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* docs/core-api: expand Fedora instructions for GCC pluginsRobert Elliott2022-09-271-1/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In Fedora 36, cross-compiling an allmodconfig configuration for other architectures on x86 fails with this problem: In file included from ../scripts/gcc-plugins/gcc-common.h:95, from ../scripts/gcc-plugins/latent_entropy_plugin.c:78: /usr/lib/gcc/aarch64-linux-gnu/12/plugin/include/builtins.h:23:10: fatal error: mpc.h: No such file or directory 23 | #include <mpc.h> | ^~~~~~~ compilation terminated. In that distro, that header file is available in the separate libmpc-devel package. Although future versions of Fedora might correctly mark that dependency, mention this additional package. To help detect such problems ahead of time, describe the gcc -print-file-name=plugin command that is used by scripts/gcc-plugins/Kconfig to detect plugins [1]. [1] https://lore.kernel.org/lkml/CAHk-=wjjiYjCp61gdAMpDOsUBU-A2hFFKJoVx5VAC7yV4K6WYg@xxxxxxxxxxxxxx/ Fixes: 43e96ef8b70c50f ("docs/core-api: Add Fedora instructions for GCC plugins"); Signed-off-by: Robert Elliott <elliott@hpe.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220827193836.2582079-1-elliott@hpe.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* gcc-plugins: Remove cyc_complexityKees Cook2021-10-211-2/+0
| | | | | | | | | | | | | | | | | | | | | This plugin has no impact on the resulting binary, is disabled under COMPILE_TEST, and is not enabled on any builds I'm aware of. Additionally, given the clarified purpose of GCC plugins in the kernel, remove cyc_complexity. Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-hardening@vger.kernel.org Cc: linux-kbuild@vger.kernel.org Cc: linux-doc@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20211020173554.38122-3-keescook@chromium.org
* gcc-plugins: Explicitly document purpose and deprecation scheduleKees Cook2021-10-211-0/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | GCC plugins should only exist when some compiler feature needs to be proven but does not exist in either GCC nor Clang. For example, if a desired feature is already in Clang, it should be added to GCC upstream. Document this explicitly. Additionally, mark the plugins with matching upstream GCC features as removable past their respective GCC versions. Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: James Morris <jmorris@namei.org> Cc: "Serge E. Hallyn" <serge@hallyn.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: linux-hardening@vger.kernel.org Cc: linux-kbuild@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: llvm@lists.linux.dev Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20211020173554.38122-2-keescook@chromium.org
* doc: gcc-plugins: update gcc-plugins.rstMasahiro Yamada2021-01-251-20/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This document was written a long time ago. Update it. [1] Drop the version information The range of the supported GCC versions are always changing. The current minimal GCC version is 4.9, and commit 1e860048c53e ("gcc-plugins: simplify GCC plugin-dev capability test") removed the old code accordingly. We do not need to mention specific version ranges like "all gcc versions from 4.5 to 6.0" since we forget to update the documentation when we raise the minimal compiler version. [2] Drop the C compiler statements Since commit 77342a02ff6e ("gcc-plugins: drop support for GCC <= 4.7") the GCC plugin infrastructure only supports g++. [3] Drop supported architectures As of v5.11-rc4, the infrastructure supports more architectures; arm, arm64, mips, powerpc, riscv, s390, um, and x86. (just grep "select HAVE_GCC_PLUGINS") Again, we miss to update this document when a new architecture is supported. Let's just say "only some architectures". [4] Update the apt-get example We are now discussing to bump the minimal version to GCC 5. The GCC 4.9 support will be removed sooner or later. Change the package example to gcc-10-plugin-dev while we are here. [5] Update the build target Since commit ce2fd53a10c7 ("kbuild: descend into scripts/gcc-plugins/ via scripts/Makefile"), "make gcc-plugins" is not supported. "make scripts" builds all the enabled plugins, including some other tools. [6] Update the steps for adding a new plugin At first, all CONFIG options for GCC plugins were located in arch/Kconfig. After commit 45332b1bdfdc ("gcc-plugins: split out Kconfig entries to scripts/gcc-plugins/Kconfig"), scripts/gcc-plugins/Kconfig became the central place to collect plugin CONFIG options. In my understanding, this requirement no longer exists because commit 9f671e58159a ("security: Create "kernel hardening" config area") moved some of plugin CONFIG options to another file. Find an appropriate place to add the new CONFIG. The sub-directory support was never used by anyone, and removed by commit c17d6179ad5a ("gcc-plugins: remove unused GCC_PLUGIN_SUBDIR"). Remove the useless $(src)/ prefix. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
* Documentation/Kbuild: Remove references to gcc-plugin.shRobert Karszniewicz2021-01-231-6/+0
| | | | | | | | | gcc-plugin.sh has been removed in commit 1e860048c53e ("gcc-plugins: simplify GCC plugin-dev capability test"). Signed-off-by: Robert Karszniewicz <r.karszniewicz@phytec.de> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
* docs: move gcc-plugins to the kbuild manualJonathan Corbet2020-03-101-0/+97
Information about GCC plugins is relevant to kernel building, so move this document to the kbuild manual. Acked-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>