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=-9.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT 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 A2849C43381 for ; Sat, 23 Feb 2019 21:13:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7248220651 for ; Sat, 23 Feb 2019 21:13:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550956392; bh=lLhzsMl61+adZZj9ZpyxxBI0h6ks0VVJ7o5u2S9EXzc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=LiYpgw+QvSn+KRcjAcKmbzGhrXKowOXt8as/6H4anMM1hPay8rH3Jgd6zZUPaaaF9 H3Gt0gL8MizeBulGCs2ZYnxdxjxd8rjPRXRauU2OXf8IsY0/cL2MJBcUBpFhZR7M75 u2tYjBFSNr8oKzFE0vaQS9JXLYe5pMI9ZGTUrOnI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730042AbfBWVNL (ORCPT ); Sat, 23 Feb 2019 16:13:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:48396 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729419AbfBWVLq (ORCPT ); Sat, 23 Feb 2019 16:11:46 -0500 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 3181820855; Sat, 23 Feb 2019 21:11:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550956306; bh=lLhzsMl61+adZZj9ZpyxxBI0h6ks0VVJ7o5u2S9EXzc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S4PSNQwTK5zlWg+COzKkIvC63eIsJAVJNNDdMh86DWfWUr3tCKRl2HVdQ/JK9HT93 8O2JnvUAcMlOygm393udkrwVwYvW7s6Wz6dv/7WpDgUWIbJ9lIK7eC9eeySwaoNVjm C6WYnuNfslSaQHzG5eyMao1rRWi/UVCr+hfXnD5o= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Max Filippov , Sasha Levin , linux-xtensa@linux-xtensa.org Subject: [PATCH AUTOSEL 3.18 06/18] xtensa: SMP: fix secondary CPU initialization Date: Sat, 23 Feb 2019 16:11:23 -0500 Message-Id: <20190223211135.203082-6-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190223211135.203082-1-sashal@kernel.org> References: <20190223211135.203082-1-sashal@kernel.org> MIME-Version: 1.0 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: Max Filippov [ Upstream commit 32a7726c4f4aadfabdb82440d84f88a5a2c8fe13 ] - add missing memory barriers to the secondary CPU synchronization spin loops; add comment to the matching memory barrier in the boot_secondary and __cpu_die functions; - use READ_ONCE/WRITE_ONCE to access cpu_start_id/cpu_start_ccount instead of reading/writing them directly; - re-initialize cpu_running every time before starting secondary CPU to flush possible previous CPU startup results. Signed-off-by: Max Filippov Signed-off-by: Sasha Levin --- arch/xtensa/kernel/head.S | 5 ++++- arch/xtensa/kernel/smp.c | 34 +++++++++++++++++++++------------- 2 files changed, 25 insertions(+), 14 deletions(-) diff --git a/arch/xtensa/kernel/head.S b/arch/xtensa/kernel/head.S index 64140998e1173..16bdb414784ad 100644 --- a/arch/xtensa/kernel/head.S +++ b/arch/xtensa/kernel/head.S @@ -281,12 +281,13 @@ should_never_return: movi a2, cpu_start_ccount 1: + memw l32i a3, a2, 0 beqi a3, 0, 1b movi a3, 0 s32i a3, a2, 0 - memw 1: + memw l32i a3, a2, 0 beqi a3, 0, 1b wsr a3, ccount @@ -323,11 +324,13 @@ ENTRY(cpu_restart) rsr a0, prid neg a2, a0 movi a3, cpu_start_id + memw s32i a2, a3, 0 #if XCHAL_DCACHE_IS_WRITEBACK dhwbi a3, 0 #endif 1: + memw l32i a2, a3, 0 dhi a3, 0 bne a2, a0, 1b diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c index 4d02e38514f54..545144d1431d5 100644 --- a/arch/xtensa/kernel/smp.c +++ b/arch/xtensa/kernel/smp.c @@ -192,9 +192,11 @@ static int boot_secondary(unsigned int cpu, struct task_struct *ts) int i; #ifdef CONFIG_HOTPLUG_CPU - cpu_start_id = cpu; - system_flush_invalidate_dcache_range( - (unsigned long)&cpu_start_id, sizeof(cpu_start_id)); + WRITE_ONCE(cpu_start_id, cpu); + /* Pairs with the third memw in the cpu_restart */ + mb(); + system_flush_invalidate_dcache_range((unsigned long)&cpu_start_id, + sizeof(cpu_start_id)); #endif smp_call_function_single(0, mx_cpu_start, (void *)cpu, 1); @@ -203,18 +205,21 @@ static int boot_secondary(unsigned int cpu, struct task_struct *ts) ccount = get_ccount(); while (!ccount); - cpu_start_ccount = ccount; + WRITE_ONCE(cpu_start_ccount, ccount); - while (time_before(jiffies, timeout)) { + do { + /* + * Pairs with the first two memws in the + * .Lboot_secondary. + */ mb(); - if (!cpu_start_ccount) - break; - } + ccount = READ_ONCE(cpu_start_ccount); + } while (ccount && time_before(jiffies, timeout)); - if (cpu_start_ccount) { + if (ccount) { smp_call_function_single(0, mx_cpu_stop, - (void *)cpu, 1); - cpu_start_ccount = 0; + (void *)cpu, 1); + WRITE_ONCE(cpu_start_ccount, 0); return -EIO; } } @@ -234,6 +239,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) pr_debug("%s: Calling wakeup_secondary(cpu:%d, idle:%p, sp: %08lx)\n", __func__, cpu, idle, start_info.stack); + init_completion(&cpu_running); ret = boot_secondary(cpu, idle); if (ret == 0) { wait_for_completion_timeout(&cpu_running, @@ -295,8 +301,10 @@ void __cpu_die(unsigned int cpu) unsigned long timeout = jiffies + msecs_to_jiffies(1000); while (time_before(jiffies, timeout)) { system_invalidate_dcache_range((unsigned long)&cpu_start_id, - sizeof(cpu_start_id)); - if (cpu_start_id == -cpu) { + sizeof(cpu_start_id)); + /* Pairs with the second memw in the cpu_restart */ + mb(); + if (READ_ONCE(cpu_start_id) == -cpu) { platform_cpu_kill(cpu); return; } -- 2.19.1