Bug 2506

Functions with the "__kprobes" decorator should also not be allowed, whether in
vmlinux or in a module.

Sometime probe in function with __init prefix should be disabled in kprobe 
kernel part. And there should be different return value when failing in 
register_kprobe, sometimes systemtap can continue to register other probepoints 
by return value from register_kprobe even if it fails to register current 
kprobe.

Added patch to block __exit probes in tapsets.cxx r1.125

I don't know how to detect __kprobes sections at compile time, so I will open
another bug on this aspect.

Please confirm that ".exit." alone is sufficient, that "has_kernel" is not also
required.  Module-level .exit. functions should probably be probable.

(In reply to comment #4)
> Please confirm that ".exit." alone is sufficient, that "has_kernel" is not also
> required.  Module-level .exit. functions should probably be probable.

The phrase "should probably be probable" is quite confusing -- perhaps you mean
"probeable"?  ;)

Care should be taken with has_kernel, as that only indicates that the probepoint
is kernel.xxx.  A probe on module("kernel").xxx is an equivalent alias.

I tried a probe on a module __exit function, and while the probe was placed
successfully, it was quite worthless.  Kprobes increases the usage count of
probed modules, so they are effectively pinned in place and cannot be rmmod'ed.
 I suppose that CONFIG_MODULE_FORCE_UNLOAD could be used to get around this, but
this is dangerous and would probably break kprobes.  Thus, I don't see any point
to allowing probes on module __exit functions.