[Bug bpf/23510] New: Tapset function println() not supported in the bpf runtime

[Bug bpf/23510] New: Tapset function println() not supported in the bpf runtime

[agentzh at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=23510

            Bug ID: 23510
           Summary: Tapset function println() not supported in the bpf
                    runtime
           Product: systemtap
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: bpf
          Assignee: systemtap at sourceware dot org
          Reporter: agentzh at gmail dot com
  Target Milestone: ---

The `println()` tapset function is not recognized in the bpf runtime mode:

```
$ stap --bpf -e 'probe begin { println("hello world") exit() }'
semantic error: unhandled statement or expression type: string 'hello world' at
<input>:1:23
        source: probe begin { println( ... hello world ... "hello world")
exit() }
                                           ^

Pass 4: compilation failed.  [man error::pass4]
```

Because it can be a popular choice for testing the bpf runtime with a hello
world one-liner, it would be great if we can have it implemented ;)

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[Bug bpf/23510] Tapset function println() not supported in the bpf runtime

[me at serhei dot io]

https://sourceware.org/bugzilla/show_bug.cgi?id=23510

Serhei Makarov <me at serhei dot io> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |me at serhei dot io
         Resolution|---                         |FIXED
           Assignee|systemtap at sourceware dot org    |me at serhei dot io

--- Comment #1 from Serhei Makarov <me at serhei dot io> ---
println() is now supported in upstream git with the latest string handling
code.

Commit 80b95e4 allowed string literals in other places than printf(), enabling
the already existing visit_print_format implementation to handle print and
println in addition to printf.

Commit 9b58c9b fixes a bug where the println() implementation would fail to
'tag' its format string properly for the transport layer, causing a segfault in
the bpf userspace interpreter when it tried to strip the nonexistent tag.

Related issues are PR23405 (string support), PR21888 (support other logging
functions).

I have personally confirmed the 'hello world' use case to work ;)

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