linux-kernel - [RFC/RFT PATCH 10/19] x86/kvm: Use RIP-relative addressing

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Message-ID: <20260108092526.28586-31-ardb@kernel.org>
Date: Thu,  8 Jan 2026 09:25:37 +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 10/19] x86/kvm: Use RIP-relative addressing

Replace absolute references in inline asm with RIP-relative ones, to
avoid the need for relocation fixups at boot time. This is a
prerequisite for PIE linking, which only permits 64-bit wide
loader-visible absolute references.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/kernel/kvm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index df78ddee0abb..1a0335f328e1 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -807,8 +807,9 @@ extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
  * restoring to/from the stack.
  */
 #define PV_VCPU_PREEMPTED_ASM						     \
- "movq   __per_cpu_offset(,%rdi,8), %rax\n\t"				     \
- "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax)\n\t" \
+ "0:leaq 0b(%rip), %rax\n\t"						     \
+ "addq   __per_cpu_offset - 0b(%rax,%rdi,8), %rax\n\t"			     \
+ "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time-0b(%rax)\n\t" \
  "setne  %al\n\t"
 
 DEFINE_ASM_FUNC(__raw_callee_save___kvm_vcpu_is_preempted,
-- 
2.47.3