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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 F18B9C4338F for ; Wed, 18 Aug 2021 11:32:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D07D46102A for ; Wed, 18 Aug 2021 11:32:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235508AbhHRLd2 (ORCPT ); Wed, 18 Aug 2021 07:33:28 -0400 Received: from mail.skyhub.de ([5.9.137.197]:49882 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233798AbhHRLd1 (ORCPT ); Wed, 18 Aug 2021 07:33:27 -0400 Received: from zn.tnic (p200300ec2f0cc300f5e19ee5ff269b4b.dip0.t-ipconnect.de [IPv6:2003:ec:2f0c:c300:f5e1:9ee5:ff26:9b4b]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id C99E01EC0236; Wed, 18 Aug 2021 13:32:47 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1629286367; 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: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=jjBnHr/ph8EqG7il00Xg4FP/yeMl6hat1Mzp9ji+YZg=; b=gAZumXR8loOLvjhvB47Anqjg1etnvbT5wxn8jJDD4dodQ+9IKHZGfH6YHCJMPyHlge9J7Q uZ7JFFNE24aeKTOBcDKNdWpyCVJO6pGweSW6aVtorRwuKcSFUq/Sn/IDnjI0OrjgfD8al2 0t0ZV9cuV9NJk86TewsizcEPD8jTwpc= Date: Wed, 18 Aug 2021 13:33:27 +0200 From: Borislav Petkov To: "Chang S. Bae" Cc: luto@kernel.org, tglx@linutronix.de, mingo@kernel.org, x86@kernel.org, len.brown@intel.com, dave.hansen@intel.com, thiago.macieira@intel.com, jing2.liu@intel.com, ravi.v.shankar@intel.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 10/26] x86/fpu/xstate: Update the XSTATE buffer address finder to support dynamic states Message-ID: References: <20210730145957.7927-1-chang.seok.bae@intel.com> <20210730145957.7927-11-chang.seok.bae@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210730145957.7927-11-chang.seok.bae@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 30, 2021 at 07:59:41AM -0700, Chang S. Bae wrote: > __raw_xsave_addr() returns the requested component's pointer in an XSTATE > buffer, by simply looking up the offset table. The offset used to be fixed, > but, with dynamic user states, it becomes variable. > > get_xstate_size() has a routine to find an offset at runtime. Refactor to > use it for the address finder. > > Signed-off-by: Chang S. Bae > Reviewed-by: Len Brown > Cc: x86@kernel.org > Cc: linux-kernel@vger.kernel.org > --- > Changes from v5: > * Updated for future proofed __raw_xsave_addr(). > > Changes from v3: > * Added the function description in the kernel-doc style. (Borislav Petkov) > * Removed 'no functional change' in the changelog. (Borislav Petkov) > --- > arch/x86/kernel/fpu/xstate.c | 78 ++++++++++++++++++++++++------------ > 1 file changed, 53 insertions(+), 25 deletions(-) > > diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c > index 26f6d5e0f1ed..98ab10e4da3b 100644 > --- a/arch/x86/kernel/fpu/xstate.c > +++ b/arch/x86/kernel/fpu/xstate.c > @@ -182,6 +182,38 @@ static bool xfeature_is_supervisor(int xfeature_nr) > return ecx & 1; > } > > +/** > + * get_xstate_comp_offset - Find the feature's offset in the compacted > + * format. > + * @mask: This bitmap tells which components reserved in the format. There's that "reserved" confusion thing. Rewrite pls. > + * @feature_nr: The feature number > + * > + * Returns: The offset value > + */ > +static unsigned int get_xstate_comp_offset(u64 mask, int feature_nr) > +{ > + u64 xmask = BIT_ULL(feature_nr + 1) - 1; > + unsigned int next_offset, offset = 0; > + int i; > + > + if ((xfeatures_mask_all & xmask) == (mask & xmask)) > + return xstate_comp_offsets[feature_nr]; > + > + /* > + * With the given mask, no relevant size is found. Calculate it by > + * summing up each state size. > + */ > + for (next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE, i = FIRST_EXTENDED_XFEATURE; > + i <= feature_nr; i++) { > + if (!(mask & BIT_ULL(i))) > + continue; > + > + offset = xstate_aligns[i] ? ALIGN(next_offset, 64) : next_offset; > + next_offset += xstate_sizes[i]; Why is this more complex than it has to be? IOW, why can't you simply do: offset = FXSAVE_SIZE + XSAVE_HDR_SIZE; for (i = FIRST_EXTENDED_XFEATURE; i <= feature_nr; i++) { if (!(mask & BIT_ULL(i))) continue; if (xstate_aligns[i]) offset = ALIGN(offset, 64); offset += xstate_sizes[i]; } return offset; like it was before? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette