From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f69.google.com (mail-vk0-f69.google.com [209.85.213.69]) by kanga.kvack.org (Postfix) with ESMTP id E48ED6B037E for ; Tue, 21 Mar 2017 13:46:19 -0400 (EDT) Received: by mail-vk0-f69.google.com with SMTP id r69so16548358vke.4 for ; Tue, 21 Mar 2017 10:46:19 -0700 (PDT) Received: from mail-vk0-x22e.google.com (mail-vk0-x22e.google.com. [2607:f8b0:400c:c05::22e]) by mx.google.com with ESMTPS id a4si951401vkh.76.2017.03.21.10.46.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Mar 2017 10:46:18 -0700 (PDT) Received: by mail-vk0-x22e.google.com with SMTP id j64so87763849vkg.3 for ; Tue, 21 Mar 2017 10:46:18 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20170321171723.GB21564@uranus.lan> References: <20170321163712.20334-1-dsafonov@virtuozzo.com> <20170321171723.GB21564@uranus.lan> From: Andy Lutomirski Date: Tue, 21 Mar 2017 10:45:57 -0700 Message-ID: Subject: Re: [PATCHv2] x86/mm: set x32 syscall bit in SET_PERSONALITY() Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Cyrill Gorcunov Cc: Dmitry Safonov , "linux-kernel@vger.kernel.org" , Dmitry Safonov <0x7f454c46@gmail.com>, Adam Borowski , "linux-mm@kvack.org" , Andrei Vagin , Borislav Petkov , "Kirill A. Shutemov" , X86 ML , "H. Peter Anvin" , Andy Lutomirski , Ingo Molnar , Thomas Gleixner On Tue, Mar 21, 2017 at 10:17 AM, Cyrill Gorcunov wrote: > On Tue, Mar 21, 2017 at 07:37:12PM +0300, Dmitry Safonov wrote: > ... >> diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c >> index d6b784a5520d..d3d4d9abcaf8 100644 >> --- a/arch/x86/kernel/process_64.c >> +++ b/arch/x86/kernel/process_64.c >> @@ -519,8 +519,14 @@ void set_personality_ia32(bool x32) >> if (current->mm) >> current->mm->context.ia32_compat = TIF_X32; >> current->personality &= ~READ_IMPLIES_EXEC; >> - /* in_compat_syscall() uses the presence of the x32 >> - syscall bit flag to determine compat status */ >> + /* >> + * in_compat_syscall() uses the presence of the x32 >> + * syscall bit flag to determine compat status. >> + * On the bitness of syscall relies x86 mmap() code, >> + * so set x32 syscall bit right here to make >> + * in_compat_syscall() work during exec(). >> + */ >> + task_pt_regs(current)->orig_ax |= __X32_SYSCALL_BIT; >> current->thread.status &= ~TS_COMPAT; > > Hi! I must admit I didn't follow close the overall series (so can't > comment much here :) but I have a slightly unrelated question -- is > there a way to figure out if task is running in x32 mode say with > some ptrace or procfs sign? You should be able to figure out of a *syscall* is x32 by simply looking at bit 30 in the syscall number. (This is unlike i386, which is currently not reflected in ptrace.) Do we actually have an x32 per-task mode at all? If so, maybe we can just remove it on top of Dmitry's series. -- 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