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@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Marco Elver <elver@google.com>
Cc: linux-arch@vger.kernel.org
Link: https://lore.kernel.org/r/20200821194310.3089815-4-keescook@chromium.org

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index f1f02a2f71b704b2e6b102f6aa45eff5d578f3e1..6b89a03e636e46cfc5f35bf0b3bdc74751a1fe00 100644 (file)
--- 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)                                                     \