From patchwork Fri Oct 22 02:16:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 12576861 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 5C333C433F5 for ; Fri, 22 Oct 2021 02:16:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39C0C61390 for ; Fri, 22 Oct 2021 02:16:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232412AbhJVCSs (ORCPT ); Thu, 21 Oct 2021 22:18:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:55266 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232411AbhJVCSr (ORCPT ); Thu, 21 Oct 2021 22:18:47 -0400 Received: from rorschach.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 9EE5F6138D; Fri, 22 Oct 2021 02:16:29 +0000 (UTC) Date: Thu, 21 Oct 2021 22:16:27 -0400 From: Steven Rostedt To: LKML Cc: Ingo Molnar , Andrew Morton , Yoshinori Sato , Rich Felker , linux-sh@vger.kernel.org Subject: [PATCH] ftrace/sh: Add arch_ftrace_ops_list_func stub to have compressed image still link Message-ID: <20211021221627.5d7270de@rorschach.local.home> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Using the linker script to fix an issue where some archs call the function tracer with just the ip (instruction pointer) and pip (parent instruction pointer) where as more up to date archs also pass in the associated ftrace_ops and the ftrace_regs pointer, the generic code will be called either with two parameters or four. To avoid any C undefined behavior of calling two parameters to four or four to two parameter function, two functions are created, where a preprocessor macro uses the one that matches the architecture. As the function pointers for them may be different, a typecast is used. But this triggers issues with newer compilers that will fail due to -Werror. A linker trick is now used to map the generic function to the function that is used (note the generic function is only used to set the default function callback). The linker trick defines ftrace_ops_list_func (the generic function) to arch_ftrace_ops_list_func (the arch defined one). Link: https://lore.kernel.org/all/20200617165616.52241bde@oasis.local.home/ But this fails sh arch because their linker script is included in their compressed image that does not define arch_ftrace_ops_list_func at all sh4-linux-ld:arch/sh/boot/compressed/../../kernel/vmlinux.lds:32: undefined symbol `arch_ftrace_ops_list_func' referenced in expression Included a stub by that name in the misc.c to allow the code to compile and link, even though it's not used. This is similar to what was done for ftrace_stub: b83b43ffc6e4b ("fgraph: Fix function type mismatches of ftrace_graph_return using ftrace_stub") Signed-off-by: Steven Rostedt (VMware) Reported-by: kernel test robot --- This is based on my tree at: git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git branch: ftrace/core I can push this change through my tree with the SuperH maintainer's acks. diff --git a/arch/sh/boot/compressed/misc.c b/arch/sh/boot/compressed/misc.c index a03b6680a9d9..ca05c99a3d5b 100644 --- a/arch/sh/boot/compressed/misc.c +++ b/arch/sh/boot/compressed/misc.c @@ -115,6 +115,9 @@ void __stack_chk_fail(void) void ftrace_stub(void) { } +void arch_ftrace_ops_list_func(void) +{ +} #define stackalign 4