[PATCH] s390: Add assembler-level include guard to insn-common-asm.h

[Steffen Eiden <seiden@linux.ibm.com>]

The CPP include guard of insn-common-asm.h is ineffective when the file
is read via a gas-level .include from inline asm. The assembler ignores
all '#' lines, so every .include redefines GR_NUM/VX_NUM and fails with
"Macro was already defined" if a translation unit emits more than one
such include. This is not the case right now but may lead to future
build issues.

Add a .ifndef guard with an L-prefixed (local, non-emitted) symbol so
the file can be include multiple times per assembly unit.

Fixes: 495bc70aa3225 ("s390/fpu: Move GR_NUM / VX_NUM macros to separate header file")
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/asm/insn-common-asm.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/s390/include/asm/insn-common-asm.h b/arch/s390/include/asm/insn-common-asm.h
index fd9b3cacb7c5..060116719846 100644
--- a/arch/s390/include/asm/insn-common-asm.h
+++ b/arch/s390/include/asm/insn-common-asm.h
@@ -9,6 +9,10 @@
 
 #ifdef __ASSEMBLER__
 
+/* Prevent duplicated GAS macro definitions. CPP guards have no effect for GAS.*/
+.ifndef .Lasm_s390_insn_common_asm_h
+.Lasm_s390_insn_common_asm_h = 1
+
 /*
  * GR_NUM - Retrieve general-purpose register number
  *
@@ -49,5 +53,7 @@
 	.endif
 .endm
 
+.endif	/* .Lasm_s390_insn_common_asm_h */
+
 #endif	/* __ASSEMBLER__ */
 #endif	/* __ASM_S390_INSN_COMMON_ASM_H */