From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753276AbcLNA4a (ORCPT ); Tue, 13 Dec 2016 19:56:30 -0500 Received: from mail-qk0-f180.google.com ([209.85.220.180]:34114 "EHLO mail-qk0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751621AbcLNA42 (ORCPT ); Tue, 13 Dec 2016 19:56:28 -0500 Date: Tue, 13 Dec 2016 19:56:14 -0500 (EST) From: Nicolas Pitre To: Michal Marek cc: Nicholas Piggin , Arnd Bergmann , viro@zeniv.linux.org.uk, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] kbuild: make modversion for exported asm symbols more convivial In-Reply-To: <9b2f99ca-0ac6-12b0-e753-5ce6feec96e8@suse.com> Message-ID: References: <1481171047-333-1-git-send-email-nicolas.pitre@linaro.org> <1481171047-333-3-git-send-email-nicolas.pitre@linaro.org> <9b2f99ca-0ac6-12b0-e753-5ce6feec96e8@suse.com> User-Agent: Alpine 2.20 (LFD 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 14 Dec 2016, Michal Marek wrote: > Dne 8.12.2016 v 05:24 Nicolas Pitre napsal(a): > > Rather than having an asm-prototypes.h file where C prototypes for exported > > asm symbols are centralized, let's have some macros that can be used > > directly in the code where those symbols are exported for genksyms > > consumption. Either the prototype is provided directly if no include > > files has it, or the include file containing it is specified. > > > > Signed-off-by: Nicolas Pitre > > --- > > include/asm-generic/export.h | 15 +++++++++++++++ > > scripts/Makefile.build | 22 +++++++++++++++------- > > 2 files changed, 30 insertions(+), 7 deletions(-) > > > > diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h > > index 39a19dc366..83dda5f840 100644 > > --- a/include/asm-generic/export.h > > +++ b/include/asm-generic/export.h > > @@ -84,11 +84,26 @@ KSYM(__kcrctab_\name): > > #define __EXPORT_SYMBOL(sym, val, sec) ___EXPORT_SYMBOL sym, val, sec > > #endif > > > > +/* in the non genksyms case those are no-ops */ > > +#define SYMBOL_CPROTO(expr) > > +#define SYMBOL_CPROTO_INCLUDE(file) > > Do we really _need_ the SYMBOL_CPROTO macro? The exported functions are > called from C files presumably, so there ought to be headers with the > declarations. If these headers can't be included easily, we should fix > them, but having copies of the declarations in the asm files is no big > improvement over the asm-prototypes.h approach, IMO. On ARM there are a few symbols that are part of the gcc support library such as division routines and so on. Those are never called directly from C code. It is the compiler that implicitly creates references to them. However, in order to be able to export those symbols, dummy C prototypes were used before it was possible to export symbols from asm code but those prototypes make no sense otherwise. So the SYMBOL_CPROTO macro is there mainly to maintain backward compatibility with the traditional symbol version signature for those symbols. The SYMBOL_CPROTO macro, being close to the actual code, could mark the intended definition for symbols in assembly code and allow for a tool to ensure there is no mismatch with the actual declaration located elsewhere. That could be useful for all global symbols, not just exported ones. But that's not the primary reason why I created it. Nicolas