On 06/20/2017 10:40 AM, Balbir Singh wrote: > On Fri, 2017-06-16 at 20:52 -0700, Ram Pai wrote: >> Memory protection keys enable applications to protect its >> address space from inadvertent access or corruption from >> itself. > > I presume by itself you mean protection between threads?
Between threads due to race conditions or from the same thread because of programming error. > >> >> The overall idea: >> >> A process allocates a key and associates it with >> a address range within its address space. > > OK, so this is per VMA? Yeah but the same key can be given to multiple VMAs. Any change will effect every VMA who got tagged by it. > >> The process than can dynamically set read/write >> permissions on the key without involving the >> kernel. > > This bit is not clear, how can the key be set without > involving the kernel? I presume you mean the key is set With pkey_mprotect() system call, all the effected PTEs get tagged for once. Switching the permission happens just by writing into the register on the fly. > in the PTE's and the access protection values can be > set without involving the kernel? PTE setting happens once, access protection values can be changed on the fly through register.
