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 A1D64C433F5 for ; Mon, 28 Mar 2022 20:15:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245760AbiC1UQr (ORCPT ); Mon, 28 Mar 2022 16:16:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344400AbiC1UQn (ORCPT ); Mon, 28 Mar 2022 16:16:43 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58F34275D1 for ; Mon, 28 Mar 2022 13:15:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ZitBryn1WWy4JC7Ax6HzXQemEGIW1dW2lNZC6FYpefM=; b=h9J6gWtLbizs6hZuyeiUFCZt9S M7+uGk9gFt1AUqZ+rZr6C50cqtp71mwK1jLFnu/x/ZSRFilHkJ9F8Q+K2fTa0/wThEgGwa2zizyOn n5uih2fP9/k0FZqcH3T1E/cQUMYidFqRAuaY/pfcwn8UMc544S7ODH108we8ti0HhGXm/nfkwnCnY vZ5n9HPQV4tgSe4jTE6eC54JwuakFMJ6kNpDNJERz4/xAZhdrjmjEnxXTVEncoGCamVAjCgIf2cuc tKHPR11SOnEK20xSqAsguvwtFqo9cvS9H5DqX7HdYDND/RgjFER3lVwGshCYP/GU64CKlhz9WrOyR ocVsy/Gw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nYvlC-00HENY-2D; Mon, 28 Mar 2022 20:14:42 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0997B3000E6; Mon, 28 Mar 2022 22:14:38 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CEBCE203E586A; Mon, 28 Mar 2022 22:14:38 +0200 (CEST) Date: Mon, 28 Mar 2022 22:14:38 +0200 From: Peter Zijlstra To: Josh Poimboeuf Cc: Christophe Leroy , "aik@ozlabs.ru" , "linux-kernel@vger.kernel.org" , "rostedt@goodmis.org" , "naveen.n.rao@linux.vnet.ibm.com" , "linuxppc-dev@lists.ozlabs.org" , Sathvika Vasireddy Subject: Re: [RFC PATCH 3/3] objtool/mcount: Add powerpc specific functions Message-ID: References: <20220318105140.43914-1-sv@linux.ibm.com> <20220318105140.43914-4-sv@linux.ibm.com> <0b55f122-4760-c1ba-840a-0911cefec2ad@csgroup.eu> <20220328195920.dqlfra3lcardko6r@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220328195920.dqlfra3lcardko6r@treble> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 28, 2022 at 12:59:20PM -0700, Josh Poimboeuf wrote: > I'm not making any major changes to the code, just shuffling things > around to make the interface more modular. I hope to have something > soon (this week). Peter recently added a big feature (Intel IBT) which > is already in -next. Hit Linus' tree yesterday :-) > Some years ago Kamalesh Babulal had a prototype of objtool for ppc64le > which did the full stack validation. I'm not sure what ever became of > that. I've also heard chatter about s390. > FWIW, there have been some objtool patches for arm64 stack validation, > but the arm64 maintainers have been hesitant to get on board with > objtool, as it brings a certain maintenance burden. Especially for the > full stack validation and ORC unwinder. But if you only want inline > static calls and/or mcount then it'd probably be much easier to > maintain. IIRC the major stumbling block for arm64 is the whole jump-table thing. Either they need to rely on compiler plugins to provide objtool that data (yuck, since we support at least 2 different compilers), disable jump-tables (yuck, for that limits code-gen just to please a tool) or use DWARF (yuck, because build times). There was a little talk about an impromptu 'abi' to communicate jump-table details to objtool without going full on DWARF, but that seems to have hit a dead end again.