e8a97e42dc
set_memory_ro() and set_memory_rw() currently only work on 4k mappings, which is good enough for module code aka the vmalloc area. However we stumbled already twice into the need to make this also work on larger mappings: - the ro after init patch set - the crash kernel resize code Therefore this patch implements automatic kernel page table splitting if e.g. set_memory_ro() would be called on parts of a 2G mapping. This works quite the same as the x86 code, but is much simpler. In order to make this work and to be architecturally compliant we now always use the csp, cspg or crdte instructions to replace valid page table entries. This means that set_memory_ro() and set_memory_rw() will be much more expensive than before. In order to avoid huge latencies the code contains a couple of cond_resched() calls. The current code only splits page tables, but does not merge them if it would be possible. The reason for this is that currently there is no real life scenarion where this would really happen. All current use cases that I know of only change access rights once during the life time. If that should change we can still implement kernel page table merging at a later time. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> |
||
|---|---|---|
| .. | ||
| asm | ||
| uapi/asm | ||