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=-4.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_PASS autolearn=ham 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 729A9C282D8 for ; Wed, 30 Jan 2019 16:58:12 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 42DF22184D for ; Wed, 30 Jan 2019 16:58:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="X7d80a3U" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 42DF22184D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=vMg6u+0Ry/oFcBOlCT8/6TXvxoRj2BDZVRpSeqwRnq4=; b=X7d80a3UcHhkoR xsi7JbZUv79WH1IZxwEX3d1ETve67ZiVUQZdHBnBO0c2ZlOTM++wNoKaCuxhkTH3Ke79s2TS77mLd ix7hDGLjZ610N+yNk8VsUXnL+YsK04jP9bNPMPLopo3J9Rfr0gHb7H4LgS0m6aGk3WfCSUoFmAcv8 Wqj5efMhWoqJh1a6bB0FXRgh6omoDSPTbYmKImDSwq/D07AYFojJkmH+7dpOgUQkgkBTFZFC1iMT1 9be7tOqNZBpGNkIjFl06XH1x9HRAkyjlOcSeJN2nSXye1uMmuBGgB4K71khrNhx72AwrjUrvJqAmZ mIM+3Fjn5RDtDki5l16Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gotBj-0007VZ-5t; Wed, 30 Jan 2019 16:58:11 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gotBf-0007UE-Mz for linux-arm-kernel@lists.infradead.org; Wed, 30 Jan 2019 16:58:09 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 81B4880D; Wed, 30 Jan 2019 08:58:06 -0800 (PST) Received: from [10.1.194.37] (e113632-lin.cambridge.arm.com [10.1.194.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 064D33F589; Wed, 30 Jan 2019 08:58:04 -0800 (PST) Subject: Re: [PATCH v3 3/4] uaccess: Check no rescheduling function is called in unsafe region To: Julien Thierry , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <1547560709-56207-1-git-send-email-julien.thierry@arm.com> <1547560709-56207-4-git-send-email-julien.thierry@arm.com> From: Valentin Schneider Message-ID: <9ba3c7a7-80a8-da29-ffb7-3841ea8548b5@arm.com> Date: Wed, 30 Jan 2019 16:58:03 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <1547560709-56207-4-git-send-email-julien.thierry@arm.com> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190130_085807_754511_E3819155 X-CRM114-Status: GOOD ( 17.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peterz@infradead.org, catalin.marinas@arm.com, will.deacon@arm.com, mingo@redhat.com, james.morse@arm.com, hpa@zytor.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 15/01/2019 13:58, Julien Thierry wrote: [...]> @@ -6151,6 +6159,20 @@ void ___might_sleep(const char *file, int line, int preempt_offset) > EXPORT_SYMBOL(___might_sleep); > #endif > > +#ifdef CONFIG_DEBUG_UACCESS_SLEEP > +void __might_resched(const char *file, int line) > +{ > + if (!unsafe_user_region_active()) > + return; > + > + printk(KERN_ERR > + "BUG: rescheduling function called from user access context at %s:%d\n", > + file, line); > + dump_stack(); Since I've been staring intensely at ___might_sleep() lately, I was thinking we could "copy" it a bit more closely (sorry for going back on what I said earlier). Coming back to the double warnings (__might_resched() + schedule_debug()), it might be better to drop the schedule_debug() warning and just have the one in __might_resched() - if something goes wrong, there'll already be a "BUG" in the log. > +} > +EXPORT_SYMBOL(__might_resched); > +#endif > + > #ifdef CONFIG_MAGIC_SYSRQ > void normalize_rt_tasks(void) > { > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index d4df5b2..d030e31 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -2069,6 +2069,14 @@ config IO_STRICT_DEVMEM > > If in doubt, say Y. > > +config DEBUG_UACCESS_SLEEP > + bool "Check sleep inside a user access region" > + depends on DEBUG_KERNEL > + help > + If you say Y here, various routines which may sleep will become very > + noisy if they are called inside a user access region (i.e. between > + a user_access_begin() and a user_access_end()) If it does get noisy, we should go for some ratelimiting - it's probably good practice even if it is not noisy actually. ___might_sleep() has this: if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) return; prev_jiffy = jiffies; > + > source "arch/$(SRCARCH)/Kconfig.debug" > > endmenu # Kernel hacking > -- > 1.9.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel