vmlinux.lds.h: Handle clang's module.{c,d}tor sections

A recent change in LLVM causes module_{c,d}tor sections to appear when
CONFIG_K{A,C}SAN are enabled, which results in orphan section warnings
because these are not handled anywhere:

ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_ctor) is being placed in '.text.asan.module_ctor'
ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_dtor) is being placed in '.text.asan.module_dtor'
ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.tsan.module_ctor) is being placed in '.text.tsan.module_ctor'

Fangrui explains: "the function asan.module_ctor has the SHF_GNU_RETAIN
flag, so it is in a separate section even with -fno-function-sections
(default)".

Place them in the TEXT_TEXT section so that these technologies continue
to work with the newer compiler versions. All of the KASAN and KCSAN
KUnit tests continue to pass after this change.

Cc: stable@vger.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/1432
Link: 7b78956224
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Fangrui Song <maskray@google.com>
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210731023107.1932981-1-nathan@kernel.org

include/asm-generic/vmlinux.lds.h

@@ -586,6 +586,7 @@
 		NOINSTR_TEXT						\
 		*(.text..refcount)					\
 		*(.ref.text)						\
+		*(.text.asan.* .text.tsan.*)				\
 		TEXT_CFI_JT						\
 	MEM_KEEP(init.text*)						\
 	MEM_KEEP(exit.text*)						\