linux-kernel - [PATCH 1/1] riscv: efi: Set NX compat flag in PE/COFF header

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Message-ID: <20240929140233.211800-1-heinrich.schuchardt@canonical.com>
Date: Sun, 29 Sep 2024 16:02:33 +0200
From: Heinrich Schuchardt <heinrich.schuchardt@...onical.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>
Cc: Ard Biesheuvel <ardb@...nel.org>,
	Emil Renner Berthing <emil.renner.berthing@...onical.com>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
	stable@...r.kernel.org
Subject: [PATCH 1/1] riscv: efi: Set NX compat flag in PE/COFF header

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@...nel.org>
Cc: <stable@...r.kernel.org>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@...onical.com>
---
 arch/riscv/kernel/efi-header.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/efi-header.S b/arch/riscv/kernel/efi-header.S
index 515b2dfbca75..c5f17c2710b5 100644
--- a/arch/riscv/kernel/efi-header.S
+++ b/arch/riscv/kernel/efi-header.S
@@ -64,7 +64,7 @@ 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
-- 
2.45.2