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Wong" , Chuck Lever , Hugh Dickins , patches@lists.linux.dev, Linux-MM , mm-commits@vger.kernel.org, Mel Gorman Subject: Re: [PATCH -final] x86/clear_user: Make it faster Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657099456; a=rsa-sha256; cv=none; b=lMclBrD+U6Y9q0NKIvUW94vwCIOWBS/xH96jEV3R+pJRDI8aS/elabneVQLvCtL6TbwwUl 1M75/Q+cci/sfOpcPrQ233pufTBLK3fxCx0Wwq6JuQu3ummlMbuGy9lMFP6rrhDsvOp/2s fGyIHoH3bL8C0Hi25sqfXWhWawlUvhg= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=T2E05GBa; spf=pass (imf22.hostedemail.com: domain of adobriyan@gmail.com designates 209.85.218.54 as permitted sender) smtp.mailfrom=adobriyan@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657099456; h=from:from:sender: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:dkim-signature; bh=mH3EsXz6QKYwAcafuhaDfR4s9oNm5ypp5DWlodyKTRg=; b=24WLjo1MwN4dXvxGmpHam6+yPAeQ3uJAG7NafONNfIUDbed8hyxYHsClXZYDT3fNuDccqh SGPG+uKWWwF1F0VSJ1ZMAduBBWhMRoTebnTgWm0BqbtfDCcETF0ylbk3Kx28Qd/qINhfzv rDHA3z0KFmYaAPsjZQik0wWTCC0iS1k= Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=T2E05GBa; spf=pass (imf22.hostedemail.com: domain of adobriyan@gmail.com designates 209.85.218.54 as permitted sender) smtp.mailfrom=adobriyan@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: gew6z33ba7j6cubenkkqqz65xrynoerh X-Rspamd-Queue-Id: 5CAD1C0056 X-HE-Tag: 1657099456-6097 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 Tue, Jul 05, 2022 at 07:01:06PM +0200, Borislav Petkov wrote: > + asm volatile( > + "1:\n\t" > + ALTERNATIVE_3("rep stosb", > + "call clear_user_erms", ALT_NOT(X86_FEATURE_FSRM), > + "call clear_user_rep_good", ALT_NOT(X86_FEATURE_ERMS), > + "call clear_user_original", ALT_NOT(X86_FEATURE_REP_GOOD)) > + "2:\n" > + _ASM_EXTABLE_UA(1b, 2b) > + : "+&c" (size), "+&D" (addr), ASM_CALL_CONSTRAINT > + : "a" (0) > + /* rep_good clobbers %rdx */ > + : "rdx"); "+c" and "+D" should be enough for 1 instruction assembly?