s390/boot: fix mem_detect extended area allocation

[ Upstream commit 22476f47b6 ]

Allocation of mem_detect extended area was not considered neither
in commit 9641b8cc73 ("s390/ipl: read IPL report at early boot")
nor in commit b2d24b97b2 ("s390/kernel: add support for kernel address
space layout randomization (KASLR)"). As a result mem_detect extended
theoretically may overlap with ipl report or randomized kernel image
position. But as mem_detect code will allocate extended area only
upon exceeding 255 online regions (which should alternate with offline
memory regions) it is not seen in practice.

To make sure mem_detect extended area does not overlap with ipl report
or randomized kernel position extend usage of "safe_addr". Make initrd
handling and mem_detect extended area allocation code move it further
right and make KASLR takes in into consideration as well.

Fixes: 9641b8cc73 ("s390/ipl: read IPL report at early boot")
Fixes: b2d24b97b2 ("s390/kernel: add support for kernel address space layout randomization (KASLR)")
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Vasily Gorbik 2023-01-23 12:49:47 +01:00 • committed by Greg Kroah-Hartman
commit 1a71a9eaf3
4 changed files with 31 additions and 52 deletions