Messages in this thread | | | Date | Wed, 21 Feb 2024 16:50:30 -0800 | From | Deepak Gupta <> | Subject | Re: [RFC PATCH v1 15/28] riscv/mm: Implement map_shadow_stack() syscall |
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On Fri, Feb 09, 2024 at 08:44:53PM +0000, Edgecombe, Rick P wrote: >On Wed, 2024-01-24 at 22:21 -0800, debug@rivosinc.com wrote: >> From: Deepak Gupta <debug@rivosinc.com> >> >> As discussed extensively in the changelog for the addition of this >> syscall on x86 ("x86/shstk: Introduce map_shadow_stack syscall") the >> existing mmap() and madvise() syscalls do not map entirely well onto >> the >> security requirements for guarded control stacks since they lead to >> windows where memory is allocated but not yet protected or stacks >> which >> are not properly and safely initialised. Instead a new syscall >> map_shadow_stack() has been defined which allocates and initialises a >> shadow stack page. >> >> This patch implements this syscall for riscv. riscv doesn't require >> token >> to be setup by kernel because user mode can do that by itself. >> However to >> provide compatiblity and portability with other architectues, user >> mode can >> specify token set flag. > >A lot of this code look very familiar. We'll have to think about at >what point we could pull some of it into the code kernel. > >I think if we had an arch write_user_shstk(), most of the code could be >shared here.
Yes it is. I'll think a little bit more on this on next set of patchsets when I send.
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