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 C6075C433F5 for ; Tue, 16 Nov 2021 02:07:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ACD72611ED for ; Tue, 16 Nov 2021 02:07:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349304AbhKPCKh (ORCPT ); Mon, 15 Nov 2021 21:10:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:40776 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239110AbhKOR7Q (ORCPT ); Mon, 15 Nov 2021 12:59:16 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7B827632D3; Mon, 15 Nov 2021 17:36:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636997761; bh=jeAAO9N6FU/lIk0v0Qimw6nQJ9ETI49fXE16TPPI/5o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PKahGOFbRj2O2boN9QAnTJrK2VAezTGmcCemM2Mp34aRvSADGwG8mp3XTlfseCWCj LXwENXbs1xrn7qI2paxZcUL4LEC+W335I1JHNXP6uxbQClKc8MoEwDLqcCC4CHVZyy jgXRkTYLX4hgyBogN3gXkute2t1rN80ij6/MHjKs= 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 5.10 266/575] x86/xen: Mark cpu_bringup_and_idle() as dead_end_function Date: Mon, 15 Nov 2021 17:59:51 +0100 Message-Id: <20211115165352.971461860@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165343.579890274@linuxfoundation.org> References: <20211115165343.579890274@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: linux-kernel@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 ec15cadbb3d3e..4261f93ce06f9 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -157,6 +157,7 @@ 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