From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ms.lwn.net (ms.lwn.net [45.79.88.28]) (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 7E750194096; Mon, 30 Sep 2024 17:20:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.79.88.28 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727716857; cv=none; b=IXl0MJyOhSUzvqrWsnvbUJaXMWuALjX7lCN5TYxNGF9DFjozxzR6u9qP3S2LLqtHIcOF0Y8GDRxzQ8a8VJ9mC+wochGjZE8QuvIUBLSkpa8qz3Sx3fl3XdOCU7hRPqGFAJYXv6R3bQH/Odgy+qwAzNslqvK5psGlO6ZpOSlY9GI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727716857; c=relaxed/simple; bh=gCGwduzLFKbfMo5sOtW9HBBlHG7VBpwpUBFvEKyrqp8=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=giqfVRlP15HwcXtODpdZSGaftA1kD7NnmANzm6Mg9fOerOoCjhkuhyO9DKe3dZEhIpXxy0Iq7xV2MO1HOX9nOlTvbbeqP5Y3gi1I6s6vrOepC6t/uea5yCEcEa9yDaIu/GN3GI3yIJH9IF2weOJ60QmH9YY9y2UDIGMtYkXpbo0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lwn.net; spf=pass smtp.mailfrom=lwn.net; dkim=pass (2048-bit key) header.d=lwn.net header.i=@lwn.net header.b=qnzVrDOb; arc=none smtp.client-ip=45.79.88.28 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lwn.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lwn.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=lwn.net header.i=@lwn.net header.b="qnzVrDOb" DKIM-Filter: OpenDKIM Filter v2.11.0 ms.lwn.net B511D42BFE DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lwn.net; s=20201203; t=1727716852; bh=VTA67/hhIeEVZwR1EvSjGu05ItIa+ynNR72w32LLj5M=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=qnzVrDObJkf3RfxcfOH80UDiO0PIiouyZ01YuYEc8oKjfx8v9zeYDBD6WPn1JEfdU +f9KosDqMHbcV63VYHOgCDpEx1iDtbFPkG864ubyFTMB0mCUVcBIUjb6Lg6HN2p/zX 6crT1BV0azMPnoWRgUkzpXbWJutJQEXuiTVWBpt7h+7w1wTTrh0JSkZdbkOXRER8Tv 8SbdwfpTdG+MwwKzqKUGOPYSKyJvFbyuFxhFXmFsrsw2fiqu45jQbvg9UX61bPfnZl 0gcAY8mtcpVMHfGmfTYMHQIQxfruMo1XSYqIGKbgsyp7lAsPtb8azOTXxL6KrmB5lu kk1Q4MIj1AzQQ== Received: from localhost (mdns.lwn.net [45.79.72.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id B511D42BFE; Mon, 30 Sep 2024 17:20:51 +0000 (UTC) From: Jonathan Corbet To: Steven Rostedt Cc: Hans de Goede , LKML , Linux trace kernel , Masami Hiramatsu , Mathieu Desnoyers , Mike Rapoport , Kees Cook , Ard Biesheuvel , linux-doc@vger.kernel.org Subject: Re: [PATCH] Documentation/tracing: Mention that RESET_ATTACK_MITIGATION can clear memory In-Reply-To: <20240930131415.1438c0b7@gandalf.local.home> References: <20240926130159.19e6d0e2@rorschach.local.home> <20240930131415.1438c0b7@gandalf.local.home> Date: Mon, 30 Sep 2024 11:20:48 -0600 Message-ID: <87ikud9hxr.fsf@trenco.lwn.net> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Steven Rostedt writes: > On Thu, 26 Sep 2024 19:54:48 +0200 > Hans de Goede wrote: > >> Hi, >> >> On 26-Sep-24 7:01 PM, Steven Rostedt wrote: >> > From: Steven Rostedt >> > >> > At the 2024 Linux Plumbers Conference, I was talking with Hans de Goede >> > about the persistent buffer to display traces from previous boots. He >> > mentioned that UEFI can clear memory. In my own tests I have not seen >> > this. He later informed me that it requires the config option: >> > >> > CONFIG_RESET_ATTACK_MITIGATION >> > >> > It appears that setting this will allow the memory to be cleared on boot >> > up, which will definitely clear out the trace of the previous boot. >> > >> > Add this information under the trace_instance in kernel-parameters.txt >> > to let people know that this can cause issues. >> > >> > Link: https://lore.kernel.org/all/20170825155019.6740-2-ard.biesheuvel@linaro.org/ >> > >> > Reported-by: Hans de Goede >> > Signed-off-by: Steven Rostedt (Google) >> >> Thanks, patch looks good to me: >> >> Reviewed-by: Hans de Goede > > Thanks, > > And I forgot to send this to the Documentation maintainers :-p > > Jon, could you take this? Do you need me to resend, or can you just pull it > from lore? I'll grab it in a bit. jon