riscv: efi: Set NX compat flag in PE/COFF header

[ Upstream commit d41373a4b910961df5a5e3527d7bde6ad45ca438 ]

The IMAGE_DLLCHARACTERISTICS_NX_COMPAT informs the firmware that the
EFI binary does not rely on pages that are both executable and
writable.

The flag is used by some distro versions of GRUB to decide if the EFI
binary may be executed.

As the Linux kernel neither has RWX sections nor needs RWX pages for
relocation we should set the flag.

Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Fixes: cb7d2dd5612a ("RISC-V: Add PE/COFF header for EFI stub")
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240929140233.211800-1-heinrich.schuchardt@canonical.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/riscv/kernel/efi-header.S b/arch/riscv/kernel/efi-header.S
index 8e733aa48ba6cbc2f2f62e1ac74b107b737676f6..c306f3a6a800e2ec33ae2f0a8f1fbc99e815c97e 100644 (file)
--- a/arch/riscv/kernel/efi-header.S
+++ b/arch/riscv/kernel/efi-header.S
@@ -59,7 +59,7 @@ extra_header_fields:
        .long   efi_header_end - _start                 // SizeOfHeaders
        .long   0                                       // CheckSum
        .short  IMAGE_SUBSYSTEM_EFI_APPLICATION         // Subsystem
-       .short  0                                       // DllCharacteristics
+       .short  IMAGE_DLL_CHARACTERISTICS_NX_COMPAT     // DllCharacteristics
        .quad   0                                       // SizeOfStackReserve
        .quad   0                                       // SizeOfStackCommit
        .quad   0                                       // SizeOfHeapReserve