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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 0A5E3C6778C for ; Fri, 6 Jul 2018 19:23:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C32E224F9 for ; Fri, 6 Jul 2018 19:23:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="cBvyLOB1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C32E224F9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=efficios.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934727AbeGFTXv (ORCPT ); Fri, 6 Jul 2018 15:23:51 -0400 Received: from mail.efficios.com ([167.114.142.138]:45810 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934536AbeGFTXl (ORCPT ); Fri, 6 Jul 2018 15:23:41 -0400 Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id 951CF1C10EF; Fri, 6 Jul 2018 15:23:40 -0400 (EDT) Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10032) with ESMTP id sEUlVwyMAtsB; Fri, 6 Jul 2018 15:23:39 -0400 (EDT) Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id CC0331C10EB; Fri, 6 Jul 2018 15:23:39 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com CC0331C10EB DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1530905019; bh=5MNr4wsxLNaZ/ZmsPc+A165ovENYMSeQJN45boPnPo4=; h=Date:From:To:Message-ID:MIME-Version; b=cBvyLOB1PGx45EuQ9Pm7pz4P4KmD4gjK0pQ3f+S25cfOySJ+RqHntXYCoGqqM3GuY aCv9f6Itx3lNQrYnJBZezIQ88Pg9SVS8KzAZRoInVWWdb6wo4eefmwGPU/sUPYK4PU 00EJpA6CdA0A4o9mkYziZfiuI4JTI0uSJRk9roWojUbPbUiP9A6dLbPGBndOkVX1un yjm3xVFGJcWLt1VLZyl+MHSoWXGBRjJ1MsHW55EyBysxS1C58PYeDGnlN8RrEcYA6v UGUBhY7l3u6xMz3HERijOAxYDNZEG/hzO6DmoK/YB+9gzmQHlVX0fHouSqMlXu/OzD ARWdqV1wI98Eg== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10026) with ESMTP id JT8ylWdGr3-7; Fri, 6 Jul 2018 15:23:39 -0400 (EDT) Received: from mail02.efficios.com (mail02.efficios.com [167.114.142.138]) by mail.efficios.com (Postfix) with ESMTP id AB4841C10E5; Fri, 6 Jul 2018 15:23:39 -0400 (EDT) Date: Fri, 6 Jul 2018 15:23:39 -0400 (EDT) From: Mathieu Desnoyers To: Thomas Gleixner Cc: linux-kernel , linux-api , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Andy Lutomirski , Dave Watson , Paul Turner , Andrew Morton , Russell King , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , Chris Lameter , Ben Maurer , rostedt , Josh Triplett , Linus Torvalds , Catalin Marinas , Will Deacon , Michael Kerrisk , Joel Fernandes Message-ID: <436937568.1359.1530905019620.JavaMail.zimbra@efficios.com> In-Reply-To: <1846432971.1245.1530892973439.JavaMail.zimbra@efficios.com> References: <20180705180601.18423-1-mathieu.desnoyers@efficios.com> <20180705180601.18423-4-mathieu.desnoyers@efficios.com> <1846432971.1245.1530892973439.JavaMail.zimbra@efficios.com> Subject: Re: [RFC PATCH for 4.18 3/5] rseq: uapi: declare rseq_cs field as union, update includes MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.142.138] X-Mailer: Zimbra 8.8.8_GA_2096 (ZimbraWebClient - FF52 (Linux)/8.8.8_GA_1703) Thread-Topic: rseq: uapi: declare rseq_cs field as union, update includes Thread-Index: dumXrrE9QXvjX6oA+zFCjsAeDEp42YgCpk5+ Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- On Jul 6, 2018, at 12:02 PM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote: > ----- On Jul 5, 2018, at 2:05 PM, Mathieu Desnoyers > mathieu.desnoyers@efficios.com wrote: > [...] > The 0-day bot noticed that __get_user() is unimplemented for 64-bit > values on arm32 (although get_user() is implemented). > > The following diff fixes this discrepancy, and allows this rseq patch > to build on arm32: > For -rc, I would favor the following simpler approach. Or I could even just use get_user() instead. Thoughts ? rseq: implement work-around for missing 8-byte __get_user on arm Now that rseq uses __u64 for its pointer fields, 32-bit architectures need to read this 64-bit value from user-space. __get_user is used to read this value, given that its access check has already been performed with access_ok() on rseq registration. arm does not implement 8-byte __get_user. Work-around this limitation by using get_user() on ARM instead, with its redundant access check. Signed-off-by: Mathieu Desnoyers CC: Thomas Gleixner Cc: Joel Fernandes Cc: Peter Zijlstra Cc: Catalin Marinas Cc: Dave Watson Cc: Will Deacon Cc: Andi Kleen Cc: "H . Peter Anvin" Cc: Chris Lameter Cc: Russell King Cc: Andrew Hunter Cc: Michael Kerrisk Cc: "Paul E . McKenney" Cc: Paul Turner Cc: Boqun Feng Cc: Josh Triplett Cc: Steven Rostedt Cc: Ben Maurer Cc: linux-api@vger.kernel.org CC: linux-arm-kernel@lists.infradead.org Cc: Andy Lutomirski Cc: Andrew Morton Cc: Linus Torvalds diff --git a/kernel/rseq.c b/kernel/rseq.c index 3081e67..0e67625 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -18,6 +18,16 @@ #define CREATE_TRACE_POINTS #include +/* + * ARM does not implement 8 bytes __get_user. Use get_user on that + * architecture instead. + */ +#ifdef CONFIG_ARM +#define __rseq_get_user get_user +#else +#define __rseq_get_user __get_user +#endif + #define RSEQ_CS_PREEMPT_MIGRATE_FLAGS (RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE | \ RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT) @@ -120,7 +130,7 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rs u32 sig; int ret; - ret = __get_user(ptr, &t->rseq->rseq_cs.ptr64); + ret = __rseq_get_user(ptr, &t->rseq->rseq_cs.ptr64); if (ret) return ret; if (!ptr) { -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com