Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S946205AbcJSRd3 (ORCPT ); Wed, 19 Oct 2016 13:33:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33528 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S942636AbcJSRd0 (ORCPT ); Wed, 19 Oct 2016 13:33:26 -0400 Date: Wed, 19 Oct 2016 13:33:25 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Dmitry Safonov cc: 0x7f454c46@gmail.com, oleg@redhat.com, linux-mm@kvack.org, gorcunov@openvz.org, xemul@virtuozzo.com, Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: x32 is broken in 4.9-rc1 due to "x86/signal: Add SA_{X32,IA32}_ABI sa_flags" In-Reply-To: Message-ID: References: User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="185206533-1321940004-1476898405=:29288" X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Wed, 19 Oct 2016 17:33:26 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2162 Lines: 57 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --185206533-1321940004-1476898405=:29288 Content-Type: TEXT/PLAIN; charset=ISO-8859-15 Content-Transfer-Encoding: 8BIT On Wed, 19 Oct 2016, Mikulas Patocka wrote: > Hi > > In the kernel 4.9-rc1, the x32 support is seriously broken, a x32 process > is killed with SIGKILL after returning from any signal handler. I should have said they are killed with SIGSEGV, not SIGKILL. > I use Debian sid x64-64 distribution with x32 architecture added from > debian-ports. > > I bisected the bug and found out that it is caused by the patch > 6846351052e685c2d1428e80ead2d7ca3d7ed913 ("x86/signal: Add > SA_{X32,IA32}_ABI sa_flags"). > > example (strace of a process after receiving the SIGWINCH signal): > > epoll_wait(10, 0xef6890, 32, -1) = -1 EINTR (Interrupted system call) > --- SIGWINCH {si_signo=SIGWINCH, si_code=SI_USER, si_pid=1772, si_uid=0} --- > poll([{fd=4, events=POLLOUT}], 1, 0) = 1 ([{fd=4, revents=POLLOUT}]) > write(4, "\0", 1) = 1 > rt_sigreturn({mask=[INT QUIT ILL TRAP BUS KILL SEGV USR2 PIPE ALRM STKFLT TSTP TTOU URG XCPU XFSZ VTALRM IO PWR SYS RTMIN]}) = 0 > --- SIGSEGV {si_signo=SIGSEGV, si_code=SI_KERNEL, si_addr=NULL} --- > +++ killed by SIGSEGV +++ > Neopr?vn?n? p??stup do pam?ti (SIGSEGV) > > Mikulas BTW. when I take core dump of the killed x32 process, it shows: ELF Header: Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 Class: ELF32 Data: 2's complement, little endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: CORE (Core file) Machine: Intel 80386 ^^^^^^^^^^^^^^^^^^^ So, the kernel somehow thinks that it is i386 process, not x32 process. A core dump of a real x32 process shows "Class: ELF32, Machine: Advanced Micro Devices X86-64". Mikulas --185206533-1321940004-1476898405=:29288--