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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 8DEE9C433E4 for ; Fri, 17 Jul 2020 08:55:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BDC3207F5 for ; Fri, 17 Jul 2020 08:55:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="XTp6bn8F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726563AbgGQIzA (ORCPT ); Fri, 17 Jul 2020 04:55:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725912AbgGQIy7 (ORCPT ); Fri, 17 Jul 2020 04:54:59 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB95DC061755; Fri, 17 Jul 2020 01:54:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=aEr7cpiEkCxbEVwXSRfLp3Ytk5hTAgwAHhMYmtgWkp8=; b=XTp6bn8FEKwlnyQgkHyasqtfQs fFYXMAUIiMSk8ZvOhG343GjKyPZe9SzrBqo4dgVstwgjT/qqnBnojwBCg02q+0+oaf4CtVI9jrQ03 ONB24bL/N5z3WjOc/fHRXLiv5pluGJgrS96d7OVkA8awqCpQdsFU7l6f1TDqUW+wjR9oMMFFmdtJn VzUhKVeV4zqZEVhYbJxkhKgUC4lOzWSbPL46WpppaNrJaSpNv9qbChKd0nKPB+YDqPSa0c4DPcASR deR1T0ijZzeJx31cEvj91bKq7KSnx5u0W411DK6OS3PyVW3svSma5utxYBHXipY7w2w6E5oKjTaT5 O7+5x+pg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jwM8j-0002lD-9h; Fri, 17 Jul 2020 08:54:45 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 79D35304D58; Fri, 17 Jul 2020 10:54:42 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5001929CF6F79; Fri, 17 Jul 2020 10:54:42 +0200 (CEST) Date: Fri, 17 Jul 2020 10:54:42 +0200 From: Peter Zijlstra To: ira.weiny@intel.com Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Fenghua Yu , x86@kernel.org, Dave Hansen , Dan Williams , Vishal Verma , Andrew Morton , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC V2 02/17] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support Message-ID: <20200717085442.GX10769@hirez.programming.kicks-ass.net> References: <20200717072056.73134-1-ira.weiny@intel.com> <20200717072056.73134-3-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200717072056.73134-3-ira.weiny@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 17, 2020 at 12:20:41AM -0700, ira.weiny@intel.com wrote: > +/* > + * Get a new pkey register value from the user values specified. > + * > + * Kernel users use the same flags as user space: > + * PKEY_DISABLE_ACCESS > + * PKEY_DISABLE_WRITE > + */ > +u32 get_new_pkr(u32 old_pkr, int pkey, unsigned long init_val) > +{ > + int pkey_shift = (pkey * PKR_BITS_PER_PKEY); > + u32 new_pkr_bits = 0; > + > + /* Set the bits we need in the register: */ > + if (init_val & PKEY_DISABLE_ACCESS) > + new_pkr_bits |= PKR_AD_BIT; > + if (init_val & PKEY_DISABLE_WRITE) > + new_pkr_bits |= PKR_WD_BIT; > + > + /* Shift the bits in to the correct place: */ > + new_pkr_bits <<= pkey_shift; > + > + /* Mask off any old bits in place: */ > + old_pkr &= ~((PKR_AD_BIT | PKR_WD_BIT) << pkey_shift); > + > + /* Return the old part along with the new part: */ > + return old_pkr | new_pkr_bits; > +} This is unbelievable junk... How about something like: u32 update_pkey_reg(u32 pk_reg, int pkey, unsigned int flags) { int pkey_shift = pkey * PKR_BITS_PER_PKEY; pk_reg &= ~(((1 << PKR_BITS_PER_PKEY) - 1) << pkey_shift); if (flags & PKEY_DISABLE_ACCESS) pk_reg |= PKR_AD_BIT << pkey_shift; if (flags & PKEY_DISABLE_WRITE) pk_reg |= PKR_WD_BIT << pkey_shift; return pk_reg; } Then we at least have a little clue wtf the thing does.. Yes I started with a rename and then got annoyed at the implementation too.