efi: Conflict efi_loader with different stub bitness

We have 2 users of the EFI headers: efi_loader and the EFI stub. Efi_loader
always expects that the bitness of the definitions it uses is identical to
the execution.

The EFI stub however allows to run x86_64 U-Boot on 32bit EFI and the other
way around, so it allows for different bitness of EFI definitions and U-Boot
environment.

This patch explicitly requests via Kconfig that efi_loader can only be enabled
if the bitness is identical. Because we can run efi_loader on x86_64 without
EFI stub enabled, it also ensures that this case propagates the correct ABI
constraints.

Signed-off-by: Alexander Graf <agraf@suse.de>

include/efi.h

@@ -19,7 +19,7 @@
 #include <linux/string.h>
 #include <linux/types.h>
 
-#ifdef CONFIG_EFI_STUB_64BIT
+#if CONFIG_EFI_STUB_64BIT || (!defined(CONFIG_EFI_STUB) && defined(__x86_64__))
 /* EFI uses the Microsoft ABI which is not the default for GCC */
 #define EFIAPI __attribute__((ms_abi))
 #else

lib/efi_loader/Kconfig

@@ -1,6 +1,10 @@
 config EFI_LOADER
 	bool "Support running EFI Applications in U-Boot"
 	depends on (ARM || X86) && OF_LIBFDT
+	# We need EFI_STUB_64BIT to be set on x86_64 with EFI_STUB
+	depends on !EFI_STUB || !X86_64 || EFI_STUB_64BIT
+	# We need EFI_STUB_32BIT to be set on x86_32 with EFI_STUB
+	depends on !EFI_STUB || !X86 || X86_64 || EFI_STUB_32BIT
 	default y
 	help
 	  Select this option if you want to run EFI applications (like grub2)