[LTP] [PATCH v5 2/2] pkey: add test for memory protection keys

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> Memory Protection Keys for Userspace (PKU aka PKEYs) is a Skylake-SP
> server feature that provides a mechanism for enforcing page-based
> protections, but without requiring modification of the page tables
> when an application changes protection domains. It works by dedicating
> 4 previously ignored bits in each page table entry to a "protection key",
> giving 16 possible keys.
> 
> Basic method for PKEYs test:
>   1. test allocates a pkey(e.g. PKEY_DISABLE_ACCESS) via pkey_alloc()
>   2. pkey_mprotect() apply this pkey to a piece of memory buffer
>   3. check if the access right of buffer has been changed and take effect
>   4. remove the access right(pkey) from this buffer via pkey_mprotect()
>   5. check if buffer area can be read or write after removing pkey
>   6. pkey_free() releases the pkey after using it
> 
> Looping around this basic test on diffenrent types of memory.
> 
> Signed-off-by: Li Wang <liwang@redhat.com>

for series:
Acked-by: Jan Stancek <jstancek@redhat.com>