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 4B835C001E0 for ; Wed, 16 Aug 2023 12:00:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244920AbjHPL7o (ORCPT ); Wed, 16 Aug 2023 07:59:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42556 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244963AbjHPL7f (ORCPT ); Wed, 16 Aug 2023 07:59:35 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2AEF2121; Wed, 16 Aug 2023 04:59:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=w4pNixXG/yujqwuAAE04Kdf6OftnyKzc8cljjGmu4i0=; b=JdVKR7WK8g11MZo+4lm3fupwxw GoLvxoGZxjzWh+wP9bd0wrNAt8ewSXQl5qjB3tp0OvS+R3xJB9Jkf7+sKU16nrgNaVC9MckkWdC1I PE1NPfdpesLNRMb+w0SupQ3T2PXmV4n09rMp41IfsqhGnqE92gMMpwaPan299rizYgBmYUVJBtwq1 eyoUIhYWVc5a3pxl86GdNmil5LhcaS2vi25ISLrhq6H4zvoRlFEA1rgDRCVxwvBMKEwx/P45ztu7f ZseukUVqOzPx9L+X2TxW+ZeByx4fUNP9K4SdRRZkdbF23SPK2uctEoorUYKNj3yxWy2SLGKAdaCwq JIu5mnFw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qWFBK-00CytP-1g; Wed, 16 Aug 2023 11:59:22 +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)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 289123001FD; Wed, 16 Aug 2023 13:59:22 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 057EE2C904588; Wed, 16 Aug 2023 13:59:22 +0200 (CEST) Date: Wed, 16 Aug 2023 13:59:21 +0200 From: Peter Zijlstra To: linux-kernel@vger.kernel.org Cc: linux-tip-commits@vger.kernel.org, "Borislav Petkov (AMD)" , x86@kernel.org Subject: Re: [tip: x86/urgent] objtool/x86: Fix SRSO mess Message-ID: <20230816115921.GH980931@hirez.programming.kicks-ass.net> References: <20230814121148.704502245@infradead.org> <169217251760.27769.15304146275480287222.tip-bot2@tip-bot2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <169217251760.27769.15304146275480287222.tip-bot2@tip-bot2> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 16, 2023 at 07:55:17AM -0000, tip-bot2 for Peter Zijlstra wrote: > The following commit has been merged into the x86/urgent branch of tip: > > Commit-ID: 4ae68b26c3ab5a82aa271e6e9fc9b1a06e1d6b40 > Gitweb: https://git.kernel.org/tip/4ae68b26c3ab5a82aa271e6e9fc9b1a06e1d6b40 > Author: Peter Zijlstra > AuthorDate: Mon, 14 Aug 2023 13:44:29 +02:00 > Committer: Borislav Petkov (AMD) > CommitterDate: Wed, 16 Aug 2023 09:39:16 +02:00 > > objtool/x86: Fix SRSO mess > > Objtool --rethunk does two things: > > - it collects all (tail) call's of __x86_return_thunk and places them > into .return_sites. These are typically compiler generated, but > RET also emits this same. > > - it fudges the validation of the __x86_return_thunk symbol; because > this symbol is inside another instruction, it can't actually find > the instruction pointed to by the symbol offset and gets upset. > > Because these two things pertained to the same symbol, there was no > pressing need to separate these two separate things. > > However, alas, along comes SRSO and more crazy things to deal with > appeared. > > The SRSO patch itself added the following symbol names to identify as > rethunk: > > 'srso_untrain_ret', 'srso_safe_ret' and '__ret' > > Where '__ret' is the old retbleed return thunk, 'srso_safe_ret' is a > new similarly embedded return thunk, and 'srso_untrain_ret' is > completely unrelated to anything the above does (and was only included > because of that INT3 vs UD2 issue fixed previous). > > Clear things up by adding a second category for the embedded instruction > thing. > > Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation") > Signed-off-by: Peter Zijlstra (Intel) > Signed-off-by: Borislav Petkov (AMD) > Link: https://lore.kernel.org/r/20230814121148.704502245@infradead.org Turns out I forgot to build with FRAME_POINTER=y, that still gives: vmlinux.o: warning: objtool: srso_untrain_ret+0xd: call without frame pointer save/setup the below seems to cure this. --- tools/objtool/check.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 7a9aaf400873..1384090530db 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2650,12 +2650,17 @@ static int decode_sections(struct objtool_file *file) return 0; } -static bool is_fentry_call(struct instruction *insn) +static bool is_special_call(struct instruction *insn) { - if (insn->type == INSN_CALL && - insn_call_dest(insn) && - insn_call_dest(insn)->fentry) - return true; + if (insn->type == INSN_CALL) { + struct symbol *dest = insn_call_dest(insn); + + if (!dest) + return false; + + if (dest->fentry || dest->embedded_insn) + return true; + } return false; } @@ -3656,7 +3661,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, if (ret) return ret; - if (opts.stackval && func && !is_fentry_call(insn) && + if (opts.stackval && func && !is_special_call(insn) && !has_valid_stack_frame(&state)) { WARN_INSN(insn, "call without frame pointer save/setup"); return 1;