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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 autolearn=ham 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 91101C10F14 for ; Tue, 15 Oct 2019 13:00:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 68C0421925 for ; Tue, 15 Oct 2019 13:00:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728769AbfJONA6 (ORCPT ); Tue, 15 Oct 2019 09:00:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:54374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725710AbfJONA6 (ORCPT ); Tue, 15 Oct 2019 09:00:58 -0400 Received: from gandalf.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 E1F6E2064B; Tue, 15 Oct 2019 13:00:56 +0000 (UTC) Date: Tue, 15 Oct 2019 09:00:55 -0400 From: Steven Rostedt To: Sami Tolvanen Cc: Kees Cook , Ingo Molnar , LKML Subject: Re: [PATCH] ftrace: fix function type mismatches Message-ID: <20191015090055.789a0aed@gandalf.local.home> In-Reply-To: References: <20191007214740.188547-1-samitolvanen@google.com> <201910101411.98362BA0@keescook> <20191011142650.36404713@gandalf.local.home> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 14 Oct 2019 13:00:09 -0700 Sami Tolvanen wrote: > On Fri, Oct 11, 2019 at 11:26 AM Steven Rostedt wrote: > > Unfortunately, this breaks function graph tracing. > > Thank you for pointing this out. I should have realized this solution > wouldn't work. > > > Is there a way to do an alias or something that can fix whatever you > > are trying to fix? > > Unfortunately, an alias doesn't work in this case either, because the > compiler still looks at the type of the target function. I'll find > another way to solve the issue. > Would this work for you? -- Steve diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index dae64600ccbf..33b36b34721b 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -111,15 +111,22 @@ #ifdef CONFIG_FTRACE_MCOUNT_RECORD #ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY +/* + * Need to also make ftrace_graph_stub point to ftrace_stub + * so that the same stub location may have different protocols + * and not mess up with C verifiers. + */ #define MCOUNT_REC() . = ALIGN(8); \ __start_mcount_loc = .; \ KEEP(*(__patchable_function_entries)) \ - __stop_mcount_loc = .; + __stop_mcount_loc = .; \ + ftrace_graph_stub = ftrace_stub; #else #define MCOUNT_REC() . = ALIGN(8); \ __start_mcount_loc = .; \ KEEP(*(__mcount_loc)) \ - __stop_mcount_loc = .; + __stop_mcount_loc = .; \ + ftrace_graph_stub = ftrace_stub; #endif #else #define MCOUNT_REC() diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 7950a0356042..fa3ce10d0405 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -332,9 +332,14 @@ int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace) return 0; } +/* + * Simply points to ftrace_stub, but with the proper protocol. + * Defined by the linker script in linux/vmlinux.lds.h + */ +extern void ftrace_graph_stub(struct ftrace_graph_ret *); + /* The callbacks that hook a function */ -trace_func_graph_ret_t ftrace_graph_return = - (trace_func_graph_ret_t)ftrace_stub; +trace_func_graph_ret_t ftrace_graph_return = ftrace_graph_stub; trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub; static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub; @@ -614,7 +619,7 @@ void unregister_ftrace_graph(struct fgraph_ops *gops) goto out; ftrace_graph_active--; - ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub; + ftrace_graph_return = ftrace_graph_stub; ftrace_graph_entry = ftrace_graph_entry_stub; __ftrace_graph_entry = ftrace_graph_entry_stub; ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);