From patchwork Mon May 8 21:19:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Zijlstra X-Patchwork-Id: 13235138 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 1E7D1C7EE2F for ; Mon, 8 May 2023 21:35:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233992AbjEHVf5 (ORCPT ); Mon, 8 May 2023 17:35:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233883AbjEHVfx (ORCPT ); Mon, 8 May 2023 17:35:53 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 42E5E9ECD; Mon, 8 May 2023 14:35:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=F/mEORQVn/+4FFZhPg8/YI2Izvfuw/wjd2XHaIHu63c=; b=Pa03uAZPkgmVJ1RZq0PF/mn8c1 HPEOlUYH9qYdyoyKnkKFpNHIQxWCxbxmPqtEcXtMCyC5MDbaWkfX0UrH0hkIb9CV8qOjWm6rgdprk niysJMBzcsXHUnMTk9nSR3egA9I3LQ1USG94wywxRwRJvHwmPKF6ayuB3A4oFDSj12zDQZmmUKHsH ttMq2ONLodkV45d9K7qsEUKCFt/NdTZ9JhtPbBg7T11iaTSKaVYre+oFuJfDMVLCbg7BB3nFk8wX6 hwrKf3Mf+048gPWaw5o1Eei5BCLQv2fvJHqreq6r/unM6mdvy4/TToL4svY6eeQDB7ymYDjRLs04F VZBXFB4g==; 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-00EW3b-6j; 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)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 9F96C30613D; Mon, 8 May 2023 23:33:48 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 38F4D2482941E; Mon, 8 May 2023 23:33:48 +0200 (CEST) Message-ID: <20230508213147.650971590@infradead.org> User-Agent: quilt/0.66 Date: Mon, 08 May 2023 23:19:55 +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 4/9] arm64/arch_timer: Provide noinstr sched_clock_read() functions References: <20230508211951.901961964@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org With the intent to provide local_clock_noinstr(), a variant of local_clock() that's safe to be called from noinstr code (with the assumption that any such code will already be non-preemptible), prepare for things by providing a noinstr sched_clock_read() function. Specifically, preempt_enable_*() calls out to schedule(), which upsets noinstr validation efforts. Signed-off-by: Peter Zijlstra (Intel) --- arch/arm64/include/asm/arch_timer.h | 8 ---- drivers/clocksource/arm_arch_timer.c | 60 ++++++++++++++++++++++++++--------- 2 files changed, 47 insertions(+), 21 deletions(-) --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -88,13 +88,7 @@ static inline notrace u64 arch_timer_rea #define arch_timer_reg_read_stable(reg) \ ({ \ - u64 _val; \ - \ - preempt_disable_notrace(); \ - _val = erratum_handler(read_ ## reg)(); \ - preempt_enable_notrace(); \ - \ - _val; \ + erratum_handler(read_ ## reg)(); \ }) /* --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -191,22 +191,40 @@ u32 arch_timer_reg_read(int access, enum return val; } -static notrace u64 arch_counter_get_cntpct_stable(void) +static noinstr u64 _arch_counter_get_cntpct_stable(void) { return __arch_counter_get_cntpct_stable(); } -static notrace u64 arch_counter_get_cntpct(void) +static notrace u64 arch_counter_get_cntpct_stable(void) +{ + u64 val; + preempt_disable_notrace(); + val = __arch_counter_get_cntpct_stable(); + preempt_enable_notrace(); + return val; +} + +static noinstr u64 arch_counter_get_cntpct(void) { return __arch_counter_get_cntpct(); } -static notrace u64 arch_counter_get_cntvct_stable(void) +static noinstr u64 _arch_counter_get_cntvct_stable(void) { return __arch_counter_get_cntvct_stable(); } -static notrace u64 arch_counter_get_cntvct(void) +static notrace u64 arch_counter_get_cntvct_stable(void) +{ + u64 val; + preempt_disable_notrace(); + val = __arch_counter_get_cntvct_stable(); + preempt_enable_notrace(); + return val; +} + +static noinstr u64 arch_counter_get_cntvct(void) { return __arch_counter_get_cntvct(); } @@ -753,14 +771,14 @@ static int arch_timer_set_next_event_phy return 0; } -static u64 arch_counter_get_cnt_mem(struct arch_timer *t, int offset_lo) +static noinstr u64 arch_counter_get_cnt_mem(struct arch_timer *t, int offset_lo) { u32 cnt_lo, cnt_hi, tmp_hi; do { - cnt_hi = readl_relaxed(t->base + offset_lo + 4); - cnt_lo = readl_relaxed(t->base + offset_lo); - tmp_hi = readl_relaxed(t->base + offset_lo + 4); + cnt_hi = __raw_readl(t->base + offset_lo + 4); + cnt_lo = __raw_readl(t->base + offset_lo); + tmp_hi = __raw_readl(t->base + offset_lo + 4); } while (cnt_hi != tmp_hi); return ((u64) cnt_hi << 32) | cnt_lo; @@ -1060,7 +1078,7 @@ bool arch_timer_evtstrm_available(void) return cpumask_test_cpu(raw_smp_processor_id(), &evtstrm_available); } -static u64 arch_counter_get_cntvct_mem(void) +static noinstr u64 arch_counter_get_cntvct_mem(void) { return arch_counter_get_cnt_mem(arch_timer_mem, CNTVCT_LO); } @@ -1074,6 +1092,13 @@ struct arch_timer_kvm_info *arch_timer_g static void __init arch_counter_register(unsigned type) { + /* + * Default to cp15 based access because arm64 uses this function for + * sched_clock() before DT is probed and the cp15 method is guaranteed + * to exist on arm64. arm doesn't use this before DT is probed so even + * if we don't have the cp15 accessors we won't have a problem. + */ + u64 (*scr)(void) = arch_counter_get_cntvct; u64 start_count; int width; @@ -1083,21 +1108,28 @@ static void __init arch_counter_register if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) || arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) { - if (arch_timer_counter_has_wa()) + if (arch_timer_counter_has_wa()) { rd = arch_counter_get_cntvct_stable; - else + scr = _arch_counter_get_cntvct_stable; + } else { rd = arch_counter_get_cntvct; + scr = arch_counter_get_cntvct; + } } else { - if (arch_timer_counter_has_wa()) + if (arch_timer_counter_has_wa()) { rd = arch_counter_get_cntpct_stable; - else + scr = _arch_counter_get_cntpct_stable; + } else { rd = arch_counter_get_cntpct; + scr = arch_counter_get_cntpct; + } } arch_timer_read_counter = rd; clocksource_counter.vdso_clock_mode = vdso_default; } else { arch_timer_read_counter = arch_counter_get_cntvct_mem; + scr = arch_counter_get_cntvct_mem; } width = arch_counter_get_width(); @@ -1113,7 +1145,7 @@ static void __init arch_counter_register timecounter_init(&arch_timer_kvm_info.timecounter, &cyclecounter, start_count); - sched_clock_register(arch_timer_read_counter, width, arch_timer_rate); + sched_clock_register(scr, width, arch_timer_rate); } static void arch_timer_stop(struct clock_event_device *clk)