From patchwork Tue Dec 12 02:02:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Moon X-Patchwork-Id: 13488311 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b="NE71hSvD" Received: from mx0b-0031df01.pphosted.com (mx0b-0031df01.pphosted.com [205.220.180.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 896F69F; Mon, 11 Dec 2023 18:04:06 -0800 (PST) Received: from pps.filterd (m0279872.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.24/8.17.1.24) with ESMTP id 3BC1xlnu028454; Tue, 12 Dec 2023 02:03:14 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h= from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding:content-type; s=qcppdkim1; bh=ggdoTQX GQlyccgy7MpErs64XVDViBmAQKfJh1l2iFuU=; b=NE71hSvDtCqGF6ZJU1pqP3W b3k4IVjTqakrn9W3oLJRfYvYbbSerBbukqqEqTfmYGys/asYPltlJoGkglv5GQr/ f+nVncIz+NG9UZDkVIgvGhzYVeLdg4kR2Hz3Ra+8deiFpoqk/1TYSejshY3cXaI3 NqFaFb7WBPBuDQDTE4uRG9oYhgyzSkEdlQ4WomJojJn5qMCZroDZWMh5sepTJE1o eQylXL2K/vTd/ZieZcep+kZDh5TXAp+9roF9zV166TP7fTP/iBhRQB8eGYaBo9Dk pC1At2l+u3ucq4Y7rXaFjbuJBe7s5/Pzytky57Y8vY3ydTVmXJxhRYCl9JgrGrA= = Received: from nalasppmta05.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3ux20esrkq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 12 Dec 2023 02:03:14 +0000 (GMT) Received: from nalasex01b.na.qualcomm.com (nalasex01b.na.qualcomm.com [10.47.209.197]) by NALASPPMTA05.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 3BC23CXB012400 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 12 Dec 2023 02:03:12 GMT Received: from hu-johmoo-lv.qualcomm.com (10.49.16.6) by nalasex01b.na.qualcomm.com (10.47.209.197) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Mon, 11 Dec 2023 18:03:09 -0800 From: John Moon To: Masahiro Yamada , Nathan Chancellor , Nick Desaulniers , "Nicolas Schier" , Jonathan Corbet CC: John Moon , , , , , , Greg Kroah-Hartman , Rob Herring , Carlos O'Donell , Randy Dunlap , Arnd Bergmann , Bjorn Andersson , Todd Kjos , Matthias Maennich , Giuliano Procida , , , Dodji Seketeli , Trilok Soni , Satya Durga Srinivasu Prabhala , Jordan Crouse Subject: [PATCH v7 0/3] Validating UAPI backwards compatibility Date: Mon, 11 Dec 2023 18:02:56 -0800 Message-ID: <20231212020259.2451253-1-quic_johmoo@quicinc.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: nalasex01c.na.qualcomm.com (10.47.97.35) To nalasex01b.na.qualcomm.com (10.47.209.197) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: -NGv-g96EJ6YXDR75wvtJ9LWiFr6MskK X-Proofpoint-ORIG-GUID: -NGv-g96EJ6YXDR75wvtJ9LWiFr6MskK X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-09_01,2023-12-07_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 adultscore=0 mlxscore=0 mlxlogscore=876 spamscore=0 lowpriorityscore=0 bulkscore=0 clxscore=1011 suspectscore=0 priorityscore=1501 phishscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2311290000 definitions=main-2312120014 The kernel community has rigorously enforced a policy of backwards compatibility in its userspace interfaces for a long time. This has allowed user applications to enjoy stability across kernel upgrades without recompiling. Our goal is to add tooling and documentation to help kernel developers maintain this stability. In terms of tooling, I've attached a couple of shell scripts we've been internally to validate backwards compatibility of our UAPI headers. The check-uapi.sh script uses libabigail's[1] tool abidiff[2] to compare a modified header's ABI before and after a patch is applied. If an existing UAPI is modified in a way that's not backwards compatibile, the script exits non-zero. We use this script in our continuous integration system to block changes that fail the check. It generates output like this when a backwards incompatible change is made to a UAPI header: ABI differences detected in include/uapi/linux/bpf.h from HEAD~1 -> HEAD [C] 'struct bpf_insn' changed: type size hasn't changed 2 data member changes: '__u8 dst_reg' offset changed from 8 to 12 (in bits) (by +4 bits) '__u8 src_reg' offset changed from 12 to 8 (in bits) (by -4 bits) The check-module-params.sh script is quite a bit simpler. It basically greps for module_param.* calls and compares their arguments before/after a change is applied. We wanted to share these scripts with the community and hopefully also receive general feedback when it comes to tooling/policy surrounding UAPI stability. Since v6 of this patch, I also presented a talk at LPC[4] on this topic in case anyone would like to review that. I've CC'd a few attendees who participated in discussion during the presentation. Previous discussion on v6 of this patch can be found here[5]. [1] https://sourceware.org/libabigail/manual/libabigail-overview.html [2] https://sourceware.org/libabigail/manual/abidiff.html [3] http://mirrors.kernel.org/sourceware/libabigail/libabigail-2.4.tar.xz [4] https://www.youtube.com/watch?v=4ijcLgvmcek [5] https://lore.kernel.org/all/20231027193016.27516-1-quic_johmoo@quicinc.com/T/#t P.S. While at Qualcomm, Jordan Crouse authored the original version of the UAPI checker script. Thanks Jordan! John Moon (3): check-uapi: Introduce check-uapi.sh docs: dev-tools: Add UAPI checker documentation check-module-params: Introduce check-module-params.sh Documentation/dev-tools/checkuapi.rst | 477 +++++++++++++++++++++ Documentation/dev-tools/index.rst | 1 + scripts/check-module-params.sh | 371 +++++++++++++++++ scripts/check-uapi.sh | 573 ++++++++++++++++++++++++++ 4 files changed, 1422 insertions(+) create mode 100644 Documentation/dev-tools/checkuapi.rst create mode 100755 scripts/check-module-params.sh create mode 100755 scripts/check-uapi.sh base-commit: a39b6ac3781d46ba18193c9dbb2110f31e9bffe9 --- 2.34.1