Messages in this thread Patch in this message | | | From | Anshuman Khandual <> | Subject | [PATCH V3] arm64/mm: Validate hotplug range before creating linear mapping | Date | Fri, 13 Nov 2020 13:00:14 +0530 |
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During memory hotplug process, the linear mapping should not be created for a given memory range if that would fall outside the maximum allowed linear range. Else it might cause memory corruption in the kernel virtual space.
Maximum linear mapping region is [PAGE_OFFSET..(PAGE_END -1)] accommodating both its ends but excluding PAGE_END. Max physical range that can be mapped inside this linear mapping range, must also be derived from its end points.
This ensures that arch_add_memory() validates memory hot add range for its potential linear mapping requirements, before creating it with __create_pgd_mapping().
Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Fixes: 4ab215061554 ("arm64: Add memory hotplug support") Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> --- This applies on 5.10-rc3
Changes in V3:
- Dropped comment paragraphs from code and commit message per Ard - Dropped parenthesis brackets in the comparison per Ard
Changes in V2: (https://lore.kernel.org/linux-arm-kernel/1605236574-14636-1-git-send-email-anshuman.khandual@arm.com/)
- Replaced (start + size) with (start + size - 1) in the comparison per Ard - Dropped parenthesis brackets in the comparison per Ard
Changes in V1: (https://lore.kernel.org/linux-arm-kernel/1600332402-30123-1-git-send-email-anshuman.khandual@arm.com/)
arch/arm64/mm/mmu.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 1c0f3e02f731..ca692a815731 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1444,11 +1444,28 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size) free_empty_tables(start, end, PAGE_OFFSET, PAGE_END); } +static bool inside_linear_region(u64 start, u64 size) +{ + /* + * 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); +} + int arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params) { int ret, flags = 0; + if (!inside_linear_region(start, size)) { + pr_err("[%llx %llx] is outside linear mapping region\n", start, start + size); + return -EINVAL; + } + if (rodata_full || debug_pagealloc_enabled()) flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; -- 2.20.1
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