[tip: x86/boot] x86/boot/startup: Disable objtool validation for library code

[tip-bot2 for Ard Biesheuvel]

The following commit has been merged into the x86/boot branch of tip:

Commit-ID:     d9fa398fe82728ee703ad2bd9cf5247df9626470
Gitweb:        https://git.kernel.org/tip/d9fa398fe82728ee703ad2bd9cf5247df9626470
Author:        Ard Biesheuvel <ardb@xxxxxxxxxx>
AuthorDate:    Tue, 08 Apr 2025 10:52:56 +02:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 09 Apr 2025 11:59:03 +02:00

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@xxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: David Woodhouse <dwmw@xxxxxxxxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20250408085254.836788-10-ardb+git@xxxxxxxxxx
---
 arch/x86/boot/startup/Makefile | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/boot/startup/Makefile b/arch/x86/boot/startup/Makefile
index 73946a3..8919a1c 100644
--- 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