x86/boot/startup: Disable objtool validation for library code

The library code built under arch/x86/boot/startup is not intended to be
linked into vmlinux but only into the decompressor and/or the EFI stub.

This means objtool validation is not needed here, and may result in
false positive errors for things like missing retpolines.

So disable it for all objects added to lib-y

Tested-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20250408085254.836788-10-ardb+git@google.com

diff --git a/arch/x86/boot/startup/Makefile b/arch/x86/boot/startup/Makefile
index 73946a3f6b3baab721751a10b3801e3710ed3871..8919a1cbcb5aec4b6ffe8fdfa2838506150f3739 100644 (file)
--- a/arch/x86/boot/startup/Makefile
+++ b/arch/x86/boot/startup/Makefile
@@ -4,3 +4,9 @@ KBUILD_AFLAGS           += -D__DISABLE_EXPORTS
 
 lib-$(CONFIG_X86_64)           += la57toggle.o
 lib-$(CONFIG_EFI_MIXED)                += efi-mixed.o
+
+#
+# Disable objtool validation for all library code, which is intended
+# to be linked into the decompressor or the EFI stub but not vmlinux
+#
+$(patsubst %.o,$(obj)/%.o,$(lib-y)): OBJECT_FILES_NON_STANDARD := y