Messages in this thread | | | Subject | Re: [PATCH] x86/entry/64: randomize kernel stack offset upon syscall | From | Andy Lutomirski <> | Date | Sat, 27 Apr 2019 06:59:36 -0700 |
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> On Apr 26, 2019, at 11:02 AM, Theodore Ts'o <tytso@mit.edu> wrote: > >> On Fri, Apr 26, 2019 at 10:44:20AM -0700, Eric Biggers wrote: >> Would it be possibly to call ChaCha20 through the actual crypto API so that SIMD >> instructions (e.g. AVX-2) could be used? That would make it *much* faster. >> Also consider AES-CTR with AES-NI instructions. > > It's not obvious SIMD instructions will be faster in practice, since > it requires saving and restoring the vector/FPU registers. If you're > going to be doing a *lot* of vector processing (for example when doing > block-level RAID-5 / RAID-6 computations), it might be worth it. But > if you're only going to be turning the crank for 12 or 20 rounds, the > overhead of calling kernel_fpu_begin() and kernel_fpu_end() is > probably going to make this worth it. >
So generate a whole page or more of random bytes at a time and save them up for when they’re needed.
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