From patchwork Mon May 8 21:19:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Zijlstra X-Patchwork-Id: 13235135 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C931C7EE2C for ; Mon, 8 May 2023 21:35:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233449AbjEHVe7 (ORCPT ); Mon, 8 May 2023 17:34:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232428AbjEHVe5 (ORCPT ); Mon, 8 May 2023 17:34:57 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D705CC; Mon, 8 May 2023 14:34:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Subject:Cc:To:From:Date:Message-ID: Sender:Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To:References; bh=2UuvzVvkJajpSRztAlbWQE/ujN4VBnGx7txBk9UwFEs=; b=KneIF4sIX1hMULcaWZ2QHQseOH 2g0MVeiYasQ3hb/DQWVc4LIuYtwArZXQukDYTNn/60vn84poNQxzfX6ZYJLkO4eWYGtQRAq2h2if7 1894SeywnNYoNqO1A9CSpliV+NkbiPjv6Rom4KvFbtpdGVg/i2TvfxseNX1MI0sW5lLGPu6uib8QL 0wwd0wZNbkIK7JYS+DMjGeOheRRV+VgJ5lNgvkRCjwiFQnXIXuWyrJt8l9ZDM5i2yvADD/aH9eTE0 i815ZD49VHy76hKDbEfOVg6wb4QNuyqYz7jN8xcax6kBKY+xyMIOjjXvRDB2G5XrKbcmHnQ1gWnOA wgjAfVxQ==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1pw8UY-00EW3h-Pu; Mon, 08 May 2023 21:33:58 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 64B4130026A; Mon, 8 May 2023 23:33:48 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 273602482941B; Mon, 8 May 2023 23:33:48 +0200 (CEST) Message-ID: <20230508211951.901961964@infradead.org> User-Agent: quilt/0.66 Date: Mon, 08 May 2023 23:19:51 +0200 From: Peter Zijlstra To: bigeasy@linutronix.de Cc: mark.rutland@arm.com, maz@kernel.org, catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org, kernel@xen0n.name, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, pbonzini@redhat.com, wanpengli@tencent.com, vkuznets@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, jgross@suse.com, boris.ostrovsky@oracle.com, daniel.lezcano@linaro.org, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, rafael@kernel.org, peterz@infradead.org, longman@redhat.com, boqun.feng@gmail.com, pmladek@suse.com, senozhatsky@chromium.org, rostedt@goodmis.org, john.ogness@linutronix.de, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jstultz@google.com, sboyd@kernel.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-pm@vger.kernel.org Subject: [RFC][PATCH 0/9] local_clock() vs noinstr Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi all! A recent commit of mine marked local_clock() as noinstr. 776f22913b8e ("sched/clock: Make local_clock() noinstr") Sadly both me and objtool missed the fact that this is subly broken; but Sebastian tripped over it [*]: | vmlinux.o: warning: objtool: native_sched_clock+0x97: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section | vmlinux.o: warning: objtool: kvm_clock_read+0x22: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section | vmlinux.o: warning: objtool: local_clock+0xb4: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section Specifically, local_clock() (and many of the sched_clock() implementation is relies upon) use preempt_{dis,en}able_notrace() which obviously calls out to schedule(). Now, noinstr code *should* never trigger this and already run in non-preemptible code. Specifically entry code should have IRQs disabled while __cpuidle code should have preemption disabled. So while it is mostly harmless, I figured it wouldn't be too hard to clean this up a little -- but that was ~10 patches. Anyway, here goes... Compile tested only on x86_64/s390/arm64 -- I've just fed it to the robots. --- arch/arm64/include/asm/arch_timer.h | 8 +---- arch/arm64/include/asm/io.h | 12 +++---- arch/loongarch/include/asm/loongarch.h | 2 +- arch/loongarch/kernel/time.c | 6 ++-- arch/s390/include/asm/timex.h | 13 +++++--- arch/s390/kernel/time.c | 11 ++++++- arch/x86/kernel/kvmclock.c | 4 +-- arch/x86/kernel/tsc.c | 38 ++++++++++++++++----- arch/x86/xen/time.c | 3 +- drivers/clocksource/arm_arch_timer.c | 60 ++++++++++++++++++++++++++-------- drivers/clocksource/hyperv_timer.c | 4 +-- drivers/cpuidle/cpuidle.c | 8 ++--- drivers/cpuidle/poll_state.c | 4 +-- include/clocksource/hyperv_timer.h | 4 +-- include/linux/rbtree_latch.h | 2 +- include/linux/sched/clock.h | 17 +++++++++- include/linux/seqlock.h | 15 +++++---- kernel/printk/printk.c | 2 +- kernel/sched/clock.c | 19 +++++++---- kernel/time/sched_clock.c | 24 ++++++++++---- kernel/time/timekeeping.c | 4 +-- 21 files changed, 176 insertions(+), 84 deletions(-) * https://lkml.kernel.org/r/20230309072724.3F6zRkvw@linutronix.de TL;DR: PREEMPT_DYNAMIC=n PREEMPT=y DEBUG_ENTRY=y