[Bug translator/6711] need script syntax for extending blacklist

["jistone at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

------- Additional Comments From jistone at redhat dot com  2010-01-21 20:22 -------
(In reply to comment #4)
> Created an attachment (id=4544)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4544&action=view)
> Updated patch

s/forbidded/forbidden/ throughout the patch.

> 
> Provide new keyword "fobid" to define those forbidden probe, also
> permit mistake in declaration
> 
> Example:
> $ cat /tmp/1.stp
> 
> global i
> 
> forbid kernel.function("sys_w*"), kernel.function("no_such")

I'm not sure that I like "forbid" as a keyword... maybe "noprobe" would be
better (along the lines of the original "~probe" suggestion).

Also, if I understand your patch, it will only work if the forbidden probes are
listed in the primary script (and possibly tapset files that are included
incidentally).  We need this to have a global effect, so any defined in a tapset
blacklist will do their job.

> probe kernel.function("sys_write") {
> println("wrong")
> exit()
> }

If "sys_write" is blocked, then this probe should be an error as it has no
resolved probepoints.  This needs to be an error in pass-2, otherwise, the '?'
and '!' probe resolution won't work correctly.  Listing mode should also not
report probes that would be blocked.

I suggest parsing the forbidden probes immediately into a session global list. 
Resolve those before anything else, so you have a blacklist to compare against
while resolving the real probes.


Something else to think about -- the existing blacklist is able to block probes
based on the function name or filename, regardless of where the probe is in that
function or file.  As it stands, this "forbid" definition is only blocking exact
address matches, which is not as useful IMO.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6711

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