Re: [PATCH v2 0/7] perf trace pagefaults

From: Stanislav Fomichev
Date: Fri Jun 20 2014 - 12:19:18 EST


> Hey, haven't you seen the vfs_getname probe? Idea is to hook on where
> the relevant copy_from_user is done and insert that into the ring
> buffer, as we already do for mapping fd -> pathname.
I saw it but didn't actually try because it needs all the debugging
stuff enabled and in place.

> I.e. no need for actual tracepoints from day one, just wannabe
> tracepoints using whatever probe inserting gizmo the kprobes_tracer used
> by 'perf probe' now thinks its best to use.
But we then need to predefine many probes for decoding to work in the form of
func:offset, and then play catch-up with all the kernel changes.
Or I miss something important here?

> For now try:
>
> perf probe 'vfs_getname=getname_flags:65 pathname=result->name:string'
> trace
>
> And look at how it manages to decode fds.
I will try, but does 65 still work after c4ad8f98bef77c7356aa6a9ad9188a6acc6b849d? :-)
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