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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 56387C433F5 for ; Mon, 15 Nov 2021 18:44:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F93A635CB for ; Mon, 15 Nov 2021 18:44:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242128AbhKOSrZ (ORCPT ); Mon, 15 Nov 2021 13:47:25 -0500 Received: from mail.kernel.org ([198.145.29.99]:51380 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241250AbhKOSof (ORCPT ); Mon, 15 Nov 2021 13:44:35 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 987AB63377; Mon, 15 Nov 2021 18:06:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636999570; bh=fvr+5w+bjma+qsLtoh+nkd4ztTw4tT0MYDHOrOKsB/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SJ+WwTOOp5fCAII1BpnAaCQZ8Tat/jIek+FV461UrYMh9vDdlkSNrR7IJ59Ehp7zd gBYzRS9DFWpHiR/FLwPAd+/wqauSi98Smk1Hyh16IXcD3Z/QxZMq31cvnvx83i5D90 tDuE6k5JvZKpjC84uGHhoEUrjU3y7O2OYwT6TwQU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Peter Zijlstra (Intel)" , Juergen Gross , Miroslav Benes , Sasha Levin Subject: [PATCH 5.14 345/849] x86/xen: Mark cpu_bringup_and_idle() as dead_end_function Date: Mon, 15 Nov 2021 17:57:08 +0100 Message-Id: <20211115165431.900379758@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165419.961798833@linuxfoundation.org> References: <20211115165419.961798833@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Peter Zijlstra [ Upstream commit 9af9dcf11bda3e2c0e24c1acaacb8685ad974e93 ] The asm_cpu_bringup_and_idle() function is required to push the return value on the stack in order to make ORC happy, but the only reason objtool doesn't complain is because of a happy accident. The thing is that asm_cpu_bringup_and_idle() doesn't return, so validate_branch() never terminates and falls through to the next function, which in the normal case is the hypercall_page. And that, as it happens, is 4095 NOPs and a RET. Make asm_cpu_bringup_and_idle() terminate on it's own, by making the function it calls as a dead-end. This way we no longer rely on what code happens to come after. Fixes: c3881eb58d56 ("x86/xen: Make the secondary CPU idle tasks reliable") Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Juergen Gross Reviewed-by: Miroslav Benes Link: https://lore.kernel.org/r/20210624095147.693801717@infradead.org Signed-off-by: Sasha Levin --- tools/objtool/check.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index e5947fbb9e7a6..0e3981d91afc1 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -173,6 +173,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, "rewind_stack_do_exit", "kunit_try_catch_throw", "xen_start_kernel", + "cpu_bringup_and_idle", }; if (!func) -- 2.33.0