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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 8B508C433DF for ; Wed, 20 May 2020 10:05:57 +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 5EC31207FB for ; Wed, 20 May 2020 10:05:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="rY/AzvkC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5EC31207FB 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:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=jDC6LFVoKfdAoNxJDl5zd6XiW8Qcd8pPhmr0CMvUxrg=; b=rY/AzvkCfXX1Wb k7fToQH7A2L92RK4p6MKmfLvIBiYzAp/YAFJJQOUk/MGxlQne8sK9BTDwurxzAIfo4UI/APAxjOU2 6kS/cXhH6VasqTY5rocmjcOycroPGLAhrE96Ao8TYeQIu7r3iXLuvzrMs1ytIhYGqKwxQxjckvQ37 canGC9/j7lH2MksBxLeFdbdzN2ryJArq/hORvLB2b83d53jsnr3evzYnaPlR2t5myBi+lPCXgxzQs JVH0weLeiuoa1vPnbbd5JZT+bCypuS5j5Ojp7FwbgwmCd1KM4e7l4690j6phzv1rvZIRtdQAWj5kG H37hKCusg07v4cOpMZZA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jbLbp-0001n4-0r; Wed, 20 May 2020 10:05:57 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jbLbl-0001lX-LD for linux-arm-kernel@lists.infradead.org; Wed, 20 May 2020 10:05:55 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 98C0F31B; Wed, 20 May 2020 03:05:51 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 873B53F68F; Wed, 20 May 2020 03:05:50 -0700 (PDT) Date: Wed, 20 May 2020 11:05:44 +0100 From: Catalin Marinas To: Sudeep Holla Subject: Re: [PATCH] arm64: Fix PTRACE_SYSEMU semantics Message-ID: <20200520100543.GA18302@gaia> References: <20200515222253.GA38408@juliacomputing.com> <20200518114119.GB32394@willie-the-truck> <20200519120725.GA20313@gaia> <20200520100330.GA25430@bogus> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200520100330.GA25430@bogus> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200520_030553_781315_5B9371B0 X-CRM114-Status: GOOD ( 28.24 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: will.deacon@arm.com, linux-kernel@vger.kernel.org, oleg@redhat.com, Keno Fischer , Will Deacon , linux-arm-kernel@lists.infradead.org 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 Wed, May 20, 2020 at 11:03:30AM +0100, Sudeep Holla wrote: > On Tue, May 19, 2020 at 01:07:27PM +0100, Catalin Marinas wrote: > > On Mon, May 18, 2020 at 12:41:20PM +0100, Will Deacon wrote: > > > On Fri, May 15, 2020 at 06:22:53PM -0400, Keno Fischer wrote: > > > > Quoth the man page: > > > > ``` > > > > If the tracee was restarted by PTRACE_SYSCALL or PTRACE_SYSEMU, the > > > > tracee enters syscall-enter-stop just prior to entering any system > > > > call (which will not be executed if the restart was using > > > > PTRACE_SYSEMU, regardless of any change made to registers at this > > > > point or how the tracee is restarted after this stop). > > > > ``` > > > > > > > > The parenthetical comment is currently true on x86 and powerpc, > > > > but not currently true on arm64. arm64 re-checks the _TIF_SYSCALL_EMU > > > > flag after the syscall entry ptrace stop. However, at this point, > > > > it reflects which method was used to re-start the syscall > > > > at the entry stop, rather than the method that was used to reach it. > > > > Fix that by recording the original flag before performing the ptrace > > > > stop, bringing the behavior in line with documentation and x86/powerpc. > > > > > > > > Signed-off-by: Keno Fischer > > > > --- > > > > arch/arm64/kernel/ptrace.c | 8 +++++--- > > > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > > > > index b3d3005d9515..b67b4d14aa17 100644 > > > > --- a/arch/arm64/kernel/ptrace.c > > > > +++ b/arch/arm64/kernel/ptrace.c > > > > @@ -1829,10 +1829,12 @@ static void tracehook_report_syscall(struct pt_regs *regs, > > > > > > > > int syscall_trace_enter(struct pt_regs *regs) > > > > { > > > > - if (test_thread_flag(TIF_SYSCALL_TRACE) || > > > > - test_thread_flag(TIF_SYSCALL_EMU)) { > > > > + u32 flags = READ_ONCE(current_thread_info()->flags) & > > > > + (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE); > > > > + > > > > + if (flags) { > > > > > > nit: but I'd rather the '&' operation was in the conditional so that the > > > 'flags' variable holds all of the flags. > > > > > > With that: > > > > > > Acked-by: Will Deacon > > > > > > Also needs: > > > > > > Cc: > > > Fixes: f086f67485c5 ("arm64: ptrace: add support for syscall emulation") > > > > > > Catalin -- can you pick this up for 5.7 please, with my 'nit' addressed? > > > > I'll queue it with the above addressed. I think flags also needs to be > > unsigned long rather than u32. > > > > However, before sending the pull request, I'd like Sudeep to confirm > > that it doesn't break his original use-case for this feature. > > I just tested it with my simple programs I had before. I have also asked > teams working on gvisor to test. They have tested it and see no > regression. I will ask them to reply here. > > Tested-by: Sudeep Holla Thanks Sudeep. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel