On 03/07/2016 11:46 AM, Khalid Aziz wrote: > On 03/07/2016 12:22 PM, David Miller wrote: >> Khalid, maybe you should share notes with the folks working on x86 >> protection keys. > > Good idea. Sparc ADI feature is indeed similar to x86 protection keys > sounds like. There are definitely some similarities. But protection keys doesn't have any additional tables in which to keep metadata. It keeps all of its data in the page tables. It also doesn't have an impact on the virtual address layout. But, it does have metadata to store in the VMA, has a special siginfo->si_code, and it uses mprotect() (although a new pkey_mprotect() variant that takes an extra argument). Protection Keys are described a bit more here: > http://git.kernel.org/cgit/linux/kernel/git/daveh/x86-pkeys.git/tree/Documentation/x86/protection-keys.txt?h=pkeys-v025&id=1b5b8a8836de8eb667027178b4820665dea5a038 MPX is another Intel feature separate from protection keys, but *it* has some tables that it keep its metadata memory and special special instructions to move metadata in and out of it. It also has a prctl() to enable/disable kernel assistance for the feature. Unlike ADI, the tables are exposed (and accessible) to user applications in normal application memory. MPX's documentation is here: > http://git.kernel.org/cgit/linux/kernel/git/daveh/x86-pkeys.git/tree/Documentation/x86/intel_mpx.txt Overall, I'm not seeing much overlap at all between the features, honestly. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
