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s390/boot: cleanup number of page table levels setup
[ Upstream commit 8ddccc8a7d
]
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@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@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:
parent
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commit
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1 changed files with 4 additions and 5 deletions
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@ -176,6 +176,7 @@ static unsigned long setup_kernel_memory_layout(void)
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unsigned long asce_limit;
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unsigned long rte_size;
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unsigned long pages;
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unsigned long vsize;
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unsigned long vmax;
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pages = ident_map_size / PAGE_SIZE;
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@ -183,11 +184,9 @@ static unsigned long setup_kernel_memory_layout(void)
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vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page);
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/* choose kernel address space layout: 4 or 3 levels. */
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vmemmap_start = round_up(ident_map_size, _REGION3_SIZE);
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if (IS_ENABLED(CONFIG_KASAN) ||
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vmalloc_size > _REGION2_SIZE ||
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vmemmap_start + vmemmap_size + vmalloc_size + MODULES_LEN >
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_REGION2_SIZE) {
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vsize = round_up(ident_map_size, _REGION3_SIZE) + vmemmap_size + MODULES_LEN;
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vsize = size_add(vsize, vmalloc_size);
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if (IS_ENABLED(CONFIG_KASAN) || (vsize > _REGION2_SIZE)) {
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asce_limit = _REGION1_SIZE;
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rte_size = _REGION2_SIZE;
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} else {
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