From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 CDC82849C for ; Mon, 30 Jun 2025 07:54:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751270096; cv=none; b=D/c0B31gp1l4Ybd6SXFAWlugaMr6+WbVwebOXUIixC2DoCfIvB6ujls8NMHRqi40u88jFYElilu7hqJjpkMbIU3hpTEuuhKPV4WdNC069fh3O3lKE6n8V6kx67PKl6e3kldGbVvSOVPKMr3aPUsNDCzn7hFh0vwN4rKdIMDAmZ0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751270096; c=relaxed/simple; bh=VGgquOZqegLVJkgABck09CmGKgEjEiT+mSU1NLWYgi4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BS5GKFGXwS9/5BnSjdnW26/61zn6JEX+hLOmNsI6mc30iX6vtWSY+eniua9dSyp5cmcBVSOhrzsh72R1bB4KNlp5aUhUln35KJhlNJxkm/eSle12UGFwR75uMiNRb71Vrwjt2XpWXSjPp5wgQM7/3CoR6aNj3FPxC2oouB6e8c4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=mv4r+kdT; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mv4r+kdT" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=k4wd26zsMwoAGUvYXBkWmVvkFxqrPlCdo7gexf345Gk=; b=mv4r+kdTSiYO4d9ed64OcRs3v5 sAZ8UHooLckuVMQzGXaK8xTV7YAmvGUk/xpGr9J3H+zpErZp4vkz6p69HyAp1oGp4Iax7mJv5F1rU T2cQg35+ve3qYFFa0+/+LTqMUi24F7LkO3Omr1XKXwRGwjngfNZ8O52+16/zo3WL4MmA9GEKtvfgW RSEOzZnHtt0HYDbjZfM6shEgngZrInHHtta8zFbkJ+91G2WMe5+5df1xX9KceGIHtnych2dhbcNbm vYCnDFSIBqyg4S+9P/nppY/ffEVhesVVio0Ji/yVzssHgqwBICRefp1EskgMFXp71RAyr6B8XiOSj fJ43eWDw==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uW9Lj-00000006k8v-1aNm; Mon, 30 Jun 2025 07:54:47 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id E7032300158; Mon, 30 Jun 2025 09:54:46 +0200 (CEST) Date: Mon, 30 Jun 2025 09:54:46 +0200 From: Peter Zijlstra To: Alexander Potapenko Cc: quic_jiangenj@quicinc.com, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Aleksandr Nogikh , Andrey Konovalov , Borislav Petkov , Dave Hansen , Dmitry Vyukov , Ingo Molnar , Josh Poimboeuf , Marco Elver , Thomas Gleixner Subject: Re: [PATCH v2 08/11] kcov: add ioctl(KCOV_UNIQUE_ENABLE) Message-ID: <20250630075446.GI1613200@noisy.programming.kicks-ass.net> References: <20250626134158.3385080-1-glider@google.com> <20250626134158.3385080-9-glider@google.com> <20250627082730.GS1613200@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Jun 27, 2025 at 03:58:59PM +0200, Alexander Potapenko wrote: > There are two modes, -fsanitize-coverage=edge and > -fsanitize-coverage=bb, with edge being the default one. Thanks for the details! > > Also, dynamic edges are very hard to allocate guard variables for, while > > target guards are trivial, even in the face of dynamic edges. > > All edges are known statically, because they are within the same > function - calls between functions are not considered edges. Oooh, that simplifies things a bit. I suppose that even in the case of computed gotos you can create these intermediate thunks because you have the whole thing at compile time (not that there are a lot of those in the kernel).