From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:44082 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728321AbgGFIz5 (ORCPT ); Mon, 6 Jul 2020 04:55:57 -0400 From: Sumanth Korikkar Subject: Re: bpf: bpf_probe_read helper restriction on s390x Date: Mon, 6 Jul 2020 10:54:56 +0200 Message-Id: <20200706085456.48306-1-sumanthk@linux.ibm.com> In-Reply-To: <20200705194225.GB3356590@krava> References: <20200705194225.GB3356590@krava> Sender: linux-s390-owner@vger.kernel.org List-ID: To: jolsa@redhat.com Cc: Sumanth.Korikkar@ibm.com, sumanthk@linux.ibm.com, agordeev@linux.ibm.com, ast@kernel.org, bas@baslab.org, bpf@vger.kernel.org, brendan.d.gregg@gmail.com, daniel@iogearbox.net, dxu@dxuuu.xyz, linux-s390@vger.kernel.org, mat@mmarchini.me, netdev@vger.kernel.org, yauheni.kaliuta@redhat.com Hi Jiri, Sorry about the noise. My email seems to be rejected to the list. Resending with plain text. s390 has overlapping address space. As suggested by the commit, ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE should not be enabled for s390 kernel. This should be changed in bpftrace application. Even if we enable ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE, bpf_probe_read will only work in certain cases like kernel pointer deferences (kprobes). User pointer deferences in uprobes/kprobes/etc will fail or have some invalid data I am looking forward to this fix: https://github.com/iovisor/bpftrace/pull/1141 OR probe split in bpftrace. Thank you Best Regards Sumanth