linux-kernel - [PATCH v3 5/6] x86/boot: Move .head.text into its own output section

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Message-ID: <20241125170411.1898410-13-ardb+git@google.com>
Date: Mon, 25 Nov 2024 18:04:16 +0100
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-kernel@...r.kernel.org
Cc: x86@...nel.org, Ard Biesheuvel <ardb@...nel.org>, Tom Lendacky <thomas.lendacky@....com>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, Andy Lutomirski <luto@...nel.org>, 
	Arnd Bergmann <arnd@...db.de>, Kees Cook <keescook@...omium.org>, Brian Gerst <brgerst@...il.com>, 
	Kevin Loughlin <kevinloughlin@...gle.com>
Subject: [PATCH v3 5/6] x86/boot: Move .head.text into its own output section

From: Ard Biesheuvel <ardb@...nel.org>

In order to be able to double check that vmlinux is emitted without
absolute symbol references in .head.text, it needs to be distinguishable
from the rest of .text in the ELF metadata.

So move .head.text into its own ELF section.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/kernel/vmlinux.lds.S | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index c98bc91bafef..9c194df2c8e4 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -135,8 +135,6 @@ SECTIONS
 #endif
 		ALIGN_ENTRY_TEXT_END
 
-		/* bootstrapping code */
-		HEAD_TEXT
 		TEXT_TEXT
 		SCHED_TEXT
 		LOCK_TEXT
@@ -151,6 +149,11 @@ SECTIONS
 
 	} :text = 0xcccccccc
 
+	/* bootstrapping code */
+	.head.text : AT(ADDR(.head.text) - LOAD_OFFSET) {
+		HEAD_TEXT
+	} :text = 0xcccccccc
+
 	/* End of text section, which should occupy whole number of pages */
 	_etext = .;
 	. = ALIGN(PAGE_SIZE);
-- 
2.47.0.371.ga323438b13-goog