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s390/maccess: add no DAT mode to kernel_write

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[ 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>
This commit is contained in:
Vasily Gorbik 2020-06-24 17:39:14 +02:00 committed by Greg Kroah-Hartman
parent 627d15eecb
commit 1a70857590
1 changed files with 9 additions and 5 deletions
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14
arch/s390/mm/maccess.c
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@ -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);