On Tue, Feb 19, 2019 at 8:18 AM Steven Rostedt rostedt@goodmis.org wrote:
So it would be good to not just say "user or kernel", but actually say what *kind* of kernel access it expects.
Note, kprobes are a different kind of beast. I've used kprobes to probe userspace information as well as kernel. Heck, I could see someone even using kprobes to probe IO memory to check if a device is doing what they expect it's doing.
Note that even if that is the case, you _need_ to special "user vs kernel" information.
Because the exact same address might exist in both.
Right now I think that only happens on sparc32, but vendors used to have that issue on x86-32 too (if they had the 4G:4G patches).
Basically, a kprobe is mostly used for debugging what's happening in a live kernel, to read any address.
My point is that "any address" is not sufficient to begin with. You need "kernel or user".
Having a flag for what _kind_ of kernel address is ok might then be required for other cases if they might not be ok with following page tables to IO space..
Linus