Messages in this thread | | | Date | Mon, 26 Apr 2021 12:11:15 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH v25 29/30] mm: Update arch_validate_flags() to include vma anonymous |
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On Mon, Apr 26, 2021 at 09:40:56AM +0300, Kirill A. Shutemov wrote: > On Thu, Apr 15, 2021 at 03:14:18PM -0700, Yu-cheng Yu wrote: > > When newer VM flags are being created, such as VM_MTE, it becomes necessary > > for mmap/mprotect to verify if certain flags are being applied to an > > anonymous VMA. > > > > To solve this, one approach is adding a VM flag to track that MAP_ANONYMOUS > > is specified [1], and then using the flag in arch_validate_flags(). > > > > Another approach is passing vma_is_anonymous() to arch_validate_flags(). > > To prepare the introduction of PROT_SHSTK, which creates a shadow stack > > mapping and can only be applied to an anonymous VMA, update arch_validate_ > > flags() to include anonymous VMA information. > > I would rather pass down whole vma. Who knows what else > arch_validate_flags() would need to know about the VMA tomorrow: > > arch_validate_flags(vma, newflags); > > should do the trick.
A reason why we added a separate VM_MTE_ALLOWED flag was that we wanted MTE on other RAM-based based mappings, not just anonymous pages. See 51b0bff2f703 ("mm: Allow arm64 mmap(PROT_MTE) on RAM-based files").
Anyway, the above change doesn't get in the way.
-- Catalin
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