[PATCH] s390/percpu: Fix MVIY_PERCPU() with older binutils

[Karl Mehltretter]

Commit a737737cdb9c ("s390/percpu: Infrastructure for more efficient
this_cpu operations") introduced MVIY_PERCPU(), which stringifies
arguments that are already C string literals. This generates an
assembler macro invocation with whitespace-separated quoted arguments:

  GEN_MVIY "459712" "%r3"

GNU as versions prior to binutils 2.39 drop the separating whitespace
between quoted macro arguments during input scrubbing. They
consequently parse the invocation as a single argument and emit
repeated warnings:

  Warning: missing closing `"'

The .ifc in GEN_MVIY never matches and GNU as exits successfully
without emitting the mviy instruction. As a result, the interrupted
per-CPU sequence is not marked in lowcore and the exception return
path cannot repair the per-CPU address register after migration.

All MVIY_PERCPU() callers pass C string literals. Use them directly
and separate the assembler macro arguments with an explicit comma. The
resulting invocation is:

  GEN_MVIY 459712, %r3

This form is unambiguous for GNU as and LLVM's integrated assembler.
This behavior was fixed in GNU as from binutils 2.39, but Linux
supports binutils 2.30.

Fixes: a737737cdb9c ("s390/percpu: Infrastructure for more efficient this_cpu operations")
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Karl Mehltretter <kmehltretter@xxxxxxxxx>
---
 arch/s390/include/asm/percpu.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h
index 1d955dd0defa3..feb58acf87d69 100644
--- a/arch/s390/include/asm/percpu.h
+++ b/arch/s390/include/asm/percpu.h
@@ -107,8 +107,8 @@
 	"	.endif\n"							\
 	".endr\n"								\
 	".endm\n"								\
-	ALTERNATIVE("GEN_MVIY " __stringify(disp)    " " __stringify(reg) "\n",	\
-		    "GEN_MVIY " __stringify(dispalt) " " __stringify(reg) "\n",	\
+	ALTERNATIVE("GEN_MVIY " disp    ", " reg "\n",				\
+		    "GEN_MVIY " dispalt ", " reg "\n",				\
 		    ALT_FEATURE(MFEATURE_LOWCORE))				\
 	".purgem GEN_MVIY\n"
 
-- 
2.53.0