Hello.
I'm using SystemTap, and I want to know how many of hooks I implement
using SystemTap can be replaced by IO Visor.
(1) My understanding is that, due to restriction of available instruction
set in eBPF, it is impossible to call arbitrary kernel functions.
There is no way to implement a hook like
# stap -F -g -e 'probe
kernel.function("check_memalloc_stalling_tasks").return { if ($return > 0)
panic("MemAlloc stall detected."); }'
(in https://lwn.net/Articles/723447/ ) using IO Visor, isn't it?
(2) SystemTap provides USDT helper modules for (to some degree) probing
the value of arguments passed to specific Java methods (with the aid
of ByteMan) and Python 2/3 functions. I found that there is an attempt
to probe longer data at bpf-docs/blob/master/ebpf_http_filter.pdf .
But as far as I browsed, IO Visor does not provide modules for dumping
the content of object oriented languages ( bcc/tools/lib/ucalls.py
traces method/function names etc. but not the value of arguments
passed to specific method/function).
Is there a plan for IO Visor to provide modules for dumping the
content of object oriented languages? (Or technically impossible?)
Regards.
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