From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6049C433EF for ; Wed, 25 May 2022 16:58:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245514AbiEYQ6l (ORCPT ); Wed, 25 May 2022 12:58:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235187AbiEYQ6f (ORCPT ); Wed, 25 May 2022 12:58:35 -0400 Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 04B2F9CC98 for ; Wed, 25 May 2022 09:58:34 -0700 (PDT) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 24PGpCBP019535; Wed, 25 May 2022 11:51:12 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 24PGpBfh019533; Wed, 25 May 2022 11:51:11 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Wed, 25 May 2022 11:51:11 -0500 From: Segher Boessenkool To: Sathvika Vasireddy Cc: Christophe Leroy , "aik@ozlabs.ru" , jpoimboe@redhat.com, linux-kernel@vger.kernel.org, "rostedt@goodmis.org" , "peterz@infradead.org" , Paul Mackerras , Sathvika Vasireddy , "Naveen N. Rao" , mbenes@suse.cz, linuxppc-dev@lists.ozlabs.org Subject: Re: [RFC PATCH v2 0/7] objtool: Enable and implement --mcount option on powerpc Message-ID: <20220525165111.GP25951@gate.crashing.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 25, 2022 at 03:44:04PM +0530, Sathvika Vasireddy wrote: > On 24/05/22 18:47, Christophe Leroy wrote: > >This draft series adds PPC32 support to Sathvika's series. > >Verified on pmac32 on QEMU. > > > >It should in principle also work for PPC64 BE but for the time being > >something goes wrong. In the beginning I had a segfaut hence the first > >patch. But I still get no mcount section in the files. > Since PPC64 BE uses older elfv1 ABI, it prepends a dot to symbols. > And so, the relocation records in case of PPC64BE point to "._mcount", > rather than just "_mcount". We should be looking for "._mcount" to be > able to generate mcount_loc section in the files. The dotted symbol is on the actual function. The "normal" symbol is on the "official procedure descriptor" (opd), which is what you get if you (in C) take the address of a function. A procedure descriptor holds one or two more pointers, the GOT and environment pointers. We don't use the environment one, but the GOT pointer is necessary everywhere :-) Segher