From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C93C3C433E1 for ; Tue, 18 Aug 2020 16:30:40 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 922C12054F for ; Tue, 18 Aug 2020 16:30:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 922C12054F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2E6E68D0025; Tue, 18 Aug 2020 12:30:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 297B68D000B; Tue, 18 Aug 2020 12:30:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1AD568D0025; Tue, 18 Aug 2020 12:30:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0097.hostedemail.com [216.40.44.97]) by kanga.kvack.org (Postfix) with ESMTP id 038D38D000B for ; Tue, 18 Aug 2020 12:30:39 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 7991A180AD838 for ; Tue, 18 Aug 2020 16:30:39 +0000 (UTC) X-FDA: 77164227798.24.cable86_340482127020 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id 4D2C71A4A5 for ; Tue, 18 Aug 2020 16:30:39 +0000 (UTC) X-HE-Tag: cable86_340482127020 X-Filterd-Recvd-Size: 4812 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Tue, 18 Aug 2020 16:30:38 +0000 (UTC) IronPort-SDR: Xh8VoSSB9cxEhDY18TOzGcmvqb9gHUQrwa7nRKWM+P5WoM2jQtf+1wv+Nb+GnRcu+MWSvXCiVv X9Ncwjq7SIKg== X-IronPort-AV: E=McAfee;i="6000,8403,9716"; a="239777916" X-IronPort-AV: E=Sophos;i="5.76,328,1592895600"; d="scan'208";a="239777916" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2020 09:30:37 -0700 IronPort-SDR: 2oNuJKXT27GJXRvN0VtkdmZc0gFcrv+OJCOWX4A5DdH6J7GIGNZ7RhM1s4gMvEvXBlHLCy9CHL hmCjerhZ6O0Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,328,1592895600"; d="scan'208";a="279440992" Received: from ribnhajh-mobl.ger.corp.intel.com (HELO localhost) ([10.249.47.113]) by fmsmga008.fm.intel.com with ESMTP; 18 Aug 2020 09:30:34 -0700 Date: Tue, 18 Aug 2020 19:30:33 +0300 From: Jarkko Sakkinen To: Mike Rapoport Cc: Ingo Molnar , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andi Kleen , Masami Hiramatsu , Peter Zijlstra , "Naveen N. Rao" , Anil S Keshavamurthy , "David S. Miller" , Jessica Yu , Ard Biesheuvel Subject: Re: [PATCH v5 5/6] kprobes: Use text_alloc() and text_free() Message-ID: <20200818163033.GF137138@linux.intel.com> References: <20200724050553.1724168-1-jarkko.sakkinen@linux.intel.com> <20200724050553.1724168-6-jarkko.sakkinen@linux.intel.com> <20200724092746.GD517988@gmail.com> <20200725031648.GG17052@linux.intel.com> <20200726081408.GB2927915@kernel.org> <20200818053029.GE44714@linux.intel.com> <20200818115141.GO752365@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200818115141.GO752365@kernel.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo X-Rspamd-Queue-Id: 4D2C71A4A5 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 18, 2020 at 02:51:41PM +0300, Mike Rapoport wrote: > On Tue, Aug 18, 2020 at 08:30:29AM +0300, Jarkko Sakkinen wrote: > > On Sun, Jul 26, 2020 at 11:14:08AM +0300, Mike Rapoport wrote: > > > > > > > > I'm not still sure that I fully understand this feedback as I don't see > > > > any inherent and obvious difference to the v4. In that version fallbacks > > > > are to module_alloc() and module_memfree() and text_alloc() and > > > > text_memfree() can be overridden by arch. > > > > > > The major difference between your v4 and my suggestion is that I'm not > > > trying to impose a single ARCH_HAS_TEXT_ALLOC as an alternative to > > > MODULES but rather to use per subsystem config option, e.g. > > > HAVE_KPROBES_TEXT_ALLOC. > > > > > > Another thing, which might be worth doing regardless of the outcome of > > > this discussion is to rename alloc_insn_pages() to text_alloc_kprobes() > > > because the former is way too generic and does not emphasize that the > > > instruction page is actually used by kprobes only. > > > > What if we in kernel/kprobes.c just: > > > > #ifndef CONFIG_ARCH_HAS_TEXT_ALLOC > > I don't think that CONFIG_ARCH_HAS_TEXT_ALLOC will work for all > architectures. > > If an architecture has different restrictions for allocation of text > for, say, modules, kprobes, bfp, it won't be able to use a single > ARCH_HAS_TEXT_ALLOC. Which means that this architecture is stuck with > dependency of kprobes on MODULES until the next rework. I was thinking to name it as CONFIG_HAS_KPROBES_ALLOC_PAGE, alogn the lines described below, so it is merely a glitch in my example. > > > void __weak *alloc_insn_page(void) > > { > > return module_alloc(PAGE_SIZE); > > } > > > > void __weak free_insn_page(void *page) > > { > > module_memfree(page); > > } > > #endif > > > > In Kconfig (as in v5): > > > > config KPROBES > > bool "Kprobes" > > depends on MODULES || ARCH_HAS_TEXT_ALLOC > > > > I checked architectures that override alloc_insn_page(). With the > > exception of x86, they do not call module_alloc(). > > > > If no rename was done, then with this approach a more consistent. > > config flag name would be CONFIG_ARCH_HAS_ALLOC_INSN_PAGE. > > > > I'd call the function just as kprobes_alloc_page(). Then the > > config flag would become CONFIG_HAS_KPROBES_ALLOC_PAGE. > > > > > -- > > > Sincerely yours, > > > Mike. > > > > Thanks for the feedback! > > > > /Jarkko > > -- > Sincerely yours, > Mike. BR, /Jarkko