Diagnose 224 stores 4k bytes, which currently cannot be deduced from
the inline assembly constraints. This leads to KMSAN false positives.

Fix the constraints by using a 4k-sized struct instead of a raw
pointer. While at it, prettify them too.

Suggested-by: Heiko Carstens <h...@linux.ibm.com>
Reviewed-by: Alexander Potapenko <gli...@google.com>
Signed-off-by: Ilya Leoshkevich <i...@linux.ibm.com>
---
 arch/s390/kernel/diag.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/s390/kernel/diag.c b/arch/s390/kernel/diag.c
index 8dee9aa0ec95..8a7009618ba7 100644
--- a/arch/s390/kernel/diag.c
+++ b/arch/s390/kernel/diag.c
@@ -278,12 +278,14 @@ int diag224(void *ptr)
        int rc = -EOPNOTSUPP;
 
        diag_stat_inc(DIAG_STAT_X224);
-       asm volatile(
-               "       diag    %1,%2,0x224\n"
-               "0:     lhi     %0,0x0\n"
+       asm volatile("\n"
+               "       diag    %[type],%[addr],0x224\n"
+               "0:     lhi     %[rc],0\n"
                "1:\n"
                EX_TABLE(0b,1b)
-               : "+d" (rc) :"d" (0), "d" (addr) : "memory");
+               : [rc] "+d" (rc)
+               , "=m" (*(struct { char buf[PAGE_SIZE]; } *)ptr)
+               : [type] "d" (0), [addr] "d" (addr));
        return rc;
 }
 EXPORT_SYMBOL(diag224);
-- 
2.45.1


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