kbuild: rebuild GCC plugins when the compiler is upgraded

Linus reported a build error due to the GCC plugin incompatibility
when the compiler is upgraded. [1]

GCC plugins are tied to a particular GCC version. So, they must be
rebuilt when the compiler is upgraded.

This seems to be a long-standing flaw since the initial support of
GCC plugins.

Extend commit 8b59cd81dc5e ("kbuild: ensure full rebuild when the
compiler is updated"), so that GCC plugins are covered by the
compiler upgrade detection.

[1]: https://lore.kernel.org/lkml/CAHk-=wieoN5ttOy7SnsGwZv+Fni3R6m-Ut=oxih6bbZ28G+4dw@mail.gmail.com/

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/linux/compiler-version.h b/include/linux/compiler-version.h
new file mode 100644
index 000000000000..2b2972c77c62
--- /dev/null
+++ b/include/linux/compiler-version.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifdef  __LINUX_COMPILER_VERSION_H
+#error "Please do not include <linux/compiler-version.h>. This is done by the build system."
+#endif
+#define __LINUX_COMPILER_VERSION_H
+
+/*
+ * This header exists to force full rebuild when the compiler is upgraded.
+ *
+ * When fixdep scans this, it will find this string "CONFIG_CC_VERSION_TEXT"
+ * and add dependency on include/config/cc/version/text.h, which is touched
+ * by Kconfig when the version string from the compiler changes.
+ */