From patchwork Thu Aug 20 09:20:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 248031 Delivered-To: patch@linaro.org Received: by 2002:a05:6e02:522:0:0:0:0 with SMTP id h2csp1256539ils; Thu, 20 Aug 2020 04:19:48 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxO1rnQxzzOCIy9ABFVQu+mT06GcppiSS0IzC4oM8qk9AkhDn8ohjNAuQSOyq/d5VWgWBle X-Received: by 2002:a17:906:4047:: with SMTP id y7mr2651224ejj.21.1597922387853; Thu, 20 Aug 2020 04:19:47 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1597922387; cv=none; d=google.com; s=arc-20160816; b=qRZqM7HRTMnEXTHo8KSMg5GMTgRrCuFEAhy76m6ZVCGbJZ3ZvVCHBOfoaeah+3XKNN EfXqJuc4ro4CuWk8D3Q3hQG1CxT0RhXiIWGyqLeeMZkWTDPQDv/7jIlzuIrW8A1L+4em 07tcCsonZsNGc5Y6xggNQRUaeKpZJqWXJWlOeBkRNmIy5CiV/kn8yUvZDUrmWr5hC6j4 uWjTapssrKrCqjhRtQKg8wi+mk3VoD73d+JKJ2lzLL9vGMSvKlF7jjZUQcr4P6Ef2hvj SjA+7tOhrM2kXa5NosZ4DIo4voxwNXhcXFC6I6DABOYtcOXFgspYnrfsNoSmrw8NPuCE H3Jw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=lStICc+HIWQJNXuZSGmVgQQy2/rv9Qo18RRFkn0vkFM=; b=APYlT1H6g0Wd7UvG4POSkpgL9oAAL06yDd3yieI/bLYrnGjsOi3XILGaVu3EANvqdr 5Mc8Jetco5Jr7+UBsjvvX5yMLCYxI9XkBvvhvQXuSmnitqx6d54C9vYVSkwEhvMyRzQ6 hM48sz6KXMg5vU/aaBMfPjwMrwkxgcIzOBWnrFgvDjnixg9RI4HHDEqgyO7U6+/0Bs8N iHBfsgjwqobSUxfhq91sDpHDfRuo/TMT6mLvqxJIDHTOBx8CZ/3wskG8634vf3cDICOo 4ENQgVoLMnNqlzxx8F34uUgQUAyseF+bu30uAySTgPNQp+ZCTL4kCN+4xdFpL6nBmLVN liig== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=HtAHmF84; spf=pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id cz6si1402870edb.350.2020.08.20.04.19.47; Thu, 20 Aug 2020 04:19:47 -0700 (PDT) Received-SPF: pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=HtAHmF84; spf=pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728737AbgHTLTf (ORCPT + 15 others); Thu, 20 Aug 2020 07:19:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:38958 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726731AbgHTKHy (ORCPT ); Thu, 20 Aug 2020 06:07:54 -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 7C15E20724; Thu, 20 Aug 2020 10:07:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597918074; bh=KF+GuQztWDvaQBGOE1HeqpVVHLeZgbDx9dY40x+uHY4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HtAHmF84Wh3uOyryK0bm6FKIWNoGXZYwgpZmYAy6E8CzZUrnFgPPyWekdWe6MIy3i 0YWUMuXmDGDTEJvH0gZwNTitVy+2UmIhjD5uu7ejAY7NGylRDgpngTLW9xQgNG5r82 v+8sW0JeemWM1tpOT3D0LiYJKc5RTTJ9edXDznWY= 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 4.14 043/228] tracepoint: Mark __tracepoint_strings __used Date: Thu, 20 Aug 2020 11:20:18 +0200 Message-Id: <20200820091609.736830467@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200820091607.532711107@linuxfoundation.org> References: <20200820091607.532711107@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 @@ -318,7 +318,7 @@ extern void syscall_unregfunc(void); 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