From patchwork Fri Aug 23 11:57:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cristian Marussi X-Patchwork-Id: 11111489 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id AB2A11395 for ; Fri, 23 Aug 2019 11:58:39 +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 892FC22CE3 for ; Fri, 23 Aug 2019 11:58:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="fwcBU/Za" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 892FC22CE3 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+patchwork-linux-arm=patchwork.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:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: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:In-Reply-To: References:List-Owner; bh=lZ1RBa/7eRVrLRM5LUqtu7/AX3cTRbh8WDohSOUedXo=; b=fwc BU/ZaDuky0Tdce1FxrlH984lIKFpfMLwVJnperNGlc3fj3qVWcdLUO7N6jKzVWQBqm3LlPTRlh8uh oBXPrGA8pllHDWMa3SgwiCkS53Are3H629vuL7UPybdZ5HBAa/iYLp2VQYvVnVWjAyoQUbebXEFf8 PQrPa7vo0hlFwBhLQKE9VA53s3Ds58vVJKedYJHFEuRaLOXhdnpEn6+tf7LW+M9iW6RWSzHT2eb/S iITFLmSyW1m0KMPjkTyuPquvF7yB4E69yG2mVjYxfTy0Xj8VivbUpUUccMX81VRP9Is61Ip8TnJul p2GVfl9bodXlugT++mqTGmKs42j2BmQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i18DG-0001ro-CC; Fri, 23 Aug 2019 11:58:38 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i18D5-0001gA-BA for linux-arm-kernel@lists.infradead.org; Fri, 23 Aug 2019 11:58:28 +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 15A1E337; Fri, 23 Aug 2019 04:58:23 -0700 (PDT) Received: from e120937-lin.cambridge.arm.com (e120937-lin.cambridge.arm.com [10.1.197.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7DDF03F246; Fri, 23 Aug 2019 04:58:21 -0700 (PDT) From: Cristian Marussi To: linux-kernel@vger.kernel.org Subject: [RFC PATCH 0/7] Unify SMP stop generic logic to common code Date: Fri, 23 Aug 2019 12:57:13 +0100 Message-Id: <20190823115720.605-1-cristian.marussi@arm.com> X-Mailer: git-send-email 2.17.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190823_045827_471217_EE4F8615 X-CRM114-Status: GOOD ( 11.80 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 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-arch@vger.kernel.org, mark.rutland@arm.com, peterz@infradead.org, catalin.marinas@arm.com, takahiro.akashi@linaro.org, james.morse@arm.com, hidehiro.kawai.ez@hitachi.com, tglx@linutronix.de, will@kernel.org, dave.martin@arm.com, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Hi all, the logic underlying SMP stop and kexec crash procedures, beside containing some arch-specific bits, is mostly generic and common across all archs: despite this fact, such logic is now scattered across all architectures and on some of them is flawed, in such a way that, under some specific conditions, you can end up with a CPU left still running after a panic and possibly lost across a subsequent kexec crash reboot. [1] Beside the flaws on some archs, there is anyway lots of code duplication, so this patch series attempts to move into common code all the generic SMP stop and crash logic, fixing observed issues, and leaving only the arch specific bits inside properly provided arch-specific helpers. An architecture willing to rely on this SMP common logic has to define its own helpers and set CONFIG_ARCH_USE_COMMON_SMP_STOP=y. The series wire this up for arm64. Behaviour is not changed for architectures not adopting this new common logic. Tested as follows: - arm64: 1. boot/reboot 2. panic on a starting CPU within a 2 CPUs system (freezing properly) 3. kexec reboot after a panic like 2. (not losing any CPU on reboot) 4. kexec reboot after a panic like 2. and a simultaneous reboot (instrumenting code to delay the stop messages transmission to have time to inject a reboot -f) - x86: 1. boot/reboot 2. panic 3. kexec crash Thanks Cristian [1] [root@arch ~]# echo 1 > /sys/devices/system/cpu/cpu1/online [root@arch ~]# [ 152.583368] ------------[ cut here ]------------ [ 152.583872] kernel BUG at arch/arm64/kernel/cpufeature.c:852! [ 152.584693] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP [ 152.585228] Modules linked in: [ 152.586040] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0-rc5-00001-gcabd12118c4a-dirty #2 [ 152.586218] Hardware name: Foundation-v8A (DT) [ 152.586478] pstate: 000001c5 (nzcv dAIF -PAN -UAO) [ 152.587260] pc : has_cpuid_feature+0x35c/0x360 [ 152.587398] lr : verify_local_elf_hwcaps+0x6c/0xf0 [ 152.587520] sp : ffff0000118bbf60 [ 152.587605] x29: ffff0000118bbf60 x28: 0000000000000000 [ 152.587784] x27: 0000000000000000 x26: 0000000000000000 [ 152.587882] x25: ffff00001167a010 x24: ffff0000112f59f8 [ 152.587992] x23: 0000000000000000 x22: 0000000000000000 [ 152.588085] x21: ffff0000112ea018 x20: ffff000010fe5518 [ 152.588180] x19: ffff000010ba3f30 x18: 0000000000000036 [ 152.588285] x17: 0000000000000000 x16: 0000000000000000 [ 152.588380] x15: 0000000000000000 x14: ffff80087a821210 [ 152.588481] x13: 0000000000000000 x12: 0000000000000000 [ 152.588599] x11: 0000000000000080 x10: 00400032b5503510 [ 152.588709] x9 : 0000000000000000 x8 : ffff000010b93204 [ 152.588810] x7 : 00000000800001d8 x6 : 0000000000000005 [ 152.588910] x5 : 0000000000000000 x4 : 0000000000000000 [ 152.589021] x3 : 0000000000000000 x2 : 0000000000008000 [ 152.589121] x1 : 0000000000180480 x0 : 0000000000180480 [ 152.589379] Call trace: [ 152.589646] has_cpuid_feature+0x35c/0x360 [ 152.589763] verify_local_elf_hwcaps+0x6c/0xf0 [ 152.589858] check_local_cpu_capabilities+0x88/0x118 [ 152.589968] secondary_start_kernel+0xc4/0x168 [ 152.590530] Code: d53801e0 17ffff58 d5380600 17ffff56 (d4210000) [ 152.592215] ---[ end trace 80ea98416149c87e ]--- [ 152.592734] Kernel panic - not syncing: Attempted to kill the idle task! [ 152.593173] Kernel Offset: disabled [ 152.593501] CPU features: 0x0004,20c02008 [ 152.593678] Memory Limit: none [ 152.594208] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]--- [root@arch ~]# bash: echo: write error: Input/output error [root@arch ~]# [root@arch ~]# [root@arch ~]# echo HELO HELO Cristian Marussi (7): smp: add generic SMP-stop support to common code smp: unify crash_ and smp_send_stop() logic smp: coordinate concurrent crash/smp stop calls smp: address races of starting CPUs while stopping arm64: smp: use generic SMP stop common code arm64: smp: use SMP crash-stop common code arm64: smp: add arch specific cpu parking helper arch/arm64/Kconfig | 3 + arch/arm64/include/asm/smp.h | 2 - arch/arm64/kernel/smp.c | 127 ++++++++-------------------- include/linux/smp.h | 44 ++++++++++ kernel/panic.c | 26 ------ kernel/smp.c | 158 +++++++++++++++++++++++++++++++++++ 6 files changed, 239 insertions(+), 121 deletions(-)