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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 6C0B7C7618B for ; Mon, 29 Jul 2019 11:23:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49B252067D for ; Mon, 29 Jul 2019 11:23:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387629AbfG2LXF (ORCPT ); Mon, 29 Jul 2019 07:23:05 -0400 Received: from foss.arm.com ([217.140.110.172]:42244 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387450AbfG2LXF (ORCPT ); Mon, 29 Jul 2019 07:23:05 -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 3A15F28; Mon, 29 Jul 2019 04:23:05 -0700 (PDT) Received: from [10.1.196.72] (e119884-lin.cambridge.arm.com [10.1.196.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2726E3F694; Mon, 29 Jul 2019 04:23:04 -0700 (PDT) Subject: Re: [patch 4/5] x86/vdso/32: Use 32bit syscall fallback To: Thomas Gleixner , LKML Cc: x86@kernel.org, Andy Lutomirski , Sean Christopherson , Kees Cook , Paul Bolle , Will Deacon References: <20190728131251.622415456@linutronix.de> <20190728131648.879156507@linutronix.de> From: Vincenzo Frascino Message-ID: <3baf0efb-dcae-4953-66aa-06c5ee9fbdf7@arm.com> Date: Mon, 29 Jul 2019 12:23:03 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190728131648.879156507@linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/07/2019 14:12, Thomas Gleixner wrote: > The generic VDSO implementation uses the Y2038 safe clock_gettime64() and > clock_getres_time64() syscalls as fallback for 32bit VDSO. This breaks > seccomp setups because these syscalls might be not (yet) allowed. > > Implement the 32bit variants which use the legacy syscalls and select the > variant in the core library. > > The 64bit time variants are not removed because they are required for the > time64 based vdso accessors. > Reviewed-by: Vincenzo Frascino > Reported-by: Sean Christopherson > Reported-by: Paul Bolle > Suggested-by: Andy Lutomirski > Fixes: 7ac870747988 ("x86/vdso: Switch to generic vDSO implementation") > Signed-off-by: Thomas Gleixner > --- > arch/x86/include/asm/vdso/gettimeofday.h | 36 +++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > --- a/arch/x86/include/asm/vdso/gettimeofday.h > +++ b/arch/x86/include/asm/vdso/gettimeofday.h > @@ -96,6 +96,8 @@ long clock_getres_fallback(clockid_t _cl > > #else > > +#define VDSO_HAS_32BIT_FALLBACK 1 > + > static __always_inline > long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) > { > @@ -114,6 +116,23 @@ long clock_gettime_fallback(clockid_t _c > } > > static __always_inline > +long clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) > +{ > + long ret; > + > + asm ( > + "mov %%ebx, %%edx \n" > + "mov %[clock], %%ebx \n" > + "call __kernel_vsyscall \n" > + "mov %%edx, %%ebx \n" > + : "=a" (ret), "=m" (*_ts) > + : "0" (__NR_clock_gettime), [clock] "g" (_clkid), "c" (_ts) > + : "edx"); > + > + return ret; > +} > + > +static __always_inline > long gettimeofday_fallback(struct __kernel_old_timeval *_tv, > struct timezone *_tz) > { > @@ -146,6 +165,23 @@ clock_getres_fallback(clockid_t _clkid, > : "edx"); > > return ret; > +} > + > +static __always_inline > +long clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) > +{ > + long ret; > + > + asm ( > + "mov %%ebx, %%edx \n" > + "mov %[clock], %%ebx \n" > + "call __kernel_vsyscall \n" > + "mov %%edx, %%ebx \n" > + : "=a" (ret), "=m" (*_ts) > + : "0" (__NR_clock_getres), [clock] "g" (_clkid), "c" (_ts) > + : "edx"); > + > + return ret; > } > > #endif > > -- Regards, Vincenzo