This is a note to let you know that I've just added the patch titled
s390/maccess: add no DAT mode to kernel_write
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-maccess-add-no-dat-mode-to-kernel_write.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d6df52e9996dcc2062c3d9c9123288468bb95b52 Mon Sep 17 00:00:00 2001
From: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Date: Wed, 24 Jun 2020 17:39:14 +0200
Subject: s390/maccess: add no DAT mode to kernel_write
From: Vasily Gorbik <gor@xxxxxxxxxxxxx>
commit d6df52e9996dcc2062c3d9c9123288468bb95b52 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/mm/maccess.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
--- a/arch/s390/mm/maccess.c
+++ b/arch/s390/mm/maccess.c
@@ -58,13 +58,19 @@ static notrace long s390_kernel_write_od
*/
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;
+ }
}
}
Patches currently in stable-queue which might be from gor@xxxxxxxxxxxxx are
queue-4.19/s390-setup-init-jump-labels-before-command-line-parsing.patch
queue-4.19/s390-maccess-add-no-dat-mode-to-kernel_write.patch
queue-4.19/s390-kprobes-fix-irq-mask-clobbering-on-kprobe-reenter-from-post_handler.patch
queue-4.19/s390-kprobes-fix-current_kprobe-never-cleared-after-kprobes-reenter.patch
