linux-kernel - [PATCH 17/28] efi/x86: Add kernel preferred address to PE header

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Message-Id: <20200308080859.21568-18-ardb@kernel.org>
Date:   Sun,  8 Mar 2020 09:08:48 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ard Biesheuvel <ardb@...nel.org>, linux-kernel@...r.kernel.org,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Christoph Hellwig <hch@....de>,
        David Hildenbrand <david@...hat.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Guenter Roeck <linux@...ck-us.net>,
        Heinrich Schuchardt <xypron.glpk@....de>,
        Jonathan Corbet <corbet@....net>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nikolai Merinov <n.merinov@...ngo-systems.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Vladis Dronov <vdronov@...hat.com>
Subject: [PATCH 17/28] efi/x86: Add kernel preferred address to PE header

From: Arvind Sankar <nivedita@...m.mit.edu>

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>
Link: https://lore.kernel.org/r/20200303221205.4048668-4-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 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..736b3a0c9454 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	image_base, (LOAD_PHYSICAL_ADDR + 0xffff) & ~0xffff
 #ifdef CONFIG_X86_32
-	.long	0				# ImageBase
+	.long	image_base			# ImageBase
 #else
-	.quad	0				# ImageBase
+	.quad	image_base			# ImageBase
 #endif
 	.long	0x20				# SectionAlignment
 	.long	0x20				# FileAlignment
-- 
2.17.1