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=-8.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 4988BC2D0E4 for ; Tue, 17 Nov 2020 17:00:16 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ADF3222447 for ; Tue, 17 Nov 2020 17:00:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="WYcHvhFO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ADF3222447 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=briE1OVluYiA7IgwK7gEZA3jXEbzAAG9Zs4CtANQog0=; b=WYcHvhFO6yXk+7y+8O9+l72Jv de3SrijvgmoyhbLm2qxgBLGcGA5W0yOWBD11iRsfm0D6yORjUAV5BEhGhO65dcQidbgZhmIbPfIVw k0zNQtFQbveQpvL/ugnGyPuB/dQmDkb1423FfUtQWIns/AIHREf8l6nYxhJd9wSz7fZkl9aA4D7Ec LM9gZcFg3Sk0UuhIk0rDQrO1piv5RrdOiPjahYYT6YBcPHXf724rYbPx1pp1JF8s3gYnjXH0vPpVo AIGW3JZEnxFOIWTAEXTHklAbxnU4xAli9IZQSWuckwK7ZR4Qa6kjkdP0fJmv+QBluVwCO/ZFalJgL JPFDwKHrQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kf4KV-0008B8-Ku; Tue, 17 Nov 2020 16:59:43 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kf4KT-0008AM-EG for linux-arm-kernel@lists.infradead.org; Tue, 17 Nov 2020 16:59:42 +0000 Received: from trantor (unknown [2.26.170.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C22EB24248; Tue, 17 Nov 2020 16:59:39 +0000 (UTC) Date: Tue, 17 Nov 2020 16:59:37 +0000 From: Catalin Marinas To: Vladimir Murzin Subject: Re: [RFC PATCH 2/2] arm64: Expose EPAN support via HWCAPS2_EPAN Message-ID: References: <20201113152023.102855-1-vladimir.murzin@arm.com> <20201113152023.102855-3-vladimir.murzin@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201113152023.102855-3-vladimir.murzin@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201117_115941_602578_A9E4426F X-CRM114-Status: GOOD ( 12.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: keescook@chromium.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Nov 13, 2020 at 03:20:23PM +0000, Vladimir Murzin wrote: > So user have a clue whether exec-only permissions will work. I do think we should tell user the PROT_EXEC actually gives execute-only permission. > --- a/arch/arm64/include/uapi/asm/hwcap.h > +++ b/arch/arm64/include/uapi/asm/hwcap.h > @@ -75,5 +75,6 @@ > #define HWCAP2_RNG (1 << 16) > #define HWCAP2_BTI (1 << 17) > #define HWCAP2_MTE (1 << 18) > +#define HWCAP2_EPAN (1 << 19) However, I wonder whether EPAN is meaningful to the user. PAN is a kernel protection that doesn't say much from a user perspective. Maybe something like HWCAP2_EXECONLY? That said, we do have a precedent on 32-bit where we exposed HWCAP_LPAE to the user meaning that 64-bit atomics are available. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel