linux-kernel - [RFC/RFT PATCH 16/19] x86/kexec: Use 64-bit wide absolute reference from relocated code

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Message-ID: <20260108092526.28586-37-ardb@kernel.org>
Date: Thu,  8 Jan 2026 09:25:43 +0000
From: Ard Biesheuvel <ardb@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: x86@...nel.org,
	Ard Biesheuvel <ardb@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Kees Cook <kees@...nel.org>,
	Uros Bizjak <ubizjak@...il.com>,
	Brian Gerst <brgerst@...il.com>,
	linux-hardening@...r.kernel.org
Subject: [RFC/RFT PATCH 16/19] x86/kexec: Use 64-bit wide absolute reference from relocated code

The virtual_mapped() kexec routine runs from a different virtual address
than it was linked at, and so it needs to use an absolute reference to
load the address of 'saved_context'. Change this reference to a 64-bit
wide one, to make the code compatible with linking in PIE mode.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/kernel/relocate_kernel_64.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 4ffba68dc57b..3fc1a3002e32 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -311,7 +311,7 @@ SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
 
 #ifdef CONFIG_KEXEC_JUMP
 	/* Saved in save_processor_state. */
-	movq    $saved_context, %rax
+	movabsq $saved_context, %rax
 	lgdt    saved_context_gdt_desc(%rax)
 #endif
 
-- 
2.47.3