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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 D72CDC433E0 for ; Wed, 20 May 2020 10:03:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A81302075F for ; Wed, 20 May 2020 10:03:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726833AbgETKDk (ORCPT ); Wed, 20 May 2020 06:03:40 -0400 Received: from foss.arm.com ([217.140.110.172]:51960 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726435AbgETKDk (ORCPT ); Wed, 20 May 2020 06:03:40 -0400 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 CF56531B; Wed, 20 May 2020 03:03:39 -0700 (PDT) Received: from bogus (unknown [10.37.12.114]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A71583F68F; Wed, 20 May 2020 03:03:37 -0700 (PDT) Date: Wed, 20 May 2020 11:03:30 +0100 From: Sudeep Holla To: Catalin Marinas Cc: Will Deacon , will.deacon@arm.com, linux-kernel@vger.kernel.org, oleg@redhat.com, Keno Fischer , Sudeep Holla , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] arm64: Fix PTRACE_SYSEMU semantics Message-ID: <20200520100330.GA25430@bogus> References: <20200515222253.GA38408@juliacomputing.com> <20200518114119.GB32394@willie-the-truck> <20200519120725.GA20313@gaia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200519120725.GA20313@gaia> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Catalin, 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 -- Regards, Sudeep 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 E66CBC433E0 for ; Wed, 20 May 2020 10:03:45 +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 B43FD2075F for ; Wed, 20 May 2020 10:03:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="DM9xN0ch" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B43FD2075F 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=gK8fVDq1ExSl3a4Cg5Dd+OzQ2ZsRqPwWpdFlCJiMYh4=; b=DM9xN0chC/PQcw A5UDEDXe9Ff4kfbaEsWz0jVbNlf+yEMyC4vUV7hRnoch/s6RoanBXA2xSx1F8GhVW6p+F5N2giVG7 JOF/T5jt/+c1G2Bg9g/epmCJ1tsep5PR1cMT1J9bN2cpUAn2M3C6ijS7tzOZ4/wYwCOInRItRQNxJ b9OrVLrobtctbz8bysuHAa+ptpiCqIBEL85O47uhY2uTWsmJ8P78TtZKhDUbFQLOfAs9/vf7o29Cy LKuYo40EaLdGrP4V568u4kaCuChNAHYfDdKq8clcSrUXYD4PwBZjYRvzLuBD7Lp7CqkDDt9uv24F1 1k3+9swX4Of1RjNPsbIQ==; 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 1jbLZh-0007Rt-E0; Wed, 20 May 2020 10:03:45 +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 1jbLZe-0007R8-Qj for linux-arm-kernel@lists.infradead.org; Wed, 20 May 2020 10:03:44 +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 CF56531B; Wed, 20 May 2020 03:03:39 -0700 (PDT) Received: from bogus (unknown [10.37.12.114]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A71583F68F; Wed, 20 May 2020 03:03:37 -0700 (PDT) Date: Wed, 20 May 2020 11:03:30 +0100 From: Sudeep Holla To: Catalin Marinas Subject: Re: [PATCH] arm64: Fix PTRACE_SYSEMU semantics Message-ID: <20200520100330.GA25430@bogus> References: <20200515222253.GA38408@juliacomputing.com> <20200518114119.GB32394@willie-the-truck> <20200519120725.GA20313@gaia> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200519120725.GA20313@gaia> User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200520_030342_910953_DC8BB7BA X-CRM114-Status: GOOD ( 27.21 ) 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 , Sudeep Holla , 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 Hi Catalin, 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 -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel