[U-Boot] [PATCH 1/1] efi_loader: restrict EFI_LOADER to armv7 and armv8 on ARM

[Heinrich Schuchardt]

fatload USB was reported to fail on the Sheevaplug. Debugging showed that
this was caused by an incorrect unaligned write to memory in
path_to_uefi().

UEFI on ARM requires that unaligned memory access is enabled.

* ARMv5 does not support unaligned access at all.
* ARMv6 supports unaligned access when we clear the A flag and set the
  U flag.
* On ARMv7 unaligned access is possible when clearing the aligned flag,
  which we do in function allow_unaligned() (arch/arm/cpu/armv7/sctlr.S).
  For none of the other cpus in arch/arm/cpu/ we have implemented a
  similar function.
* ARMv8 allows unaligned access.

Let EFI_LOADER on ARM depend on SYS_CPU=armv7 or SYS_CPU=armv8.

Once we have implemented allow_unaligned() for other ARM CPUs we can add
these to Kconfig.

Reported-by: Gray Remlin <gryrmln at gmail.com>
Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 lib/efi_loader/Kconfig | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index c7027a9676..2f40e485ef 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -1,6 +1,9 @@
 config EFI_LOADER
 	bool "Support running UEFI applications"
-	depends on (ARM || X86 || RISCV || SANDBOX) && OF_LIBFDT
+	depends on OF_LIBFDT && ( \
+		ARM && (SYS_CPU = armv7 || \
+			SYS_CPU = armv8) || \
+		X86 || RISCV || SANDBOX)
 	# 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
--
2.24.0