From patchwork Wed Mar 23 23:05:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12790207 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC0E9C433FE for ; Wed, 23 Mar 2022 23:05:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6EC098D0002; Wed, 23 Mar 2022 19:05:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 69CE36B007E; Wed, 23 Mar 2022 19:05:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 53CF78D0002; Wed, 23 Mar 2022 19:05:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 42CE26B007D for ; Wed, 23 Mar 2022 19:05:41 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 11006603FB for ; Wed, 23 Mar 2022 23:05:41 +0000 (UTC) X-FDA: 79277184882.07.D744EDB Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf12.hostedemail.com (Postfix) with ESMTP id 9EEA640043 for ; Wed, 23 Mar 2022 23:05:40 +0000 (UTC) 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 dfw.source.kernel.org (Postfix) with ESMTPS id C21F9617E9; Wed, 23 Mar 2022 23:05:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D902C340E8; Wed, 23 Mar 2022 23:05:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1648076739; bh=+f3rUuDNxc81m2Jg3Zqw6cT9a2fhWcGb1YWcyGTif48=; h=Date:To:From:In-Reply-To:Subject:From; b=vafyV8D3ZJ44kEH1usoYM/BcueKMhSsjCTE/TCA7BvmTCul9J9cyO0/0g4xmpLgwN Ht618XsacXiPtvGun1cJ/5A9WOlrDLYhzxz7BQ4LTRoGrhLgl9389ba81iyRyVgp8G SuNt3rkS4bIbcH7+pLmq84ycFaHObB3vE54ddM1I= Date: Wed, 23 Mar 2022 16:05:38 -0700 To: penguin-kernel@I-love.SAKURA.ne.jp,ndesaulniers@google.com,nathan@kernel.org,masahiroy@kernel.org,arnd@arndb.de,keescook@chromium.org,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220323160453.65922ced539cbf445b191555@linux-foundation.org> Subject: [patch 07/41] Kconfig.debug: make DEBUG_INFO selectable from a choice Message-Id: <20220323230539.1D902C340E8@smtp.kernel.org> X-Rspam-User: Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=vafyV8D3; spf=pass (imf12.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 9EEA640043 X-Stat-Signature: txnzs9onmanzic4xokxr7e8dis3ss1t1 X-HE-Tag: 1648076740-976825 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Kees Cook Subject: Kconfig.debug: make DEBUG_INFO selectable from a choice Currently it's not possible to enable DEBUG_INFO for an all*config build, since it is marked as "depends on !COMPILE_TEST". This generally makes sense because a debug build of an all*config target ends up taking much longer and the output is much larger. Having this be "default off" makes sense. However, there are cases where enabling DEBUG_INFO for such builds is useful for doing treewide A/B comparisons of build options, etc. Make DEBUG_INFO selectable from any of the DWARF version choice options, with DEBUG_INFO_NONE being the default for COMPILE_TEST. The mutually exclusive relationship between DWARF5 and BTF must be inverted, but the result remains the same. Additionally moves DEBUG_KERNEL and DEBUG_MISC up to the top of the menu because they were enabling features _above_ it, making it weird to navigate menuconfig. [keescook@chromium.org: make DEBUG_INFO always default=n] Link: https://lkml.kernel.org/r/20220128214131.580131-1-keescook@chromium.org Link: https://lore.kernel.org/lkml/YfRY6+CaQxX7O8vF@dev-arch.archlinux-ax161 Link: https://lkml.kernel.org/r/20220125075126.891825-1-keescook@chromium.org Signed-off-by: Kees Cook Suggested-by: Arnd Bergmann Reviewed-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers Reviewed-by: Masahiro Yamada Cc: Nick Desaulniers Cc: Tetsuo Handa Signed-off-by: Andrew Morton --- lib/Kconfig.debug | 139 +++++++++++++++++++++++--------------------- 1 file changed, 74 insertions(+), 65 deletions(-) --- a/lib/Kconfig.debug~kconfigdebug-make-debug_info-selectable-from-a-choice +++ a/lib/Kconfig.debug @@ -208,20 +208,87 @@ config DEBUG_BUGVERBOSE endmenu # "printk and dmesg options" +config DEBUG_KERNEL + bool "Kernel debugging" + help + Say Y here if you are developing drivers or trying to debug and + identify kernel problems. + +config DEBUG_MISC + bool "Miscellaneous debug code" + default DEBUG_KERNEL + depends on DEBUG_KERNEL + help + Say Y here if you need to enable miscellaneous debug code that should + be under a more specific debug option but isn't. + menu "Compile-time checks and compiler options" config DEBUG_INFO - bool "Compile the kernel with debug info" - depends on DEBUG_KERNEL && !COMPILE_TEST + bool help - If you say Y here the resulting kernel image will include - debugging info resulting in a larger kernel image. + A kernel debug info option other than "None" has been selected + in the "Debug information" choice below, indicating that debug + information will be generated for build targets. + +choice + prompt "Debug information" + depends on DEBUG_KERNEL + help + Selecting something other than "None" results in a kernel image + that will include debugging info resulting in a larger kernel image. This adds debug symbols to the kernel and modules (gcc -g), and is needed if you intend to use kernel crashdump or binary object tools like crash, kgdb, LKCD, gdb, etc on the kernel. - Say Y here only if you plan to debug the kernel. - If unsure, say N. + Choose which version of DWARF debug info to emit. If unsure, + select "Toolchain default". + +config DEBUG_INFO_NONE + bool "Disable debug information" + help + Do not build the kernel with debugging information, which will + result in a faster and smaller build. + +config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT + bool "Rely on the toolchain's implicit default DWARF version" + select DEBUG_INFO + help + The implicit default version of DWARF debug info produced by a + toolchain changes over time. + + This can break consumers of the debug info that haven't upgraded to + support newer revisions, and prevent testing newer versions, but + those should be less common scenarios. + +config DEBUG_INFO_DWARF4 + bool "Generate DWARF Version 4 debuginfo" + select DEBUG_INFO + help + Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+. + + If you have consumers of DWARF debug info that are not ready for + newer revisions of DWARF, you may wish to choose this or have your + config select this. + +config DEBUG_INFO_DWARF5 + bool "Generate DWARF Version 5 debuginfo" + select DEBUG_INFO + depends on !CC_IS_CLANG || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502))) + help + Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc + 5.0+ accepts the -gdwarf-5 flag but only had partial support for some + draft features until 7.0), and gdb 8.0+. + + Changes to the structure of debug info in Version 5 allow for around + 15-18% savings in resulting image and debug info section sizes as + compared to DWARF Version 4. DWARF Version 5 standardizes previous + extensions such as accelerators for symbol indexing and the format + for fission (.dwo/.dwp) files. Users may not want to select this + config if they rely on tooling that has not yet been updated to + support DWARF Version 5. + +endchoice # "Debug information" if DEBUG_INFO @@ -267,56 +334,12 @@ config DEBUG_INFO_SPLIT to know about the .dwo files and include them. Incompatible with older versions of ccache. -choice - prompt "DWARF version" - help - Which version of DWARF debug info to emit. - -config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT - bool "Rely on the toolchain's implicit default DWARF version" - help - The implicit default version of DWARF debug info produced by a - toolchain changes over time. - - This can break consumers of the debug info that haven't upgraded to - support newer revisions, and prevent testing newer versions, but - those should be less common scenarios. - - If unsure, say Y. - -config DEBUG_INFO_DWARF4 - bool "Generate DWARF Version 4 debuginfo" - help - Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+. - - If you have consumers of DWARF debug info that are not ready for - newer revisions of DWARF, you may wish to choose this or have your - config select this. - -config DEBUG_INFO_DWARF5 - bool "Generate DWARF Version 5 debuginfo" - depends on !CC_IS_CLANG || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502))) - depends on !DEBUG_INFO_BTF - help - Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc - 5.0+ accepts the -gdwarf-5 flag but only had partial support for some - draft features until 7.0), and gdb 8.0+. - - Changes to the structure of debug info in Version 5 allow for around - 15-18% savings in resulting image and debug info section sizes as - compared to DWARF Version 4. DWARF Version 5 standardizes previous - extensions such as accelerators for symbol indexing and the format - for fission (.dwo/.dwp) files. Users may not want to select this - config if they rely on tooling that has not yet been updated to - support DWARF Version 5. - -endchoice # "DWARF version" - config DEBUG_INFO_BTF bool "Generate BTF typeinfo" depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST depends on BPF_SYSCALL + depends on !DEBUG_INFO_DWARF5 help Generate deduplicated BTF type information from DWARF debug info. Turning this on expects presence of pahole tool, which will convert @@ -585,20 +608,6 @@ source "lib/Kconfig.kcsan" endmenu -config DEBUG_KERNEL - bool "Kernel debugging" - help - Say Y here if you are developing drivers or trying to debug and - identify kernel problems. - -config DEBUG_MISC - bool "Miscellaneous debug code" - default DEBUG_KERNEL - depends on DEBUG_KERNEL - help - Say Y here if you need to enable miscellaneous debug code that should - be under a more specific debug option but isn't. - menu "Networking Debugging" source "net/Kconfig.debug"