From 8bd51a2ba3c3bb81a693fff17e983d02d914c14c Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 20 Oct 2021 10:35:53 -0700 Subject: gcc-plugins: Explicitly document purpose and deprecation schedule 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 Cc: Michal Marek Cc: Nick Desaulniers Cc: Jonathan Corbet Cc: James Morris Cc: "Serge E. Hallyn" Cc: Nathan Chancellor 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 Reviewed-by: Nathan Chancellor Reviewed-by: Miguel Ojeda Acked-by: Nick Desaulniers Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20211020173554.38122-2-keescook@chromium.org --- Documentation/kbuild/gcc-plugins.rst | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'Documentation/kbuild') diff --git a/Documentation/kbuild/gcc-plugins.rst b/Documentation/kbuild/gcc-plugins.rst index 3349966f213d..4b28c7a4032f 100644 --- a/Documentation/kbuild/gcc-plugins.rst +++ b/Documentation/kbuild/gcc-plugins.rst @@ -32,6 +32,32 @@ This infrastructure was ported from grsecurity [6]_ and PaX [7]_. .. [7] https://pax.grsecurity.net/ +Purpose +======= + +GCC plugins are designed to provide a place to experiment with potential +compiler features that are neither in GCC nor Clang upstream. Once +their utility is proven, the goal is to upstream the feature into GCC +(and Clang), and then to finally remove them from the kernel once the +feature is available in all supported versions of GCC. + +Specifically, new plugins should implement only features that have no +upstream compiler support (in either GCC or Clang). + +When a feature exists in Clang but not GCC, effort should be made to +bring the feature to upstream GCC (rather than just as a kernel-specific +GCC plugin), so the entire ecosystem can benefit from it. + +Similarly, even if a feature provided by a GCC plugin does *not* exist +in Clang, but the feature is proven to be useful, effort should be spent +to upstream the feature to GCC (and Clang). + +After a feature is available in upstream GCC, the plugin will be made +unbuildable for the corresponding GCC version (and later). Once all +kernel-supported versions of GCC provide the feature, the plugin will +be removed from the kernel. + + Files ===== -- cgit v1.2.3