From patchwork Thu May 4 19:02:43 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13231526 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 032E5C7EE2A for ; Thu, 4 May 2023 19:04:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230332AbjEDTEO (ORCPT ); Thu, 4 May 2023 15:04:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51546 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230148AbjEDTDh (ORCPT ); Thu, 4 May 2023 15:03:37 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FFDB7A97; Thu, 4 May 2023 12:02:50 -0700 (PDT) Message-ID: <20230504185937.858955768@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1683226964; 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=x1gYrMcqzm40p2bz6RsOmSrXlBcSvXXbnfB8HNeCbJU=; b=F9VwenKVSYd9QFli8bXNV/fz9qUSdzJcPELJ1ngRD9BxyzaHEgcu2cC0/b4kuprOfTMBsR NCkyPWtTcKTi4mTU6aAeMY6PYflFdg/QnWMligdTnr5DQ53G/59w7N1RxTuaJMuxKaB+6k fnxGx7t6MsQx4TP0A/Wv1B3YJqsjI01JirGXHQPo53zTdX5Z488sLyftTciloBgiN9k5k/ bzf3t4Qwlj6lxCy0qHukKPQMZGDuh3h1yP7MJWtYXWHVZt3htrK/Qtw9ul4ERCfXuX9Nze it6Ui4ad23Dml/cuVbhr6i6cHXzKyVbR3juE2BxVW820qfkeEJiZvG833WVS3g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1683226964; 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=x1gYrMcqzm40p2bz6RsOmSrXlBcSvXXbnfB8HNeCbJU=; b=PK3VhwCrlpzYLlITMOVdXxhPHsDqoA73a6Tz+/QOqHPRfKtGaiwEqnA7EtTcL4VMvMoxp6 ebRWKW/d8KnEHmAA== 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)" , David Woodhouse Subject: [patch V2 28/38] cpu/hotplug: Reset task stack state in _cpu_up() References: <20230504185733.126511787@linutronix.de> MIME-Version: 1.0 Date: Thu, 4 May 2023 21:02:43 +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 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. * Prevent irq alloc/free across the bringup. @@ -1583,6 +1577,12 @@ 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;