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Re: thoughts about exception-handling requirements for kprobes
anil.s.keshavamurthy wrote:
> [...] Yes, by fixing up the exceptions(fixup_exception() call) you
> are avoiding falling back to do_page_fault(), but the
> copy_from_user() which generated the exception will fail and we can
> not 100% reliably support copy from user from pre/post handlers even
> for valid address. [...]
I think that's an acceptable trade-off. It may be possible to let a
systemtap user bias the system for success by arranging to page-in or
even "mlock" selected processes.
> Do we know how reliable is Dtrace in this respect?
IIRC the documentation says that user data that is paged out at the moment
of a probe will cause an error if accessed. If so, we're "tied".
- FChE