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=-4.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS 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 459F4C10F13 for ; Sun, 14 Apr 2019 10:47:20 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 138C9218D3 for ; Sun, 14 Apr 2019 10:47:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="S2YueXmB"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="qJbS/wbQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 138C9218D3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Mime-Version:Message-Id:Subject:To:From :Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=aJmLtrv3oy4SPg2dR6HzvV/RttVnndId24bayuuifVs=; b=S2YueXmB57zAdl I6E1/fhw5q/gG4gYympUXy3serUHyD8b0AaK2Kxp1wU9f3Tkx4+RetmWt4VutoLG3xi8e/K9BrGvQ olTHJ/7U6prEULEOyMwi7LCPSEKEhq5UagWW00X3xAVENPGhlvX21RtfUnij3R9rTbvJ0ayZA9mBt ni6+cIUJ6P97N2Kh3Ro9BAGMIR3zTga6SnZM1EPcAX27LHY08632BJHddBSVwwhp/Vn000wfunxE+ 4B2ySgShPTCaAw392HrcPNXBabOS3h3McCVR4Oa0zoC+eZqgbYNlOBS+9b15l3pNrqp+DKkN9M6Yp iRC4zzF9lGhc20yTaHlA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hFcfL-0001cv-UM; Sun, 14 Apr 2019 10:47:15 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hFcfI-0001cR-MV for linux-arm-kernel@lists.infradead.org; Sun, 14 Apr 2019 10:47:14 +0000 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 BDBA220848; Sun, 14 Apr 2019 10:47:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555238830; bh=Q/iW8KXrTCP1yOHKTs5MY3WThmjAYJS3G/J6OzgP1gU=; h=Date:From:To:Cc:Subject:From; b=qJbS/wbQGWOBdCaKCJxZYScVOLgN4Jt3D9ajCo7XIgie97i96TitrUE1sf+eHIbUT 4/Tmts7nC/wPClRvvZmEek6FTCHKwrfAI8LP7MKrrTjbQVKbx6N7B0q+Kl8/FXQ4Wy BTi4E7W5jCG2H/Q1a6W4WsyUIlprXcMmMxOrnpKY= Date: Sun, 14 Apr 2019 19:47:05 +0900 From: Masami Hiramatsu To: Steven Rostedt , Stefan Agner , Arnd Bergmann , Masahiro Yamada Subject: Kconfig dependency issue on function-graph tracer and frame pointer on arm Message-Id: <20190414194705.2e10802aca2df36c8f27f349@kernel.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190414_034712_754252_C201FFE7 X-CRM114-Status: GOOD ( 12.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Russell King , naresh.kamboju@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hello, Recently, Naresh reported that the function-graph tracer on the latest kernel crashes on arm. I could reproduce it and bisected. I finally found the commit f9b58e8c7d03 ("ARM: 8800/1: use choice for kernel unwinders") was the first bad commit. Actually, this commit is just changing Kconfig for making kernel unwinder choosable. However, as a side effect, this makes CONFIG_FRAME_POINTER=n by default even if CONFIG_FUNCTION_GRAPH_TRACER=y. (Note that function-graph tracer implementation on arm depends on FRAME_POINTER.) This seems odd, because the commit introduced below code +choice + prompt "Choose kernel unwinder" + default UNWINDER_ARM if AEABI && !FUNCTION_GRAPH_TRACER + default UNWINDER_FRAME_POINTER if !AEABI || FUNCTION_GRAPH_TRACER + help So, it seems UNWINDER_FRAME_POINTER is used if FUNCTION_GRAPH_TRACER=y. However, it seems not working. (I guess this is a wrong syntax for Kconfig) Moreover, since this just setting default value, there seems no direct dependency to FRAME_POINTER from FUNCTION_GRAPH_TRACER. I guess user can change it... I made a fix below (which I tested). This is ugly (arch specific dependency in generic part) but works. It enables both of FRAME_POINTER and UNWINDER_ARM. However I still have some questions. - Is above choice+default a correct syntax for Kconfig? (Masahiro?) - Can UNWINDER_ARM work with FRAME_POINTER? (Arnd?) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 5e3de28c7677..f79c54680f3b 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -160,6 +160,7 @@ config FUNCTION_GRAPH_TRACER depends on HAVE_FUNCTION_GRAPH_TRACER depends on FUNCTION_TRACER depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE + select ARCH_WANT_FRAME_POINTERS if ARM default y help Enable the kernel to trace a function at both its return Thank you, -- Masami Hiramatsu _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel