[PATCH 4/4] x86/percpu: Introduce %rip-relative addressing to PER_CPU_VAR macro

[Uros Bizjak <ubizjak@xxxxxxxxx>]

Introduce x86_64 %rip-relative addressing to PER_CPU_VAR macro.
Instruction with %rip-relative address operand is one byte shorter than
its absolute address counterpart and is also compatible with position
independent executable (-fpie) build.

Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
---
 arch/x86/include/asm/percpu.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 34734d730463..9a5f1896c5ef 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -4,16 +4,18 @@
 
 #ifdef CONFIG_X86_64
 #define __percpu_seg           gs
+#define __percpu_rel           (%rip)
 #else
 #define __percpu_seg           fs
+#define __percpu_rel
 #endif
 
 #ifdef __ASSEMBLY__
 
 #ifdef CONFIG_SMP
-#define PER_CPU_VAR(var)       %__percpu_seg:var
+#define PER_CPU_VAR(var)       %__percpu_seg:(var)##__percpu_rel
 #else /* ! SMP */
-#define PER_CPU_VAR(var)       var
+#define PER_CPU_VAR(var)       (var)##__percpu_rel
 #endif /* SMP */
 
 #ifdef CONFIG_X86_64_SMP
-- 
2.41.0