This is a note to let you know that I've just added the patch titled
arm64: mm: correct the inside linear map range during hotplug check
to the 5.10-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:
arm64-mm-correct-the-inside-linear-map-range-during-.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c21b6b6fb625942c4ff182d36d5ecb5dd8e8de15
Author: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Date: Mon Mar 29 10:28:47 2021 -0400
arm64: mm: correct the inside linear map range during hotplug check
[ Upstream commit ee7febce051945be28ad86d16a15886f878204de ]
Memory hotplug may fail on systems with CONFIG_RANDOMIZE_BASE because the
linear map range is not checked correctly.
The start physical address that linear map covers can be actually at the
end of the range because of randomization. Check that and if so reduce it
to 0.
This can be verified on QEMU with setting kaslr-seed to ~0ul:
memstart_offset_seed = 0xffff
START: __pa(_PAGE_OFFSET(vabits_actual)) = ffff9000c0000000
END: __pa(PAGE_END - 1) = 1000bfffffff
Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Fixes: 58284a901b42 ("arm64/mm: Validate hotplug range before creating linear mapping")
Tested-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Link: https://lore.kernel.org/r/20210216150351.129018-2-pasha.tatashin@xxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 6aabf1eced31..afdad7607850 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1447,14 +1447,30 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size)
static bool inside_linear_region(u64 start, u64 size)
{
+ u64 start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual));
+ u64 end_linear_pa = __pa(PAGE_END - 1);
+
+ if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+ /*
+ * Check for a wrap, it is possible because of randomized linear
+ * mapping the start physical address is actually bigger than
+ * the end physical address. In this case set start to zero
+ * because [0, end_linear_pa] range must still be able to cover
+ * all addressable physical addresses.
+ */
+ if (start_linear_pa > end_linear_pa)
+ start_linear_pa = 0;
+ }
+
+ WARN_ON(start_linear_pa > end_linear_pa);
+
/*
* Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)]
* accommodating both its ends but excluding PAGE_END. Max physical
* range which can be mapped inside this linear mapping range, must
* also be derived from its end points.
*/
- return start >= __pa(_PAGE_OFFSET(vabits_actual)) &&
- (start + size - 1) <= __pa(PAGE_END - 1);
+ return start >= start_linear_pa && (start + size - 1) <= end_linear_pa;
}
int arch_add_memory(int nid, u64 start, u64 size,
