On 8/5/22 10:24, Dave Hansen wrote: > On 8/3/22 20:16, Kyle Huey wrote: >> When management of the PKRU register was moved away from XSTATE, emulation >> of PKRU's existence in XSTATE was added for APIs that read XSTATE, but not >> for APIs that write XSTATE. This can be seen by running gdb and executing >> `p $pkru`, `set $pkru = 42`, and `p $pkru`. On affected kernels (5.14+) the >> write to the PKRU register (which gdb performs through ptrace) is ignored. > Do you happen to have a reproducer for this sitting around? I'd love to > get an addition to the pkeys selftest/ in place to make sure we don't > break this again. PKRU is a very special snowflake. Let me put this another way: I'm much more likely to quickly merge fixes that come with a selftest that demonstrates the breakage and the fix. An in-kernel test ensures: 1. There is a problem now 2. The patch fixes the problem 3. The problem does not recur
