commit 3d5854d75e3187147613130561b58f0b06166172 upstream.
When /proc/kcore is read an attempt to read the first two pages results in
HW-specific page swap on s390 and another (so called prefix) pages are
accessed instead. That leads to a wrong read.
Allow architecture-specific translation of memory addresses using
kc_xlate_dev_mem_ptr() and kc_unxlate_dev_mem_ptr() callbacks similarily
to /dev/mem xlate_dev_mem_ptr() and unxlate_dev_mem_ptr() callbacks. That
way an architecture can deal with specific physical memory ranges.
Re-use the existing /dev/mem callback implementation on s390, which
handles the described prefix pages swapping correctly.
For other architectures the default callback is basically NOP. It is
expected the condition (vaddr == __va(__pa(vaddr))) always holds true for
KCORE_RAM memory type.
Link: https://lkml.kernel.org/r/20240930122119.1651546-1-agordeev@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ac527766ac