789131466; c=relaxed/simple; bh=zOfxGfnMVAGLF2Ai5d4EjnHiGKazB0/xsLntadvkbOU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=if0y+8FMSb8Noq0hzSPQXO61e1X0dW5QxN7sYnc3kg962ch/HSiT1ux+9MIoves9SIdYxlosZYozQ47Ib44vmWQxhMjJ6I8t1nIjiF78CoSEoDRTaZtShu3DFIL+uzdhFZfGzkhTjL9mXEDsMRM1P7E/un63cVCsVvufQfO+Kig= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ABtrpNHQ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ABtrpNHQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55C4D1F000FF; Fri, 11 Sep 2026 12:57:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789131451; bh=KvPW7wKGOhZ34dEtOElqCP0STW8GW9Yph3VIV+NYOy4=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=ABtrpNHQBjrHI8UNkItVZR13xICohMB9qqyHFacl9IWKzwCWekVxNVh66cHEYgczo BtKsUAEFXVc9VuCD1LSZC+IyjyysF5WAvEqE4bUF7bhlQwY3PHp+KSoK9wJxZLL+XV ws0ZabKyxvxgrtobDy9Akib81YVkhPSrAimCON33XJSgbURaNvUDJ99eZPkyXLHtPJ xgP3twIB0iw11wfuZX1l83lNpTQ3baF+JMypaK70NnlX73D7cJixy9zghAaYndHYVn iozTTbGVYxe2s1/qCO23ZDZIlwV2l2OX7EIZF4PKCM/M1zDAGIpNoinKMDsea59qUY 4O5FOyfX8o6fg== Date: Fri, 11 Sep 2026 13:57:25 +0100 From: Will Deacon To: David Laight Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Arnd Bergmann , Ard Biesheuvel , Ada Couprie Diaz , David Hildenbrand , Catalin Marinas , Vladimir Murzin , Mark Rutland , Mostafa Saleh , Lorenzo Stoakes , Oliver Upton , Linus Walleij , Marc Zyngier Subject: Re: [PATCH 06/21] arm64: Store 'current' in TPIDRRO_EL0 instead of SP_EL0 Message-ID: References: <20260907164247.17223-1-will@kernel.org> <20260907164247.17223-7-will@kernel.org> <20260908141950.37e9ed3d@pumpkin> 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=us-ascii Content-Disposition: inline In-Reply-To: <20260908141950.37e9ed3d@pumpkin> On Tue, Sep 08, 2026 at 02:19:50PM +0100, David Laight wrote: > On Mon, 7 Sep 2026 17:42:31 +0100 > Will Deacon wrote: > > > To make SP_EL0 available to point at the per-cpu kernel overflow stack, > > we must relocate 'current' elsewhere. With TPIDRRO_EL0 now restored late > > in the return-to-user path, we can otherwise use it to hold 'current' > > and update the various accessors accordingly. > > > > Move 'current' from SP_EL0 to TPIDRRO_EL0. > > Is it worth having a #define for the name of the register that stores 'current'? > (And probably the other similar registers.) > That would avoid the bisection problems with the following two patches > and might make other code a bit more readable. We don't tend to reallocate 'current' all that often, so I don't think it's worth the indirection tbh. The following patches are to a GDB script and a bpf selftest, so I'm not going to lose sleep about bisection. Will