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Alexandre Ghiti <alexghiti@rivosinc.com> says: Those 2 patches fix the set_memory_XX() and set_direct_map_XX() APIs, which in turn fix STRICT_KERNEL_RWX and memfd_secret(). Those were broken since the permission changes were not applied to the linear mapping because the linear mapping is mapped using hugepages and walk_page_range_novma() does not split such mappings. To fix that, patch 1 disables PGD mappings in the linear mapping as it is hard to propagate changes at this level in *all* the page tables, this has the downside of disabling PMD mapping for sv32 and PUD (1GB) mapping for sv39 in the linear mapping (for specific kernels, we could add a Kconfig to enable ARCH_HAS_SET_DIRECT_MAP and STRICT_KERNEL_RWX if needed, I'm pretty sure we'll discuss that). patch 2 implements the split of the huge linear mappings so that walk_page_range_novma() can properly apply the permissions. The whole split is protected with mmap_sem in write mode, but I'm wondering if that's enough, any opinion on that is appreciated. * b4-shazam-merge: riscv: Fix set_memory_XX() and set_direct_map_XX() by splitting huge linear mappings riscv: Don't use PGD entries for the linear mapping Link: https://lore.kernel.org/r/20231108075930.7157-1-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Linux kernel
============
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There are various text files in the Documentation/ subdirectory,
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