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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT 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 CABE2C04AB4 for ; Fri, 17 May 2019 09:10:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9243720848 for ; Fri, 17 May 2019 09:10:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="SKmI1NEQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728766AbfEQJKs (ORCPT ); Fri, 17 May 2019 05:10:48 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:40992 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727620AbfEQJKs (ORCPT ); Fri, 17 May 2019 05:10:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=CJyIw/+rjKasvY8yMkFNMy6qA00M4WMYrpzsHPZXP0o=; b=SKmI1NEQDf0K6UeUHIvTwBCD6 0gNAHx3VCb4KiNi5xS4/Dd8NPHqgyaRxLzvW5SPXElZG0Te2fn9jiDuupxq5/jvAMS39JHcKgYy0z S5A1gZxlM6I9ubC+SGpLHy3c4Ck2l0xz+wCjlOcaskWUYvO5PhQWjpg34ce1XniaPJYllL21aXNXK n7WdXv2NYxJB2xbOqnGL0rIHH7lBw2I/oNa3H62OER5aTjCX/3egb5+/k4cftAnlYwvMpgsBcZIzs mHQ1V8RoyaO4tfV3wshfJmzjjmc5AeWkXeGDqKeBMSnzDlkpjx0qqNPdm2TTyopKZNEfS5wg8ZV9O QIls9CoWA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hRYt4-00034I-2W; Fri, 17 May 2019 09:10:46 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8A82E2029B0A3; Fri, 17 May 2019 11:10:44 +0200 (CEST) Date: Fri, 17 May 2019 11:10:44 +0200 From: Peter Zijlstra To: Kairui Song Cc: Song Liu , lkml , Kernel Team , Josh Poimboeuf Subject: Re: Getting empty callchain from perf_callchain_kernel() Message-ID: <20190517091044.GM2606@hirez.programming.kicks-ass.net> References: <3CD3EE63-0CD2-404A-A403-E11DCF2DF8D9@fb.com> <20190517074600.GJ2623@hirez.programming.kicks-ass.net> <20190517081057.GQ2650@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 17, 2019 at 04:15:39PM +0800, Kairui Song wrote: > Hi, I think the actual problem is that bpf_get_stackid_tp (and maybe > some other bfp functions) is now broken, or, strating an unwind > directly inside a bpf program will end up strangely. It have following > kernel message: Urgh, what is that bpf_get_stackid_tp() doing to get the regs? I can't follow.