From patchwork Fri May 12 21:07:43 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13239789 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 525F8C77B75 for ; Fri, 12 May 2023 21:09:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240352AbjELVJp (ORCPT ); Fri, 12 May 2023 17:09:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33518 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240169AbjELVIu (ORCPT ); Fri, 12 May 2023 17:08:50 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BAB1CAD22; Fri, 12 May 2023 14:07:55 -0700 (PDT) Message-ID: <20230512205257.027075560@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1683925664; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=QdUmczWTVhK7K/GEDp21ZZBW6QiyoqITsSHkVbZTwSo=; b=QxFsCk8M0IwU/AWXJTbXBb8OmrmczN7eSVShQBD/xtp9CSloxhz1odBQguueWNc/vEM52/ 0Kl3gldkf4/0GgZgMmCaVqarwnt6c2WxoW5biu9zyuJifvGtM9/Jij2+5GahK4gODm1Y1Q 1hd8RJJvQbU0l+Gnh64z7qRhDPk39TNRP842ELWqPXiUeNBVOhZ36Jqvxt0WeLRCeD/TLr 8ppgeI8QfGvfUVwsNNPzx6acsMuK+QD0Sy+DuKWmGes0FQJYbkh9eWywGTaBGzAG8N39CJ IMTWuS0FUzsmcC8AS5xDPopwnYu51b4FiPLMJd67kDoqwu/y1krpwzf6eMhGgw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1683925664; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=QdUmczWTVhK7K/GEDp21ZZBW6QiyoqITsSHkVbZTwSo=; b=kpZz6QyptBqFfMzJcx1ZcoW9ytkNNQFs/6P8KAIUryIP/ZE4SXsEP30lmowL1TlGesMnkc +R008NAdqKJ6jZCQ== From: Thomas Gleixner To: LKML Cc: x86@kernel.org, David Woodhouse , Andrew Cooper , Brian Gerst , Arjan van de Veen , Paolo Bonzini , Paul McKenney , Tom Lendacky , Sean Christopherson , Oleksandr Natalenko , Paul Menzel , "Guilherme G. Piccoli" , Piotr Gorski , Usama Arif , Juergen Gross , Boris Ostrovsky , xen-devel@lists.xenproject.org, Russell King , Arnd Bergmann , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Guo Ren , linux-csky@vger.kernel.org, Thomas Bogendoerfer , linux-mips@vger.kernel.org, "James E.J. Bottomley" , Helge Deller , linux-parisc@vger.kernel.org, Paul Walmsley , Palmer Dabbelt , linux-riscv@lists.infradead.org, Mark Rutland , Sabin Rapan , "Michael Kelley (LINUX)" , Ross Philipson , David Woodhouse Subject: [patch V4 29/37] cpu/hotplug: Reset task stack state in _cpu_up() References: <20230512203426.452963764@linutronix.de> MIME-Version: 1.0 Date: Fri, 12 May 2023 23:07:43 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org From: David Woodhouse Commit dce1ca0525bf ("sched/scs: Reset task stack state in bringup_cpu()") ensured that the shadow call stack and KASAN poisoning were removed from a CPU's stack each time that CPU is brought up, not just once. This is not incorrect. However, with parallel bringup the idle thread setup will happen at a different step. As a consequence the cleanup in bringup_cpu() would be too late. Move the SCS/KASAN cleanup to the generic _cpu_up() function instead, which already ensures that the new CPU's stack is available, purely to allow for early failure. This occurs when the CPU to be brought up is in the CPUHP_OFFLINE state, which should correctly do the cleanup any time the CPU has been taken down to the point where such is needed. Signed-off-by: David Woodhouse Signed-off-by: Thomas Gleixner Tested-by: Mark Rutland Tested-by: Michael Kelley Reviewed-by: Mark Rutland --- kernel/cpu.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -771,12 +771,6 @@ static int bringup_cpu(unsigned int cpu) return -EAGAIN; /* - * Reset stale stack state from the last time this CPU was online. - */ - scs_task_reset(idle); - kasan_unpoison_task_stack(idle); - - /* * Some architectures have to walk the irq descriptors to * setup the vector space for the cpu which comes online. * @@ -1587,6 +1581,12 @@ static int _cpu_up(unsigned int cpu, int ret = PTR_ERR(idle); goto out; } + + /* + * Reset stale stack state from the last time this CPU was online. + */ + scs_task_reset(idle); + kasan_unpoison_task_stack(idle); } cpuhp_tasks_frozen = tasks_frozen;