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=-11.7 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,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 234C8C64E7C for ; Wed, 2 Dec 2020 18:24:29 +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 AE5FD22240 for ; Wed, 2 Dec 2020 18:24:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE5FD22240 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=5m40gaE3urXCfgck4pYGX+E0uAcdDHiVFbNqzvGFHz8=; b=FT54BWgOXpi5Oc96RJ12fLF+m gt6iuWj9+leLofoksCYXM9fWYMAKBPVeWBmtCAmNoaVTeJyIJz3aF4I8M+g5rU+LUNUi2HutZs7Xw x7fQwUbuJOXxxH6/2Iz0yzF3UynlkAQWiOTEbaJle+VPfXKJnuJb8NqJQsCPSCUzaiMlMwojn05XF cZJBpCyGXsqTGoownJil3cuz02DiPNKVhbu04vMfpSgbV4B7zxUkSIwHIQQzvNWukvojOz3mwzD6m yZPYrOU2T5TRhQ70IVYfEAoEQx+8SR+zi2l/XZKf03iixnMWX+z/h3RIdLejv07x+rUZy6iNH1EsR DIHMEWN8Q==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kkWmX-0005Md-9B; Wed, 02 Dec 2020 18:23:13 +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 1kkWmU-0005Lw-3S for linux-arm-kernel@lists.infradead.org; Wed, 02 Dec 2020 18:23:11 +0000 Date: Wed, 2 Dec 2020 18:23:03 +0000 From: Catalin Marinas To: Vladimir Murzin Subject: Re: [PATCH 1/2] arm64: Support execute-only permissions with Enhanced PAN Message-ID: <20201202182303.GC21091@gaia> References: <20201119133953.15585-1-vladimir.murzin@arm.com> <20201119133953.15585-2-vladimir.murzin@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201119133953.15585-2-vladimir.murzin@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201202_132310_232345_40878A50 X-CRM114-Status: GOOD ( 13.08 ) 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 Thu, Nov 19, 2020 at 01:39:52PM +0000, Vladimir Murzin wrote: > diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h > index 174817b..19147b6 100644 > --- a/arch/arm64/include/asm/sysreg.h > +++ b/arch/arm64/include/asm/sysreg.h > @@ -579,6 +579,7 @@ > #endif > > /* SCTLR_EL1 specific flags. */ > +#define SCTLR_EL1_EPAN (BIT(57)) > #define SCTLR_EL1_ATA0 (BIT(42)) > > #define SCTLR_EL1_TCF0_SHIFT 38 > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index dcc165b..540245c 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -1602,6 +1602,14 @@ static void cpu_enable_pan(const struct arm64_cpu_capabilities *__unused) > } > #endif /* CONFIG_ARM64_PAN */ > > +#ifdef CONFIG_ARM64_EPAN > +static void cpu_enable_epan(const struct arm64_cpu_capabilities *__unused) > +{ > + sysreg_clear_set(sctlr_el1, 0, SCTLR_EL1_EPAN); > + local_flush_tlb_all(); > +} > +#endif /* CONFIG_ARM64_EPAN */ Thinking about this, can we not set the SCTLR_EL1.EPAN bit in proc.S directly, regardless of whether the system supports it or not (it should be write-ignored)? It would go in INIT_SCTLR_EL1_MMU_ON. We use the cpufeature entry only for detection, not enabling. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel