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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 35C89C2D0CF for ; Tue, 24 Dec 2019 07:06:04 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 E7F7520706 for ; Tue, 24 Dec 2019 07:06:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="i2p/HIkI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E7F7520706 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-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=bombadil.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:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=gGWOv5X2tKSmh0aeiyVnpWypTTNztm9s3Nz0QekLo2k=; b=i2p/HIkIVuCDvN X1KSumbLEJYdSOsX88abAp71YwJ9ZMZfhaEaEA+FhfO6lFKbxFzmfyhMrlwIo/ehgJfxnUFWoy6IU lHp9yJ8xdqAUjdFr0Yi9Po7lsjZelS0IyOX49egKsR655vzWCKpHIuss2g7uE85P7zhoxmfTn96ai zzHDaYTgaHEg0AsVKEAUmQdNPxrM6W+b0zche2P1QWik3p9SuXEMgGv9s+R0zEcutiXQcnoeEBXqG zdk7FnUaaAaa5eQRuBLdmTVnvVcEJGXxTGxtJ/jb1W5v2HQ7XUHipZAM9Ew/asxedLRYRQV8eoVWS kTIGZPzEFaGQqu/WukdQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ijeGY-0005Ln-CJ; Tue, 24 Dec 2019 07:06:02 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ijeGV-0005LB-GB for linux-arm-kernel@lists.infradead.org; Tue, 24 Dec 2019 07:06:00 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7957431B; Mon, 23 Dec 2019 23:05:55 -0800 (PST) Received: from [10.163.1.130] (unknown [10.163.1.130]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B2BE43F6CF; Mon, 23 Dec 2019 23:08:53 -0800 (PST) Subject: Re: [PATCH] arm64: Set SSBS for user threads while creation To: Srinivas Ramana , will@kernel.org, catalin.marinas@arm.com, maz@kernel.org, will.deacon@arm.com References: <1577106146-8999-1-git-send-email-sramana@codeaurora.org> From: Anshuman Khandual Message-ID: Date: Tue, 24 Dec 2019 12:36:34 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1577106146-8999-1-git-send-email-sramana@codeaurora.org> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191223_230559_582182_95882658 X-CRM114-Status: GOOD ( 19.07 ) 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: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.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+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 12/23/2019 06:32 PM, Srinivas Ramana wrote: > Current SSBS implementation takes care of setting the > SSBS bit in start_thread() for user threads. While this works > for tasks launched with fork/clone followed by execve, for cases > where userspace would just call fork (eg, Java applications) this > leaves the SSBS bit unset. This results in performance > regression for such tasks. > > It is understood that commit cbdf8a189a66 ("arm64: Force SSBS > on context switch") masks this issue, but that was done for a > different reason where heterogeneous CPUs(both SSBS supported > and unsupported) are present. It is appropriate to take care > of the SSBS bit for all threads while creation itself. So this fixes the situation (i.e low performance) from the creation time of a task with fork() which will never see a subsequent execve, till it gets context switched for the very first time ? > > Fixes: 8f04e8e6e29c ("arm64: ssbd: Add support for PSTATE.SSBS rather than trapping to EL3") > Signed-off-by: Srinivas Ramana > --- > arch/arm64/kernel/process.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index 71f788cd2b18..a8f05cc39261 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -399,6 +399,13 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, > */ > if (clone_flags & CLONE_SETTLS) > p->thread.uw.tp_value = childregs->regs[3]; > + > + if (arm64_get_ssbd_state() != ARM64_SSBD_FORCE_ENABLE) { > + if (is_compat_thread(task_thread_info(p))) > + set_compat_ssbs_bit(childregs); > + else > + set_ssbs_bit(childregs); > + } > } else { > memset(childregs, 0, sizeof(struct pt_regs)); > childregs->pstate = PSR_MODE_EL1h; > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel