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SubjectRE: [PATCH] x86/entry/64: randomize kernel stack offset upon syscall
Date
> * Reshetova, Elena <elena.reshetova@intel.com> wrote:
>
> > CONFIG_PAGE_TABLE_ISOLATION=n:
> >
> > base: Simple syscall: 0.0510 microseconds
> > get_random_bytes(4096 bytes buffer): Simple syscall: 0.0597 microseconds
> >
> > So, pure speed wise get_random_bytes() with 1 page per-cpu buffer wins.
>
> It still adds +17% overhead to the system call path, which is sad.
> Why is it so expensive?

I guess I can experiment further with buffer size increase and/or
using HW acceleration (I mostly played around different rdrand paths now).

What would be acceptable overheard approximately (so that I know how
much I need to squeeze this thing)?

Best Regards,
Elena.

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