linux-kernel - [PATCH] x86: Set the NX-compatibility flag in the PE header

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Message-Id: <20220329184743.798513-1-pjones@redhat.com>
Date:   Tue, 29 Mar 2022 14:47:43 -0400
From:   Peter Jones <pjones@...hat.com>
To:     baskov@...ras.ru
Cc:     ardb@...nel.org, Matthew Garrett <mjg59@...f.ucam.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        X86 ML <x86@...nel.org>, linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Peter Jones <pjones@...hat.com>
Subject: [PATCH] x86: Set the NX-compatibility flag in the PE header

Following Baskov Evgeniy's "Handle UEFI NX-restricted page tables"
patches, it's safe to set this compatibility flag to let loaders know
they don't need to make special accommodations for kernel to load if
pre-boot NX is enabled.

Signed-off-by: Peter Jones <pjones@...hat.com>
---
 arch/x86/boot/header.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 6dbd7e9f74c..0352e4589ef 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -163,7 +163,11 @@ extra_header_fields:
 	.long	0x200				# SizeOfHeaders
 	.long	0				# CheckSum
 	.word	IMAGE_SUBSYSTEM_EFI_APPLICATION	# Subsystem (EFI application)
+#ifdef CONFIG_DXE_MEM_ATTRIBUTES
+	.word	IMAGE_DLL_CHARACTERISTICS_NX_COMPAT	# DllCharacteristics
+#else
 	.word	0				# DllCharacteristics
+#endif
 #ifdef CONFIG_X86_32
 	.long	0				# SizeOfStackReserve
 	.long	0				# SizeOfStackCommit
-- 
2.35.1