From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f199.google.com (mail-qk0-f199.google.com [209.85.220.199]) by kanga.kvack.org (Postfix) with ESMTP id 0A0406B0260 for ; Wed, 19 Oct 2016 13:33:28 -0400 (EDT) Received: by mail-qk0-f199.google.com with SMTP id o68so22938210qkf.3 for ; Wed, 19 Oct 2016 10:33:28 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id r126si24926892qkf.286.2016.10.19.10.33.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Oct 2016 10:33:27 -0700 (PDT) Date: Wed, 19 Oct 2016 13:33:25 -0400 (EDT) From: Mikulas Patocka 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: MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="185206533-1321940004-1476898405=:29288" Sender: owner-linux-mm@kvack.org List-ID: 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 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 +++ > Neopravniny poistup do pamiti (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-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org