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=-1.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 80A56C43381 for ; Tue, 19 Feb 2019 04:14:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E97D021773 for ; Tue, 19 Feb 2019 04:14:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nifty.com header.i=@nifty.com header.b="P3L6jNDw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726124AbfBSEO5 (ORCPT ); Mon, 18 Feb 2019 23:14:57 -0500 Received: from conssluserg-05.nifty.com ([210.131.2.90]:31526 "EHLO conssluserg-05.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725497AbfBSEO5 (ORCPT ); Mon, 18 Feb 2019 23:14:57 -0500 Received: from mail-vk1-f169.google.com (mail-vk1-f169.google.com [209.85.221.169]) (authenticated) by conssluserg-05.nifty.com with ESMTP id x1J4ElIV008320; Tue, 19 Feb 2019 13:14:48 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-05.nifty.com x1J4ElIV008320 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1550549688; bh=s2rmefywG5qxRfRX9Ispy/WfF/VrvGNX/NJKAR+FOgQ=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=P3L6jNDwzr1EB2636z7AQnlpfMbyj+LnMf900heL9+Ndk32TtOinAaxEoM3eg+Rx2 9UD1YGia+VwuHWVHrP5DpQrvjb24LS7gHlBFwiABApsAfYA2q/6jhCyn/n8gsmI2R6 YJ1iTbdLAhIQkXKUnVN+swpGv6BrGoyJXF2pH+4HJJ9dc3iOknEdQJKqhTRnjPdl+3 IWtdazLHP57x2qtdxlz0hNMBQD1BTbDxlRJL5qIAD2LuEsKf8RxI/aClvzL5kPMALD zmSKYsfFuM5w9pPqk8kG5b6bjJJ3ZBX9AJHkxIJEO5JtP1ks/3AS2cvjIxa0URQMba lwjkl1ykuQvfw== X-Nifty-SrcIP: [209.85.221.169] Received: by mail-vk1-f169.google.com with SMTP id h128so4351596vkg.11; Mon, 18 Feb 2019 20:14:48 -0800 (PST) X-Gm-Message-State: AHQUAubfAMYUu67mKnQIpRCqchKHKFB9RGW2qWI8VRveEh3YZP2BIpkd jlveAJCpEanCqP8+NXrT0wvn1yVNq/ph7aw2wFw= X-Google-Smtp-Source: AHgI3IZo5AE7PNvPF825jn5n7M6ABkfNkD3bMbBFDTxwEOkbOxLdQFDki0790yv0sV2JLjhr45qp9yNq9QHzV7LaeY4= X-Received: by 2002:a1f:5e96:: with SMTP id s144mr13298575vkb.74.1550549687283; Mon, 18 Feb 2019 20:14:47 -0800 (PST) MIME-Version: 1.0 References: <20190211143600.15021-1-joel@joelfernandes.org> <20190215031926.ljzluy2cfxp64u6o@ast-mbp> In-Reply-To: <20190215031926.ljzluy2cfxp64u6o@ast-mbp> From: Masahiro Yamada Date: Tue, 19 Feb 2019 13:14:11 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 1/2] Provide in-kernel headers for making it easy to extend the kernel To: Alexei Starovoitov , "Joel Fernandes (Google)" Cc: Networking , Linux Kernel Mailing List , Andrew Morton , Alexei Starovoitov , atish patra , Daniel Colascione , Dan Williams , Greg Kroah-Hartman , Jonathan Corbet , Karim Yaghmour , Kees Cook , kernel-team@android.com, "open list:DOCUMENTATION" , "open list:KERNEL SELFTEST FRAMEWORK" , Manoj Rao , Paul McKenney , "Peter Zijlstra (Intel)" , Randy Dunlap , Steven Rostedt , Shuah Khan , Thomas Gleixner , Yonghong Song Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 15, 2019 at 11:48 PM Alexei Starovoitov wrote: > > On Mon, Feb 11, 2019 at 09:35:59AM -0500, Joel Fernandes (Google) wrote: > > Introduce in-kernel headers and other artifacts which are made available > > as an archive through proc (/proc/kheaders.txz file). The extension '.txz' is not used in kernel code. '.tar.xz' is used for 'tarxz-pkg', 'perf-tarxz-src-pkg' etc. $ git grep '\.txz' $ git grep '\.tar\.xz' Documentation/admin-guide/README.rst: xz -cd linux-4.X.tar.xz | tar xvf - arch/x86/crypto/camellia-aesni-avx-asm_64.S: * http://koti.mbnet.fi/axh/crypto/camellia-BSD-1.2.0-aesni1.tar.xz crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz crypto/testmgr.h: * https://bench.cr.yp.to/supercop/supercop-20170228.tar.xz scripts/package/Makefile: @echo ' perf-tarxz-src-pkg - Build $(perf-tar).tar.xz source tarball' tools/testing/selftests/gen_kselftest_tar.sh: ext=".tar.xz" I prefer '.tar.xz' for consistency. BTW, have you ever looked at scripts/extract-ikconfig? You added IKHD_ST and IKHD_ED just to mimic kernel/configs.c It is currently pointless without the extracting tool, but you might think it is useful to extract headers from vmlinux or the module without mounting procfs. > > This archive makes > > it possible to build kernel modules, run eBPF programs, and other > > tracing programs that need to extend the kernel for tracing purposes > > without any dependency on the file system having headers and build > > artifacts. > > > > On Android and embedded systems, it is common to switch kernels but not > > have kernel headers available on the file system. Raw kernel headers > > also cannot be copied into the filesystem like they can be on other > > distros, due to licensing and other issues. There's no linux-headers > > package on Android. Further once a different kernel is booted, any > > headers stored on the file system will no longer be useful. By storing > > the headers as a compressed archive within the kernel, we can avoid these > > issues that have been a hindrance for a long time. > > The set looks good to me and since the main use case is building bpf progs > I can route it via bpf-next tree if there are no objections. > Masahiro, could you please ack it? Honestly, I was not tracking this thread since I did not know I was responsible for this. I just started to take a closer look, then immediately got scared. This version is not mature enough for the merge. First of all, this patch cannot be compiled out-of-tree (O= option). I do not know why 0-day bot did not catch this apparent breakage. $ make -j8 O=hoge make[1]: Entering directory '/home/masahiro/workspace/bsp/linux/hoge' GEN Makefile Using .. as source for kernel DESCEND objtool CALL ../scripts/checksyscalls.sh CHK include/generated/compile.h make[2]: *** No rule to make target 'Module.symvers', needed by 'kernel/kheaders_data.txz'. Stop. make[2]: *** Waiting for unfinished jobs.... /home/masahiro/workspace/bsp/linux/Makefile:1043: recipe for target 'kernel' failed make[1]: *** [kernel] Error 2 make[1]: *** Waiting for unfinished jobs.... make[1]: Leaving directory '/home/masahiro/workspace/bsp/linux/hoge' Makefile:152: recipe for target 'sub-make' failed make: *** [sub-make] Error 2 I was able to compile it in-tree but it makes the incremental build extremely slow. (Here, the incremental build means "make" without changing any code after the full build.) Before this patch, "make -j8" took 11 sec on my machine. real 0m11.777s user 0m16.608s sys 0m5.164s After this patch, x86_64_defconfig + CONFIG_IKHEADERS_PROC=y takes 53 sec for me since kernel/kheaders_data.txz is regenerated every time even when you did not touch any source file. $ time make -j8 DESCEND objtool CALL scripts/checksyscalls.sh CHK include/generated/compile.h GEN kernel/kheaders_data.txz UPD kernel/kheaders_data.h CC kernel/kheaders.o AR kernel/built-in.a GEN .version CHK include/generated/compile.h UPD include/generated/compile.h CC init/version.o AR init/built-in.a AR built-in.a LD vmlinux.o MODPOST vmlinux.o KSYM .tmp_kallsyms1.o KSYM .tmp_kallsyms2.o LD vmlinux SORTEX vmlinux SYSMAP System.map Building modules, stage 2. CC arch/x86/boot/version.o MODPOST 17 modules VOFFSET arch/x86/boot/compressed/../voffset.h OBJCOPY arch/x86/boot/compressed/vmlinux.bin RELOCS arch/x86/boot/compressed/vmlinux.relocs CC arch/x86/boot/compressed/kaslr.o GZIP arch/x86/boot/compressed/vmlinux.bin.gz CC arch/x86/boot/compressed/misc.o MKPIGGY arch/x86/boot/compressed/piggy.S AS arch/x86/boot/compressed/piggy.o LD arch/x86/boot/compressed/vmlinux ZOFFSET arch/x86/boot/zoffset.h OBJCOPY arch/x86/boot/vmlinux.bin AS arch/x86/boot/header.o LD arch/x86/boot/setup.elf OBJCOPY arch/x86/boot/setup.bin BUILD arch/x86/boot/bzImage Setup is 15612 bytes (padded to 15872 bytes). System is 12673 kB CRC 697aaf88 Kernel: arch/x86/boot/bzImage is ready (#6) real 0m53.024s user 0m32.076s sys 0m9.296s Also, I notice $(ARCH) must be fixed to $(SRCARCH), but that is one of minor issues. We should take time for careful review and test. Please give me more time for thorough review. -- Best Regards Masahiro Yamada