Messages in this thread | | | Date | Fri, 3 Nov 2023 11:02:36 +0100 | Subject | Re: [PATCH v2 0/2] riscv: Fix set_memory_XX() and set_direct_map_XX() | From | Alexandre Ghiti <> |
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On 27/10/2023 16:32, Alexandre Ghiti wrote: > 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. > > Changes in v2: > - Fix rv32 build > - Rebase on top of 6.6-rc6 > - Move the flush_tlb_all outside the mmap_lock > > Alexandre Ghiti (2): > riscv: Don't use PGD entries for the linear mapping > riscv: Fix set_memory_XX() and set_direct_map_XX() by splitting huge > linear mappings > > arch/riscv/mm/init.c | 12 +- > arch/riscv/mm/pageattr.c | 270 +++++++++++++++++++++++++++++++++------ > 2 files changed, 236 insertions(+), 46 deletions(-) >
Any feedback from anyone? That's a fix I'd like to see merged in 6.7, if no objection, I'll ask for Palmer to take it.
Thanks,
Alex
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