Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932305AbcLMI7J (ORCPT ); Tue, 13 Dec 2016 03:59:09 -0500 Received: from mail-wm0-f52.google.com ([74.125.82.52]:38308 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750801AbcLMI7F (ORCPT ); Tue, 13 Dec 2016 03:59:05 -0500 MIME-Version: 1.0 In-Reply-To: <1481608665-26941-1-git-send-email-maninder1.s@samsung.com> References: <1481608665-26941-1-git-send-email-maninder1.s@samsung.com> From: Dmitry Vyukov Date: Tue, 13 Dec 2016 09:58:42 +0100 Message-ID: Subject: Re: [PATCH v2] kasan: Support for r/w instrumentation control To: Maninder Singh Cc: Andrey Ryabinin , Alexander Potapenko , Jonathan Corbet , Michal Marek , Andrew Morton , kasan-dev , linux-doc@vger.kernel.org, LKML , "open list:KERNEL BUILD + fi..." , PANKAJ MISHRA , Ajeet Kumar Yadav , Vaneet narang Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2862 Lines: 80 On Tue, Dec 13, 2016 at 6:57 AM, Maninder Singh wrote: > This provide option to control sanity of read and write operations > Both read and write instrumentation increase size of uImage, So using > this option read or write instrumentation can be avoided if not required. > Useful in case of module sanity, using this uImage sanity can be avoided. > > Also user space ASAN provides this support for read/write instrumentation > control. > > Signed-off-by: Vaneet narang > Signed-off-by: Maninder Singh > Reviewed-by: Ajeet Yadav > --- > v1 -> v2: Added Documentation for the same. > > Documentation/dev-tools/kasan.rst | 16 ++++++++++++++++ > lib/Kconfig.kasan | 16 ++++++++++++++++ > scripts/Makefile.kasan | 4 ++++ > 3 files changed, 36 insertions(+) > > diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst > index f7a18f2..b8147df 100644 > --- a/Documentation/dev-tools/kasan.rst > +++ b/Documentation/dev-tools/kasan.rst > @@ -40,6 +40,22 @@ similar to the following to the respective kernel Makefile: > > KASAN_SANITIZE := n > > +Control Over Read/Write Instrumentation of kernel:: double colon at the end of line > + > +- To Disable Read Instrumentation of kernel with: Strange choice of capital letters. > + > + CONFIG_KASAN_READS = n Are configs ever set to = n? I can't find any cases in my .config file. I thought configs are disabled with: # CONFIG_KASAN_READS is not set > + > +Because in some cases we need to check only memory write sanitization > +for better performance, read instrumentation can be disabled. > + > +- To Disable Write Instrumentation of kernel with: I am not a native speaker but this looks malformed. I would say either "Disable write instrumentation of kernel with" or "To disable write instrumentation of kernel set" > + CONFIG_KASAN_WRITES = n > + > +In case when to instrument only external modules, not the entire kernel > +for read or write intrumentation or both. > + I propose something along these lines: --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -40,6 +40,14 @@ similar to the following to the respective kernel Makefile: KASAN_SANITIZE := n +Sometimes it may be useful to disable instrumentation of reads, or writes +or both for the entire kernel. For example, if binary size is a concern, +it may be useful to disable instrumentation of reads to reduce binary size but +still catch more harmful bugs on writes. Or, if one is interested only in +sanitization of a particular module and performance is a concern, she can +disable instrumentation of both reads and writes for kernel code. +Instrumentation can be disabled with CONFIG_KASAN_READS and CONFIG_KASAN_WRITES. + Error reports