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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E59A2CCA473 for ; Tue, 21 Jun 2022 06:31:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345277AbiFUGbh (ORCPT ); Tue, 21 Jun 2022 02:31:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232935AbiFUGbf (ORCPT ); Tue, 21 Jun 2022 02:31:35 -0400 Received: from alexa-out-sd-01.qualcomm.com (alexa-out-sd-01.qualcomm.com [199.106.114.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 05D9860E3; Mon, 20 Jun 2022 23:31:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1655793095; x=1687329095; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=8B6OBov+Dp//rrdGe97WOSHuT0EA9+jVckLT/ZqJALw=; b=Yti7jI5hBRbceJ9pXq6fzHoFdzwrLgG86FXFEM+pgwt6IWXTHgdBcH11 e3gJ2ovgdZz4Y5Z2yRFjhUU62Fycm0BoKZr8RIMVjLq56v1Zos9pXnSj4 g8E2VYQmRG01d86PJr15YQX6JFlmNrLYQgRhLm0l/fQ8oc1xI4tgKueGe M=; Received: from unknown (HELO ironmsg-SD-alpha.qualcomm.com) ([10.53.140.30]) by alexa-out-sd-01.qualcomm.com with ESMTP; 20 Jun 2022 23:31:34 -0700 X-QCInternal: smtphost Received: from nasanex01b.na.qualcomm.com ([10.46.141.250]) by ironmsg-SD-alpha.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jun 2022 23:31:34 -0700 Received: from [10.50.44.13] (10.80.80.8) by nasanex01b.na.qualcomm.com (10.46.141.250) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Mon, 20 Jun 2022 23:31:32 -0700 Message-ID: <00f3eb47-2529-a493-ee67-c0c0219937a3@quicinc.com> Date: Tue, 21 Jun 2022 12:01:29 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH rcu 07/12] rcu: tiny: Record kvfree_call_rcu() call stack for KASAN Content-Language: en-US To: "Paul E. McKenney" , CC: , , , Johannes Berg , Dmitry Vyukov References: <20220620222022.GA3839466@paulmck-ThinkPad-P17-Gen-1> <20220620222032.3839547-7-paulmck@kernel.org> From: Neeraj Upadhyay In-Reply-To: <20220620222032.3839547-7-paulmck@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nasanex01b.na.qualcomm.com (10.46.141.250) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/21/2022 3:50 AM, Paul E. McKenney wrote: > From: Johannes Berg > > When running KASAN with Tiny RCU (e.g. under ARCH=um, where > a working KASAN patch is now available), we don't get any > information on the original kfree_rcu() (or similar) caller > when a problem is reported, as Tiny RCU doesn't record this. > > Add the recording, which required pulling kvfree_call_rcu() > out of line for the KASAN case since the recording function > (kasan_record_aux_stack_noalloc) is neither exported, nor > can we include kasan.h into rcutiny.h. > > without KASAN, the patch has no size impact (ARCH=um kernel): > text data bss dec hex filename > 6151515 4423154 33148520 43723189 29b29b5 linux > 6151515 4423154 33148520 43723189 29b29b5 linux + patch > > with KASAN, the impact on my build was minimal: > text data bss dec hex filename > 13915539 7388050 33282304 54585893 340ea25 linux > 13911266 7392114 33282304 54585684 340e954 linux + patch > -4273 +4064 +-0 -209 > > Acked-by: Dmitry Vyukov > Signed-off-by: Johannes Berg > Signed-off-by: Paul E. McKenney > --- > include/linux/rcutiny.h | 11 ++++++++++- > kernel/rcu/tiny.c | 14 ++++++++++++++ > 2 files changed, 24 insertions(+), 1 deletion(-) > > diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h > index 5fed476f977f6..d84e13f2c3848 100644 > --- a/include/linux/rcutiny.h > +++ b/include/linux/rcutiny.h > @@ -38,7 +38,7 @@ static inline void synchronize_rcu_expedited(void) > */ > extern void kvfree(const void *addr); > > -static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > +static inline void __kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > { > if (head) { > call_rcu(head, func); > @@ -51,6 +51,15 @@ static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > kvfree((void *) func); > } > > +#ifdef CONFIG_KASAN_GENERIC > +void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func); > +#else > +static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > +{ > + __kvfree_call_rcu(head, func); > +} > +#endif > + > void rcu_qs(void); > > static inline void rcu_softirq_qs(void) > diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c > index 340b3f8b090d4..58ff3721d975c 100644 > --- a/kernel/rcu/tiny.c > +++ b/kernel/rcu/tiny.c > @@ -217,6 +217,20 @@ bool poll_state_synchronize_rcu(unsigned long oldstate) > } > EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu); > > +#ifdef CONFIG_KASAN_GENERIC > +void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > +{ > + if (head) { > + void *ptr = (void *) head - (unsigned long) func; > + > + kasan_record_aux_stack_noalloc(ptr); > + } For the !head case; similar to Tree RCU's kvfree_call_rcu() implementation, we do not need to record 'ptr' (which will be 'func')? Thanks Neeraj > + > + __kvfree_call_rcu(head, func); > +} > +EXPORT_SYMBOL_GPL(kvfree_call_rcu); > +#endif > + > void __init rcu_init(void) > { > open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);