s390/maccess: add no DAT mode to kernel_write

[ Upstream commit d6df52e9996dcc2062c3d9c9123288468bb95b52 ]

To be able to patch kernel code before paging is initialized do plain
memcpy if DAT is off. This is required to enable early jump label
initialization.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c
index 22a0be655f27abaf4e6aced1f09559b9676e8f7d..1d17413b319a456669efafdcb72fc18b24b741dd 100644 (file)
--- a/arch/s390/mm/maccess.c
+++ b/arch/s390/mm/maccess.c
@@ -62,11 +62,15 @@ notrace void *s390_kernel_write(void *dst, const void *src, size_t size)
        long copied;
 
        spin_lock_irqsave(&s390_kernel_write_lock, flags);
-       while (size) {
-               copied = s390_kernel_write_odd(tmp, src, size);
-               tmp += copied;
-               src += copied;
-               size -= copied;
+       if (!(flags & PSW_MASK_DAT)) {
+               memcpy(dst, src, size);
+       } else {
+               while (size) {
+                       copied = s390_kernel_write_odd(tmp, src, size);
+                       tmp += copied;
+                       src += copied;
+                       size -= copied;
+               }
        }
        spin_unlock_irqrestore(&s390_kernel_write_lock, flags);