From patchwork Fri Jul 22 18:06:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 12926709 X-Patchwork-Delegate: bpf@iogearbox.net 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 4F4F5CCA489 for ; Fri, 22 Jul 2022 18:07:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236186AbiGVSHC (ORCPT ); Fri, 22 Jul 2022 14:07:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230193AbiGVSG6 (ORCPT ); Fri, 22 Jul 2022 14:06:58 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D78E2982B; Fri, 22 Jul 2022 11:06:58 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id EF7CBB829E2; Fri, 22 Jul 2022 18:06:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B09EC341CA; Fri, 22 Jul 2022 18:06:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1658513215; bh=D+x8CqdaXbsmhEFhqyxFXaNoVxZF5fkQARi2WHcJmQM=; h=From:To:Cc:Subject:Date:From; b=qxkLir6QXtovlD9rGM/Sbc7EKi7H4BQJ8jNGmEgyj+mZlbchofbdJOGnw1RXlnJm4 b6MwdZ2W6j71rOee5xBVVwOndXAEmZGIdiVHf8BcWtUWp1Cc2wiiaq+TkMsZvavEa/ Lmhq0cLzHQYMDNTomIPLXCaKwT4doRfi8WvmweSmmcR65mpXf6q6HrM0fhmodYmv9m Rhe0ELuAyixioyL7bj8cjow1GYEGQ/YglcJysgyqWG90fyQx37qX8uRqpi7yTukwCD VkpILytuUn8d/VnyWMHk2u9vgpfyfOZIK3+7+ibmwZcDo/8txLcSvd4qs7lZQ1ydqC 4BeLjT1pw8fFA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 34F1D5C0602; Fri, 22 Jul 2022 11:06:55 -0700 (PDT) From: "Paul E. McKenney" To: bpf@vger.kernel.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org Cc: corbet@lwn.net, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, kernel-team@fb.com, "Paul E. McKenney" Subject: [PATCH bpf 1/2] bpf: Update bpf_design_QA.rst to clarify that kprobes is not ABI Date: Fri, 22 Jul 2022 11:06:40 -0700 Message-Id: <20220722180641.2902585-1-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This patch updates bpf_design_QA.rst to clarify that the ability to attach a BPF program to a given point in the kernel code via kprobes does not make that attachment point be part of the Linux kernel's ABI. Signed-off-by: Paul E. McKenney --- Documentation/bpf/bpf_design_QA.rst | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Documentation/bpf/bpf_design_QA.rst b/Documentation/bpf/bpf_design_QA.rst index 437de2a7a5de7..2ed9128cfbec8 100644 --- a/Documentation/bpf/bpf_design_QA.rst +++ b/Documentation/bpf/bpf_design_QA.rst @@ -214,6 +214,12 @@ A: NO. Tracepoints are tied to internal implementation details hence they are subject to change and can break with newer kernels. BPF programs need to change accordingly when this happens. +Q: Are places where kprobes can attach part of the stable ABI? +-------------------------------------------------------------- +A: NO. The places to which kprobes can attach are internal implementation +details, which means that they are subject to change and can break with +newer kernels. BPF programs need to change accordingly when this happens. + Q: How much stack space a BPF program uses? ------------------------------------------- A: Currently all program types are limited to 512 bytes of stack