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 6B345C433F5 for ; Tue, 22 Mar 2022 05:31:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236728AbiCVFdN (ORCPT ); Tue, 22 Mar 2022 01:33:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236720AbiCVFdM (ORCPT ); Tue, 22 Mar 2022 01:33:12 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23B25381; Mon, 21 Mar 2022 22:31:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C1EE7B81B87; Tue, 22 Mar 2022 05:31:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AAEFC340EC; Tue, 22 Mar 2022 05:31:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1647927102; bh=S9IobCk2/SCUxMjhrXXqR93XhKqnu26qc3N4ltVvvR8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=dZ631HINBxUbJBtm1PoeSI+QIhyE67UmFHGhDNIFKBnRUXqxap8EQa3cEzRAT4dy4 zzIb1x4Aot4BfF+a5L9Lrq7JRK0rfjlztcarqmFrwhvPc4G7S3T3AamX7scHq/3d2u HawIzWz2EFVrh7SrZsNd2EH+nseru+R8rR6oooEa/yUzOiGpt4rfPV2eynh5MDBlYQ lXSJzL7RKasm9PqW6anjXReLsPrJ3iTURw4IEMWYZA5fZt5/uCIKvS9O/kJfv5pyOy cHTTBwbadm0svfYtNcCquc6UfXmlTTmsM75YTGmYtkGzUYqUJckEFNNGtNEUVUp9aw vzXRbtCHt76UQ== Date: Tue, 22 Mar 2022 14:31:36 +0900 From: Masami Hiramatsu To: Peter Zijlstra Cc: Stephen Rothwell , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Linux Kernel Mailing List , Linux Next Mailing List , mhiramat@kernel.org, rostedt@goodmis.org, ast@kernel.org, hjl.tools@gmail.com, rick.p.edgecombe@intel.com, rppt@kernel.org, linux-toolchains@vger.kernel.org, Andrew.Cooper3@citrix.com, ndesaulniers@google.com Subject: Re: linux-next: build warnings after merge of the tip tree Message-Id: <20220322143136.0e78366c3521b54b7b9385b8@kernel.org> In-Reply-To: References: <20220321140327.777f9554@canb.auug.org.au> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-next@vger.kernel.org On Mon, 21 Mar 2022 17:48:54 +0100 Peter Zijlstra wrote: > On Mon, Mar 21, 2022 at 02:04:05PM +0100, Peter Zijlstra wrote: > > On Mon, Mar 21, 2022 at 01:55:49PM +0100, Peter Zijlstra wrote: > > > On Mon, Mar 21, 2022 at 02:03:27PM +1100, Stephen Rothwell wrote: > > > > Hi all, > > > > > > > > After merging the tip tree, today's linux-next build (x864 allmodconfig) > > > > produced these new warnings: > > > > > > > > vmlinux.o: warning: objtool: arch_rethook_prepare()+0x55: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: arch_rethook_trampoline_callback()+0x3e: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: unwind_next_frame()+0x93e: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: unwind_next_frame()+0x5f2: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: unwind_next_frame()+0x4a7: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: __rethook_find_ret_addr()+0x81: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: __rethook_find_ret_addr()+0x90: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: rethook_trampoline_handler()+0x8c: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > vmlinux.o: warning: objtool: rethook_trampoline_handler()+0x9b: relocation to !ENDBR: arch_rethook_trampoline+0x0 > > > > > > Hurmph, lemme go figure out where that code comes from, I've not seen > > > those. > > > > Ahh, something tracing. I'll go do some patches on top of it. > > The below gets rid of the objtool warnings. Yes, I confirmed that. > > But I still think it's fairly terrible to get a (flawed) carbon copy of > the kretprobe code. Indeed. I would like to replace the trampoline code of kretprobe with rethook, eventually. There is no reason why we keep the clone. (But I need more arch maintainers help for that, there are too many archs implemented kretprobes) > Also, I think both should fix regs->ss. I'm not sure this part. Since the return trampoline should run in the same context of the called function, isn't ss same there too? Thank you, > > --- > diff --git a/arch/x86/kernel/rethook.c b/arch/x86/kernel/rethook.c > index f0f2f0608282..227a1890a984 100644 > --- a/arch/x86/kernel/rethook.c > +++ b/arch/x86/kernel/rethook.c > @@ -20,6 +20,7 @@ asm( > ".type arch_rethook_trampoline, @function\n" > "arch_rethook_trampoline:\n" > #ifdef CONFIG_X86_64 > + ANNOTATE_NOENDBR > /* Push a fake return address to tell the unwinder it's a kretprobe. */ > " pushq $arch_rethook_trampoline\n" > UNWIND_HINT_FUNC > @@ -48,7 +49,7 @@ asm( > " addl $4, %esp\n" > " popfl\n" > #endif > - " ret\n" > + ASM_RET > ".size arch_rethook_trampoline, .-arch_rethook_trampoline\n" > ); > NOKPROBE_SYMBOL(arch_rethook_trampoline); -- Masami Hiramatsu