On Tue, Oct 29, 2024 at 04:03:31PM -1000, Linus Torvalds wrote:
> Hmm. So it strikes me that this still does the "access_ok()", but
> that's pointless for the actual pointer masking case. One of the whole
> points of the pointer masking is that we can just do this without
> actually checking the ad
On Mon, 28 Oct 2024 at 15:56, Josh Poimboeuf wrote:
>
> The barrier_nospec() in 64-bit copy_from_user() is slow. Instead use
> pointer masking to force the user pointer to all 1's if the access_ok()
> mispredicted true for an invalid address.
>
> The kernel test robot reports a 2.6% improvement i
On Mon, Oct 28, 2024 at 06:56:14PM -0700, Josh Poimboeuf wrote:
> The barrier_nospec() in 64-bit copy_from_user() is slow. Instead use
> pointer masking to force the user pointer to all 1's if the access_ok()
> mispredicted true for an invalid address.
>
> The kernel test robot reports a 2.6% imp
The barrier_nospec() in 64-bit copy_from_user() is slow. Instead use
pointer masking to force the user pointer to all 1's if the access_ok()
mispredicted true for an invalid address.
The kernel test robot reports a 2.6% improvement in the per_thread_ops
benchmark (see link below).
To avoid regre
