ubsan: disable UBSAN_ALIGNMENT under COMPILE_TEST

The documentation for UBSAN_ALIGNMENT already mentions that it should
not be used on all*config builds (and for efficient-unaligned-access
architectures), so just refactor the Kconfig to correctly implement this
so randconfigs will stop creating insane images that freak out objtool
under CONFIG_UBSAN_TRAP (due to the false positives producing functions
that never return, etc).

Link: http://lkml.kernel.org/r/202005011433.C42EA3E2D@keescook
Fixes: 0887a7e ("ubsan: add trap instrumentation option")
Signed-off-by: Kees Cook <[email protected]>
Reported-by: Randy Dunlap <[email protected]>
  Link: https://lore.kernel.org/linux-next/202004231224.D6B3B650@keescook/
Signed-off-by: Andrew Morton <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: kees

lib/Kconfig.ubsan

@@ -60,18 +60,15 @@ config UBSAN_SANITIZE_ALL
 	  Enabling this option will get kernel image size increased
 	  significantly.
 
-config UBSAN_NO_ALIGNMENT
-	bool "Disable checking of pointers alignment"
-	default y if HAVE_EFFICIENT_UNALIGNED_ACCESS
+config UBSAN_ALIGNMENT
+	bool "Enable checks for pointers alignment"
+	default !HAVE_EFFICIENT_UNALIGNED_ACCESS
+	depends on !X86 || !COMPILE_TEST
 	help
-	  This option disables the check of unaligned memory accesses.
-	  This option should be used when building allmodconfig.
-	  Disabling this option on architectures that support unaligned
+	  This option enables the check of unaligned memory accesses.
+	  Enabling this option on architectures that support unaligned
 	  accesses may produce a lot of false positives.
 
-config UBSAN_ALIGNMENT
-	def_bool !UBSAN_NO_ALIGNMENT
-
 config TEST_UBSAN
 	tristate "Module for testing for undefined behavior detection"
 	depends on m

tools/testing/selftests/wireguard/qemu/debug.config

@@ -25,7 +25,6 @@ CONFIG_KASAN=y
 CONFIG_KASAN_INLINE=y
 CONFIG_UBSAN=y
 CONFIG_UBSAN_SANITIZE_ALL=y
-CONFIG_UBSAN_NO_ALIGNMENT=y
 CONFIG_UBSAN_NULL=y
 CONFIG_DEBUG_KMEMLEAK=y
 CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE=8192