On Thu, Sep 03, 2020 at 10:46:33AM +0100, Boyan Karatotev wrote: > On 02/09/2020 17:48, Dave Martin wrote: > > On Fri, Aug 28, 2020 at 02:16:02PM +0100, Boyan Karatotev wrote: > >> Pointer Authentication (PAuth) is a security feature introduced in ARMv8.3. > >> It introduces instructions to sign addresses and later check for potential > >> corruption using a second modifier value and one of a set of keys. The > >> signature, in the form of the Pointer Authentication Code (PAC), is stored > >> in some of the top unused bits of the virtual address (e.g. [54: 49] if > >> TBID0 is enabled and TnSZ is set to use a 48 bit VA space). A set of > >> controls are present to enable/disable groups of instructions (which use > >> certain keys) for compatibility with libraries that do not utilize the > >> feature. PAuth is used to verify the integrity of return addresses on the > >> stack with less memory than the stack canary. > >> > >> This patchset adds kselftests to verify the kernel's configuration of the > >> feature and its runtime behaviour. There are 7 tests which verify that: > >> * an authentication failure leads to a SIGSEGV > >> * the data/instruction instruction groups are enabled > >> * the generic instructions are enabled > >> * all 5 keys are unique for a single thread > >> * exec() changes all keys to new unique ones > >> * context switching preserves the 4 data/instruction keys > >> * context switching preserves the generic keys > >> > >> The tests have been verified to work on qemu without a working PAUTH > >> Implementation and on ARM's FVP with a full or partial PAuth > >> implementation. > >> > >> Note: This patchset is only verified for ARMv8.3 and there will be some > >> changes required for ARMv8.6. More details can be found here [1]. Once > >> ARMv8.6 PAuth is merged the first test in this series will required to be > >> updated. > > > > Nit: is it worth running checkpatch over this series? > > > > Although this is not kernel code, there are a number of formatting > > weirdnesses and surplus blank lines etc. that checkpatch would probably > > warn about. > > > I ran it through checkpatch and it came out clean except for some > MAINTAINERS warnings. I see that when I add --strict it does complain > about multiple blank lines which I can fix for the next version. Are > there any other flags I should be running checkpatch with? Hmmm, probably not. I had thought checkpatch was generally noisier about that kind of thing. Since the issues were all minor and nobody else objected, I would suggest not to worry about them. Cheers ---Dave
