From patchwork Fri Feb 3 22:05:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josh Poimboeuf X-Patchwork-Id: 13128483 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 67BC9C05027 for ; Fri, 3 Feb 2023 22:12:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=q2DEhfAL197tpebKDysg7FwyeNDOiUIEdP/hO84g3a8=; b=L8iHPFT8Ejc4fT +lQoI9TOnnn2hchU8P0k/XqMzunCulcs7Qwz++J6G0PBtERhoAXCE3bNy0Qvfc7pP4M3v8eW081me g0mceo03o1JKpghHojhGEidp0TL3gtx4gPJRIK/zg2aMgb7lWgePqxSWi49t4BFERLKwsJ3ayZu4G Ek0vYzhkVeJ/2Xa1A7gLQB8PMZ9AIto8Y/wPEqSceQH5+HmlZak4/joQZsqJ2vijyetEbIzAaI2na OPHg26P/WWURKl8OJEVrsD2bKqgR5Iui4MhUtPmUOPaGijhQt2/9rXi/+0t2cjPLBtgnhVeMAfEwh Lo3KTNm0Sxk1pyxiuR1w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pO4Gx-003lvP-3M; Fri, 03 Feb 2023 22:11:07 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pO4Bk-003jbJ-8y for linux-arm-kernel@lists.infradead.org; Fri, 03 Feb 2023 22:05:46 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 6F7D0B82C1E; Fri, 3 Feb 2023 22:05:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C488C433EF; Fri, 3 Feb 2023 22:05:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1675461941; bh=Yfz7LDRr9C5stKW6l039uMgeR9w4g6B/htPQVWCmvo0=; h=From:To:Cc:Subject:Date:From; b=hT/RSWKOfEB8jVVNR5UZ+ZbSj3FXLQ0xxyrY0heskGWE6khYrrAFQ76LYykM4i9o8 irBoG35w/xMGiAEWy8hEkn9Q1tIzJzxmXAljxc/iWYKnUXFrHhRYGep0nxJSoT9spP 4dB2u1vvWVrwhpcumbKdCJR0B2wTRgDCB5121JafDUwhKmELKjCdPeOrwXK5eLJDjK tyz30wSd9T+Wd8Rt8ftd27zDruJpmQXIwZCt+CSiXATiejyCyi516LIlzhPyorZH8T WTNmRq1LmErrBsj/ynnHP8Qccsk6gRrw9tAaXNUSu/osCJkwqecmj01XHOVKQ9ef7f Ezggi0dcZPCBQ== From: Josh Poimboeuf To: linux-kernel@vger.kernel.org Cc: jgross@suse.com, richard.henderson@linaro.org, ink@jurassic.park.msu.ru, mattst88@gmail.com, linux-alpha@vger.kernel.org, linux@armlinux.org.uk, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, linux-csky@vger.kernel.org, linux-ia64@vger.kernel.org, chenhuacai@kernel.org, kernel@xen0n.name, loongarch@lists.linux.dev, f.fainelli@gmail.com, bcm-kernel-feedback-list@broadcom.com, tsbogend@alpha.franken.de, linux-mips@vger.kernel.org, jiaxun.yang@flygoat.com, mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, linuxppc-dev@lists.ozlabs.org, ysato@users.sourceforge.jp, dalias@libc.org, linux-sh@vger.kernel.org, davem@davemloft.net, sparclinux@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, chris@zankel.net, jcmvbkbc@gmail.com, linux-xtensa@linux-xtensa.org, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, paulmck@kernel.org Subject: [PATCH 00/22] cpu,sched: Mark arch_cpu_idle_dead() __noreturn Date: Fri, 3 Feb 2023 14:05:09 -0800 Message-Id: X-Mailer: git-send-email 2.39.0 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230203_140544_667420_86A081C6 X-CRM114-Status: GOOD ( 12.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org These are some minor changes to enable the __noreturn attribute for arch_cpu_idle_dead(). (If there are no objections, I can merge the entire set through the tip tree.) Until recently [1], in Xen, when a previously offlined CPU was brought back online, it unexpectedly resumed execution where it left off in the middle of the idle loop by returning from play_dead() and its caller arch_cpu_idle_dead(). There were some clever hacks to make that work, but the behavior was surprising as do_idle() doesn't expect an offlined CPU to return from the dead in the middle of the function. Now that Xen has been fixed, make sure arch_cpu_idle_dead() never returns by marking it __noreturn. This causes the compiler to complain if an arch-specific implementation might return. It also improves code generation for both caller and callee. Patches 1-20 update the arch-specific implementations of the function so they don't actually return (even in error cases), and make that visible to the compiler. That's typically done by ending the function with a call to another noreturn function, or with a BUG(). Patch 21 fixes the weak implementation. Patch 22 actually adds the __noreturn attribute. [1] 076cbf5d2163 ("x86/xen: don't let xen_pv_play_dead() return") Josh Poimboeuf (22): alpha/cpu: Expose arch_cpu_idle_dead()'s prototype declaration alpha/cpu: Make sure arch_cpu_idle_dead() doesn't return arm/cpu: Make sure arch_cpu_idle_dead() doesn't return arm64/cpu: Mark cpu_die() __noreturn csky/cpu: Make sure arch_cpu_idle_dead() doesn't return ia64/cpu: Mark play_dead() __noreturn loongarch/cpu: Make sure play_dead() doesn't return loongarch/cpu: Mark play_dead() __noreturn mips/cpu: Expose play_dead()'s prototype definition mips/cpu: Make sure play_dead() doesn't return mips/cpu: Mark play_dead() __noreturn powerpc/cpu: Mark start_secondary_resume() __noreturn sh/cpu: Make sure play_dead() doesn't return sh/cpu: Mark play_dead() __noreturn sh/cpu: Expose arch_cpu_idle_dead()'s prototype definition sparc/cpu: Mark cpu_play_dead() __noreturn x86/cpu: Make sure play_dead() doesn't return x86/cpu: Mark play_dead() __noreturn xtensa/cpu: Make sure cpu_die() doesn't return xtensa/cpu: Mark cpu_die() __noreturn sched/idle: Make sure weak version of arch_cpu_idle_dead() doesn't return sched/idle: Mark arch_cpu_idle_dead() __noreturn arch/alpha/kernel/process.c | 2 ++ arch/arm/kernel/smp.c | 2 ++ arch/arm64/include/asm/smp.h | 2 +- arch/csky/kernel/smp.c | 2 ++ arch/ia64/kernel/process.c | 4 ++-- arch/loongarch/include/asm/smp.h | 2 +- arch/loongarch/kernel/smp.c | 2 +- arch/mips/include/asm/smp.h | 2 +- arch/mips/kernel/smp-bmips.c | 3 +++ arch/mips/loongson64/smp.c | 1 + arch/powerpc/include/asm/smp.h | 2 +- arch/sh/include/asm/smp-ops.h | 5 +++-- arch/sh/kernel/idle.c | 1 + arch/sparc/include/asm/smp_64.h | 2 +- arch/x86/include/asm/smp.h | 3 ++- arch/x86/kernel/process.c | 2 +- arch/xtensa/include/asm/smp.h | 2 +- arch/xtensa/kernel/smp.c | 2 ++ include/linux/cpu.h | 2 +- kernel/sched/idle.c | 2 +- tools/objtool/check.c | 1 + 21 files changed, 31 insertions(+), 15 deletions(-)