From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752519AbcFCK3D (ORCPT ); Fri, 3 Jun 2016 06:29:03 -0400 Received: from mail-db3on0125.outbound.protection.outlook.com ([157.55.234.125]:14304 "EHLO emea01-db3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751649AbcFCK3A (ORCPT ); Fri, 3 Jun 2016 06:29:00 -0400 Authentication-Results: virtuozzo.com; dkim=none (message not signed) header.d=none;virtuozzo.com; dmarc=none action=none header.from=virtuozzo.com; Subject: Re: [PATCH 5/6] x86/ptrace: down with test_thread_flag(TIF_IA32) To: Cyrill Gorcunov References: <1464786697-20639-1-git-send-email-dsafonov@virtuozzo.com> <1464786697-20639-6-git-send-email-dsafonov@virtuozzo.com> <20160603095748.GC2431@uranus> CC: , , , , , , <0x7f454c46@gmail.com>, , , , Andy Lutomirski From: Dmitry Safonov Message-ID: Date: Fri, 3 Jun 2016 13:27:33 +0300 User-Agent: Mozilla/5.0 (X11; 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X-Microsoft-Exchange-Diagnostics: =?Windows-1252?Q?1;AM5PR0801MB1282;23:qEhSarjEJdFX73VYv/rLfBSpjjfr/ZNGRL4?= =?Windows-1252?Q?Hy4sOk1Eg54vl6k+CknvbBM9rP1NQZb29vZaiVnK3CtJnCWw+v1W+sGl?= =?Windows-1252?Q?/8NL2LuVm9ssZbIWpY1NmT14mO9y5kVNcWBjfR96Tza06K2p9l75Pe/P?= =?Windows-1252?Q?MDHvrCUunx/NPAryH2xRtun4AlBjnbSE41Jd+hmFHcZltp0huDTfvf/J?= =?Windows-1252?Q?fP+4ttmx7vrDib69rA1uh7Sx4lxr9pRe24v9WeWUiT++lKkVAXbwmCyk?= =?Windows-1252?Q?S6y5yKgb2qQrSfO3BcR6r6CqUoDuLPROE/yzjeUbik09WJesT50i+ALg?= =?Windows-1252?Q?GqlaA49NmJRUC7XV2tXNeSnd2wOAPksD6idWiErpLFUoufeG/rFFWwhj?= =?Windows-1252?Q?PFXFyjakuKi0iVi1bPJylh57lgILuOhr7/IuG14us2xYQrHPGAK2Mdid?= =?Windows-1252?Q?TZQbWw2KnE4MkLb8CuWQciHGLRO3k0H9f4J6/fTAX+GwvMSvNpoUVCSc?= =?Windows-1252?Q?yJ9n0903lzBlRfKqs2C/Jgq7iqFopCGTaGyH69MQ9RXLDQvFvX5/rQIa?= =?Windows-1252?Q?n73j2YHmfjTi6jcahBD/5lRFCZq3XDQZlL3cgtxMWokQged3qhckZ2Sx?= =?Windows-1252?Q?r0ZlHY4/xtUz29O+oQmWsTsaiYsEQF/CpyHAkf7G+NQiCXpSyQfEZlPG?= =?Windows-1252?Q?1xnXgK96WHST640vb6CWfpUA0fwRFBYpgRy0vcAIx7cnolx1fBCAW9Zm?= =?Windows-1252?Q?m4RQ/k+0ueKXToHL0+Pq0YxBg2gshbJmV+fUneMCen1v7/QrIRdnV2l5?= =?Windows-1252?Q?XrEuuFEu6Kjy89+BCP4LDeMjCEn8Qaqz6F8QwbMzIkf7L60ZjJy8Oor6?= =?Windows-1252?Q?FN/SxhRt84lMacn+3No6EZjRNXlU4DVZN0OQ9QYzLB+bU/U2+44KENTa?= =?Windows-1252?Q?TzMks5+ixZPoNYiQRIF955JHzQSJy+1AJhNQ54kXF0WWNtcKIf589uzN?= =?Windows-1252?Q?6/qKq9S66IimnKBKggHyQrQo90/6Lp4jM9n9jfKSFaa7rov68xikMLvQ?= =?Windows-1252?Q?bRY4g/sU3ICh7EwCkc6LasUxHStAGzhHscWephsCzqnFVdyd5Vm1rkW2?= =?Windows-1252?Q?2VjLC4RBkOHz+uENaFNgnJMoWvRpPbQ8SZWdocFhcPxfDd34A4EAJhp8?= =?Windows-1252?Q?5Yu8dfMJBmuCG2RRwkdZu718bODKJ5+o=3D?= X-Microsoft-Exchange-Diagnostics: 1;AM5PR0801MB1282;5:IowAqYcYLepunDYUlZf1k70qrHuxWYqcNOerufR5XwaC63lUeMHz/fNAWjulCaAu/JMmnfHxSrsQa3qm7p1Q+yVqcYP+jTq5oLOtc2IWD+VEw0DN8b8qozDgp8kPTUvN9AYSXyy9b9QZJ2ocvdNEOA==;24:40zW2HqLiCu9O+TfPJbPrLkZfI/b7ftbQsO1v9LlgqY9TTazPRub3oEWsZSyR/HAbW+vQOhaqA16TaqxQJYrxAu/3qC4nvll8eDQ82VY+Xc=;7:SxeMZuRYxY4nzr2ZIDYF1RBnFcm6cO3koQSh+TBw9ZPJBjAszAOOcau3PH5yAijYfqtlZDwDMEZ52dAYnt9AcqJ7Q4p2tvL2ibDa0yn9gNJ1CNbhS08rDo6dvbg0i3oOgmbyD08mmhySMimaRJXQsvWgMVpE+ZTma3Wd7HfJSa47j2Gmni+uk4xxEtIyZNoakh4pIV/PyTW6qjm7crQWxOSySeBHVGLK04+GOMi1t3Y=;20:5c+KobLx5aRMUipExfjhVlYaTFZ4Mi2Y6C1pCbxo7FstldlibDEbPKuCGyYXUJqrbpPlRG+ZUdV5Lk0h1eSSAUn2pgvCOvQT139YwsFYsnN/7Ydvd5ottMZw17v9u7UVVev128sYNoP7ZZtqOq71UzFbSMkg4JOPIQQ1XXrHMxs= SpamDiagnosticOutput: 1:23 SpamDiagnosticMetadata: NSPM X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Jun 2016 10:28:55.6749 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM5PR0801MB1282 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/03/2016 12:57 PM, Cyrill Gorcunov wrote: > On Wed, Jun 01, 2016 at 04:11:36PM +0300, Dmitry Safonov wrote: >> As the task isn't executing at the moment of {GET,SET}REGS, >> return regset that corresponds to code selector, rather than >> value of TIF_IA32 flag. >> I.e. if we ptrace i386 elf binary that has just changed it's >> code selector to __USER_CS, than GET_REGS will return >> full x86_64 register set. >> >> Note, that this will work only if application has changed it's CS. >> If the application does 32-bit syscall with __USER_CS, ptrace >> will still return 64-bit register set. Which might be still confusing >> for tools that expect TS_COMPACT to be exposed [1, 2]. >> >> So this this change should make PTRACE_GETREGSET more reliable and >> this will be another step to drop TIF_{IA32,X32} flags. >> >> [1]: https://sourceforge.net/p/strace/mailman/message/30471411/ >> [2]: https://lkml.org/lkml/2012/1/18/320 >> >> Cc: Andy Lutomirski >> Cc: Ingo Molnar >> Cc: Thomas Gleixner >> Cc: "H. Peter Anvin" >> Cc: Oleg Nesterov >> Signed-off-by: Dmitry Safonov > > Looks reasonable! Still if cs has been changed to non-compat > selector and we now return 64bit registers set, won't it > cause problems for old tools? I suspect it should not but > still. > Thanks! Hmm, strace works fine - I'll check gdb to be sure. What else could be bothered by this?