On Tue, 2017-06-27 at 03:11 -0700, Ram Pai wrote: > Memory protection keys enable applications to protect its > address space from inadvertent access or corruption from > itself. > > The overall idea: > > A process allocates a key and associates it with > a address range within its address space. > The process than can dynamically set read/write > permissions on the key without involving the > kernel. Any code that violates the permissions > off the address space; as defined by its associated > key, will receive a segmentation fault. > > This patch series enables the feature on PPC64 HPTE > platform. > > ISA3.0 section 5.7.13 describes the detailed specifications. > > > Testing: > This patch series has passed all the protection key > tests available in the selftests directory. > The tests are updated to work on both x86 and powerpc. > > version v4: > (1) patches no more depend on the pte bits to program > the hpte -- comment by Balbir > (2) documentation updates > (3) fixed a bug in the selftest. > (4) unlike x86, powerpc lets signal handler change key > permission bits; the change will persist across > signal handler boundaries. Earlier we allowed > the signal handler to modify a field in the siginfo > structure which would than be used by the kernel > to program the key protection register (AMR) > -- resolves a issue raised by Ben. > "Calls to sys_swapcontext with a made-up context > will end up with a crap AMR if done by code who > didn't know about that register". > (5) these changes enable protection keys on 4k-page > kernel aswell.
I have not looked at the full series, but it seems cleaner than the original one and the side-effect is that we can support 4k as well. Nice! Balbir Singh.
