commit d6df52e9996dcc2062c3d9c9123288468bb95b52 upstream.
The backport has been slightly adjusted to avoid a dependency
on the s390/jump_label rework. Specifically, commit a646ef398e72
("s390/jump_label: replace stop_machine with smp_call_function") depends
on HAVE_ARCH_JUMP_LABEL_RELATIVE, which has not been backported to
versions 4.19 and earlier.
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@xxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
---
arch/s390/mm/maccess.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c
index 7be06475809b..a40739ea3805 100644
--- a/arch/s390/mm/maccess.c
+++ b/arch/s390/mm/maccess.c
@@ -58,13 +58,19 @@ static notrace long s390_kernel_write_odd(void *dst, const void *src, size_t siz
*/
void notrace s390_kernel_write(void *dst, const void *src, size_t size)
{
+ unsigned long flags;
long copied;
- while (size) {
- copied = s390_kernel_write_odd(dst, src, size);
- dst += copied;
- src += copied;
- size -= copied;
+ flags = arch_local_save_flags();
+ if (!(flags & PSW_MASK_DAT)) {
+ memcpy(dst, src, size);
+ } else {
+ while (size) {
+ copied = s390_kernel_write_odd(dst, src, size);
+ dst += copied;
+ src += copied;
+ size -= copied;
+ }
}
}
--
2.38.1
