linux-kernel - [PATCH 3/5] efi/x86: Add kernel preferred address to PE header

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Message-Id: <20200301230537.2247550-4-nivedita@alum.mit.edu>
Date:   Sun,  1 Mar 2020 18:05:35 -0500
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     linux-efi@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/5] efi/x86: Add kernel preferred address to PE header

Store the kernel's link address as ImageBase in the PE header. Note that
the PE specification requires the ImageBase to be 64k aligned. The
preferred address should almost always satisfy that, except for 32-bit
kernel if the configuration has been customized.

Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
---
 arch/x86/boot/header.S | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 4ee25e28996f..0d8d2cb28fd9 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -138,10 +138,12 @@ optional_header:
 #endif
 
 extra_header_fields:
+	# PE specification requires ImageBase to be 64k-aligned
+	.set	ImageBase, (LOAD_PHYSICAL_ADDR+0xffff) & ~0xffff
 #ifdef CONFIG_X86_32
-	.long	0				# ImageBase
+	.long	ImageBase			# ImageBase
 #else
-	.quad	0				# ImageBase
+	.quad	ImageBase			# ImageBase
 #endif
 	.long	0x20				# SectionAlignment
 	.long	0x20				# FileAlignment
-- 
2.24.1