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 X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIM_ADSP_ALL, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E560C4332F for ; Tue, 7 Sep 2021 22:00:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B56461131 for ; Tue, 7 Sep 2021 22:00:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347452AbhIGWBw (ORCPT ); Tue, 7 Sep 2021 18:01:52 -0400 Received: from home.keithp.com ([63.227.221.253]:56072 "EHLO elaine.keithp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347380AbhIGWBv (ORCPT ); Tue, 7 Sep 2021 18:01:51 -0400 Received: from localhost (localhost [127.0.0.1]) by elaine.keithp.com (Postfix) with ESMTP id 136533F30867; Tue, 7 Sep 2021 15:00:19 -0700 (PDT) X-Virus-Scanned: Debian amavisd-new at keithp.com Received: from elaine.keithp.com ([127.0.0.1]) by localhost (elaine.keithp.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id LYoWbEmDiZX3; Tue, 7 Sep 2021 15:00:18 -0700 (PDT) Received: from keithp.com (168-103-156-98.tukw.qwest.net [168.103.156.98]) by elaine.keithp.com (Postfix) with ESMTPSA id A3F673F30861; Tue, 7 Sep 2021 15:00:18 -0700 (PDT) Received: by keithp.com (Postfix, from userid 1000) id D854B1E6013A; Tue, 7 Sep 2021 15:00:40 -0700 (PDT) From: Keith Packard To: linux-kernel@vger.kernel.org Cc: Abbott Liu , Andrew Morton , Andrey Ryabinin , Anshuman Khandual , Ard Biesheuvel , Arnd Bergmann , Bjorn Andersson , Christoph Lameter , Dennis Zhou , Geert Uytterhoeven , Jens Axboe , Joe Perches , Kees Cook , Keith Packard , Krzysztof Kozlowski , Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, Manivannan Sadhasivam , Marc Zyngier , Masahiro Yamada , Mike Rapoport , Nathan Chancellor , Nick Desaulniers , Nick Desaulniers , Nicolas Pitre , Russell King , Tejun Heo , Thomas Gleixner , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Valentin Schneider , Viresh Kumar , "Wolfram Sang (Renesas)" , YiFei Zhu Subject: [PATCH 4/7] ARM: Use hack from powerpc to get current cpu number Date: Tue, 7 Sep 2021 15:00:35 -0700 Message-Id: <20210907220038.91021-5-keithpac@amazon.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210907220038.91021-1-keithpac@amazon.com> References: <20210904060908.1310204-1-keithp@keithp.com> <20210907220038.91021-1-keithpac@amazon.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When we enable THREAD_INFO_IN_TASK, the cpu number will disappear from thread_info and reappear in task_struct. As we cannot include linux/sched.h in asm/smp.h, there's no way to use that struct type in the raw_smp_processor_id macro. Instead, a hack from the powerpc code is used. This pulls the TI_CPU offset out of asm-offsets.h and uses that to find the cpu value. Signed-off-by: Keith Packard --- arch/arm/Makefile | 8 ++++++++ arch/arm/include/asm/smp.h | 18 +++++++++++++++++- 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/arch/arm/Makefile b/arch/arm/Makefile index 415c3514573a..6752995d2914 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -284,6 +284,14 @@ stack_protector_prepare: prepare0 $(eval GCC_PLUGINS_CFLAGS += $(SSP_PLUGIN_CFLAGS)) endif +ifdef CONFIG_SMP +prepare: task_cpu_prepare + +PHONY += task_cpu_prepare +task_cpu_prepare: prepare0 + $(eval KBUILD_CFLAGS += -D_TI_CPU=$(shell awk '{if ($$2 == "TI_CPU") print $$3;}' include/generated/asm-offsets.h)) +endif + all: $(notdir $(KBUILD_IMAGE)) diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index d43b64635d77..f77ba3753bc4 100644 --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -15,7 +15,23 @@ # error " included in non-SMP build" #endif -#define raw_smp_processor_id() (current_thread_info()->cpu) +/* + * This is particularly ugly: it appears we can't actually get the + * definition of task_struct here, but we need access to the CPU this + * task is running on, which is stored in task_struct when + * THREAD_INFO_IN_TASK is set. Instead of using task_struct we're + * using TI_CPU which is extracted from asm-offsets.h by kbuild to get + * the current processor ID. + * + * This also needs to be safeguarded when building asm-offsets.s + * because at that time TI_CPU is not defined yet. + */ +#ifndef _TI_CPU +#define raw_smp_processor_id() (0) +#else +#define raw_smp_processor_id() \ + (*(unsigned int *)((void *)current_thread_info() + _TI_CPU)) +#endif struct seq_file; -- 2.33.0