[Bug bpf/26234] New: utrace_derived_probes (and others?) being silently ignored by bpf backend

[Bug bpf/26234] New: utrace_derived_probes (and others?) being silently ignored by bpf backend

[me at serhei dot io]

https://sourceware.org/bugzilla/show_bug.cgi?id=26234

            Bug ID: 26234
           Summary: utrace_derived_probes (and others?) being silently
                    ignored by bpf backend
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: bpf
          Assignee: systemtap at sourceware dot org
          Reporter: me at serhei dot io
  Target Milestone: ---

process.begin probes are triggered by the SystemTap's runtime's task_finder
component. I'm not sure yet if BPF provides any equivalent functionality at all
-- will investigate further. The examples I can find so far would run the probe
in the wrong context.

In that case, to start with, we really should print a warning instead of
silently ignoring the probe. {Internally, the process.begin probe is added to
the utrace_derived_probes array, which isn't processed by the BPF backend....}

{The same might be true for others.}

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[Bug bpf/26234] utrace_derived_probes (and others?) being silently ignored by bpf backend

[me at serhei dot io]

https://sourceware.org/bugzilla/show_bug.cgi?id=26234

--- Comment #1 from Serhei Makarov <me at serhei dot io> ---
commit 601778117 adds the initial warning

There is more to be done..

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[Bug bpf/26234] utrace_derived_probes (and others?) being silently ignored by bpf backend

[me at serhei dot io]

https://sourceware.org/bugzilla/show_bug.cgi?id=26234

--- Comment #2 from Serhei Makarov <me at serhei dot io> ---
40dbe72afa2 adds warnings for the other probe types
though in some cases they may still be overridden by earlier, more confusing
warnings

e.g. 
sudo stap --bpf -ve 'probe process("/bin/ls").insn { println("hello") exit() }'

Pass 1: parsed user script and 51 library scripts using
40640virt/23544res/9372shr/13872data kb, in 0usr/0sys/7real ms.
semantic error: while resolving probe point: identifier 'process' at
<input>:1:7
        source: probe process("/bin/ls").insn { println("hello", execname(),
pid()) }
                      ^

semantic error: while resolving probe point: identifier 'process' at :1:7
        source: probe process("/bin/ls").insn { println("hello", execname(),
pid()) }
                      ^

semantic error: process probes not available without kernel CONFIG_UTRACE

Pass 2: analyzed script: 0 probes, 0 functions, 0 embeds, 0 globals using
40640virt/23544res/9372shr/13872data kb, in 0usr/0sys/0real ms.
Pass 2: analysis failed.  [man error::pass2]

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