On Mon, 11 Jul 2022, James Clark wrote: > On 06/07/2022 17:01, Vince Weaver wrote: > > So in this case you are leaking ARM64-specific info into the generic > > perf_event_open() call? Is there any way the kernel could implement this > > without userspace having to deal with the issue? > > The alternative to this change is just to call it "PERF_SAMPLE_POINTER_AUTH_MASK" > and then it's not Arm specific, it's just that only Arm implements it for now. > This is definitely an option. > > But if no platform ever implements something similar then that bit is wasted. > The intention of adding "PERF_SAMPLE_ARCH_1" was to prevent wasting that bit. > But as you say, maybe making it arch specific isn't the right way either. I don't know what the current kernel policy is on this kind of thing, but in the past perf_event_open was meant to be a generic as possible. Having architecture-specific magic bits is best avoided. However I'm not the maintainer for this so really my opinion doesn't really matter. I'm just speaking up as a userspace coder who is trying to write cross-platform tools, and having to maintain obscure arch-specific code paths in every single utility ends up being a huge pain. And isn't the whole point of an operating system to abstract this away? > > can tell there haven't been any documentation patches included for the > > Makefile. > > We plan to update the docs for the syscall, but it's in another repo, and > we'll wait for this change to be finalised first. I'm not sure what you > mean about the Makefile? sorry, that was a mis-type. I meant "manpage" not Makefile. Vince Weaver vincent.weaver@xxxxxxxxx
