From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A15EC433F5 for ; Thu, 30 Sep 2021 13:12:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A5FE61278 for ; Thu, 30 Sep 2021 13:12:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350294AbhI3NOY (ORCPT ); Thu, 30 Sep 2021 09:14:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:36726 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349892AbhI3NOT (ORCPT ); Thu, 30 Sep 2021 09:14:19 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7256761528 for ; Thu, 30 Sep 2021 13:12:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633007556; bh=vHSfNPWmgwIIa9+j2tmKGBTEDiaUE/7eNtYnP7G/W4Q=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=MGtqMo5E4xGTkHt1jJrxW8YHOcPFO6LUA7iPXBkoNrThnA0ffRV3HacMGjBlXi7AH RNHpE4lexIfAM7aq6K6LgijwPx/6A6p5Y5SrzoY8RO4nc3WV3U9+Do//3GcXknocn1 wS7kEkFjzHqyOuluSTRw5D3ZZgG8uiokciZXS3uctswM3fwsUotYXHTKlp1i512dHM tdtjS4eJw2XqnTU27/hYsF7pp7cV5k8CswjDFvpdYwFaNYFkFJiBOdmwgF5KllrrHI JZ619kzb9PZiCVhV0p3CVsLaR8bB0IjAyylIqYloWAsSpF1ZMCv9JaviPjyRfkrNml tntDlL5n/8AbA== Received: by mail-oi1-f172.google.com with SMTP id s24so7147426oij.8 for ; Thu, 30 Sep 2021 06:12:36 -0700 (PDT) X-Gm-Message-State: AOAM530Fq5hzv4ls2HuodYk0ZwAbKfc41/qlYDdvUt52s4ib4+MdrozP mcpWj1E0jsTfYhO8fq4NVEhE3IBORGvEajSIkMk= X-Google-Smtp-Source: ABdhPJw8aCnwIHEA1Jv1HQMZO8zxfC4IOKBOuq+3Wj+bcPVnd8wKzwVnaZWqAwug1Q+dyXuyUb6l+3W1Ethn3DDUZGo= X-Received: by 2002:a05:6808:1148:: with SMTP id u8mr2628592oiu.33.1633007555710; Thu, 30 Sep 2021 06:12:35 -0700 (PDT) MIME-Version: 1.0 References: <20210930125813.197418-1-ardb@kernel.org> <20210930125813.197418-6-ardb@kernel.org> <427566ca-80c0-56eb-880b-908bd4a71e9a@csgroup.eu> In-Reply-To: <427566ca-80c0-56eb-880b-908bd4a71e9a@csgroup.eu> From: Ard Biesheuvel Date: Thu, 30 Sep 2021 15:12:24 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 5/7] sched: move CPU field back into thread_info if THREAD_INFO_IN_TASK=y To: Christophe Leroy Cc: Linux Kernel Mailing List , Keith Packard , Russell King , Catalin Marinas , Will Deacon , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Heiko Carstens , Mark Rutland Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 30 Sept 2021 at 15:09, Christophe Leroy wrote: > > > > Le 30/09/2021 =C3=A0 14:58, Ard Biesheuvel a =C3=A9crit : > > THREAD_INFO_IN_TASK moved the CPU field out of thread_info, but this > > causes some issues on architectures that define raw_smp_processor_id() > > in terms of this field, due to the fact that #include'ing linux/sched.h > > to get at struct task_struct is problematic in terms of circular > > dependencies. > > > > Given that thread_info and task_struct are the same data structure > > anyway when THREAD_INFO_IN_TASK=3Dy, let's move it back so that having > > access to the type definition of struct thread_info is sufficient to > > reference the CPU number of the current task. > > > > Note that this requires THREAD_INFO_IN_TASK's definition of the > > task_thread_info() helper to be updated, as task_cpu() takes a > > pointer-to-const, whereas task_thread_info() (which is used to generate > > lvalues as well), needs a non-const pointer. So make it a macro instead= . > > > > Signed-off-by: Ard Biesheuvel > > Acked-by: Catalin Marinas > > Acked-by: Mark Rutland > > Acked-by: Michael Ellerman > > --- > > arch/arm64/kernel/asm-offsets.c | 1 - > > arch/arm64/kernel/head.S | 2 +- > > arch/powerpc/kernel/asm-offsets.c | 2 +- > > arch/powerpc/kernel/smp.c | 2 +- > > include/linux/sched.h | 13 +------------ > > kernel/sched/sched.h | 4 ---- > > 6 files changed, 4 insertions(+), 20 deletions(-) > > > > diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-of= fsets.c > > index cee9f3e9f906..0bfc048221af 100644 > > --- a/arch/arm64/kernel/asm-offsets.c > > +++ b/arch/arm64/kernel/asm-offsets.c > > @@ -27,7 +27,6 @@ > > int main(void) > > { > > DEFINE(TSK_ACTIVE_MM, offsetof(struct task_struct, acti= ve_mm)); > > - DEFINE(TSK_CPU, offsetof(struct task_struct, cpu)); > > BLANK(); > > DEFINE(TSK_TI_CPU, offsetof(struct task_struct, thre= ad_info.cpu)); > > DEFINE(TSK_TI_FLAGS, offsetof(struct task_struct, thre= ad_info.flags)); > > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > > index 17962452e31d..6a98f1a38c29 100644 > > --- a/arch/arm64/kernel/head.S > > +++ b/arch/arm64/kernel/head.S > > @@ -412,7 +412,7 @@ SYM_FUNC_END(__create_page_tables) > > scs_load \tsk > > > > adr_l \tmp1, __per_cpu_offset > > - ldr w\tmp2, [\tsk, #TSK_CPU] > > + ldr w\tmp2, [\tsk, #TSK_TI_CPU] > > Why do you need to change the name ? > > For powerpc64, you leave TASK_CPU. > Because arm64 has a clear idiom here, where TSK_TI_ is used for thread_info fields accessed via a task_struct pointer. Also, it only occurs once in the code. Power does not seem to have this idiom, and TASK_CPU is used in many more places, so I don't think it makes sense to change its name. > > ldr \tmp1, [\tmp1, \tmp2, lsl #3] > > set_this_cpu_offset \tmp1 > > .endm > > diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/as= m-offsets.c > > index e563d3222d69..e37e4546034e 100644 > > --- a/arch/powerpc/kernel/asm-offsets.c > > +++ b/arch/powerpc/kernel/asm-offsets.c > > @@ -93,7 +93,7 @@ int main(void) > > #endif /* CONFIG_PPC64 */ > > OFFSET(TASK_STACK, task_struct, stack); > > #ifdef CONFIG_SMP > > - OFFSET(TASK_CPU, task_struct, cpu); > > + OFFSET(TASK_CPU, task_struct, thread_info.cpu); > > #endif > > > > #ifdef CONFIG_LIVEPATCH > > ...