From patchwork Tue Sep 3 15:06:26 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Matthias_M=C3=A4nnich?= X-Patchwork-Id: 11128143 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3FA3E14F7 for ; Tue, 3 Sep 2019 15:07:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0EB332339D for ; Tue, 3 Sep 2019 15:07:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="W1kHB/tZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729540AbfICPHK (ORCPT ); Tue, 3 Sep 2019 11:07:10 -0400 Received: from mail-qt1-f201.google.com ([209.85.160.201]:44705 "EHLO mail-qt1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728860AbfICPHK (ORCPT ); Tue, 3 Sep 2019 11:07:10 -0400 Received: by mail-qt1-f201.google.com with SMTP id x11so19207630qtm.11 for ; Tue, 03 Sep 2019 08:07:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=hNr8T/9gNzuEDlnpxznbVrBSAUbvdXRiy1rCWsF0n2E=; b=W1kHB/tZ7YClRTpT8BdeFzp8+giupK7HNS98ECGbb2bo1vSoTUXrJnGWXWyzJTqMjB G+OgNYTIYC2yvdCSeYIAa5phAgPlBe1atBEhABcLCty4uZh1ost3f8hngjLxCmoQvBhP c/7v0vfL2JJlPXgOwDWELXQF35on5j65XIwSL4vdXMeXknMcZMJ5QEOAHJSDyGfAB+S7 GB8enhAmcWjzKmbAbBLTOzcvZtAHCk4aOD1hHzRofSlj1FcQbu7vF9SXtIndwgFgvbz1 7qu5KhebJ1BDFLihWzzHXKpMZSdnkqm+3Fu9fUJS7x5O1xDD9HSIgyK9ymyP0CdNLvAH 9aRQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=hNr8T/9gNzuEDlnpxznbVrBSAUbvdXRiy1rCWsF0n2E=; b=E9uxbpBoZnQHXXxVCJIh38vHrHvMxW1801VQBws7KV+dwKKZA+jCSokZyNSSJNnjra 9njwOY7oMIzowEMrbLgn/37PmBIT8w6gg5x706W+bOiMoy1q2KYXPaOUoWT6/NED92Bq OchUhohW4CEy3+ycjIAwB/D7cWcTqQpsshWXWxXRCIcy7Gaiozh/U3nR9EvNuek4rHg+ ta+Y6guwO8G1YxF65OM1Hw8noYQddiaKsQt9ujMoi+viAPbtqr+EMwDhsrpdeBpbqGLU rqZLDgMMkR/Sww0WnQykEAo+5yPCw0iFk+yKtPCDVJT1KWSxKbrbWQDpYAGqhposKajf CDsw== X-Gm-Message-State: APjAAAVn4uUO7ALIECzRsT6p+YjfXKE/3o4ydaYTBRRkLz7b+a0eKmbh Fzy+28hhiSbDHVJncTPVyKsu02Trrs0irw== X-Google-Smtp-Source: APXvYqxywyK88KqR9EH6QS9ukdJLXV/QzWjnqDtKLmWl890k2IzTxT5xZZxMP2O6UERMtA0+We+LtTKs7PCxWQ== X-Received: by 2002:a05:6214:1369:: with SMTP id c9mr13911042qvw.3.1567523228617; Tue, 03 Sep 2019 08:07:08 -0700 (PDT) Date: Tue, 3 Sep 2019 16:06:26 +0100 In-Reply-To: <20180716122125.175792-1-maco@android.com> Message-Id: <20190903150638.242049-1-maennich@google.com> Mime-Version: 1.0 References: <20180716122125.175792-1-maco@android.com> X-Mailer: git-send-email 2.23.0.187.g17f5b7556c-goog Subject: [PATCH v4 00/12] Symbol Namespaces From: Matthias Maennich To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, maennich@google.com, arnd@arndb.de, gregkh@linuxfoundation.org, jeyu@kernel.org, joel@joelfernandes.org, lucas.de.marchi@gmail.com, maco@android.com, sspatil@google.com, will@kernel.org, yamada.masahiro@socionext.com, linux-kbuild@vger.kernel.org, linux-modules@vger.kernel.org, linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, linux-watchdog@vger.kernel.org Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org As of Linux 5.3-rc7, there are 31207 [1] exported symbols in the kernel. That is a growth of roughly 1000 symbols since 4.17 (30206 [2]). There seems to be some consensus amongst kernel devs that the export surface is too large, and hard to reason about. Generally, these symbols fall in one of these categories: 1) Symbols actually meant for drivers 2) Symbols that are only exported because functionality is split over multiple modules, yet they really shouldn't be used by modules outside of their own subsystem 3) Symbols really only meant for in-tree use When module developers try to upstream their code, it regularly turns out that they are using exported symbols that they really shouldn't be using. This problem is even bigger for drivers that are currently out-of-tree, which may be using many symbols that they shouldn't be using, and that break when those symbols are removed or modified. This patch allows subsystem maintainers to partition their exported symbols into separate namespaces, and module authors to import such namespaces only when needed. This allows subsystem maintainers to more easily limit availability of these namespaced symbols to other parts of the kernel. It can also be used to partition the set of exported symbols for documentation purposes; for example, a set of symbols that is really only used for debugging could be in a "SUBSYSTEM_DEBUG" namespace. The series contains two RFC patches that do not need to be merged along with the rest of the series, but they serve as a reference for using the symbol namespaces. Especially, the watchdog subsystem might not be affected by the issues addressed by Symbol Namespaces. I left the patch in for reference anyway for demonstration purposes. I continued the work mainly done by Martijn Coenen. Changes in v2: - Rather than adding and evaluating separate sections __knsimport_NS, use modinfo tags to declare the namespaces a module introduces. Adjust modpost and the module loader accordingly. - Also add support for reading multiple modinfo values for the same tag to allow list-like access to modinfo tags. - The macros in export.h have been cleaned up to avoid redundancy in the macro parameters (ns, nspost, nspost2). - The introduction of relative references in the ksymtab entries caused a rework of the macros to accommodate that configuration as well. - Alignment of kernel_symbol in the ksymtab needed to be fixed to allow growing the kernel_symbol struct. - Modpost does now also append the namespace suffix to the symbol entries in Module.symvers. - The configuration option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS allows relaxing the enforcement of properly declared namespace imports at module loading time. - Symbols can be collectively exported into a namespace by defining DEFAULT_SYMBOL_NAMESPACE in the corresponding Makefile. - The requirement for a very recent coccinelle spatch has been lifted by simplifying the script. - nsdeps does now ensures MODULE_IMPORT_NS statements are sorted when patching the module source files. - Some minor bugs have been addressed in nsdeps to allow it to work with modules that have more than one source file. - The RFC for the usb-storage symbols has been simplified by using DEFAULT_SYMBOL_NAMESPACE=USB_STORAGE rather than explicitly exporting each and every symbol into that new namespace. Changes in v3: - Reword the documentation for the MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS option for clarification. - Fix printed required version of spatch in coccinelle script. - Adopt kbuild changes for modpost: .mod files are no longer generated in .tmp_versions. Similarely, generate the .ns_deps files in the tree along with the .mod files. Also, nsdeps now uses modules.order as source for the list modules to consider. - Add an RFC patch to introduce the namespace WATCHDOG_CORE for symbols exported in watchdog_core.c. Changes in v4: - scripts/nsdeps: - exit on first error - support out-of-tree builds O=... - scripts/mod/modpost: make the namespace a separate field when exporting to Module.symvers (rather than symbol.NS) - scripts/export_report.pl: update for new Module.symvers format - include/linux/export.h: fixed style nits - kernel/module.c: ensure namespaces are imported before taking a reference to the owner module - Documentation: document the Symbol Namespace feature and update references to Module.symvers and EXPORT_SYMBOL* This patch series was developed against v5.3-rc7. [1] git grep "^EXPORT_SYMBOL\w*(" v5.3-rc7 | wc -l [2] git grep "^EXPORT_SYMBOL\w*(" v4.17 | wc -l Cc: arnd@arndb.de Cc: gregkh@linuxfoundation.org Cc: jeyu@kernel.org Cc: joel@joelfernandes.org Cc: lucas.de.marchi@gmail.com Cc: maco@android.com Cc: sspatil@google.com Cc: will@kernel.org Cc: yamada.masahiro@socionext.com Cc: linux-kbuild@vger.kernel.org Cc: linux-modules@vger.kernel.org Cc: linux-usb@vger.kernel.org Cc: usb-storage@lists.one-eyed-alien.net Cc: linux-watchdog@vger.kernel.org Matthias Maennich (12): module: support reading multiple values per modinfo tag export: explicitly align struct kernel_symbol module: add support for symbol namespaces. modpost: add support for symbol namespaces module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS export: allow definition default namespaces in Makefiles or sources modpost: add support for generating namespace dependencies scripts: Coccinelle script for namespace dependencies. docs: Add documentation for Symbol Namespaces usb-storage: remove single-use define for debugging RFC: usb-storage: export symbols in USB_STORAGE namespace RFC: watchdog: export core symbols in WATCHDOG_CORE namespace .gitignore | 1 + Documentation/kbuild/modules.rst | 7 +- Documentation/kbuild/namespaces.rst | 154 ++++++++++++++++++++ Documentation/kernel-hacking/hacking.rst | 18 +++ MAINTAINERS | 5 + Makefile | 14 +- arch/m68k/include/asm/export.h | 1 - drivers/hwmon/ftsteutates.c | 1 + drivers/hwmon/sch56xx-common.c | 1 + drivers/rtc/rtc-abx80x.c | 1 + drivers/usb/storage/Makefile | 2 + drivers/usb/storage/alauda.c | 1 + drivers/usb/storage/cypress_atacb.c | 1 + drivers/usb/storage/datafab.c | 1 + drivers/usb/storage/debug.h | 2 - drivers/usb/storage/ene_ub6250.c | 1 + drivers/usb/storage/freecom.c | 1 + drivers/usb/storage/isd200.c | 1 + drivers/usb/storage/jumpshot.c | 1 + drivers/usb/storage/karma.c | 1 + drivers/usb/storage/onetouch.c | 1 + drivers/usb/storage/realtek_cr.c | 1 + drivers/usb/storage/scsiglue.c | 2 +- drivers/usb/storage/sddr09.c | 1 + drivers/usb/storage/sddr55.c | 1 + drivers/usb/storage/shuttle_usbat.c | 1 + drivers/usb/storage/uas.c | 1 + drivers/watchdog/armada_37xx_wdt.c | 1 + drivers/watchdog/asm9260_wdt.c | 1 + drivers/watchdog/aspeed_wdt.c | 1 + drivers/watchdog/at91sam9_wdt.c | 1 + drivers/watchdog/atlas7_wdt.c | 1 + drivers/watchdog/bcm2835_wdt.c | 1 + drivers/watchdog/bcm47xx_wdt.c | 1 + drivers/watchdog/bcm7038_wdt.c | 1 + drivers/watchdog/bcm_kona_wdt.c | 1 + drivers/watchdog/bd70528_wdt.c | 1 + drivers/watchdog/cadence_wdt.c | 1 + drivers/watchdog/da9052_wdt.c | 1 + drivers/watchdog/da9055_wdt.c | 1 + drivers/watchdog/da9062_wdt.c | 1 + drivers/watchdog/da9063_wdt.c | 1 + drivers/watchdog/davinci_wdt.c | 1 + drivers/watchdog/digicolor_wdt.c | 1 + drivers/watchdog/dw_wdt.c | 1 + drivers/watchdog/ebc-c384_wdt.c | 1 + drivers/watchdog/ep93xx_wdt.c | 1 + drivers/watchdog/ftwdt010_wdt.c | 1 + drivers/watchdog/gpio_wdt.c | 1 + drivers/watchdog/hpwdt.c | 1 + drivers/watchdog/i6300esb.c | 1 + drivers/watchdog/iTCO_wdt.c | 1 + drivers/watchdog/ie6xx_wdt.c | 1 + drivers/watchdog/imgpdc_wdt.c | 1 + drivers/watchdog/imx2_wdt.c | 1 + drivers/watchdog/intel-mid_wdt.c | 1 + drivers/watchdog/it87_wdt.c | 1 + drivers/watchdog/kempld_wdt.c | 1 + drivers/watchdog/lpc18xx_wdt.c | 1 + drivers/watchdog/max63xx_wdt.c | 1 + drivers/watchdog/max77620_wdt.c | 1 + drivers/watchdog/mei_wdt.c | 1 + drivers/watchdog/mena21_wdt.c | 1 + drivers/watchdog/menf21bmc_wdt.c | 1 + drivers/watchdog/menz69_wdt.c | 1 + drivers/watchdog/meson_gxbb_wdt.c | 1 + drivers/watchdog/meson_wdt.c | 1 + drivers/watchdog/mlx_wdt.c | 1 + drivers/watchdog/moxart_wdt.c | 1 + drivers/watchdog/mtk_wdt.c | 1 + drivers/watchdog/ni903x_wdt.c | 1 + drivers/watchdog/nic7018_wdt.c | 1 + drivers/watchdog/npcm_wdt.c | 1 + drivers/watchdog/of_xilinx_wdt.c | 1 + drivers/watchdog/omap_wdt.c | 1 + drivers/watchdog/pm8916_wdt.c | 1 + drivers/watchdog/qcom-wdt.c | 1 + drivers/watchdog/rave-sp-wdt.c | 1 + drivers/watchdog/renesas_wdt.c | 1 + drivers/watchdog/retu_wdt.c | 1 + drivers/watchdog/rn5t618_wdt.c | 1 + drivers/watchdog/rza_wdt.c | 1 + drivers/watchdog/s3c2410_wdt.c | 1 + drivers/watchdog/sama5d4_wdt.c | 1 + drivers/watchdog/sirfsoc_wdt.c | 1 + drivers/watchdog/softdog.c | 1 + drivers/watchdog/sp5100_tco.c | 1 + drivers/watchdog/sprd_wdt.c | 1 + drivers/watchdog/st_lpc_wdt.c | 1 + drivers/watchdog/stmp3xxx_rtc_wdt.c | 1 + drivers/watchdog/stpmic1_wdt.c | 1 + drivers/watchdog/sunxi_wdt.c | 1 + drivers/watchdog/tangox_wdt.c | 1 + drivers/watchdog/tegra_wdt.c | 1 + drivers/watchdog/tqmx86_wdt.c | 1 + drivers/watchdog/ts4800_wdt.c | 1 + drivers/watchdog/ts72xx_wdt.c | 1 + drivers/watchdog/twl4030_wdt.c | 1 + drivers/watchdog/uniphier_wdt.c | 1 + drivers/watchdog/via_wdt.c | 1 + drivers/watchdog/w83627hf_wdt.c | 1 + drivers/watchdog/watchdog_core.c | 10 +- drivers/watchdog/wdat_wdt.c | 1 + drivers/watchdog/wm831x_wdt.c | 1 + drivers/watchdog/wm8350_wdt.c | 1 + drivers/watchdog/xen_wdt.c | 1 + drivers/watchdog/ziirave_wdt.c | 1 + include/asm-generic/export.h | 14 +- include/linux/export.h | 98 +++++++++++-- include/linux/module.h | 2 + init/Kconfig | 13 ++ kernel/module.c | 67 ++++++++- scripts/Makefile.modpost | 4 +- scripts/coccinelle/misc/add_namespace.cocci | 23 +++ scripts/export_report.pl | 2 +- scripts/mod/modpost.c | 150 ++++++++++++++++--- scripts/mod/modpost.h | 9 ++ scripts/nsdeps | 60 ++++++++ 118 files changed, 697 insertions(+), 57 deletions(-) create mode 100644 Documentation/kbuild/namespaces.rst create mode 100644 scripts/coccinelle/misc/add_namespace.cocci create mode 100644 scripts/nsdeps