forked from Minki/linux
arm64: mm: detect bad __create_mapping uses
If a caller of __create_mapping provides a PA and VA which have different sub-page offsets, it is not clear which offset they expect to apply to the mapping, and is indicative of a bad caller. In some cases, the region we wish to map may validly have a sub-page offset in the physical and virtual addresses. For example, EFI runtime regions have 4K granularity, yet may be mapped by a 64K page kernel. So long as the physical and virtual offsets are the same, the region will be mapped at the expected VAs. Disallow calls with differing sub-page offsets, and WARN when they are encountered, so that we can detect and fix such cases. Cc: Laura Abbott <labbott@fedoraproject.org> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Steve Capper <steve.capper@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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@ -251,6 +251,13 @@ static void __create_mapping(struct mm_struct *mm, pgd_t *pgd,
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{
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unsigned long addr, length, end, next;
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/*
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* If the virtual and physical address don't have the same offset
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* within a page, we cannot map the region as the caller expects.
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*/
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if (WARN_ON((phys ^ virt) & ~PAGE_MASK))
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return;
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addr = virt & PAGE_MASK;
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length = PAGE_ALIGN(size + (virt & ~PAGE_MASK));
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