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 A692FBA50; Wed, 23 Apr 2025 13:02:42 +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=1745413365; cv=none; b=KoLmlo49X39e3BJTRaYZVqZz3b9LmduNOKzDG6PTAGmeqUHC0xP0wdLzWUzDxMUs9eeSf7ou1ICkqNNjbUc2bcl3DEj+h9+L3KrQ6fonvjcjiKUMJa2MGxPPV9256/uLnByfeI4yZbGOggM2dF2ZMch1Jgoj9/afApWJSTfRF7k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745413365; c=relaxed/simple; bh=B8bMV3NwRcE1hzN4J3o3cRGIKHoOIzyacT+46rTZMrQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=CWqiPNrCqeKIEkI2TFfnC+fOw9qDuxiHbPNxhExi8QIBBogAeNHwXn3+B9UqFuPIyJqiOghFKfC0jdXRUJ5LX+Gl1xWzDD4mrmCPPX/IwV7z1UW7xU12H97wY4g2eUanbNE7HNzgVfFMlWyussF2osAGJ4mTeu28eH6a/m3Dm50= 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=cdEUE4gx; 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="cdEUE4gx" Received: by mail.gandi.net (Postfix) with ESMTPSA id 056361FCE9; Wed, 23 Apr 2025 13:02:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1745413355; 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=B8bMV3NwRcE1hzN4J3o3cRGIKHoOIzyacT+46rTZMrQ=; b=cdEUE4gxp1nKhx3LhaZV5bNGMQw2LTagDxZwhXwlyigGUjuYZ+CzjtrJjdGn3hfT0V0ekp L8pkeZKfiq1FS6//Jkt1UHLiFNZgmgDt/rJlKerX8KSTuXE7qLXq18Xo0pqM45dbcJMYYV Xwo2xKsZ6a64WDQKgKtDQD++Ae/NvoehAJ0IGzbz0No1wMzV50MEOTerP1hfZKf6iCKOVH EmJA3gHWC2LIZNKBG8l9yD2xTfTv8IOlvo0AzRdvEy1hoHd6uD/NVORXp3VbvzEZPQqGLr DgRDWQIW6KN8j5wbv1vtIBA5ZAk9UaMPQbPKkJV8taEUFn5zp0KT/6LjgroO5g== Date: Wed, 23 Apr 2025 15:02:33 +0200 From: Maxime Chevallier To: Alexis =?UTF-8?B?TG90aG9yw6k=?= Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Alexandre Torgue , Richard Cochran , Daniel Machon , Thomas Petazzoni , netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, "Russell King (Oracle)" Subject: Re: [PATCH net v2 2/2] net: stmmac: fix multiplication overflow when reading timestamp Message-ID: <20250423150233.38fb5437@device-40.home> In-Reply-To: <20250423-stmmac_ts-v2-2-e2cf2bbd61b1@bootlin.com> References: <20250423-stmmac_ts-v2-0-e2cf2bbd61b1@bootlin.com> <20250423-stmmac_ts-v2-2-e2cf2bbd61b1@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: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgddvgeeiieejucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpeffhffvvefukfgjfhhoofggtgfgsehtqhertdertdejnecuhfhrohhmpeforgigihhmvgcuvehhvghvrghllhhivghruceomhgrgihimhgvrdgthhgvvhgrlhhlihgvrhessghoohhtlhhinhdrtghomheqnecuggftrfgrthhtvghrnhepuefhfefggfdthffghfdvhffhhfetuedtkeetgffhteevheehjeejgfduieduhedunecukfhppedvrgdtudemtggsudelmeekugegheemgeeltddtmeeiheeikeemvdelsgdumeelvghfheemvgektgejnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepvdgrtddumegtsgduleemkegugeehmeegledttdemieehieekmedvlegsudemlegvfhehmegvkegtjedphhgvlhhopeguvghvihgtvgdqgedtrdhhohhmvgdpmhgrihhlfhhrohhmpehmrgigihhmvgdrtghhvghvrghllhhivghrsegsohhothhlihhnrdgtohhmpdhnsggprhgtphhtthhopeduiedprhgtphhtthhopegrlhgvgihishdrlhhothhhohhrvgessghoohhtlhhinhdrtghomhdprhgtphhtthhopegrnhgurhgvfidonhgvthguvghvsehluhhnnhdrtghhpdhrtghpthhtohepuggrvhgvmhesuggrv hgvmhhlohhfthdrnhgvthdprhgtphhtthhopegvughumhgriigvthesghhoohhglhgvrdgtohhmpdhrtghpthhtohepkhhusggrsehkvghrnhgvlhdrohhrghdprhgtphhtthhopehprggsvghnihesrhgvughhrghtrdgtohhmpdhrtghpthhtohepmhgtohhquhgvlhhinhdrshhtmhefvdesghhmrghilhdrtghomhdprhgtphhtthhopegrlhgvgigrnhgurhgvrdhtohhrghhuvgesfhhoshhsrdhsthdrtghomh X-GND-Sasl: maxime.chevallier@bootlin.com On Wed, 23 Apr 2025 09:12:10 +0200 Alexis Lothor=C3=A9 wrote: > The current way of reading a timestamp snapshot in stmmac can lead to > integer overflow, as the computation is done on 32 bits. The issue has > been observed on a dwmac-socfpga platform returning chaotic timestamp > values due to this overflow. The corresponding multiplication is done > with a MUL instruction, which returns 32 bit values. Explicitly casting > the value to 64 bits replaced the MUL with a UMLAL, which computes and > returns the result on 64 bits, and so returns correctly the timestamps. >=20 > Prevent this overflow by explicitly casting the intermediate value to > u64 to make sure that the whole computation is made on u64. While at it, > apply the same cast on the other dwmac variant (GMAC4) method for > snapshot retrieval. >=20 > Fixes: 477c3e1f6363 ("net: stmmac: Introduce dwmac1000 timestamping opera= tions") > Signed-off-by: Alexis Lothor=C3=A9 Reviewed-by: Maxime Chevallier Thanks, Maxime