From patchwork Fri Apr 14 23:44:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13212123 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 EC60AC77B71 for ; Fri, 14 Apr 2023 23:46:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230335AbjDNXqX (ORCPT ); Fri, 14 Apr 2023 19:46:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230339AbjDNXpq (ORCPT ); Fri, 14 Apr 2023 19:45:46 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C218CB766; Fri, 14 Apr 2023 16:45:04 -0700 (PDT) Message-ID: <20230414232310.941680232@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1681515899; 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=PwaT1nVbkmNxpYn2jntunVyX300rI6JOSPoxKblUFxc=; b=J4d36wqGXDsa4D15fuC6bgECzfAAInQki6KA3SUyC98aD0yQW6gcNLFjQOCHcXv2J+orZG 5Qmhd0e6dbHL514sP/COcIuWz15soNEsWHzEh1yBv2+hd5B8wqzYOidLR2BE5cayvWqW8Z HTkU8Nrl6+H70MJnTBAZDmHlfDfKJpBLY0P7kmzee0usDqsCKruEINfZUsjihRGa5dTOub nsf1V7hsU0pvXa2Ve2ehvBeS9w4NMv0lT4Qar9j26QhzX8zbcfe2cv28EW7JmGjaOXAvGg fSx2t8XhhVFut65VN9kClCBXCqftJpibwk/DAZDt6leoEUA5kSkPTRcDM8b5qA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1681515899; 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=PwaT1nVbkmNxpYn2jntunVyX300rI6JOSPoxKblUFxc=; b=GT9ybsNnlf8a2CqrpgJaThMxA4ODF78eIoN2mtLu9TxUz4hUltbB6uZ6jFavUSEgOGT604 TxVe7hxr4awf6HAw== 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 , David Woodhouse , Mark Rutland , 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, Sabin Rapan Subject: [patch 28/37] cpu/hotplug: Reset task stack state in _cpu_up() References: <20230414225551.858160935@linutronix.de> MIME-Version: 1.0 Date: Sat, 15 Apr 2023 01:44:59 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-parisc@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 @@ -769,12 +769,6 @@ 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. @@ -1581,6 +1575,12 @@ 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;