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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS 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 71FD7C43219 for ; Fri, 3 May 2019 07:54:25 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 26A982075E for ; Fri, 3 May 2019 07:54:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 26A982075E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44wPXv11j9zDqtV for ; Fri, 3 May 2019 17:54:23 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44wNKZ6xkgzDqS6 for ; Fri, 3 May 2019 16:59:30 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Received: by ozlabs.org (Postfix, from userid 1034) id 44wNKY504cz9sPZ; Fri, 3 May 2019 16:59:29 +1000 (AEST) X-powerpc-patch-notification: thanks X-powerpc-patch-commit: e2b36d591720d81741f37e047a6f0047e8c89369 X-Patchwork-Hint: ignore In-Reply-To: <20190502052107.24738-1-npiggin@gmail.com> To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org From: Michael Ellerman Subject: Re: [PATCH] powerpc/64: Don't trace code that runs with the soft irq mask unreconciled Message-Id: <44wNKY504cz9sPZ@ozlabs.org> Date: Fri, 3 May 2019 16:59:29 +1000 (AEST) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, 2019-05-02 at 05:21:07 UTC, Nicholas Piggin wrote: > "Reconciling" in terms of interrupt handling, is to bring the soft irq > mask state in to synch with the hardware, after an interrupt causes > MSR[EE] to be cleared (while the soft mask may be enabled, and hard > irqs not marked disabled). > > General kernel code should not be called while unreconciled, because > local_irq_disable, etc. manipulations can cause surprising irq traces, > and it's fragile because the soft irq code does not really expect to > be called in this situation. > > When exiting from an interrupt, MSR[EE] is cleared to prevent races, > but soft irq state is enabled for the returned-to context, so this is > now an unreconciled state. restore_math is called in this state, and > that can be ftraced, and the ftrace subsystem disables local irqs. > > Mark restore_math and its callees as notrace. Restore a sanity check > in the soft irq code that had to be disabled for this case, by commit > 4da1f79227ad4 ("powerpc/64: Disable irq restore warning for now"). > > Signed-off-by: Nicholas Piggin Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/e2b36d591720d81741f37e047a6f0047 cheers