Add a central location for exclusion checks. We check here if function is excluded from FBT instrumentation

[emaste]

sys/cddl/dev/fbt/fbt.c

129–130

A comment perhaps?

132–137

Should this be limited to arm/arm64, or apply to all archs?

[andrew]

sys/cddl/dev/fbt/fbt.c

133–134

How about something like the following?

When DTrace is built into the kernel we need to exclude the FBT functions from instrumentation.

[andrew]

sys/cddl/dev/fbt/fbt.c

132–137

This will apply to all archs.

[markj]

sys/cddl/dev/fbt/fbt.c

132–137

This isn't foolproof: what if one enables both fbt::systrace_probe:entry and a syscall probe?

I think we've discussed this problem before, but there isn't an obvious/straightforward solution. It seems to me that fixing this properly will involve something along the lines of: identify object files we want to avoid tracing, modify the build to dump their symbols and generate a table that's linked into fbt.ko or the kernel, and use the table to do lookups in fbt_excluded().

I don't object to this change, but it doesn't seem like the right approach to me. Perhaps it should at least be conditionalized on #ifndef _KLD_MODULE?

[emaste]

sys/cddl/dev/fbt/fbt.c

132–137

Perhaps it should at least be conditionalized on #ifndef _KLD_MODULE?

Seems like that would be a reasonable interim solution.