[S390] add __ucmpdi2() helper function

Provide __ucmpdi2() helper function on 31 bit so we don't run
again and again in compile errors like this one:

kernel/built-in.o: In function `T.689':
perf_counter.c:(.text+0x56c86): undefined reference to `__ucmpdi2'

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/arch/s390/lib/ucmpdi2.c b/arch/s390/lib/ucmpdi2.c
new file mode 100644
index 000000000000..3e05ff532582
--- /dev/null
+++ b/arch/s390/lib/ucmpdi2.c
@@ -0,0 +1,26 @@
+#include <linux/module.h>
+
+union ull_union {
+        unsigned long long ull;
+        struct {
+                unsigned int high;
+                unsigned int low;
+        } ui;
+};
+
+int __ucmpdi2(unsigned long long a, unsigned long long b)
+{
+        union ull_union au = {.ull = a};
+        union ull_union bu = {.ull = b};
+
+        if (au.ui.high < bu.ui.high)
+                return 0;
+        else if (au.ui.high > bu.ui.high)
+                return 2;
+        if (au.ui.low < bu.ui.low)
+                return 0;
+        else if (au.ui.low > bu.ui.low)
+                return 2;
+        return 1;
+}
+EXPORT_SYMBOL(__ucmpdi2);