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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E4271C433DB for ; Tue, 9 Feb 2021 02:03:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 947F864EBA for ; Tue, 9 Feb 2021 02:03:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230373AbhBICDT (ORCPT ); Mon, 8 Feb 2021 21:03:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229851AbhBICDR (ORCPT ); Mon, 8 Feb 2021 21:03:17 -0500 Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4EE35C061788 for ; Mon, 8 Feb 2021 18:02:37 -0800 (PST) Received: by mail-pf1-x433.google.com with SMTP id b145so10926184pfb.4 for ; Mon, 08 Feb 2021 18:02:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:subject:to:cc:references:in-reply-to:mime-version :message-id:content-transfer-encoding; bh=utXHPcgvm9Y8ZwC4DuYoSqZra3dkj+8uEXyKJK77MuM=; b=n2kVSQ1XlJX6xUt/1m2yXy+XedXCXDvoOAa1zzTkBmgiUEn/AWSkU+NLDGSkqgrmmX ViwTenSuk6hs2X6eou1rCXLEuV7j89e3DPN+E2yhAIvBRZNd0rMBd0f2eToxAAdWgyby 0MwZltwqg/OaRiWmqvqZfrRjVntRB2LyDqX9maj0UUyc3E2AqF7BIebDlzA7pOy7EX09 9Qhz9umMzOXQ1xdIqrm5Iayyaz38/Xu+DnJ2m1OBdkwiZK/B6m9uOU3xlD4E7aPkVtNX u3SWi/C7AdB7M3L+AGRNGmyqyGCyeLEAGJ1jIkTDF8cgNU7LKMvDUyfOoxVIJs27Rm5O TRsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=utXHPcgvm9Y8ZwC4DuYoSqZra3dkj+8uEXyKJK77MuM=; b=geECI1oC+CnzElKVbgC6ACkPhmZgYJxgdP37yosKSuSsyBQ2uQbtmV1q7xpLrHMRVY xM7R5LmjySs7awFL6+kUV6q0pYCF3wZsX64Okq4q/eL4oiufjtcZwPhLHsEFzH6DIAIU xeGJ6IJ4jvTDzkwU9R86dQzGjrEKPcD88RW0uT1ZxrOVQzk4B8NSKatftU//s4TZ+0Tr QvvZ7HQMpNFmx7DpH/EbzgDvpxV0Z1e0msL+ZZjWsEhyFesY5NdXtr7GxoVLlVccRMMm 7G8742uCaqi6uZkBSs32SVODKAajmRJ2V/zUOIGvIfaL5IQVKjQ9OB3Wj3185Zb3wOiH O+Jw== X-Gm-Message-State: AOAM532IN4fJxd+4QiRHJp4lviH0ehAG3gUXWydeJ9mNN7H2VCSz8aZt +7XFdPxkofeWbSeJ5SZbe9U= X-Google-Smtp-Source: ABdhPJzuY8MD5OC5cvECJcPWzH/iIf6UjSZt7cny9SeK3VphHxxRpE48XhJHGnrzAOnUZgSXJJjn8w== X-Received: by 2002:a65:6207:: with SMTP id d7mr20641495pgv.92.1612836156934; Mon, 08 Feb 2021 18:02:36 -0800 (PST) Received: from localhost ([220.240.226.199]) by smtp.gmail.com with ESMTPSA id y20sm19944613pfo.210.2021.02.08.18.02.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Feb 2021 18:02:36 -0800 (PST) Date: Tue, 09 Feb 2021 12:02:30 +1000 From: Nicholas Piggin Subject: Re: [PATCH v5 18/22] powerpc/syscall: Remove FULL_REGS verification in system_call_exception To: Benjamin Herrenschmidt , Christophe Leroy , Michael Ellerman , msuchanek@suse.de, Paul Mackerras Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <6bef4d9ba0cba50160d13e344ee4627ebdf801dc.1612796617.git.christophe.leroy@csgroup.eu> In-Reply-To: <6bef4d9ba0cba50160d13e344ee4627ebdf801dc.1612796617.git.christophe.leroy@csgroup.eu> MIME-Version: 1.0 Message-Id: <1612836023.l122pe2n2b.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Excerpts from Christophe Leroy's message of February 9, 2021 1:10 am: > For book3s/64, FULL_REGS() is 'true' at all time, so the test voids. > For others, non volatile registers are saved inconditionally. >=20 > So the verification is pointless. >=20 > Should one fail to do it, it would anyway be caught by the > CHECK_FULL_REGS() in copy_thread() as we have removed the > special versions ppc_fork() and friends. >=20 > null_syscall benchmark reduction 4 cycles (332 =3D> 328 cycles) I wonder if we rather make a CONFIG option for a bunch of these simpler debug checks here (and also in interrupt exit, wrappers, etc) rather than remove them entirely. Thanks, Nick >=20 > Signed-off-by: Christophe Leroy > --- > arch/powerpc/kernel/interrupt.c | 1 - > 1 file changed, 1 deletion(-) >=20 > diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interr= upt.c > index 8fafca727b8b..55e1aa18cdb9 100644 > --- a/arch/powerpc/kernel/interrupt.c > +++ b/arch/powerpc/kernel/interrupt.c > @@ -42,7 +42,6 @@ notrace long system_call_exception(long r3, long r4, lo= ng r5, > if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x)) > BUG_ON(!(regs->msr & MSR_RI)); > BUG_ON(!(regs->msr & MSR_PR)); > - BUG_ON(!FULL_REGS(regs)); > BUG_ON(arch_irq_disabled_regs(regs)); > =20 > #ifdef CONFIG_PPC_PKEY > --=20 > 2.25.0 >=20 >=20