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=-14.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 D9F3CC433E1 for ; Mon, 24 Aug 2020 17:16:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B4FC02067C for ; Mon, 24 Aug 2020 17:16:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598289365; bh=rpauGeZABoOovO9KdfgP02+QEUTjAZ89+rWMnfA0VKo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=EkfV/S9Y9y1RliGV+VDliB6fQAjmUhhyrIbFJUrtxnzSBbp3ua6eEP5quSKdpWF83 mfdLIokujPdzXHUWYbZBIvY9jkHe5fJoPBWjiwTeUYVH4sD3Q/qEATdEOhkFDkRES0 E6PlGlYiaOmRXcy4SFG2UdC2+OE/oLrnkzE1fuPs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728423AbgHXRQD (ORCPT ); Mon, 24 Aug 2020 13:16:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:40652 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728356AbgHXQg6 (ORCPT ); Mon, 24 Aug 2020 12:36:58 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4CC2922D00; Mon, 24 Aug 2020 16:36:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598286990; bh=rpauGeZABoOovO9KdfgP02+QEUTjAZ89+rWMnfA0VKo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Dix/HYaMCzNiuwxc3S0vIaVZ746c+uV+u71RhZeQkww9q9fRksHCuVAQtNdeqsvFJ ycy2r58HiAhtErbUhGYGiwEZGOm2NvjUyxE16JrZ2tiR4XOeXkx92ihUenAB/tIt6b rrkAPl77QeWWMMssgfM1JF29xrPamTz9/VPt2H0c= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Marc Zyngier , Sai Prakash Ranjan , Stephen Boyd , Will Deacon , Catalin Marinas , Sasha Levin , linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 5.8 62/63] arm64: Move handling of erratum 1418040 into C code Date: Mon, 24 Aug 2020 12:35:02 -0400 Message-Id: <20200824163504.605538-62-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200824163504.605538-1-sashal@kernel.org> References: <20200824163504.605538-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marc Zyngier [ Upstream commit d49f7d7376d0c0daf8680984a37bd07581ac7d38 ] Instead of dealing with erratum 1418040 on each entry and exit, let's move the handling to __switch_to() instead, which has several advantages: - It can be applied when it matters (switching between 32 and 64 bit tasks). - It is written in C (yay!) - It can rely on static keys rather than alternatives Signed-off-by: Marc Zyngier Tested-by: Sai Prakash Ranjan Reviewed-by: Stephen Boyd Acked-by: Will Deacon Link: https://lore.kernel.org/r/20200731173824.107480-2-maz@kernel.org Signed-off-by: Catalin Marinas Signed-off-by: Sasha Levin --- arch/arm64/kernel/entry.S | 21 --------------------- arch/arm64/kernel/process.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 34 insertions(+), 21 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 35de8ba60e3d5..44445d471442d 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -169,19 +169,6 @@ alternative_cb_end stp x28, x29, [sp, #16 * 14] .if \el == 0 - .if \regsize == 32 - /* - * If we're returning from a 32-bit task on a system affected by - * 1418040 then re-enable userspace access to the virtual counter. - */ -#ifdef CONFIG_ARM64_ERRATUM_1418040 -alternative_if ARM64_WORKAROUND_1418040 - mrs x0, cntkctl_el1 - orr x0, x0, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN - msr cntkctl_el1, x0 -alternative_else_nop_endif -#endif - .endif clear_gp_regs mrs x21, sp_el0 ldr_this_cpu tsk, __entry_task, x20 @@ -337,14 +324,6 @@ alternative_else_nop_endif tst x22, #PSR_MODE32_BIT // native task? b.eq 3f -#ifdef CONFIG_ARM64_ERRATUM_1418040 -alternative_if ARM64_WORKAROUND_1418040 - mrs x0, cntkctl_el1 - bic x0, x0, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN - msr cntkctl_el1, x0 -alternative_else_nop_endif -#endif - #ifdef CONFIG_ARM64_ERRATUM_845719 alternative_if ARM64_WORKAROUND_845719 #ifdef CONFIG_PID_IN_CONTEXTIDR diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 6089638c7d43f..d8a10cf28f827 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -515,6 +515,39 @@ static void entry_task_switch(struct task_struct *next) __this_cpu_write(__entry_task, next); } +/* + * ARM erratum 1418040 handling, affecting the 32bit view of CNTVCT. + * Assuming the virtual counter is enabled at the beginning of times: + * + * - disable access when switching from a 64bit task to a 32bit task + * - enable access when switching from a 32bit task to a 64bit task + */ +static void erratum_1418040_thread_switch(struct task_struct *prev, + struct task_struct *next) +{ + bool prev32, next32; + u64 val; + + if (!(IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040) && + cpus_have_const_cap(ARM64_WORKAROUND_1418040))) + return; + + prev32 = is_compat_thread(task_thread_info(prev)); + next32 = is_compat_thread(task_thread_info(next)); + + if (prev32 == next32) + return; + + val = read_sysreg(cntkctl_el1); + + if (!next32) + val |= ARCH_TIMER_USR_VCT_ACCESS_EN; + else + val &= ~ARCH_TIMER_USR_VCT_ACCESS_EN; + + write_sysreg(val, cntkctl_el1); +} + /* * Thread switching. */ @@ -530,6 +563,7 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, entry_task_switch(next); uao_thread_switch(next); ssbs_thread_switch(next); + erratum_1418040_thread_switch(prev, next); /* * Complete any pending TLB or cache maintenance on this CPU in case -- 2.25.1