From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF6EF269827; Tue, 27 May 2025 16:31:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748363475; cv=none; b=QXm51u8NzmVevEiMEsIHib59hWg7w75dGNdfyOr+wa0kRucjKUERFitFnZ8/M0NhRambP9GM4WLisyOFBC55wTP+CxGAM6anGzUz1LGDBDIkJ7BLckXKxw4HFCu6JvRZHuoiOt3vbyhuGnZLp/NVGotaVhIi7x0yV0TbdtxprzI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748363475; c=relaxed/simple; bh=JKIBHO1WBEk2DpCG4CViKibfgUWTWKWdTlFL7XeRaf8=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=U7n59ICQRr/t0oJBj8ur8DOgOXGNEIz8dszxDaSkF2fB98KcZjE1+oLnouZf+/AmNsInnVkmOwxFFdTCmiPIZwYsNopz/oZ9DDPTx4AwPxN9MBiWo4BYDJVo1BpbuXTKQOD3nQRewyjlvrGs0syr98tJcldd6ie095IB5GdxTe8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=IhRDeJrS; arc=none smtp.client-ip=217.70.183.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="IhRDeJrS" Received: by mail.gandi.net (Postfix) with ESMTPSA id 538A81FCF2; Tue, 27 May 2025 16:31:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1748363469; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UZYLROFC13QWr0WtIHITpKv2k/IYMUKl/Ik95XSzStc=; b=IhRDeJrS9jEMuIKBecnBJriiCigzhovdLdAo8PcxOnxSCbLHAg2pE5zE5zYVmw1R4+039U CK8W6lC0U0n5puU297QfUE5VkxhETbk9T+KybDCrRlalPEUgCI6a0740UOxd5Sbwd3cSL2 mYH8HJ8au6B/lR5hCQcIYrJhJye69OOHxk3cD3dKL0RXz7SNYbNHAEaaoAxe5DOl+XHiNp hu2gde3xzMIE+FeM8/T8HK4PBLAbR+2FWXws0XHzYk8mKOP1L7b/Qv0aa9Dm4dU5Z6Me3B 0gtdejge1087acIokX/hgKqRFBJKeJRrdTYh4v+2O5SPx6Mj07/+3K8M5YqlMg== Date: Tue, 27 May 2025 18:31:05 +0200 From: Maxime Chevallier To: Alexis =?UTF-8?B?TG90aG9yw6k=?= Cc: Alexandre Torgue , Jose Abreu , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Richard Cochran , Phil Reid , Thomas Petazzoni , netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] net: stmmac: add explicit check and error on invalid PTP clock rate Message-ID: <20250527183105.7c4bad49@device-24.home> In-Reply-To: <20250527-stmmac_tstamp_div-v2-1-663251b3b542@bootlin.com> References: <20250527-stmmac_tstamp_div-v2-1-663251b3b542@bootlin.com> Organization: Bootlin X-Mailer: Claws Mail 4.3.1 (GTK 3.24.43; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtddtgddvtdekieculddtuddrgeefvddrtddtmdcutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfitefpfffkpdcuggftfghnshhusghstghrihgsvgenuceurghilhhouhhtmecufedtudenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhepfffhvfevuffkjghfohfogggtgfesthhqredtredtjeenucfhrhhomhepofgrgihimhgvucevhhgvvhgrlhhlihgvrhcuoehmrgigihhmvgdrtghhvghvrghllhhivghrsegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeekheegieejkeetfffhleehteffgefhfffhueefieefffejfeethfevudetudeuueenucffohhmrghinhepkhgvrhhnvghlrdhorhhgnecukfhppeeltddrjeeirdeivddrudejudenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeeltddrjeeirdeivddrudejuddphhgvlhhopeguvghvihgtvgdqvdegrdhhohhmvgdpmhgrihhlfhhrohhmpehmrgigihhmvgdrtghhvghvrghllhhivghrsegsohhothhlihhnrdgtohhmpdhnsggprhgtphhtthhopeduiedprhgtphhtthhopegrlhgvgihishdrlhhothhhohhrvgessghoohhtlhhinhdrtghomhdprhgtphhtthhopegrlhgvgigrnhgurhgvrdhtohhrghhuvgesfhhoshhsrdhsthdrtghomhdprhgtphhtthhopehjohgrsghrvghusehshihnohhpshihshdrtghomhdprhgtphhtt hhopegrnhgurhgvfidonhgvthguvghvsehluhhnnhdrtghhpdhrtghpthhtohepuggrvhgvmhesuggrvhgvmhhlohhfthdrnhgvthdprhgtphhtthhopegvughumhgriigvthesghhoohhglhgvrdgtohhmpdhrtghpthhtohepkhhusggrsehkvghrnhgvlhdrohhrghdprhgtphhtthhopehprggsvghnihesrhgvughhrghtrdgtohhm X-GND-Sasl: maxime.chevallier@bootlin.com Hi Alexis, On Tue, 27 May 2025 08:33:44 +0200 Alexis Lothor=C3=A9 wrote: > The stmmac platform drivers that do not open-code the clk_ptp_rate value > after having retrieved the default one from the device-tree can end up > with 0 in clk_ptp_rate (as clk_get_rate can return 0). It will > eventually propagate up to PTP initialization when bringing up the > interface, leading to a divide by 0: >=20 > Division by zero in kernel. > CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.30-00001-g48313bd5= 768a #22 > Hardware name: STM32 (Device Tree Support) > Call trace: > unwind_backtrace from show_stack+0x18/0x1c > show_stack from dump_stack_lvl+0x6c/0x8c > dump_stack_lvl from Ldiv0_64+0x8/0x18 > Ldiv0_64 from stmmac_init_tstamp_counter+0x190/0x1a4 > stmmac_init_tstamp_counter from stmmac_hw_setup+0xc1c/0x111c > stmmac_hw_setup from __stmmac_open+0x18c/0x434 > __stmmac_open from stmmac_open+0x3c/0xbc > stmmac_open from __dev_open+0xf4/0x1ac > __dev_open from __dev_change_flags+0x1cc/0x224 > __dev_change_flags from dev_change_flags+0x24/0x60 > dev_change_flags from ip_auto_config+0x2e8/0x11a0 > ip_auto_config from do_one_initcall+0x84/0x33c > do_one_initcall from kernel_init_freeable+0x1b8/0x214 > kernel_init_freeable from kernel_init+0x24/0x140 > kernel_init from ret_from_fork+0x14/0x28 > Exception stack(0xe0815fb0 to 0xe0815ff8) >=20 > Prevent this division by 0 by adding an explicit check and error log > about the actual issue. >=20 > Fixes: 19d857c9038e ("stmmac: Fix calculations for ptp counters when cloc= k input =3D 50Mhz.") > Signed-off-by: Alexis Lothor=C3=A9 > --- > Changes in v2: > - Add Fixes tag > - Reword commit message to clarify the triggering cause of the issue > - Link to v1: https://lore.kernel.org/r/20250523-stmmac_tstamp_div-v1-1-b= ca8a5a3a477@bootlin.com > --- > drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 5 +++++ > 1 file changed, 5 insertions(+) >=20 > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/= net/ethernet/stmicro/stmmac/stmmac_main.c > index 918d7f2e8ba992208d7d6521a1e9dba01086058f..f68e3ece919cc88d0bf199a39= 4bc7e44b5dee095 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > @@ -835,6 +835,11 @@ int stmmac_init_tstamp_counter(struct stmmac_priv *p= riv, u32 systime_flags) > if (!(priv->dma_cap.time_stamp || priv->dma_cap.atime_stamp)) > return -EOPNOTSUPP; > =20 > + if (!priv->plat->clk_ptp_rate) { > + netdev_err(priv->dev, "Invalid PTP clock rate"); > + return -EINVAL; > + } > + > stmmac_config_hw_tstamping(priv, priv->ptpaddr, systime_flags); > priv->systime_flags =3D systime_flags; This may be some nitpick that can be addressed at a later point, but we now have a guarantee that when stmmac_ptp_register() gets called, priv->ptp_clk_rate is non-zero, right ? If so, we can drop the test in said function : if (priv->plat->has_gmac4 && priv->plat->clk_ptp_rate) priv->plat->cdc_error_adj =3D (2 * NSEC_PER_SEC) / priv->plat->clk_ptp_ra= te; There is another spot in the code, like in the EST handling, where we divide by priv->plat->ptp_clk_rate : stmmac_adjust_time(...) stmmac_est_configure(priv, priv, priv->est, priv->plat->clk_ptp_rate) .est_configure() ctrl |=3D ((NSEC_PER_SEC / ptp_rate) [...] Maybe we should fail EST configuration as well if ptp_clk_rate is 0 (probably in stmmac_tc.c's tc_taprio_configure or in the .est_configure). That can be a step for later as well, as I don't know if the setup you found this bug on even supports taprio/EST, and setups that do didn't seem to encounter the bug yet. Besides all that, Reviewed-by: Maxime Chevallier Thanks, Maxime