From patchwork Fri Nov 17 18:21:58 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 10063239 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id ACB366023A for ; Fri, 17 Nov 2017 18:27:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9E4032A9C2 for ; Fri, 17 Nov 2017 18:27:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 92CEC2ACB3; Fri, 17 Nov 2017 18:27:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 321932A9C2 for ; Fri, 17 Nov 2017 18:27:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=oIlYmfOD81bMCtk0SsgFGJL9rSbeJ2VGENl8MLAxqGI=; b=VxevEWRs5EJGNQsYfGiz83CRX9 wYgSGHrI8xmdmLfisCJEwSdPCoG3J04b+/bJn8aZe8BbvueAHa3GljGFKOa6fqv7lR2wQoP+TbQuV nbF9MD4Q0MkXV6lmhbYXPirKge49Ak1hmrZtKhrf0rY8UdLt1wjHECKCjsSjdimMsOiXnF5pTh6NR 1musFpQUfaCcHiywgoc7JOwaVF8FCpj4LHJ6WSTPNUElQtFKhlHdHC3YQRLUI0BRq4+PuPJJ7tLPY DtxHRXGWu3w6y8/r1g3A7TjupBvM0iu7GKf56EHFauoD2izHrQY5cbFKSikQhjU/1X05uuwXjdF0o yx6YtPRA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1eFlMQ-0003OD-3d; Fri, 17 Nov 2017 18:27:30 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1eFlI3-0005vW-FE for linux-arm-kernel@lists.infradead.org; Fri, 17 Nov 2017 18:23:01 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6075F19E8; Fri, 17 Nov 2017 10:21:55 -0800 (PST) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 310FE3F7B0; Fri, 17 Nov 2017 10:21:55 -0800 (PST) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id CCC341AE13AC; Fri, 17 Nov 2017 18:22:03 +0000 (GMT) From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 15/18] arm64: tls: Avoid unconditional zeroing of tpidrro_el0 for native tasks Date: Fri, 17 Nov 2017 18:21:58 +0000 Message-Id: <1510942921-12564-16-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1510942921-12564-1-git-send-email-will.deacon@arm.com> References: <1510942921-12564-1-git-send-email-will.deacon@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20171117_102259_798077_4916568A X-CRM114-Status: UNSURE ( 9.23 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, keescook@chromium.org, ard.biesheuvel@linaro.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, sboyd@codeaurora.org, linux-kernel@vger.kernel.org, Will Deacon MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP We zero tpidrro_el0 on return to the exception trampoline since it is used as a scratch register during exception entry. When the entry trampoline is being used, we can therefore avoid zeroing tpidrro_el0 in the context-switch for native tasks. Signed-off-by: Will Deacon --- arch/arm64/kernel/process.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 2dc0f8482210..c2841bda60be 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -305,16 +305,14 @@ void tls_preserve_current_state(void) static void tls_thread_switch(struct task_struct *next) { - unsigned long tpidr, tpidrro; - tls_preserve_current_state(); - tpidr = *task_user_tls(next); - tpidrro = is_compat_thread(task_thread_info(next)) ? - next->thread.tp_value : 0; + if (is_compat_thread(task_thread_info(next))) + write_sysreg(next->thread.tp_value, tpidrro_el0); + else if (arm64_kernel_mapped_at_el0()) + write_sysreg(0, tpidrro_el0); - write_sysreg(tpidr, tpidr_el0); - write_sysreg(tpidrro, tpidrro_el0); + write_sysreg(*task_user_tls(next), tpidr_el0); } /* Restore the UAO state depending on next's addr_limit */