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 X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4230C433E1 for ; Fri, 17 Jul 2020 15:18:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9244A206F4 for ; Fri, 17 Jul 2020 15:18:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594999125; bh=f1BtxKJaxkXjtdYFh9DQbVUURSaaQKnBnQ/oI8xfcDk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=jfYzizWTzvMKuSRIiDBL4p7bomZUY/FoAvVg2SN5hMTQMK4AOf8zx6Px05MrcZWR8 m8t+LZYLxhjU3vQwKLxWLR83v/OvDrIRRqGuhfW7mXDh5gKBxlJtzDQtg0aDl7l3hW zVpisVQ+iuXUhylPRwJRYwDlm4v6wQ8ow8Aj19l8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726882AbgGQPSo (ORCPT ); Fri, 17 Jul 2020 11:18:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:44436 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726071AbgGQPSo (ORCPT ); Fri, 17 Jul 2020 11:18:44 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CA702204EA; Fri, 17 Jul 2020 15:18:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594999122; bh=f1BtxKJaxkXjtdYFh9DQbVUURSaaQKnBnQ/oI8xfcDk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vq06lZsj+1EQOKS9xGWyG+EaFbACKC145UCtY5yIj5mOPNqf/XN2JYOteJ9eMx9Rj dIoLHk8Y0Z7kJbGq+LeSWS0lFba4jbbO3yQGLRbUIwMwvqGQKaWiXbhq4O3CsX+QrE dd1XEHTJ54GhVArVpb630Y71mK3/JzwltRon+/v0= Date: Fri, 17 Jul 2020 17:18:33 +0200 From: Greg KH To: gregory.herrero@oracle.com Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org, stable@vger.kernel.org Subject: Re: [PATCH] recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64. Message-ID: <20200717151833.GA3403494@kroah.com> References: <20200717143338.19302-1-gregory.herrero@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200717143338.19302-1-gregory.herrero@oracle.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 17, 2020 at 04:33:38PM +0200, gregory.herrero@oracle.com wrote: > From: Gregory Herrero > > Currently, if a section has a relocation to '_mcount' symbol, a new > __mcount_loc entry will be added whatever the relocation type is. > This is problematic when a relocation to '_mcount' is in the middle of a > section and is not a call for ftrace use. > > Such relocation could be generated with below code for example: > bool is_mcount(unsigned long addr) > { > return (target == (unsigned long) &_mcount); > } > > With this snippet of code, ftrace will try to patch the mcount location > generated by this code on module load and fail with: > > Call trace: > ftrace_bug+0xa0/0x28c > ftrace_process_locs+0x2f4/0x430 > ftrace_module_init+0x30/0x38 > load_module+0x14f0/0x1e78 > __do_sys_finit_module+0x100/0x11c > __arm64_sys_finit_module+0x28/0x34 > el0_svc_common+0x88/0x194 > el0_svc_handler+0x38/0x8c > el0_svc+0x8/0xc > ---[ end trace d828d06b36ad9d59 ]--- > ftrace failed to modify > [] 0xffffa2dbf3a3a41c > actual: 66:a9:3c:90 > Initializing ftrace call sites > ftrace record flags: 2000000 > (0) > expected tramp: ffffa2dc6cf66724 > > So Limit the relocation type to R_AARCH64_CALL26 as in perl version of > recordmcount. > > Fixes: ed60453fa8f8 ("ARM: 6511/1: ftrace: add ARM support for C version of recordmcount") > Signed-off-by: Gregory Herrero > --- > scripts/recordmcount.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c > index 7225107a9aaf..e59022b3f125 100644 > --- a/scripts/recordmcount.c > +++ b/scripts/recordmcount.c > @@ -434,6 +434,11 @@ static int arm_is_fake_mcount(Elf32_Rel const *rp) > return 1; > } > > +static int arm64_is_fake_mcount(Elf64_Rel const *rp) > +{ > + return ELF64_R_TYPE(w(rp->r_info)) != R_AARCH64_CALL26; > +} > + > /* 64-bit EM_MIPS has weird ELF64_Rela.r_info. > * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf > * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40] > @@ -547,6 +552,7 @@ static int do_file(char const *const fname) > make_nop = make_nop_arm64; > rel_type_nop = R_AARCH64_NONE; > ideal_nop = ideal_nop4_arm64; > + is_fake_mcount64 = arm64_is_fake_mcount; > break; > case EM_IA_64: reltype = R_IA64_IMM64; break; > case EM_MIPS: /* reltype: e_class */ break; > -- > 2.27.0 > This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.