1 files changed, 18 insertions, 30 deletions

diff --git a/arch/s390/lib/uaccess_std.c b/arch/s390/lib/uaccess_std.c
index 6fbd06338270..4a75d475b06a 100644
--- a/arch/s390/lib/uaccess_std.c
+++ b/arch/s390/lib/uaccess_std.c
@@ -188,6 +188,8 @@ size_t strnlen_user_std(size_t size, const char __user *src)
         register unsigned long reg0 asm("0") = 0UL;
         unsigned long tmp1, tmp2;
 
+        if (unlikely(!size))
+                return 0;
         asm volatile(
                 "   la    %2,0(%1)\n"
                 "   la    %3,0(%0,%1)\n"
@@ -204,38 +206,24 @@ size_t strnlen_user_std(size_t size, const char __user *src)
         return size;
 }
 
-size_t strncpy_from_user_std(size_t size, const char __user *src, char *dst)
+size_t strncpy_from_user_std(size_t count, const char __user *src, char *dst)
 {
-        register unsigned long reg0 asm("0") = 0UL;
-        unsigned long tmp1, tmp2;
+        size_t done, len, offset, len_str;
 
-        asm volatile(
-                "   la    %3,0(%1)\n"
-                "   la    %4,0(%0,%1)\n"
-                "   sacf  256\n"
-                "0: srst  %4,%3\n"
-                "   jo    0b\n"
-                "   sacf  0\n"
-                "   la    %0,0(%4)\n"
-                "   jh    1f\n"         /* found \0 in string ? */
-                "  "AHI"  %4,1\n"       /* include \0 in copy */
-                "1:"SLR"  %0,%1\n"      /* %0 = return length (without \0) */
-                "  "SLR"  %4,%1\n"      /* %4 = copy length (including \0) */
-                "2: mvcp  0(%4,%2),0(%1),%5\n"
-                "   jz    9f\n"
-                "3:"AHI"  %4,-256\n"
-                "   la    %1,256(%1)\n"
-                "   la    %2,256(%2)\n"
-                "4: mvcp  0(%4,%2),0(%1),%5\n"
-                "   jnz   3b\n"
-                "   j     9f\n"
-                "7: sacf  0\n"
-                "8:"LHI"  %0,%6\n"
-                "9:\n"
-                EX_TABLE(0b,7b) EX_TABLE(2b,8b) EX_TABLE(4b,8b)
-                : "+a" (size), "+a" (src), "+d" (dst), "=a" (tmp1), "=a" (tmp2)
-                : "d" (reg0), "K" (-EFAULT) : "cc", "memory");
-        return size;
+        if (unlikely(!count))
+                return 0;
+        done = 0;
+        do {
+                offset = (size_t)src & ~PAGE_MASK;
+                len = min(count - done, PAGE_SIZE - offset);
+                if (copy_from_user_std(len, src, dst))
+                        return -EFAULT;
+                len_str = strnlen(dst, len);
+                done += len_str;
+                src += len_str;
+                dst += len_str;
+        } while ((len_str == len) && (done < count));
+        return done;
 }
 
 #define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg)      \