From: Anshuman Khandual anshuman.khandual@arm.com
[ Upstream commit 1e5823c8e86de83a43d59a522b4de29066d3b306 ]
This asserts that HUGE_MAX_HSTATE is sufficient enough preventing potential hugetlb_max_hstate runtime overflow in hugetlb_add_hstate() thus triggering a BUG_ON() there after.
Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Cc: Ard Biesheuvel ardb@kernel.org Cc: Ryan Roberts ryan.roberts@arm.com Cc: Mark Rutland mark.rutland@arm.com Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual anshuman.khandual@arm.com Reviewed-by: Ryan Roberts ryan.roberts@arm.com Reviewed-by: Gavin Shan gshan@redhat.com Link: https://lore.kernel.org/r/20241202064407.53807-1-anshuman.khandual@arm.com Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/mm/hugetlbpage.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index 13fd592228b18..a5e1588780b2c 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -526,6 +526,18 @@ pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
static int __init hugetlbpage_init(void) { + /* + * HugeTLB pages are supported on maximum four page table + * levels (PUD, CONT PMD, PMD, CONT PTE) for a given base + * page size, corresponding to hugetlb_add_hstate() calls + * here. + * + * HUGE_MAX_HSTATE should at least match maximum supported + * HugeTLB page sizes on the platform. Any new addition to + * supported HugeTLB page sizes will also require changing + * HUGE_MAX_HSTATE as well. + */ + BUILD_BUG_ON(HUGE_MAX_HSTATE < 4); if (pud_sect_supported()) hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);