Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753326AbbGQUhv (ORCPT ); Fri, 17 Jul 2015 16:37:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36153 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751343AbbGQUht (ORCPT ); Fri, 17 Jul 2015 16:37:49 -0400 Date: Fri, 17 Jul 2015 15:37:46 -0500 From: Josh Poimboeuf To: Andy Lutomirski Cc: Ingo Molnar , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Michal Marek , Peter Zijlstra , Andy Lutomirski , Borislav Petkov , Linus Torvalds , Andi Kleen , Pedro Alves , X86 ML , live-patching@vger.kernel.org, "linux-kernel@vger.kernel.org" Subject: Re: [RFC PATCH 13/21] x86/asm/crypto: Fix frame pointer usage in aesni-intel_asm.S Message-ID: <20150717203746.GB12761@treble.redhat.com> References: <2ea0f0602978178eafd012e52b8bdb83cfb159d5.1437150175.git.jpoimboe@redhat.com> <20150717194307.GA26757@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2068 Lines: 64 On Fri, Jul 17, 2015 at 12:44:42PM -0700, Andy Lutomirski wrote: > On Fri, Jul 17, 2015 at 12:43 PM, Ingo Molnar wrote: > > > > * Josh Poimboeuf wrote: > > > >> ENTRY(aesni_set_key) > >> + FRAME > >> #ifndef __x86_64__ > >> pushl KEYP > >> movl 8(%esp), KEYP # ctx > >> @@ -1905,6 +1907,7 @@ ENTRY(aesni_set_key) > >> #ifndef __x86_64__ > >> popl KEYP > >> #endif > >> + ENDFRAME > >> ret > >> ENDPROC(aesni_set_key) > > > > So cannot we make this a bit more compact and less fragile? > > > > Instead of: > > > > ENTRY(aesni_set_key) > > FRAME > > ... > > ENDFRAME > > ret > > ENDPROC(aesni_set_key) > > > > > > How about writing this as: > > > > FUNCTION_ENTRY(aesni_set_key) > > ... > > FUNCTION_RETURN(aesni_set_key) > > > > which does the same thing in a short, symmetric construct? > > > > One potential problem with this approach would be that what 'looks' like an entry > > declaration, but it will now generate real code. > > > > OTOH if people find this intuitive enough then it's a lot harder to mess it up, > > and I think 'RETURN' makes it clear enough that there's a real instruction > > generated there. > > > > How about FUNCTION_PROLOGUE and FUNCTION_EPILOGUE? Perhaps the macro name should describe what the epilogue does, since frame pointers aren't required for _all_ functions, only those which don't have call instructions. What do you think about ENTRY_FRAME and ENDPROC_FRAME_RETURN? The ending macro is kind of long, but at least it a) matches the existing ENTRY/ENDPROC convention for asm functions; b) gives a clue that frame pointers are involved; and c) lets you know that the return is there. -- Josh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/