I deal with performant systems every day, on some level. Sometimes it’s just BIOS or kernel options, other times it’s queuing or threads and processes. Most of the time, I’m learning something new. This is a page for those learning experiences.
Authority Mask Register (AMR)
A CVE came across my desk having to do with AMR on PowerPC. This was new to me so I did a little digging. It’s not something I’ve ever heard of before.
A component of storage protection. The operation of the storage protection mechanism depends on the contents of one or more of the following:
- MSR bits HV, IR, DR, PR
- the key bits and N bit in the associated SLB entry
- the page protection bits, key bits, N bit, and Gattribute in the associated PTE
- the AMR, IAMR, AMOR, and UAMOR
The Virtual Page Class Key Protection mechanism provides the means to assign virtual pages to one of 32 classes, and to modify data access permissions for each class by modifying the AMR and to modify instruction access permissions for each class by modifying the Instruction AMR (IAMR).[1]
References
[1] https://wiki.raptorcs.com/w/images/c/cb/PowerISA_public.v3.0B.pdf