From: Ard Biesheuvel <[email protected]> This v2 now covers intermediate level page tables as well as the PTE level page table for the fixmap. The latter is a special case, as it
a) is only accessed via the kernel image's mapping, and never via the linear map (except for ptdump etc) b) must be accessible via a read-write mapping, as all manipulation of read-only page table descriptors relies on the fixmap itself and so it is treated separately. The intermediate page tables may be shared with other mappings in the upper kernel/vmalloc region, so they must be updatable using the ordinary APIs. Build tested and boot tested on a Lenovo Yoga C630 using 16k pages. v1: https://lore.kernel.org/all/[email protected]/ Cc: Ryan Roberts <[email protected]> Cc: Anshuman Khandual <[email protected]> Cc: Kevin Brodsky <[email protected]> Cc: Liz Prucka <[email protected]> Cc: Seth Jenkins <[email protected]> Cc: Kees Cook <[email protected]> Cc: Jann Horn <[email protected]> Cc: [email protected] Ard Biesheuvel (4): arm64: mm: Map fixmap PTE tables r/o in the linear map arm64: mm: Use fault handler to permit swapper_pg_dir updates arm64: mm: Create r/o page table region that permits updates arm64: mm: Move fixmap intermediate page tables into .rodata arch/arm64/include/asm/fixmap.h | 4 ++ arch/arm64/include/asm/linkage.h | 1 + arch/arm64/include/asm/pgtable.h | 55 ++++++++------------ arch/arm64/kernel/vmlinux.lds.S | 6 +++ arch/arm64/mm/fixmap.c | 12 +++-- arch/arm64/mm/mmu.c | 48 +++++++++++++---- 6 files changed, 78 insertions(+), 48 deletions(-) -- 2.55.0.887.g758fc8c411-goog
