[PATCH v2] s390: Guard emitting assembler macros for 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 header 'asm/insn-common-asm-emit.h' that can be used by C/H files
which want to emit those macros. The header guards the GAS include to
prevent multiple includes in one compilation unit.

Co-developed-by: Andreas Grapentin <gra@linux.ibm.com>
Signed-off-by: Andreas Grapentin <gra@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
Changes in v2:
- Use a separate -emit header and CPP Guards to guard the asm .include.
  (Andreas)
- Link to v1: https://lore.kernel.org/r/20261102-insn-v1-1-df048a0be0d5@linux.ibm.com
---
 arch/s390/include/asm/fpu-insn.h             | 2 +-
 arch/s390/include/asm/insn-common-asm-emit.h | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/fpu-insn.h b/arch/s390/include/asm/fpu-insn.h
index eeb0a233d5c7..aaf1faeb3dc5 100644
--- a/arch/s390/include/asm/fpu-insn.h
+++ b/arch/s390/include/asm/fpu-insn.h
@@ -14,8 +14,8 @@
 #include <linux/instrumented.h>
 #include <linux/kmsan.h>
 #include <asm/asm-extable.h>
+#include <asm/insn-common-asm-emit.h>
 
-asm(".include \"asm/insn-common-asm.h\"\n");
 asm(".include \"asm/fpu-insn-asm.h\"\n");
 
 /*
diff --git a/arch/s390/include/asm/insn-common-asm-emit.h b/arch/s390/include/asm/insn-common-asm-emit.h
new file mode 100644
index 000000000000..26a31e8439bf
--- /dev/null
+++ b/arch/s390/include/asm/insn-common-asm-emit.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_S390_INSN_COMMON_ASM_EMIT_H
+#define __ASM_S390_INSN_COMMON_ASM_EMIT_H
+
+asm(".include \"asm/insn-common-asm.h\"\n");
+
+#endif /* __ASM_S390_INSN_COMMON_ASM_EMIT_H */