From patchwork Mon Jul 22 10:33:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11052121 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 44486138D for ; Mon, 22 Jul 2019 10:34:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2D76828475 for ; Mon, 22 Jul 2019 10:34:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1E7F82850D; Mon, 22 Jul 2019 10:34:29 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id B17C628475 for ; Mon, 22 Jul 2019 10:34:28 +0000 (UTC) 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:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: 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: List-Owner; bh=2kH0MGh6faBfKIDhIf4V8deKLKUYjTdhZQ9fcIUSfsg=; b=kV3zr9CgtF8d4j AmQHp72huYBb2EPFswr8jJytjCX/rNJwCL1bamCbGY/ujrcBML7/Na6EKAkCAMfx0IXgbwnyHKI7H sFNJgHcA8XZ15F+Do4txt3mVrMp7s1OG0pPCn27KfUrfAHCxKCs8gyJ8sTNjBHWxfNxZSK6/mobrM SfR5YUZ1q3YlJmTLUtDHl1avxwMc9frAKLRMmr8q1KSt/p7Qq0TKITD+PsGq2J1TQy4H9Qy77I+KD hNEVGbsDern3nc5+QwZRSjWTuzet080uMggcJmI7NRMCyORT7rSE2rPyBDG023NfngCPKLx3YJhkh 1+fjRzV6dI5LwopXIm9Q==; 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 1hpVeA-0003r3-Ba; Mon, 22 Jul 2019 10:34:22 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hpVda-00039n-R1 for linux-arm-kernel@lists.infradead.org; Mon, 22 Jul 2019 10:33:48 +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 926C11596; Mon, 22 Jul 2019 03:33:45 -0700 (PDT) Received: from filthy-habits.cambridge.arm.com (filthy-habits.cambridge.arm.com [10.1.197.61]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 236233F71A; Mon, 22 Jul 2019 03:33:44 -0700 (PDT) From: Marc Zyngier To: Thomas Gleixner , John Stultz , Pavel Tatashin , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Will Deacon , Catalin Marinas , Mark Rutland Subject: [PATCH 3/3] arm64: Allow early time stamping Date: Mon, 22 Jul 2019 11:33:30 +0100 Message-Id: <20190722103330.255312-4-marc.zyngier@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190722103330.255312-1-marc.zyngier@arm.com> References: <20190722103330.255312-1-marc.zyngier@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190722_033347_026806_9AC93047 X-CRM114-Status: GOOD ( 12.77 ) 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-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP In order to provide early timestamping on arm64 systems, we provide a timestamp_clock() function that is available as early as possible. This function simply returns the current counter value scales in nanoseconds, and 0-based. In order to deal with the idiosyncrasies of some broken platforms, we condition this on the frequency being set in the CNTFRQ_EL0 register, and revert back to using local_clock() as soon as it starts returning non-zero values. Signed-off-by: Marc Zyngier --- arch/arm64/Kconfig | 3 +++ arch/arm64/kernel/setup.c | 44 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 47 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 3adcec05b1f6..ac3882ddc1c2 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -911,6 +911,9 @@ config ARCH_WANT_HUGE_PMD_SHARE config ARCH_HAS_CACHE_LINE_SIZE def_bool y +config ARCH_HAS_TIMESTAMP_CLOCK + def_bool y + config ARCH_ENABLE_SPLIT_PMD_PTLOCK def_bool y if PGTABLE_LEVELS > 2 diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 9c4bad7d7131..cf21e3df7165 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -28,10 +29,12 @@ #include #include #include +#include #include #include #include +#include #include #include #include @@ -269,8 +272,49 @@ arch_initcall(reserve_memblock_reserved_regions); u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID }; +static u64 notrace ts_counter_read_cc(const struct cyclecounter *cc) +{ + return __arch_counter_get_cntvct(); +} + +static struct cyclecounter ts_cc __ro_after_init = { + .read = ts_counter_read_cc, + .mask = CLOCKSOURCE_MASK(56), +}; + +static struct timecounter ts_tc; + +static bool ts_cc_valid __ro_after_init = false; + +static __init void timestamp_clock_init(void) +{ + u64 frq = arch_timer_get_cntfrq(); + + if (!frq) + return; + + clocks_calc_mult_shift(&ts_cc.mult, &ts_cc.shift, + frq, NSEC_PER_SEC, 3600); + /* timestamp starts at 0 (local_clock is a good enough approximation) */ + timecounter_init(&ts_tc, &ts_cc, local_clock()); + ts_cc_valid = true; + pr_info("Using timestamp clock @%lluMHz\n", frq / 1000 / 1000); +} + +u64 timestamp_clock(void) +{ + u64 ns = local_clock(); + + if (likely(ns || !ts_cc_valid)) + return ns; + + return timecounter_read(&ts_tc); +} + void __init setup_arch(char **cmdline_p) { + timestamp_clock_init(); + init_mm.start_code = (unsigned long) _text; init_mm.end_code = (unsigned long) _etext; init_mm.end_data = (unsigned long) _edata;