[tip: core/build] vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections

[tip-bot2 for Kees Cook]

The following commit has been merged into the core/build branch of tip:

Commit-ID:     d812db78288d76d1e8c6df3a840c41a8875f6468
Gitweb:        https://git.kernel.org/tip/d812db78288d76d1e8c6df3a840c41a8875f6468
Author:        Kees Cook <keescook@xxxxxxxxxxxx>
AuthorDate:    Fri, 21 Aug 2020 12:42:44 -07:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 01 Sep 2020 09:50:35 +02:00

vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections

KASAN (-fsanitize=kernel-address) and KCSAN (-fsanitize=thread)
produce unwanted[1] .eh_frame and .init_array.* sections. Add them to
COMMON_DISCARDS, except with CONFIG_CONSTRUCTORS, which wants to keep
.init_array.* sections.

[1] https://bugs.llvm.org/show_bug.cgi?id=46478

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Tested-by: Marco Elver <elver@xxxxxxxxxx>
Cc: linux-arch@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20200821194310.3089815-4-keescook@xxxxxxxxxxxx
---
 include/asm-generic/vmlinux.lds.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index f1f02a2..6b89a03 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -954,7 +954,27 @@
 	EXIT_DATA
 #endif
 
+/*
+ * Clang's -fsanitize=kernel-address and -fsanitize=thread produce
+ * unwanted sections (.eh_frame and .init_array.*), but
+ * CONFIG_CONSTRUCTORS wants to keep any .init_array.* sections.
+ * https://bugs.llvm.org/show_bug.cgi?id=46478
+ */
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KCSAN)
+# ifdef CONFIG_CONSTRUCTORS
+#  define SANITIZER_DISCARDS						\
+	*(.eh_frame)
+# else
+#  define SANITIZER_DISCARDS						\
+	*(.init_array) *(.init_array.*)					\
+	*(.eh_frame)
+# endif
+#else
+# define SANITIZER_DISCARDS
+#endif
+
 #define COMMON_DISCARDS							\
+	SANITIZER_DISCARDS						\
 	*(.discard)							\
 	*(.discard.*)							\
 	*(.modinfo)							\