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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 22837C43612 for ; Fri, 21 Dec 2018 18:41:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5BDD21920 for ; Fri, 21 Dec 2018 18:41:25 +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="Ix99TSbH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391486AbeLUSlZ (ORCPT ); Fri, 21 Dec 2018 13:41:25 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:40972 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730310AbeLUSlY (ORCPT ); Fri, 21 Dec 2018 13:41:24 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=vmDgozvoxxSIRUOGhKq2UuDLDvfMVTzCj+7pKkEDXbg=; b=Ix99TSbHuikVh0WQblpZ9xHxd oqLcaIZku25DYd0mtjwTedOjN7PF7jJEm9AQmPSJgaLyndQJ9p4CNwwiuOgzvCCfnlyywuFMQBkjo CZ+TvmYrbwVbXlEZt8b5O+niZHyhw70SY6e0gzab/Gcomygebf4MQlDWEcF6bF725K7h4g1ne8UG1 0QT2dmTVPOJ4ZrS6s7i5F55X9CMuY1NCFtqbcdqhickpak+XVBRPbUYjzKQsEZiExMZZTc59sKMRm BowES9uI/G5tiGlZjpSMC3ZruXTxCnLu82CsuXEX6m3dQ/1FsTcvJq39eoAYD8g/Zdv2X4bL3f6PP u4zNONAPQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gaPjc-00022l-F7; Fri, 21 Dec 2018 18:41:20 +0000 Date: Fri, 21 Dec 2018 10:41:20 -0800 From: Matthew Wilcox To: Igor Stoppa Cc: Andy Lutomirski , Peter Zijlstra , Dave Hansen , Mimi Zohar , Thiago Jung Bauermann , igor.stoppa@huawei.com, Nadav Amit , Kees Cook , Ahmed Soliman , linux-integrity@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/12] __wr_after_init: generic functionality Message-ID: <20181221184120.GG10600@bombadil.infradead.org> References: <20181221181423.20455-1-igor.stoppa@huawei.com> <20181221181423.20455-4-igor.stoppa@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181221181423.20455-4-igor.stoppa@huawei.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 21, 2018 at 08:14:14PM +0200, Igor Stoppa wrote: > +static inline int memtst(void *p, int c, __kernel_size_t len) I don't understand why you're verifying that writes actually happen in production code. Sure, write lib/test_wrmem.c or something, but verifying every single rare write seems like a mistake to me. > +#ifndef CONFIG_PRMEM So is this PRMEM or wr_mem? It's not obvious that CONFIG_PRMEM controls wrmem. > +#define wr_assign(var, val) ((var) = (val)) The hamming distance between 'var' and 'val' is too small. The convention in the line immediately below (p and v) is much more readable. > +#define wr_rcu_assign_pointer(p, v) rcu_assign_pointer(p, v) > +#define wr_assign(var, val) ({ \ > + typeof(var) tmp = (typeof(var))val; \ > + \ > + wr_memcpy(&var, &tmp, sizeof(var)); \ > + var; \ > +}) Doesn't wr_memcpy return 'var' anyway? > +/** > + * wr_memcpy() - copyes size bytes from q to p typo > + * @p: beginning of the memory to write to > + * @q: beginning of the memory to read from > + * @size: amount of bytes to copy > + * > + * Returns pointer to the destination > + * The architecture code must provide: > + * void __wr_enable(wr_state_t *state) > + * void *__wr_addr(void *addr) > + * void *__wr_memcpy(void *p, const void *q, __kernel_size_t size) > + * void __wr_disable(wr_state_t *state) This section shouldn't be in the user documentation of wr_memcpy(). > + */ > +void *wr_memcpy(void *p, const void *q, __kernel_size_t size) > +{ > + wr_state_t wr_state; > + void *wr_poking_addr = __wr_addr(p); > + > + if (WARN_ONCE(!wr_ready, "No writable mapping available") || Surely not. If somebody's called wr_memcpy() before wr_ready is set, that means we can just call memcpy().