From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755837AbdGLJZ1 (ORCPT ); Wed, 12 Jul 2017 05:25:27 -0400 Received: from mail.skyhub.de ([5.9.137.197]:50452 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751291AbdGLJZ0 (ORCPT ); Wed, 12 Jul 2017 05:25:26 -0400 Date: Wed, 12 Jul 2017 11:25:14 +0200 From: Borislav Petkov To: Ingo Molnar Cc: Andy Lutomirski , x86-ml , lkml , Thomas Gleixner , "H. Peter Anvin" Subject: Re: Remove __end_entry_SYSENTER_compat? Message-ID: <20170712092514.GA24119@nazgul.tnic> References: <20170712041336.GD23362@nazgul.tnic> <20170712084803.ar6v3fiks65v25lc@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170712084803.ar6v3fiks65v25lc@gmail.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 12, 2017 at 10:48:03AM +0200, Ingo Molnar wrote: > Hm, I'd argue that the old code is much clearer: we need both the start and the > end of a function and have the properly named symbols for that. > > That entry_SYSCALL_compat() happens to start just where > __end_entry_SYSENTER_compat is an accident of placement. Yeah, probably not worth the effort of actually making it less reliable this way... > Is it even true - doesn't ENTRY() imply an .align, in which case it might be that > __end_entry_SYSENTER_compat != entry_SYSCALL_compat? Yes, ENTRY does .p2align: .globl __end_entry_SYSENTER_compat; __end_entry_SYSENTER_compat: .type entry_SYSENTER_compat, @function ; .size entry_SYSENTER_compat, .-entry_SYSENTER_compat # 184 "arch/x86/entry/entry_64_compat.S" .globl entry_SYSCALL_compat ; .p2align 4, 0x90 ; entry_SYSCALL_compat: ^^^^^^ Pads to an alignment of 4 with NOPs. > In fact that appears to be the case for my defconfig: > > ffffffff81942f90 T entry_SYSENTER_compat > ffffffff81942feb T __end_entry_SYSENTER_compat > ffffffff81942ff0 T entry_SYSCALL_compat > > So unless there's some disadvantage beyond having one more symbol, I'd favor the > old approach. Yeah, my only concern was getting rid of the global symbol but it doesn't work in this case. Thanks. -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. --