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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 4F8ADC433DF for ; Mon, 17 Aug 2020 15:52:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1FBD020882 for ; Mon, 17 Aug 2020 15:52:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597679578; bh=3vfQKMttlM0pOTyMoFBwaEXl9k9Q1/ngIocA8s8nfjU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=sCc5bszQXMVSrKlRRPM7ijwQ9rGqcsOe564PoletrB3ftNQMEKYdlA7hZLnkuWhx+ kWWA62cQNHYXTHA1HU63FmKSgYY/6TiMWis5v6tCRMlIBl+XPaSLHuL9/KQjEkwN3v Xm05hOmZA8wptm+wamtQXYQN2C2UQinP6QXwXfM0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387880AbgHQPwz (ORCPT ); Mon, 17 Aug 2020 11:52:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:48708 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730677AbgHQPkn (ORCPT ); Mon, 17 Aug 2020 11:40:43 -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 481F32075B; Mon, 17 Aug 2020 15:40:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597678842; bh=3vfQKMttlM0pOTyMoFBwaEXl9k9Q1/ngIocA8s8nfjU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Dh1ZpV+X/2Pej+WxVo7EmU2fCW0rGz9YdvGfHJmGx9CoJdr7ajflJPFp2Ylzd4tnQ hbOf6uEBYz/XqNYRMD4EXCY9BE55+PYn0GQZxtBlwRn8RQV2VdsxYUcQMimM3L6aIO 3JfyOt7CJfbygP5kI+hMHDFXq+f7hfGuCBbo+zfY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ingo Molnar , Miguel Ojeda , Tim Murray , Simon MacMullen , Greg Hackmann , Nick Desaulniers , "Steven Rostedt (VMware)" Subject: [PATCH 5.7 001/393] tracepoint: Mark __tracepoint_strings __used Date: Mon, 17 Aug 2020 17:10:51 +0200 Message-Id: <20200817143819.658929848@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200817143819.579311991@linuxfoundation.org> References: <20200817143819.579311991@linuxfoundation.org> User-Agent: quilt/0.66 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nick Desaulniers commit f3751ad0116fb6881f2c3c957d66a9327f69cefb upstream. __tracepoint_string's have their string data stored in .rodata, and an address to that data stored in the "__tracepoint_str" section. Functions that refer to those strings refer to the symbol of the address. Compiler optimization can replace those address references with references directly to the string data. If the address doesn't appear to have other uses, then it appears dead to the compiler and is removed. This can break the /tracing/printk_formats sysfs node which iterates the addresses stored in the "__tracepoint_str" section. Like other strings stored in custom sections in this header, mark these __used to inform the compiler that there are other non-obvious users of the address, so they should still be emitted. Link: https://lkml.kernel.org/r/20200730224555.2142154-2-ndesaulniers@google.com Cc: Ingo Molnar Cc: Miguel Ojeda Cc: stable@vger.kernel.org Fixes: 102c9323c35a8 ("tracing: Add __tracepoint_string() to export string pointers") Reported-by: Tim Murray Reported-by: Simon MacMullen Suggested-by: Greg Hackmann Signed-off-by: Nick Desaulniers Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- include/linux/tracepoint.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -361,7 +361,7 @@ static inline struct tracepoint *tracepo static const char *___tp_str __tracepoint_string = str; \ ___tp_str; \ }) -#define __tracepoint_string __attribute__((section("__tracepoint_str"))) +#define __tracepoint_string __attribute__((section("__tracepoint_str"), used)) #else /* * tracepoint_string() is used to save the string address for userspace