NAPOT Fixes #671
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NAPOT Fixes #671
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February 29, 2024 18:23
This reverts commit ce17347. We cannot correctly deal with NAPOT mappings in vmalloc/vmap because if some part of a NAPOT mapping is unmapped, the remaining mapping is not updated accordingly. For example: ptr = vmalloc_huge(64 * 1024, GFP_KERNEL); vunmap_range((unsigned long)(ptr + PAGE_SIZE), (unsigned long)(ptr + 64 * 1024)); leads to the following kernel page table dump: 0xffff8f8000ef0000-0xffff8f8000ef1000 0x00000001033c0000 4K PTE N .. .. D A G . . W R V Meaning the first entry which was not unmapped still has the N bit set, which, if accessed first and cached in the TLB, could allow access to the unmapped range. That's because the logic to break the NAPOT mapping does not exist and likely won't. Indeed, to break a NAPOT mapping, we first have to clear the whole mapping, flush the TLB and then set the new mapping ("break- before-make" equivalent). That works fine in userspace since we can handle any pagefault occurring on the remaining mapping but we can't handle a kernel pagefault on such mapping. So fix this by reverting the commit that introduced the vmap/vmalloc support. Fixes: ce17347 ("riscv: mm: support Svnapot in huge vmap") Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
pte_leaf_size() must be reimplemented to add support for NAPOT mappings. Fixes: 82a1a1f ("riscv: mm: support Svnapot in hugetlb page") Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
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At least one diff in series https://patchwork.kernel.org/project/linux-riscv/list/?series=830425 irrelevant now. Closing PR. |
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Pull request for series with
subject: NAPOT Fixes
version: 1
url: https://patchwork.kernel.org/project/linux-riscv/list/?series=830425