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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45D96C46CA0 for ; Sun, 26 Nov 2023 00:52:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229732AbjKZAwA (ORCPT ); Sat, 25 Nov 2023 19:52:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35306 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229448AbjKZAv6 (ORCPT ); Sat, 25 Nov 2023 19:51:58 -0500 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [IPv6:2001:41d0:1004:224b::ae]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3948F111 for ; Sat, 25 Nov 2023 16:52:02 -0800 (PST) Message-ID: <0f210cef-c6e9-41c1-9ba8-225f046435e5@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700959920; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=NPg+/Q1bfdSOekshqxIavDgK/xM+ZX8z48MtbsXRZC0=; b=ajEzRZqYRvm0a8tqOnR9BhAiabu7ctEBf1vosMXD+gbq/fKZPgDo0ZHXLOCxYbD5mxFGHC QmdB4wjhWfSaaTgEpk5zg7m9Sh7NKSRDEOhPDFGzLruUks42SOo8suBz1ZY032FYOGZ6cf SbdeooZLsqotxux1If0H6Y/nxbnhHzQ= Date: Sat, 25 Nov 2023 16:51:51 -0800 MIME-Version: 1.0 Subject: Re: [PATCH ipsec-next v1 6/7] bpf: selftests: test_tunnel: Disable CO-RE relocations Content-Language: en-GB To: Daniel Xu , shuah@kernel.org, daniel@iogearbox.net, andrii@kernel.org, ast@kernel.org, steffen.klassert@secunet.com, antony.antony@secunet.com, alexei.starovoitov@gmail.com, Eddy Z Cc: mykolal@fb.com, martin.lau@linux.dev, song@kernel.org, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, devel@linux-ipsec.org, netdev@vger.kernel.org References: <391d524c496acc97a8801d8bea80976f58485810.1700676682.git.dxu@dxuuu.xyz> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: <391d524c496acc97a8801d8bea80976f58485810.1700676682.git.dxu@dxuuu.xyz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/22/23 1:20 PM, Daniel Xu wrote: > Switching to vmlinux.h definitions seems to make the verifier very > unhappy with bitfield accesses. The error is: > > ; md.u.md2.dir = direction; > 33: (69) r1 = *(u16 *)(r2 +11) > misaligned stack access off (0x0; 0x0)+-64+11 size 2 > > It looks like disabling CO-RE relocations seem to make the error go > away. Thanks for reporting. I did some preliminary investigation and the failure is due to that we do not support CORE-based bitfield store yet. Besides disabling CORE-relocation as in this patch, there are a few ways to do this: - Change the code to avoid bitfield store and use 1/2/4/8 byte(s) store. A little bit ugly but it should work. - Use to-be-supported 'preserve_static_offset' (https://reviews.llvm.org/D133361) to preserve the offset. This might work (I didn't try it yet). - Eduard did some early study trying to remove CORE attribute (preserve_access_index) from UAPI structures. In this particular case, erspan_metadata is in /usr/include/linux/erspan.h. We will also investigate whether we could store bitfield store directly with CORE. > > Co-developed-by: Antony Antony > Signed-off-by: Antony Antony > Signed-off-by: Daniel Xu > --- > tools/testing/selftests/bpf/progs/test_tunnel_kern.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c > index 3065a716544d..ec7e04e012ae 100644 > --- a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c > +++ b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c > @@ -6,6 +6,7 @@ > * modify it under the terms of version 2 of the GNU General Public > * License as published by the Free Software Foundation. > */ > +#define BPF_NO_PRESERVE_ACCESS_INDEX This is a temporary workaround and hopefully we can lift it in the near future. Please add a comment here with prefix 'Workaround' to explain why this is needed and later on we can earliy search the keyword and remember to tackle this. > #include "vmlinux.h" > #include > #include