From: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
[ Upstream commit 8ddccc8a7d06f7ea4d8579970c95609d1b1de77b ]
The separate vmalloc area size check against _REGION2_SIZE
is needed in case user provided insanely large value using
vmalloc= kernel command line parameter. That could lead to
overflow and selecting 3 page table levels instead of 4.
Use size_add() for the overflow check and get rid of the
extra vmalloc area check.
With the current values of CONFIG_MAX_PHYSMEM_BITS and
PAGES_PER_SECTION the sum of maximal possible size of
identity mapping and vmemmap area (derived from these
macros) plus modules area size MODULES_LEN can not
overflow. Thus, that sum is used as first addend while
vmalloc area size is second addend for size_add().
Suggested-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Acked-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/s390/boot/startup.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 64bd7ac3e35d1..f8d0550e5d2af 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -176,6 +176,7 @@ static unsigned long setup_kernel_memory_layout(void)
unsigned long asce_limit;
unsigned long rte_size;
unsigned long pages;
+ unsigned long vsize;
unsigned long vmax;
pages = ident_map_size / PAGE_SIZE;
@@ -183,11 +184,9 @@ static unsigned long setup_kernel_memory_layout(void)
vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page);
/* choose kernel address space layout: 4 or 3 levels. */
- vmemmap_start = round_up(ident_map_size, _REGION3_SIZE);
- if (IS_ENABLED(CONFIG_KASAN) ||
- vmalloc_size > _REGION2_SIZE ||
- vmemmap_start + vmemmap_size + vmalloc_size + MODULES_LEN >
- _REGION2_SIZE) {
+ vsize = round_up(ident_map_size, _REGION3_SIZE) + vmemmap_size + MODULES_LEN;
+ vsize = size_add(vsize, vmalloc_size);
+ if (IS_ENABLED(CONFIG_KASAN) || (vsize > _REGION2_SIZE)) {
asce_limit = _REGION1_SIZE;
rte_size = _REGION2_SIZE;
} else {
--
2.40.1
