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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 175E4C433DB for ; Mon, 8 Mar 2021 16:59:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 746A66522C for ; Mon, 8 Mar 2021 16:59:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 746A66522C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DF6BF8D0051; Mon, 8 Mar 2021 11:59:12 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DA5498D001D; Mon, 8 Mar 2021 11:59:12 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C48108D0051; Mon, 8 Mar 2021 11:59:12 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0244.hostedemail.com [216.40.44.244]) by kanga.kvack.org (Postfix) with ESMTP id A5FE28D001D for ; Mon, 8 Mar 2021 11:59:12 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 53F5B1DF8 for ; Mon, 8 Mar 2021 16:59:12 +0000 (UTC) X-FDA: 77897317344.21.A597474 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf15.hostedemail.com (Postfix) with ESMTP id 761B5A001AB3 for ; Mon, 8 Mar 2021 16:59:08 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id E424E6522C; Mon, 8 Mar 2021 16:58:49 +0000 (UTC) Date: Mon, 8 Mar 2021 16:58:47 +0000 From: Catalin Marinas To: Andrey Konovalov Cc: Vincenzo Frascino , Alexander Potapenko , Marco Elver , Andrew Morton , Will Deacon , Dmitry Vyukov , Andrey Ryabinin , Peter Collingbourne , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/5] arm64: kasan: allow to init memory when setting tags Message-ID: <20210308165847.GF15644@arm.com> References: <755161094eac5b0fc15273d609c78a459d4d07b9.1615218180.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <755161094eac5b0fc15273d609c78a459d4d07b9.1615218180.git.andreyknvl@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Stat-Signature: ecio5sof56iiqurcbezx4xb9jx5kbiw7 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 761B5A001AB3 Received-SPF: none (kernel.org>: No applicable sender policy available) receiver=imf15; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: none/none X-HE-Tag: 1615222748-544848 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Mar 08, 2021 at 04:55:14PM +0100, Andrey Konovalov wrote: > @@ -68,10 +69,16 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag) > * 'asm volatile' is required to prevent the compiler to move > * the statement outside of the loop. > */ > - asm volatile(__MTE_PREAMBLE "stg %0, [%0]" > - : > - : "r" (curr) > - : "memory"); > + if (init) > + asm volatile(__MTE_PREAMBLE "stzg %0, [%0]" > + : > + : "r" (curr) > + : "memory"); > + else > + asm volatile(__MTE_PREAMBLE "stg %0, [%0]" > + : > + : "r" (curr) > + : "memory"); > > curr += MTE_GRANULE_SIZE; > } while (curr != end); Is 'init' always a built-in constant here? If not, checking it once outside the loop may be better (or check the code generation, maybe the compiler is smart enough). -- Catalin