From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752025AbeFCM3X (ORCPT ); Sun, 3 Jun 2018 08:29:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:55454 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751963AbeFCM25 (ORCPT ); Sun, 3 Jun 2018 08:28:57 -0400 From: Greg Kroah-Hartman To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Josh Poimboeuf , Arnd Bergmann , David Laight , Greg KH , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , damian , Ingo Molnar Subject: [PATCH 25/29] objtool: Fix "noreturn" detection for recursive sibling calls Date: Sun, 3 Jun 2018 14:26:48 +0200 Message-Id: <20180603122652.17453-26-gregkh@linuxfoundation.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180603122652.17453-1-gregkh@linuxfoundation.org> References: <20180603122652.17453-1-gregkh@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Josh Poimboeuf commit 0afd0d9e0e7879d666c1df2fa1bea4d8716909fe upstream. Objtool has some crude logic for detecting static "noreturn" functions (aka "dead ends"). This is necessary for being able to correctly follow GCC code flow when such functions are called. It's remotely possible for two functions to call each other via sibling calls. If they don't have RET instructions, objtool's noreturn detection logic goes into a recursive loop: drivers/char/ipmi/ipmi_ssif.o: warning: objtool: return_hosed_msg()+0x0: infinite recursion (objtool bug!) drivers/char/ipmi/ipmi_ssif.o: warning: objtool: deliver_recv_msg()+0x0: infinite recursion (objtool bug!) Instead of reporting an error in this case, consider the functions to be non-dead-ends. Reported-and-tested-by: Randy Dunlap Signed-off-by: Josh Poimboeuf Acked-by: Peter Zijlstra (Intel) Cc: Arnd Bergmann Cc: David Laight Cc: Greg KH Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: damian Link: http://lkml.kernel.org/r/7cc156408c5781a1f62085d352ced1fe39fe2f91.1525923412.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- tools/objtool/check.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 2299eae155ac..e128d1c71c30 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -207,9 +207,13 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func, /* local sibling call */ if (recursion == 5) { - WARN_FUNC("infinite recursion (objtool bug!)", - dest->sec, dest->offset); - return -1; + /* + * Infinite recursion: two functions + * have sibling calls to each other. + * This is a very rare case. It means + * they aren't dead ends. + */ + return 0; } return __dead_end_function(file, dest->func, -- 2.17.1