On Fri, Nov 10, 2017 at 07:10:31PM +0100, Christophe LEROY wrote: > Hi > > Le 06/11/2017 à 09:56, Ram Pai a écrit : > >Memory protection keys enable applications to protect its > >address space from inadvertent access from or corruption > >by itself. > > > >These patches along with the pte-bit freeing patch series > >enables the protection key feature on powerpc; 4k and 64k > >hashpage kernels. It also changes the generic and x86 > >code to expose memkey features through sysfs. Finally > >testcases and Documentation is updated. > > > >All patches can be found at -- > >https://github.com/rampai/memorykeys.git memkey.v9 > > As far as I can see you are focussing the implementation on 64 bits > powerpc. This could also be implemented on 32 bits powerpc, for > instance the 8xx has MMU Access Protection Registers which can be > used to define 16 domains and could I think be used for implementing > protection keys. I was assuming non-existence of any 32bit powerpc systems supporting memory keys. Sounds like it was a wrong assumption. However, I think, the framework as it stands today should work. All the functionality is captured in pkeys.c and pkeys.h which are generic ppc files. Its just a matter of providing the 32-bit implementation for whichever sub-arch that support it. Can you point me to problem areas? I will fix them. Thanks for you interest. Togather we should be able to make it happen. > Of course the challenge after that would be to find 4 spare PTE > bits, I'm sure we can find them on the 8xx, at least when using 16k > pages we have 2 bits already available, then by merging PAGE_SHARED > and PAGE_USER and by reducing PAGE_RO to only one bit we can get the > 4 spare bits. yes. This needs to happen parallely. RP > > Therefore I think it would be great if you could implement a > framework common to both PPC32 and PPC64.
